1. Access and Trocar Complications

2. Pneumoperitoneum-Related Problems

3. Thermal Energy in Minimally Invasive Surgery - Science and Safety

4. Conversion: When, how and why?

5. Inguinal Hernia Repair

6. Complications Following Laparoscopic Ventral Hernia Repair

7. Appendectomy

8. Colectomy

9. Antireflux surgery - Intraoperative

10. Management of New and Recurrent Symptoms Following Laparoscopic Fundoplication

11. GASTRIC BY PASS

12. Splenectomy

13. Strategies to Prevent and Treat Bile Duct Injuries During Laparoscopic Cholecystectomy

14. Anesthetic Complications and Their Prevention

15. Pharmacologic Therapies to Minimize Perioperative Problems

16. PREOPERATIVE SIMULATION STRATEGIES

17. Training and Determination of Outcomes and Competency

Joel Leroy, MD; Erik Dutson, MD; Margaret Henri, MD;
Jacques Marescaux, MD

EITS/IRCAD Hôpital Universitaire- 1, place de l'Hôpital, 67091 Strasbourg Cedex, France
Direct correspondence to Professor Leroy

 

Introduction

Laparoscopy has greatly evolved in the past 20 years. First developed by gynecologic surgeons, it has been revolutionising general surgery for the last 10 years.

Apart from its known advantages, laparoscopy bears specific morbidities.

20 to 40% of laparoscopic complications are caused by incidents that occur in the first steps of a laparoscopic procedure and especially during positioning of the first trocar (Hashizume, 1997). Although rare--5 per 10 000 to 3 per 1000-(Champault, 1996; Deziel, 1993) these injuries have serious consequences, with a mortality rate of up to 13% and are potentially preventable.

We will review the different access techniques, injuries, as well as treatment and prevention of injuries associated with minimally invasive peritoneal access.

 

Instrumentation

Types of trocars/access devices

 

Shielded pyramidal

Shielded blade

Conical

Radial expandable

Optical

Winged cone

Short-stroke knife

Veress needle

Hasson open/blunt trocar

 

No particular device has been shown to be safer. (Chandler, Bhoyrul). It should be remembered that even the Hasson-type, open-incision, blunt cannulas are associated with small bowel injury, which might be lethal, retroperitoneal vascular injury, death, as well as abdominal-wall vessel laceration, and other visceral injury. (JACS192(4) April 2001)

 

Anatomy

Thorough knowledge of the anatomical relations of the abdominal wall and cavity is essential in order to try to prevent visceral and vascular injuries.

Aortic bifurcation and iliac vessels:

The cephalocaudal relationship between the aortic bifurcation and the umbilicus has been studied by radiological means and during laparoscopy . The umbilicus is often located at or cephalad to the aortic bifurcation, and consistently located cephalad to where the left common iliac vein crosses the midline. The aortic bifurcation is located more caudad to the umbilicus in the Trendelenburg position than in the supine position. Distance of the aorta from the umbilicus ranges from 0.1 cm in thin patients to 2.7 cm in obese patients. (Nezhat , 1998; Hurd,1992)

Viscera

Trocar injuries to abdominal viscera occur if the viscera are unusually close to the point of trocar insertion. Distances between parietal peritoneum and underlying viscera can be increased to 6-7cm by lifting the abdominal wall at the umbilicus with towel clips applied on the fascia of the umbilicus incision, and the distance is not reduced when force is applied at trocar insertion.(Roy, 2001)

It should be kept in mind that reports show that 59% of patients with previous midline incisions and 28% of patients with previous suprapubic transverse incisions have anterior wall adhesions that might contain bowel.(Levrant ,1997)

In addition, a full bladder or stomach can be injured if not emptied prior to Veress needle or trocar insertion.

 

Injuries

Types of injuries

Injury of visceral organs (more common)

· Small bowel

· Colon

· Urinary bladder

· Stomach

· Liver

· Spleen

The small bowel has been shown to be the single most commonly injured organ, followed by large bowel and liver (Shafer, 2001). Injuries to the small bowel and colon are significantly more likely to go unrecognised for more than 24 hours, and more than half of all bowel injuries do in fact go unrecognised (Chandler, 2001). This greatly increases mortality, up to 26% in some series (Bhoyrul, 2001; Chandler, 2001).

 

Vascular injuries (less common)

· Epigastric vessels

· Omentum

· Aorta

· Iliac vessels

· IMA

· IVC

· Portal vein

· Hepatic vessels

· Mesenteric vessels

The epigastric vessels are the vessels most commonly injured, followed by injuries to the greater omentum and mesenteric vessels, and least common are injuries to the retroperitoneal vessels (Shafer, 2001). Injury to a major visceral vessel (i.e., portal vein, hepatic artery, gastroduodenal artery) can carry a mortality rate of up to 44% (Chandler, 2001).

 

Treatment of injuries

The key to minimizing morbidity in cases of access injury is immediate recognition. Upon recognition, a standard repair of visceral injuries should be carried out, and in many cases this can be accomplished laparoscopically. If visualization of the injury is inadequate, or the surgeon is relatively inexperienced or uncomfortable with the situation, rapid conversion should be undertaken.

In cases of vascular injury, conversion is the rule. It is imperative, however, to make an initial, rapid attempt to get control of the bleeding PRIOR to conversion. Conversion takes time, and a large injury to the aorta or vena cava can become lethal in the time it takes to convert to open. Initial control of the bleeding can almost always be accomplished with placement of a sponge through the trocar and applying direct pressure to the injury. This allows time, often, to get a better assessment of the situation and to identify the rare situation when a laparoscopic repair can be undertaken. In these rare cases, the same basic principles of vascular surgery apply: obtain proximal and distal control, and affect a repair or perform a ligation, depending on the involved vessel. The last point that must not be forgotten if a laparoscopic vascular repair is undertaken is the unique potential for CO2 embolus because of pneumoperitoneum. This risk alone should discourage almost all attempts to manage a serious venous injury laparoscopically.

 

Techniques of entry access

Direct vision technique

These techniques are increasingly used and are recommended by general surgeons.

 

1. Hasson (1971): It is the safest technique to insert the first trocar (Bonjer, 1997). It may also be
used for placement of other trocars. Relative indications for use include the following:

· Multiple scars

· Thin patients

· Muscular patients

· Children

Technique involves direct open visualization of the tissues at every level until the peritoneum is
opened, followed by placement of anchoring sutures in the fascia to secure a conical collar. The trocar is then placed through the collar to establish pneumoperitoneum and access. Disadvantages include persistent uncontrolled CO2 leakage in many cases, increased incision size, and increased time for placement.

 

2. Optical trocars

Allow for decreased skin incision, visualization of tissues as they are penetrated, and have been shown in large series to be a safe and fast way to access the peritoneal space. Additionally, injuries can be recognized immediately, thereby reducing their potential morbidity. Disadvantages include inability to remove the trocar during its initial advancement, which may change the original tract and confuse orientation, plus cause difficulty in recognition of the peritoneal layer (String, 2001). Lastly, FDA reports confirm deaths from major vascular injuries associated with the use of optical trocars (Bhoyrul, 2001).

 

3. Pseudo-open technique (Personal technique)

· Verify patient positioning on the table

· Know the anatomy of the abdominal wall and cavity in order to evaluate positioning of vessels in relation to BMI (the aorta can be less than 25mm away from the skin in very thin patients.

· Complete muscle relaxation

· Peri-umbilical incision (most often supra-umbilical) with a number 11 blade without pushing the tip of the blade further than the skin

· Dissection of subcutaneous fat down to the fascia

· The fascia is incised and grasped, and the peritoneum is grasped with a Kelly clamp and opened under direct vision

· Traction is maintained on the fascia while the blunt-tipped trocar is introduced under direct vision

· The minimal incision on the fascia opens up with the perpendicular force exerted on it by the trocar. The use of this technique makes a purse-string suture unnecessary as it prevents air leaks
· The scope is then introduced in the trocar

 

Blind technique (Veress needle)

A small incision is made on the skin in order to allow the Veress needle to be inserted. The left sub-costal margin localisation was advocated by Palmer in the 1940s because visceral-parietal adhesions are rarely encountered in that area. In addition, some feel that because the abdominal wall in that area is supported by the rigid thoracic wall, insertion of the needle is more controlled than in the peri-umbilical area. Others prefer the umbilicus to access the peritoneal cavity because in this location the abdominal wall is thin, even in obese patients. The Veress needle has a spring-loaded obturator, and a sharp-edged oval aperture that converts into a blunt tip when it passes the parietal peritoneum. Two distinct pops are felt as the surgeon, using constant pressure, passes through the fascia and the peritoneum. The abdomen is then inflated with at least 3.5 L of CO2.

In order to introduce the needle safely and avoid inflating in the wrong anatomical plans, we believe that the following principles should be followed:

· Use of a disposable needle, which makes a worn out spring-load mechanism and dull-edge unlikely

· Incision of the skin prior insertion of the needle to diminish resistance, avoid use of excessive force, and prevent potential injuries

· Use of an insufflation system that incorporates an electronically regulated feedback mechanism in order to avoid insufflation in a high-pressure area. These systems also prevents over-insufflation, regulate flow rate, and even initiate desufflation if pressure becomes too high.

Technical errors for insertion of trocar after creation of a pneumoperitoneum are the most common causes of injury: inadequate stabilisation of the abdominal wall, excessive resistance to trocar insertion, and excessive, misdirected or uncontrolled force applied by the surgeon along the axis of the trocar (Bhoyrul et al, Chandler et al). It is therefore important to:

· Stabilise the abdominal wall by full insufflation, complete muscle relaxation, and use of counter-traction of the fascia or manual lateral or epigastric compression to increase the distance between the anterior abdominal wall and the retro-peritoneal vessels

· Ensure that the skin incision is of sufficient length and that the reusable trocar tip is sharp so that no resistance, which would force the surgeon to use excessive and uncontrolled force, is offered.

· Use balanced agonist force (muscles being used half way between full contraction and extension, strong muscles used at sub-maximal level, trocar inserted slowly), associated with an antagonist force to stop further progress when resistance from the abdominal wall abruptly decreases after penetration of the trocar in the pneumoperitoneum. The table should be placed at comfortable height, and the surgeon should avoid reaching across the patient to place a lateral port.

· Many surgeons recommend introducing the umbilical trocar at an axis directed towards the pelvis to avoid the aorta/vena cava (i.e., below the bifurcations), however, anatomical relationships are variable with patient body habitus and level of insufflation.

 

Comments

The open technique presents 2 major advantages over the classical Veress needle technique:

· Injuries to major abdominal vessels are less frequent (Catarci, 2001)

· Visceral injuries, even if equal in incidence, can be recognised and repaired immediately (String, 2001).

Despite these advantages, two aortic injuries have been reported with the use of the Hasson trocar (Hanney, 1999). Furthermore, there is no evidence to support an open technique in the absence of a hostile abdomen (body habitus or multiple scars), as systematic use of the open technique in the peri-umbilical area has not been shown to cancel the risk of bowel injury in the absence of risk factors (Cravello, Bhoyrul). Non-recognized visceral injuries still occur with the open technique, as reported by Chandler et al.

 

Conclusion

Whether during laparotomy or laparoscopy, the opening of the peritoneal cavity is a dangerous stage of the procedure. Additionally, with the expected evolution of microinstrumentation in laparoscopy, greater diligence will be required when it comes to initial access.

Minimization of complications can occur if the following points are kept in mind with each procedure:

· Complete a check list prior to starting (much like a pilot)

· Presence of all members of the team (mentally as well as physically) is mandatory

· Human error is often the cause of problems

· Management of incidents must anticipated BEFORE they occur (i.e., will there be a vascular surgeon available if needed?)

· Technology diminishes but does not eliminate risks

· Experience diminishes but does not eliminate risks

Finally, penetrating the abdominal cavity necessitates:

· Analysis of the abdominal wall

· Knowledge of the abdominal content

· Extreme awareness

· Taking one's time

 

References

 

1. Hashizume M, Sugimachi K. Needle and trocar injury during laparoscopic surgery in Japan. Surg Endosc 1997 Dec;11(12):1198-201

2. Bonjer HJ, Hazebroek EJ, Kazemier G, Giuffrida MC, Meijer WS, Lange JF. Open versus closed establishment of pneumoperitoneum in laparoscopic surgery. Br J Surg. 1997 May;84(5):599-602. Review.

3. String A, Berber E, Foroutani A, Macho JR, Pearl JM, Siperstein AE. Use of the optical access trocar for safe and rapid entry in various laparoscopic procedures. Surg Endosc. 2001 Jun;15(6):570-3.

4. Catarci M, Carlini M, Gentileschi P, Santoro E. Major and minor injuries during the creation of pneumoperitoneum. A multicenter study on 12,919 cases. Surg Endosc. 2001 Jun;15(6):566-9.

5. Chandler JG, Corson SL, Way LW. Three spectra of laparoscopic entry access injuries. J Am Coll Surg. 2001 Apr;192(4):478-90; discussion 490-1.

6. Hasson HM. A modified instrument and method for laparoscopy. Am J Obstet Gynecol. 1971 Jul 15;110(6):886-7

7. Bhoyrul S, Vierra MA, Nezhat CR, Krummel TM, Way LW. Trocar injuries in laparoscopic surgery. J Am Coll Surg 2001 Jun;192(6):677-83

8. Cravello L, Agostini A, Roger V, Blanc B. L'open c?lioscopie ou c?lioscopie ouverte. Endomag, no. 35. June, 2001.

9. Hanney RM, Carmalt HL, Merret N, Tait N. Use of the Hasson cannula producing major vascular injury at laparoscopy. Surg Endosc. 1999 Dec;13(12):1238-40.

10. Champault G, Cazacu F, Taffinder N.

Serious trocar accidents in laparoscopic surgery: a French survey of 103,852 operations.

Surg Laparosc Endosc 1996 Oct;6(5):367-70

11. Schafer M, Lauper M, Krahenbuhl L. Trocar and Veress needle injuries during laparoscopy. Surg Endosc 2001 Mar;15(3):275-80

12. Hurd WW, Bude RO, DeLancey JO, Pearl ML The relationship of the umbilicus to the aortic bifurcation: implications for laparoscopic technique. Obstet Gynecol 1992 Jul;80(1):159

13. Nezhat F, Brill AI, Nezhat CH, Nezhat A, Seidman DS, Nezhat C Laparoscopic appraisal of the anatomic relationship of the umbilicus to the aortic bifurcation. J Am assoc Gynecol Laparosc 1998 May;5(2):135-40

14. Roy GM, Bazzurini L, Solima E, Luciano AA Safe technique for laparoscopic entry into the abdominal cavity

J Am Assoc Gynecol Laparosc 2001 Nov; 8(4):519-28

15. Levrant SG, Bicher EJ, Barnes RB Anterior wall adhesions after laparotomy or laparoscopy

J Am Assoc Gynecol Laparosc 1997 May; 4(3):353-6

 

2. Pneumoperitoneum-Related Problems

Mark A Talamini, MD

Associate Professor of Surgery, Johns Hopkins University School of Medicine
600 N. Wolfe St; Blalock 665, Baltimore, MD 21287-4665
Email: talamini@jhmi.edu Phone: 410-955-0377

 

 

The common features to virtually all minimally invasive general surgery procedures is the CO2 pneumoperitoneum. Blowing up body cavities with CO2 gas is a curious occurrence (at least from a historical perspective) now being applied to millions of patients. What does this do to our patients? Is it a good thing, or a bad thing? What role does this gas play in the clear advantages of laparoscopic surgery?

 

Cardiac

The primary effect of the pneumoperitoneum upon the heart relates to mechanical pressure upon the vena cava, which reduces filling pressures within the heart, potentially reducing blood pressure. This effect can be modified by extremes of position, which are common in laparoscopic surgery. CO2 also has a direct myocardial depressant effect.

 

These effects become more important when the mediastinum as well as the peritoneum are insufflated. We have demonstrated in both a pig model and in humans a substantial decrease (about 30%) in cardiac output during laparoscopic Nissen fundoplication. This appears to be due to additional mechanical effects of pressure around baro-receptors in the heart, but may also be due to effects upon the rennin-angiotensin axis. Most patients are able to easily tolerate this sort of a hit on their cardiac output. However, those with class III or IV heart failure, or significant coronary artery disease should probably receive additional attention. They should undergo a careful pre-operative workup, and may be served by supplemental monitoring during surgery (arterial catheter, etc.).

 

Pulmonary

Pulmonary effects fall into two broad categories: mechanical effects, and metabolic effects. The pneumoperitoneum causes direct pressure up onto the diaphragms, transmitting pressure into the thoracic cavity. During surgery, this is observed as increased peak expiratory airway pressure. The effect can be augmented by trendelenburg position. In some cases, inspiratory pressure has to be increased to compensate for this problem. These mechanical effects are real: studies have shown that the trachea moves up (towards the head) during a pneumoperitnoem. The metabolic effects consist simply of increased amounts of CO2 gas that needs to be disposed of via ventilation during the operation. Again, in almost every instance, this is easily managed by increasing the ventilator rate and monitering the end-tidal CO2. But in those with limiting pulmonary disease, prolonged intubation and ventilation may be necessary to clear CO2.

 

Metabolic

The metabolic effects of the CO2 pnemoperitoneum are far beyond that which one would expect by observing patients who do so much better after a laparoscopic operation as opposed to an open operation. By most visible parameters, a CO2 pneumo laparoscopic patient suffers a far smaller insult than an open patient. And yet, the evolving body of research shows that there are big differences in metabolic response to the CO2 pneumoperitoneum. It may even turn out that a CO2 pneumoperitoneum enhances the immune response. It may also modulate (down regulate) the inflammatory cascade that can be so dangerous in MODS (multiple organ dysfunction syndrome). We have demonstrated that rats undergoing CO2 pneumo procedures have a reduced induction of at least two acute phase proteins in the liver (alpha-2 macroglobulin and beta-fibrinogen.

 

Blood Flow

The combined effects of the CO2 pneumo upon the heart, the peripheral vasculature, and upon fluid balance result in changes in blood flow to various body tissues. There are a variety of means of measuring blood flow, such as dopplar flow probes. In a series of pig experiments, we directly measured blood flow with the use of radioactive microsphere injections. In general, blood flow to the abdominal viscera, including the gut, liver, and kidneys, are all decreased during laparoscopy. The most reasonable clinical response to this information is to ensure that patients undergoing laparoscopic operations are adequately hydrated.

 

Miscellaneous

There are a number of practical CO2 related problems of which the clinician needs to be mindful. When the dissection involves large areas of tissue, with open capillaries and venules, the amount of absorbed CO2 rises substantially. The degree of hypercarbia in this situation can sneak up upon the anethesiologist very quickly. In addition, when large blood vessels are open during surgery, CO2 embolus is possible, and can be very dangerous.

 

Summary

In general, pneumoperitoneum with CO2 is safe, and is associated with the markedly improved outcomes we have come to appreciate with laparoscopic surgery. However, there are a host of effects of the CO2 pneumoperitoneum, some positive, but many of them problems, which are important.

 

References:

1. Fahy BG. Cardiopulmonary effects of laparoscopic surgery, revisited. Chest 1997; 111(6):1787-1788.

2. Glaser F, Sannwald GA, Buhr HJ, Kuntz C, Mayer H, Klee F et al. General stress response to conventional and laparoscopic cholecystectomy. Ann Surg 1995; 221(4):372-380.

3. Joris J, Cigarini I, Legrand M, Jacquet N, De Groote D, Franchimont P et al. Metabolic and respiratory changes after cholecystectomy performed via laparotomy or laparoscopy. Br J Anaesth 1992; 69(4):341-345.

4. Volz J, Koster S, Spacek Z, Paweletz N. Characteristic alterations of the peritoneum after carbon dioxide pneumoperitoneum. Surg Endosc 1999; 13(6):611-614.

5. Gitzelmann CA, Mendoza-Sagaon M, Talamini MA, Ahmad SA, Pegoli W, Jr., Paidas CN. Cell-mediated immune response is better preserved by laparoscopy than laparotomy. Surgery 2000; 127(1):65-71.

6. Hardacre JM, Talamini MA. Pulmonary and hemodynamic changes during laparoscopy--are they important? Surgery 2000; 127(3):241-244.

7. Mendoza-Sagaon M, Kutka M, Talamini MA, Hanly E, Gitzelmann CA, Herreman-Suquet K et al. Comparison of the stress response after laparoscopic and open cholecystectomy. Surgical Endoscopy .

Ref Type: Generic

8. Mendoza-Sagaon M, Gitzelmann CA, Herreman-Suquet K, Pegoli W, Jr., Talamini MA, Paidas CN. Immune response: effects of operative stress in a pediatric model. J Pediatr Surg 1998; 33(2):388-393.

9. Talamini MA, Mendoza-Sagaon M, Gitzelmann CA, Ahmad S, Moesinger R, Kutka M et al. Increased mediastinal pressure and decreased cardiac output during laparoscopic Nissen fundoplication. Surgery 1997; 122(2):345-352.

 

3. Thermal Energy in Minimally Invasive Surgery - Science and Safety

Joseph F. Amaral, MD

Professor Surgery, Brown University School of Medicine
President and CEO, Rhode Island Hospital, Providence, RI

 

I. ELECTROSURGERY

A. Introduction

Electrosurgery is the use of radio frequency, alternating current to cut and coagulate tissues. It has proven a major advance in surgery by minimizing blood loss, reducing operative time and providing a dry surgical field without the need to tie all blood vessels. Initially introduced for endoscopy by Edwin Beer in 1910 to remove bladder tumors (1), it was popularized by Harvey Cushing and William T. Bovie in 1928 (2).

Cutting and coagulating tissues with electrosurgery is possible because the tissues of the body act as electrical conductors due to the electrolyte composition of cells. In essence, tissues act as the pathway through which electrical current travels. Electric current may be direct, in which the electrons flow in one direction, like a battery, or alternating, in which the direction of current flow is constantly reversing, like household current (Figure 1.). The number of times the current is reversed per second is the frequency of that current measured in Hertz.

Electrosurgery uses an alternating current with a frequency of 500,000 to 2 million Hertz (Figure 2.). This rapid reversal of current means ion positions across cellular membranes do not change. As a result, neuromuscular membranes do not depolarize and there is no danger of cardiac defibrillation at these high frequencies (3). Neuromuscular stimulation occurs at alternating current frequencies of less than 100,000 hertz (Figure 2.). Household current, with its low frequency of 60 Hertz, can produce ventricular fibrillation but electrosurgery, with its high frequencies, can not. Direct currents, which do not reverse the direction of electron flow produce cellular depolarization and can lead to ventricular fibrillation. Fortunately, direct currents are usually of sufficiently low voltage that they do not present a risk.

The terms electrocautery and electrosurgery are often used interchangeably in modern surgical practice. However, these terms define two distinctly different modalities (Table 1). Electrocautery is the use of electricity to heat a metallic object. This heated object is then used to coagulate or burn a site on another object by dissipating the heat it has stored. Common examples of electrocautery are wood burning pencils used to write on wood or branding irons used to mark cattle. It is important to realize there is no current flow through the object being marked or cauterized with electrocautery. The flow of current is limited to the element that is being heated whether it be a pencil, a branding iron, or a surgical instrument.

Electrosurgery on the other hand uses the electrical current itself to heat the tissues. As a result, the electrical current must pass through the tissues to produce the effect. The pencil, in this case, is an electrode that passes the current to the tissues. The current then flows through the tissues to produce heat. Heat results from the excitation of the cellular ions. The excited ions in the cell collide with each other and release energy in the form of heat.

 

B. Physics of Electrosurgery

The basic principle of electricity is that current flow follows the path of least resistance. The resistance to current flow in living tissues is inversely proportion to the water content. The more water present the greater current flow through that tissue because of the lower resistance. Therefore, current flow is greatest in tissues of high water content, such as blood, and least in those of low water content, such as bone. In general, electrical current flows preferentially through blood, then nerve, then muscle, then adipose tissue, and finally bone.

The path the electrical current takes through the body is not always predictable nor is it always the obvious one. Heat is generated as the current passes through the tissue. This dries out or desiccates the tissue resulting in an increase in electrical resistance, (decreased water content). Consequently, nearby tissues that formerly had a higher resistance to those through which the current flowed may now have a relatively lower resistance. For example, electrical current is applied to a blood vessel and nerve lying next to each other. Since the electrical resistance is lower in the blood vessel than the nerve, current will preferentially flow through the blood vessel. As time passes, the blood vessel begins to desiccate and resistance increases. A time is reached at which the resistance of the blood vessel and nerve are the same. Current now flows through both structures. Continued current flow will desiccate these structures and increase their electrical resistance. Eventually a point will be reached at which current flow through these structures will no longer be possible. The current must now flow either through nearby tissues of lower electrical resistance, a so-called alternate pathway, or not at all. Thus, the flow of current through living tissues is never constant nor predictable.

1. Electric Current

There are three basic types of current. The direct or DC current is a unidirectional electron flow that is continuous between opposite poles (Figure 1). Also known as galvanic current, this type of current is used in medicine for acupuncture and endothermy but not for electrosurgery. Alternating current is a bi-directional flow of electrons in which the polarity changes rhythmically in a sinusoidal fashion(Figure 1). There is no net gain in electrons at either pole of the electric circuit. This is the current used in electrosurgery. The final form of electric current is the pulsed current in which a high amount of electrical energy is discharged in a short period of time. This current is used for electromyography and nerve stimulation.

Current flow is described by Ohm's law as: Voltage = current x resistance or V=IR

Current (I) is the flow of electrons through a medium and is measured in amperes. Voltage (V) is the force driving the movement of electrons and is measured in volts. The higher the voltage the further an electron can move. Resistance (R) is the impedance provided by the medium to the flow of electrons and is measured in ohms. Another way to consider this equation therefore is that the flow of a substance is proportional to the force pushing the substance through a medium divided by the resistance the medium provides to the movement of a substance in that medium. We use this same relationship when we consider fluid movement in cardiovascular hemodynamics wherein:

cardiac output = blood pressure/vascular resistance.

The flow of water through a garden hose is a good analogy to think about when considering electrical flow through the body. The amount of water flowing through the hose is the current and the water pressure in the hose driving the water from one end of the hose to the other is the voltage. If you put your finger at one end of the hose you increase the resistance to the flow of the water. The same amount of water will come out the end of the hose if you increase the pressure enough. However, it will squirt out farther than it did before you partially occluded the hose because the pressure or driving force has increased. However, if the pressure does not increase, less water will come out the end of the hose even though it may go further.

We can now add an alternate pathway by placing a "Y" connector at the end of the hose. This is similar to electric current flow in the body in that there are multiple pathways along which the current can travel. If the resistance to water flow increases on one side of the connector, more water will flow out the other side. This augmented flow out the low resistance side will increase as the resistance is increased on the high resistance side until all the water is flowing out the low resistance side. This point is reached when the resistance to water flow on the high resistance side overcomes the force driving the water through it, i.e. it is totally occluded. This analogy is equivalent to that of electrical current passing through a blood vessel and nearby nerve described earlier.

Electric power is the energy produced or used over a period of time, measured in watts. It is equivalent to current times voltage (I * V) = (V/R)*V = V2/R. The actual calculation of power results in joules/sec, where one joule per sec equals one watt. Typical household current is driven at 120 volts. If we apply this voltage to a 25-watt bulb we will draw 0.21 amperes of current through the bulb. If we apply this to a 100-watt bulb we will draw 0.84 amperes of current through it and if we apply it to a 1200-watt hairdryer we will draw 10 amperes of current. Which are we most likely to be electrocuted by? The risk is the same for all three, since the voltage of 120 and the frequency of 60 hertz are the same for all three devices. What is the resistance provided by these three devices? Since R= V2/W, the hairdryer has the lowest resistance and the 25 watt light bulb the highest.

It is important to realize that the effect of a 20-watt depends on the voltage it is provided. For example, a 20-watt bulb driven by 20 volts will draw 1 ampere of current, whereas the same bulb driven by 2000 volts will draw only 0.01 ampere of current. Clearly, the resistance of the device must increase for the current flow to decrease in the bulb. Since that can not happen, the current flow remains at its higher rate and the bulb burns out. However, the resistance of a pathway in the human body can change as the tissue heats and desiccates. Therefore, the application of 20 watts of power in one circumstance to the body is not necessarily the same as the same 20 watts applied in another. Therefore, electrosurgical generators must deliver current at voltages that are matched to the expected tissue resistance of the human body. Otherwise, current flow can be too low to produce the desired effect or too great resulting in injury.

Ultimately, the effect at the tissue is determined by the current that flows through it. This concept is referred to as the current density. Current density = Amperes/area = Amperes / cm2

This explains why the pinpoint tip of an electrosurgical pencil works more effectively than a spatula. The area of contact for the pinpoint tip is much less than that of the spatula which in turn means the current density is much greater. For example, 20 milliamps applied to 1 cm has a current density of 20 milliamps / cm2 whereas the same current applied to 1 mm has a current density of 2000 milliamps / cm2. It follows that in laparoscopy, the less area of contact of the electrode with the intended site of effect, the greater the effect. Thus, if one is coagulating a site in the liver bed with the tip of the electrode and the side of the electrode is in contact with the liver itself, there will be less thermal effect at the desired site than if the desired site was the sole site of contact.

The production of heat is the ultimate result of electrosurgery that produces cutting and coagulation of tissues. The amount of heat released is directly proportional to the resistance of the tissues. Water, which has a low electrical resistance, liberates little heat, whereas skin, with its high electrical resistance, produces large amounts of heat. Heat production is also inversely proportional to the cross sectional area of the tissue through which the current is flowing.

Temperature = (amps / cm2) 2 = (current density) 2

Thus, the amount of heat released is inversely proportional to the cube of the contact site. The amount of heat generated in the example above at the 1 mm contact point would be 10,000 times greater than that produced at the 1 cm site.

2. Electrical Circuits

A complete circuit is necessary for the flow of current. That is, electrons must leave an electrode and return to mother earth to complete the circuit. There are two basic types of electrical circuits: monopolar and bipolar. In a monopolar circuit, current flows between two electrodes held widely apart. These two electrodes are the active electrode which is small, thereby providing a high power and current density, and the return or indifferent electrode which is large, thereby providing a low current density (Figure 3.). It is important to remember that the indifferent electrode is just as capable of producing injury as the active electrode. The key element in avoiding injury at the indifferent electrode is to have a large surface area of contact. In this manner, the current is dispersed over a large area, thereby reducing the current density. Consequently, the indifferent electrode must be placed over an area that will allow uniform contact with the body. If contact is only partial, current density at the indifferent electrode will be greater and injury can result. The return or indifferent electrode is often referred to as the grounding pad. This however is incorrect. The indifferent electrode carries current back to the generator, not to ground.

The path of least resistance is always taken to the indifferent electrode in a monopolar circuit. As a result, consideration should be given to what the operative procedure will be when the indifferent electrode is applied to the patient. The indifferent electrode should always be as close to the operative site as possible to minimize the volume the current will need to travel. For example, the indifferent electrode is better applied to the right flank during gallbladder surgery than to a thigh. The reason is that the distance between the operative site and the indifferent electrode is diminished when applied in the right flank, thereby providing a closer and more direct pathway for the circuit to be completed. This should reduce the likelihood of injury at a site other than that intended because current flow through the body is less (Figure 4).

The distance between the active and the indifferent electrodes in a bipolar circuit is very small since both electrodes are adjacent to each other. The distance the current flows is therefore small and contained in the vicinity of the two electrodes (Figure 5.). As current passes through the tissue from one electrode to the other, the tissue is desiccated and the resistance increases. When this occurs, local alternate pathways may develop at the electrode that may injury nearby structures.

3. Actions of Electrosurgery

There are three definable effects of electrosurgery as current passes through the tissue: cutting; fulguration; and desiccation. Electrosurgical cutting is the process by which electrons cut a furrow in the tissue. The electrosurgical cutting most often performed in surgery is not true electrosurgical cutting but mechanical cutting. The surgeon heats the tissue with electrosurgery to a point where he or she can cut through the tissue with a relatively sharp object such as a spatula. True electrosurgical cutting is a non-contact activity in which the electrosurgical instrument must be a short distance from the tissues to be cut. If there is contact, desiccation will ensue rather than cutting.

Cutting requires the generation of sparks of brief duration between the electrode and the tissue (Figure 6). The heat from these sparks is transferred to the tissue producing cutting. As electrons in the form of sparks bombard cells, the energy transferred to them increases the temperature in a cell. As the temperature in the cell continues to rapidly increase, the pressure and volume of gases in the cell must also increase (PV=nrT). As a result, a temperature is reached at which the cell explodes. The best wave for cutting is a non-modulated pure sine wave because current is delivered to the tissue almost 100% of the time the electrosurgical delivery device is activated (Figure 7).

Fulguration also requires that there not be contact between the electrosurgical delivery device and the tissue. In contrast to cutting, fulguration requires a high enough voltage to produce sparks but a low power to produce coagulation rather than cutting. This is achieved by intermittent short bursts of high voltage (Figure 7). When the coagulation or fulguration current is activated, an active electrical wave is present only 10% of the time the electrosurgical delivery device is activated. That is, the so called duty cycle is only 10 %. In effect, the temperature of the cell increases when it is hit by sparks but then returns towards normal as there is a prolonged period without any electron bombardment. This results in the coagulation effect of fulguration rather than cutting. The fulguration current is delivered via the coagulation switch of the electrosurgical generator.

Desiccation is the process by which the tissue is heated and the water in the cell boils to steam, resulting in a drying out of the cell. Desiccation can be achieved with either the cutting or the coagulation current by contact of the electrosurgical device with the tissue because no sparks are generated (Figure 6.). Therefore, desiccation is a low power coagulation without sparking and it is the most common electrosurgical effect used by surgeons.

Two additional types of circuits are possible when electrical current is delivered in either a monopolar or bipolar circuit (Figure 7.). These are open and closed circuits. In a closed circuit, the resistance to current flow is less than the voltage and the current is able to pass through the medium. In an open circuit, the resistance to current flow is greater than the voltage and current can not pass. Open circuits typically result when the electrosurgical delivery device is not in contact with tissue or when there has been sufficient desiccation of the tissue in contact with the electrode to increase the electrical resistance of the tissue and, therefore, stop current flow.

Open circuits present a potential danger because the generator increases the voltage it delivers in an attempt to close the circuit. The high resistance provided by an open circuit is interpreted by the generated as a need to provide maximum voltage to drive electrons across this area of resistance. In addition, the waveform becomes erratic. For example the coagulation current has very high peak voltages in an open circuit. However, the peak voltage for the cutting current does not increase much when it is delivered to an open circuit. This makes the cutting current much safer than the coagulation current for general use; that is the cutting current has the most constant peak to peak voltage and, in general, lower peak voltage than that observed with the coagulation current in an open circuit.

We have discussed the presence of a cutting current and a coagulation or fulguration current. However, what if we want to hemostatically cut tissue. The cutting current will cut the tissue but will provide poor hemostasis. The coagulation current will provide excellent coagulation but minimal cutting. The blend current is an intermediate current between the cutting and fulguration currents but it is not a combination of the cutting and the coagulation current as one might expect. In actuality, it is a cutting current in which the duty cycle or time that the current is actually flowing when the electrosurgical delivery device is activated, is decreased from 100% of the time to 50% to 80% (Figure 8). It is important to note that setting the generator to the blend mode does nothing to alter the coagulation current that is provided. Only the cutting current is altered to one in which the duty cycle is reduced to provide more hemostasis.

Electrosurgical generators today are microprocessor controlled electrical generators that deliver power according to needs and provide the aforementioned waveforms (Figure 9.). This is done within certain maximums and minimums for each variable controlled. Electrosurgical generators are essentially of two types: ground and isolated. Early electrosurgical generators are of the grounded type. Current is driven from these generators irrespective of whether it is returning back to itself. For example, even though an indifferent electrode is placed on the patient, any conductor that is in contact with the patient and with mother earth serves as the return. Therefore, if the patient is in contact with a metal arm that in turn is in contact with the floor, current will flow. If the site of contact is small, a burn may result at that alternate site of exit. Isolated generators should eliminate the possibility of an alternate site burn by requiring the current return to the generator. Therefore if the current leaves the patient by a site other than the return electrode, the generator should shut off before injury ensues.

Another important distinction among electrosurgical generators is the mechanism by which the current is delivered to the tissue. Household current in the United states is delivered at 60 Hz with a constant voltage 110 volts. Therefore, if resistance increases, current flow decreases. This explains how a 60 watt bulb is brighter than a 25 watt one. The resistance in the 60 watt bulb is less. Standard electrosurgical generators, on the other hand deliver the wattage set by the operator on the generator and are consequently power driven. If tissue resistance increases, voltage increases in an attempt to meet the power set. As a result, high peak voltages may be needed to provide the same power to high resistance tissues.

A recent advance in generator design is the introduction of voltage regulated systems such as the Intelligent Coagulation Cutting® generator by Erbe, LTD (Figure 10.). These generators control either output voltage or spark intensity constant to provide five defined tissues actions. These are high cut, endo cut, soft coag, forced coag and spray coag. This eliminates the wide variations in voltages seen with conventional generators. Furthermore, these systems are independent of electrode geometry and reduce considerably thermal damage and charring.

C. Monopolar Electrosurgery and its Appropriate Use

Pearce, a noted researcher of electrosurgery has noted that "The goal of electrosurgery is to initiate thermal damage of tissues at the surgical site alone (4)." However, numerous potential dangers and risks have been identified since the introduction of electrosurgery (Table 2) because the injury is not always confined to the surgical site. Refinements in the delivery of energy and various monitoring systems have reduced these risks. Nonetheless, it is important to realize the potential dangers of electrosurgery in order to prevent mishaps.

The use of electrosurgery in the laparoscopic surgery is complicated by the unique environment present in laparoscopy. The laparoscopic environment is different from that present in open because of the presence of the insufflating gas which has a low heat capacity. As a result, instruments may not cool as rapidly as in the open environment. In addition the high water content of the gas increases the conductive capacity of the medium. The gas itself may support combustion such as is the case for nitrous oxide. Limited access to the tissues requires the use of cannulas to pass instruments into the abdomen. These cannulas are the source for capacitive or direct coupling. Finally, the limited field of view and narrow focus on a small area allows events to occur unnoticed outside these fields of view.

The majority of surgeons today use monopolar electrosurgery in open and laparoscopic surgery. Tucker in a survey performed at the 1993 Clinical Congress of The American College of Surgeons found 85.6% of surgeons used monopolar electrosurgery, whereas only 12.1 % used bipolar electrosurgery (5). Of those using monopolar electrosurgery, 74% principally used the coagulation current, 21% the blend current and only 5% the cut current. The principle power setting typically used by these surgeons was 20 to 30 watts (47.3%). Interestingly, only 17.8% of those using monopolar electrosurgery used it for its safety, whereas 326.4% of those using bipolar electrosurgery did so because of its safety. Finally, although only 18% of those in the survey had experienced an electrosurgical injury as a result of the use of monopolar electrosurgery, 54.1% knew of a surgeon who had had such an injury (5).

Clearly, most surgeons today do not recall having had an electrosurgical injury in their practice and therefore question the significance of all these warnings. In fact, numerous break throughs in the delivery of electrosurgical energy have indeed reduced the risk. Nonetheless, injuries do occur. The problem may reside in the fact that we often do not associate the complication which occurs as being the result of electrosurgery. For example, bile duct injuries (6) bile leaks, intestinal injuries (7) anastomotic leaks and postoperative bleeding may from the inappropriate or injudicious use of electrosurgery. However, we tend to only attribute alternate site injuries and grounding pad injuries to electrosurgery and rarely consider the role of electrosurgery in other complications that occur after surgery. Fortunately, most if not almost all injuries can be eliminated by the use of isolated generators, return electrode monitoring systems and active electrode monitoring systems.

1. Ground Pad Failures

The return electrode must be in uniform contact on the patient over a large surface area and away from any metal prostheses. This is a cardinal rule of safe use of electrosurgery. As noted earlier, the ground pad is not really a ground at all but an indifferent electrode which is capable of producing electrosurgical injury. The reason it does not produce injury is that the large surface area of contact it provides allows the current to be dispersed over a large enough area that the current density at any one site on the electrode is small enough to not produce thermal damage. Lack of uniform contact can result in significant current concentration and damage (Figure 11). Return electrode monitoring electrodes are available to monitor the area of contact and ensure that it is adequate enough to prevent injury because it is not always possible to be sure the pad has not moved or become detached during the operative procedure. These electrodes monitor the resistance to current flow across the electrode. Since the skin has a high electrical resistance, a large surface area should provide the monitor with a high electrical resistance. When surface contact is less that optimal, the total electrical resistance at the site is low, the generator stops providing current to the electrode and the system alerts the user there is a problem with an audible sound.

2. Alternate site injuries

Since current delivered to the patient must return to mother earth, any conductive, low resistance, object in contact with the patient and mother earth can serve as the conduit. Exit of current at these alternate sites can produce injury at an alternate site. Usually, such injury results when the site of contact is small thereby providing a high current density (Figure 12).

Early models of electrosurgical generators are of the grounded type. Current is driven from these generators irrespective of whether the current returns to the generator or not. For example, even though an indifferent electrode is placed on the patient, any conductor that is in contact with the patient and with mother earth serves as the return. If the patient is in contact with any metal that in turn is in contact with the floor, current will flow from the patient through the metal to the floor. If the site of contact is small, a burn may result. This was often seen at the site of electrocardiographic leads when these generators were used.

Isolated generators essentially eliminate the possibility of an alternate site burn by requiring the current return to the generator. If the current leaves the patient by a site other than the return electrode, not enough current returns to the generator and it can not deliver more current to the electrode. The introduction of isolated generators has dramatically reduced the incidence of alternate site injuries. Nonetheless, precautions should be taken to ensure there is no possible alternate exit site present by ensuring there is no contact of the patient with any highly (metal) conductive objects while on the operating table.

3. Demodulated Currents

Demodulated currents are low frequency alternating currents (<100 kHz) that cause muscle and nerve depolarization (8). Modern generators have filters that remove these currents from the current delivered to the patient so that only electrical current of 250 to 2000 kHz is delivered. However, lower frequency currents can be produced locally at the end of the electrode during the use of electrosurgery. This occurs most commonly when an electrosurgical instrument is activated off metal and then touched to the metal, such as the common practice of "buzzing a hemostat". Demodulated currents produce neuromuscular activity which is usually of no significance unless directly coupled to the heart through a catheter or during a cardio-thoracic surgical procedure. Another example of demodulated currents is muscle fasciculation at the site of a laparoscopic cannula during the use of electrosurgery. This usually indicates insulation failure of capacitive coupling is occurring resulting in the creation of demodulated currents that manifest themselves as the unusual muscle twitching around the cannula site.

4. Insulation Failure:

Insulation failure is thought to be the most common reason for electrosurgical injury during laparoscopic procedures (5,9). In large part, this stems from the inability to see the entire instrument during the procedure. Voyles and Tucker (9) have classified insulation failure into four potential zones of injury (Figure 13). Failure in Zone 1 is usually within the view of the surgeon. It can result from: use of high voltage coagulation waveform; repeated trauma during insertion through the valves; repeated electrical heating; repeated sterilization; and manufacture's defect. Failure in Zone 2 is detectable only by careful prior inspection (Figure 14). It results from the same causes as Zone 1. If the break is small or the area of contact is small, a high current density will be achieved that can lead to significant injury. Failure in Zone 3 may be detected by the appearance of demodulated low frequency currents created by arcing to the cannula from the electrode. These demodulated currents will cause neuromuscular stimulation, such as abdominal wall jerking or interference on the video monitor. Zone 4 injuries are unlikely to injure the patient but are a source of injury to the operating room personnel. These injuries are the ones felt by the surgeon and usually result in or from a hole in a surgical glove.

The key factor that determines the magnitude of injury from insulation failure resides in the size of the break in the insulation. Paradoxically, the smaller the break, the greater the likelihood of injury if contact of tissue with that site occurs (Figure 15). This is related to the concept of power density. The small break results in current concentration at a small surface area. Since the current is not dissipated over a large area, injury results. Unfortunately, these small breaks are often not visible without very careful inspection. Furthermore, they occasionally are the result of imperfections in the insulator itself.

Protection against insulation failure is provided by the active electrode monitoring system (AEM®) (9,10). This system uses conductive sheaths that are placed over laparoscopic instruments used with electrosurgery or specially designed instruments that contain this sheath (Figure 16). The conductive sheath collects any stray energy that results from insulation failure or capacitive coupling and returns this current to the generator. If this current reaches a threshold value where injury may be possible, the generator shuts off and the user alerted through an audible tone.

5. Current Concentration

Although the goal of electrosurgery is to initiate thermal damage of tissues, it must occur only at the intended surgical site. Current passing through structures of small cross sectional area may have current unknowingly to the surgeon concentrated there with resultant unintentional thermal injury (11,12). For example, if the testicle and cord are skeletonized and mobilized from the scrotum, application of energy to the testicle can result in damage to the cord. This is because the surface area where the energy is applied, the testicle, is much larger than the surface area or diameter of where the cord enters the abdomen. Since the current must all return to the indifferent electrode, it must pass through the small diameter cord before it is dissipated in the body through numerous pathways. This means the concentration of current at the small diameter cord will be much greater than at the testicle (Figure 17).

Another example of potential injury by this phenomena can occur when cutting an adhesive band from the gallbladder to the duodenum with electrosurgery. If the adhesion is wider near the gallbladder than on the duodenum, the current density will be greater on the duodenum than at the adhesion near the gallbladder. The attention of the surgeon, however is focused on the gallbladder. The surgeon is not aware that the current is injuring the duodenum. Furthermore, if electrosurgery is applied to the adhesion near the gallbladder until the tissue desiccates and then reapplied to the adhesion between this area and the duodenum, all the current will go to the duodenum (Figure 18). The current density will be much higher at the duodenum and injury can result. Usually this is represented by a delayed perforation since a few days are required for necrosis of the area with resulting perforation to occur.

6. Sparking and Arcing

Jumping of sparks from the electrode to tissues does occur and is the mechanism for fulguration and true electrosurgical cutting. However, the important question is whether this is like to occur in an unintended fashion such that injury results. The ability of electrical sparks to travel over a distance in a gaseous environment is increased when the tissue desiccates and there is a moist, smoky environment. Since the electrical resistance at the surgical site is high, the current will seek an alternate pathway of lower resistance. For example, current applied to tissue near the duodenum by an electrode passing over the duodenum can jump to the duodenum if the resistance at the surgical site is greater than at the duodenum. Current can jump from any place on the uninsulated end of the electrode and need not jump from the tip. In addition, build up of eschar on the electrosurgical instrument may promote arcing to a secondary site.

Overall, the risk of sparking with monopolar electric current is small. At 30-35 watts, the standard power setting used for laparoscopic surgery, sparks jump 2-3 mm 50% of the time (12). Furthermore, the standard maximum voltage used in electrosurgery is not enough to allow significant air gaps to

be bridged. For example, at 5000 volts only 4 to 5 mm can be bridged. Therefore, under normal operating circumstances, the voltage used in electrosurgery is not enough to allow significant air or carbon dioxide gaps to be bridged.

7. Direct Coupling:

Direct coupling occurs when an electrosurgical device is in contact with a conductive instrument.

This may be intentional as occurs when a forceps is activated by an electrosurgical pencil to coagulate a small vessel or unintentional as occurs when electrosurgery is used on the liver near the fundus of the gallbladder and another instrument is touched. Direct coupling can be reduced by using only insulated instruments and careful attention to avoid contact with any metallic object in the operative field.

Direct coupling can be avoided by never activating the electrosurgical electrode outside the visual field and never near another metal object such as a clip, staple, laparoscope or metal instrument. Heat production beneath a clip can lead to necrosis of the tissue underlying the clip and later sloughing of the clip. Clearly the practice of dividing a structure with electrosurgery should be abandoned as it has no useful purpose and can potentially produce a delayed complication. Similarly, electrosurgery should never be used at a staple line to control bleeding because the tissue beneath the staples can subsequently undergo necrosis with anastomotic dehiscence resulting.

8. Capacitive Coupling

A classic and fortunately historical example of capacitance coupling resulting in injury is the burn around the eye that occurred to gynecological laparoscopists during the use of electrosurgery via an operating scope without a video system. Capacitance is stored electrical charge which occurs when two conductors are separated by an insulator (13,14). The capacitively coupled current wants to complete the circuit by finding a pathway to the patient's return electrode. The charge is stored in the capacitor until either the generator is deactivated or a pathway to complete the circuit is achieved (Figure 19). In the example, the current was stored in the operative scope and discharged to the gynecologist's skin around the eye where the scope was in contact with it.

Capacitive coupling is related to the length of the capacitor (L), the radius of the cannula(b), the radius of the active electrode (a) and the dielectric constant of the insulator (k). This is represented in the calculation of capacitance where

C = L /2k ln(b/a)

L = cannula length, k = the dielectric constant of the insulation,

b = radius of the cannula and a = radius of active electrode.

Therefore, the larger the cannula or the smaller the active electrode, the less likely it is that capacitance coupling will occur. Capacitive coupling is greatest in the coagulation mode when there is no load on the circuit (open circuit)(13). The reason is the higher peak voltages attained with the coagulation current when compared to the cutting current in a no load situation (Table 3). When there is a load, capacitive coupling is approximately the same for either the cutting or coagulation current and in both cases low (Figure 20). Capacitive coupling is considerably greater through a 5 mm cannula than an 11 mm cannula (Figure 21) and greater the longer the length of the cannula (13).

Because capacitance is greatest with a the coagulation current, the cutting current should be used whenever possible. Furthermore, open no load circuits should be avoided by activating electrodes only when in contact with tissue. The latter includes keeping electrodes free of eschar which will produce an open circuit because of the high resistance to current flow provided by the eschar.

The conductors of a capacitor are referred to as plates. The insulator is referred to as the dielectric because it is composed of bipolar molecules which do not easily dissociate. It is therefore a poor conductor.

Every object in the room - the surgeon, the patient, the operating room table - all have a small but finite parasitic capacitance to earth. Areas of possible capacitance include: an active electrosurgical cable wrapped around a towel clamp; a metal total hip prosthesis; sweating skin inside an intact surgical glove; a wet insulated electrosurgical instrument; a metal cannula around an active electrosurgical instrument (Figure 22). The most likely situation for capacitive coupling is a metal cannula with a plastic grip. The least likely is a plastic grip with a plastic cannula. In all these situations the skin may be considered as a conductor. In the example of a plastic cannula alone, one can consider the cannula and air gap as insulator between the active electrode and the conductive skin. However, this increases the radius of the insulator and therefore reduces capacitance. Furthermore, the large surface area of contact reduces the potential injury that can be incurred by the skin/subcutaneous tissue (Figure 23). Considerable work has been done evaluating suction irrigation devices with internal electrosurgical electrodes as potential sources of capacitance current (14). This problem can be eliminated by using irrigation devices constructed of special materials that do not allow capacitance or by using the active electrode monitoring system noted earlier.

Capacitance can occur in either a DC or AC current. The electricity stored by a capacitor when charged by a DC current voltage is in the form of discrete electrical charges held on the surface of the plates. One plate has a positive charge and the other has a negative charge. No current flows unless there is a leak through the dielectric (insulator). A capacitor charged by an alternating current voltage source is alternately charged and discharged each half cycle. During the alteration of polarity of the plates, the charges in the dielectric (insulator) must be displaced first in one direction and then in the other. This leads to the production of heat known as dielectric loss. Alternating current will pass readily - a displacement current, because unlike DC current in which charges actually move through the dielectric, in AC current the charges are only displaced.

9. Surgical Glove Injuries

Studies have documented the presence of holes in 15% of new surgical gloves and 50% of gloves after use in surgery (15). Some of these holes result from the use of electrosurgery as is known to every surgeon who has ever gotten zapped. Three mechanisms exist for these holes and burns. High voltage dielectric breakdown occurs because the high and repetitive voltages across the glove (dielectric) break the insulative capacity of the glove resulting in conduction of current to the surgeon and a burn in the glove. DC Ohmic conduction is the result of insufficient conductive resistance of the glove. The resistance of gloves decreases with time and with exposure to saline (sweat). The third mechanism is capacitive coupling. The risk of capacitive coupling is inversely proportional to the thickness of the gloves. No surgical glove can withstand maximum voltage from an electrosurgical generator in the open coagulation mode. This is likely to occur when a current is applied to a hand held hemostat. The higher the voltage and the longer the contact time, the more likely dielectric breakdown will occur. Therefore, energizing the active electrode in the air and then touching a hemostat subjects the surgeon to a potential burn and the patient to low frequency demodulated currents because of sparking from ionization of air between the two (15). This practice should be avoided.

10. Explosion

The original risk in the operating room for explosion was from the use of explosive anesthetic agents such as ether and cyclopropane. These gases could ignite by any arc discharge of sufficient energy - even static discharges. In the absence of ether and other explosive anesthetic agents, there is still a significant explosive hazard when electrosurgery is used: intestinal gas explosions. Indeed, 43% of unprepared bowel contains a potentially explosive mixture of gases. Hydrogen-air mixtures anywhere between 4-7% hydrogen are potentially explosive. Gas mixtures with 5-15% methane are also in the explosive range. For this reason, mannitol, which promotes the production of methane should be avoided in bowel preparations.

The reason an explosion occurs is that there is a very rapid, oxidative reaction that produces heat (rapid exothermic oxidative reaction). The gases are produced so rapidly that the product gases cannot diffuse out of the way of subsequent combustion products. If this occurs in excess of the speed of sound a pressure or shock wave is formed which moves away from the source creating an explosion. Nitrous oxide is a gas which is capable of supporting such a reaction. Although debated, studies have documented levels of nitrous oxide in the peritoneal cavity during laparoscopy that can support combustion (17). It is also for this reason that nitrous oxide should not be used as the insufflating gas when the use of electrosurgery is planned or contemplated.

11. Electrosurgical byproducts

The burning of tissue by electrosurgery results in the production of numerous by-products. These can be broadly classified as biologicals such as viral particles and other microbes and chemicals and irritants (18). A partial list of chemicals produced includes: acroloin, acetonitrile, acetylene, alkyl benzenes, benzene, butadiene, butene, carbon monoxide, creosols, ethane, ethene, ethylene, formaldehyde, free radicals, hydrogen cyanide, isobutene, methane, phenol, PAH, propene, propylene, pyridine, pyrrole, styrene, toluene, and xylene. While many of these may be mutagenic and or carcinogenic, there are no documented adverse effects in the literature with regards to this issue in either patients or operating room personnel. The presence of these chemicals and particles in electrosurgical smoke, however, do suggest the use of smoke evacuating systems with electrosurgery.

The best studied chemicals in laparoscopy patients that are potentially generated by laparoscopy are methemoglobin and carboxyhemoglobin. Methemoglobin is the oxidative product of hemoglobin in which the reduced ferrous iron form (Fe+2) has been converted to the ferric form (Fe+3). This form of hemoglobin is not capable of carrying oxygen or carbon dioxide. Carboxyhemoglobin is a high affinity form that prevents oxygen transfer because of the high affinity of hemoglobin for carbon monoxide. Although some studies suggest concentrations of methemoglobin and carboxyhemoglobin in the blood of patients undergoing laparoscopy with prolonged electrosurgical use are increased (18,19), none of these studies have found these concentrations to reach toxic or dangerous levels. Furthermore, other studies (20-22) strongly show the concentrations of these chemicals do not increase. Therefore, there seems to be insufficient evidence to support any danger from the potential generation of methemoglobin and carboxyhemoglobin during laparoscopic surgery in combination with electrosurgery.

12. Tissue injury and infection

Monopolar electrosurgery in general is associated with more tissue damage than that observed with a conventional cold steel scalpel for cutting tissue (23). Animal and human studies have attributed this increased volume of injured tissue for the slower wound healing (23, 24), lower threshold for infection (25,26) greater incidence of adhesions (23) and more frequent formation of seroma (27) when these two modalities are compared. These findings are most significant when the coagulation current. For example, in the studies of Rappaport and colleagues (23), wound tensile strength and adhesion formation following midline laparotomies in rodents were not different from a cold steel scalpel when the cutting current was used but markedly inferior when the coagulation current was used. Similarly, thresholds for infection were lower when the coagulation current was compared to the cutting current and the latter lower than a cold steel scalpel in the studies of Kim et al (25).

However, it is equally important to realize that many of these studies show less blood loss when monopolar electrosurgery is used in comparison to a cold steel scalpel (27). In this regard, the bloodless operative field and rapidity of surgery may more than justify the negative features associated with electrosurgery. However, future consideration should be given to studying these areas since infection, seroma formation and poor wound healing may have a significant impact on the length of hospital stay and , therefore, the overall cost of health care.

13. Bowel injuries

Bowel injuries following laparoscopic surgery are a feared complication. They usually are unrecognized when they occur and present 3 to 7 days after surgery. Because of this they carry a high mortality (28). The potential role of electrosurgery in the genesis of bowel perforations following laparoscopic surgery resulted from the early experience with tubal sterilization using monopolar electrosurgery. The incidence of bowel injuries during laparoscopic tubal sterilization with monopolar electrosurgery was 0.5 in 1000(29). This lead the American Association of Gynecologic Laparoscopists in 1981 to declare "Since laparoscopic sterilization using unipolar electrocoagulation has an increased risk of electrical accidents, alternative methods of laparoscopic sterilization are preferable (30)." This resulted in the marked decrease and eventual near abandonment of monopolar electrosurgery for tubal sterilization and the adoption of bipolar electrosurgery.

Gynecologists debated potential mechanisms for these injuries. Hypothesis included tissue heated by electrosurgery touching bowel, hot instruments touching bowel, true electrosurgical injuries or mechanical injuries. Subsequent studies showed bowel injuries could not be attributed to contact with hot tissue not to contact with non activated but hot instruments (31,32). Levy and Soderstrom (30) in their classic study then showed that most bowel injuries during tubal sterilization attributed to monopolar electrosurgery where actually the result of mechanical injury form trocars and instruments. This was proven by noting the histological differences between electrosurgical bowel injuries and mechanical ones and a subsequent histological review of supposed electrosurgical bowel injuries in patients. Based upon this work the AAGL withdrew their earlier condemnation of monopolar electrosurgery. "There was no suggestion that the unipolar technique involved more bowel injury than did others. In view of the better understanding of the various mechanisms of intra-abdominal injuries during laparoscopy, the Board of AAGL does not feel their position of 6/11/81 is necessarily valid and withdraws it (30)." However, bipolar electrosurgery, remains the most common energy used for tubal sterilization today.

14. Argon Beam Coagulator

Argon gas is an inert, non-combustible and easily ionized gas that is used in conjunction with monopolar electrosurgery to produce fulguration. Essentially, the electrical current ionizes the argon gas thereby making a more efficient pathway for the current to flow (Figure 24.). The gas is more conductive than air, therefore, providing a bridge between the tissue and the electrode. Less smoke is produced with the argon beam coagulator because there is less depth of tissue damage. Despite these advantages, the argon beam coagulator suffers from one very significant drawback in laparoscopic surgery, namely, high flow infusion of argon gas into the abdominal cavity. This not only increases the intraabdominal pressure to potentially dangerous levels, it has also been associated with fatal gas embolism. Although, the later may be dealt with by venting the laparoscopic cannulas, the latter complication can not be avoided if the bleeding vessel is large because argon gas is relatively insoluble in blood.

D. Bipolar electrosurgery and its appropriate use

The pioneering efforts of Cushing and Bovie with monopolar electrosurgery were followed in 1940 by the introduction of two-point or bipolar coagulation by Greenwood (33). Malis later refined this in 1960 (34) to provide us with the fundamental form of bipolar energy we use today. Corson (35) on the basis of the perceived injuries associated with monopolar electrosurgery advocated the use of bipolar electrosurgery in gynecology and the first large series was reported by Rioux (36). The rapid evolution of laparoscopic gastrointestinal surgery has brought with it interest in bipolar electrosurgery, however, less than 15% of general surgeons today use bipolar electrosurgery (5). In contrast, 45% of gynecologists use bipolar electrosurgery as their primary energy to cut and coagulate tissue (5).

The bipolar electrosurgical is produced by placing the two electrodes necessary to complete the circuit with in a few millimeters of each other. As a result current does not need to travel throughout the patients body to reach the indifferent electrode. Since the area between the two electrodes is 2-3 mm, the current is concentrated in a bipolar circuit. Furthermore, since both electrodes are capable of producing injury at the same time, and since both are small and similar in size, current concentration is achieved. Whereas the current density of a monopolar circuit is based on the second power of the radius of contact, the current density of a bipolar circuit is based on the fourth power of the radius of contact (Figure 25.) (37). Clinically, this means less electrical energy or power is need to produce a similar effect with bipolar electrosurgery when compared to monopolar electrosurgery. Furthermore, tissue damage should be reduced with bipolar electrosurgery since less energy passes through the tissue.

Various studies have indeed shown a reduction in the amount of tissue damage produce with bipolar electrosurgery when compared to monopolar circuits (37-41). These differences are least at low wattage (20-30 watts) and greatest at high wattage (40-60 watts) (39). Overall, the area of tissue damage produced by bipolar electrosurgery is two times less than that observed with bipolar electrosurgery. Furthermore, the conduction of heat is considerably less and over a much shorter distance in a bipolar circuit when compared to a monopolar one (Figure 26.)(41).

Not only is overall tissue injury reduced with bipolar electrosurgery, so is the depth of penetration when compared to a monopolar circuit (38,42). Clearly, the depth of penetration can not be much greater than the depth of tissue present between the blades. In contrast, in a monopolar circuit the current disperses over a much larger area as it travels throughout the body. The reduced depth of penetration for bipolar electrosurgery is not without drawbacks. Monopolar electrosurgery is more effective at deeper hemostatic coagulation but also has greater risk of perforation from delayed necrosis. Because coagulation is not as deep, less smoke is generated with bipolar electrosurgery and the risk of perforation is less. On the other hand, hemostasis is not as good.

The obvious advantage of bipolar electrosurgery over monopolar electrosurgery is the absence of a return electrode on the patient. This eliminates the possibility of ground pad and alternate site burns. However, other important differences that should reduce inadvertent injury are present. Capacitive coupling should almost be eliminated by the bipolar circuit because the flow of current in each electrode is so close that any leakage current is cancelled out (43). That is, change in the insulator caused by one electrode is balanced by changes from the other electrode so that there is no net current flow. Furthermore, both electrodes within the bipolar device are insulated making capacitance less likely. This also significantly reduces if not completely eliminates the risk of insulation failure. Finally, direct coupling can occur only if metal is grasped or placed between the electrodes in a bipolar circuit or extremely close to the electrodes themselves. This should not however, be implied to mean bipolar electrosurgery is safe to use between metal clips. Heat is conducted from the site of application and can lead to necrosis beneath the clips.

The typical power output for bipolar circuits is rated for 50 to 150 ohm resistance. This is considerably less than the power output for monopolar circuits in which loads of 30 to 500 ohms are used. This relates to the considerably smaller volume of tissue affected in the bipolar circuit. Overall, the power provided to a monopolar circuit is 10 % that of a monopolar circuit. In this regard, it is imperative that bipolar devices be connected only to the bipolar side of the generator. Otherwise considerable greater and potentially dangerous voltages may be provided. Furthermore, the device may act as a monopolar electrode when it is touched to the patient if an indifferent electrode is on their body.

The fact that both electrodes in a bipolar circuit are active and producing tissue damage leads to a unique feature of bipolar coagulation, namely, the tissue is cooked form the outside in. However, as the outer layers of tissue desiccates, the resistance to current flow increases. Coagulation may cease before it is complete. That is, a blood vessel may be cut before it is completely coagulated and therefore bleeds. In part this explains the occasional high rates of pregnancy following bipolar sterilization. Although they generally are comparable to that seen with monopolar sterilization, some series report incidences as high as 16%(44).

Clearly, this problem arises out of a lack of correlation between the visual endpoint (blanching, charring etc) that is external and what is occurring internally. As a result, it is recommended that bipolar electrosurgery be used in conjunction with an ammeter. Coagulation should continue by activation of the bipolar device as long as the ammeter registers current.

It is important to remember that the ammeter measures the amount of current flowing though itself and not through the tissues (43). A short in the circuit from one electrode to the other will provide a means for the ammeter to recognize continued current flow even though there is none through the tissue. Furthermore even though there may still be current flow in the tissue, it does not mean the tissue is not sufficiently coagulated for transection. Nonetheless, the ammeter provides a useful tool to aid in achieving maximum coagulation prior to transection.

The maximum coagulation with the least lateral thermal spread is achieved with bipolar electrosurgery when low voltages of 20 to 30 watts are used (Figure 27.). Higher wattage leads to rapid coagulation of the outer layers with concomitant increases in electrical resistance that may prevent complete coagulation. In this regard, the cutting waveform should almost always be used to avoid the high peak voltages associated with the coagulation waveform. Some generators, such as the Valley Lab Force 2 generator only provide the cutting waveform while other generators may provide both. The reason high voltages should be avoided is to prevent current bridging around the tissue when the tissue resistance increases. This could lead to injury to structures adjacent to the electrodes that are in this alternate pathway.

Activation of the electrode of the tissue should not be constant. More uniform coagulation is achieved if the tissue is heated with a brief period of activation, allowed to cool for a few seconds and then heated again by activation of the electrode, etc, until current flow thorough the ammeter ceases. This is achieved by tapping the bipolar pedal for a few seconds at a time.

A significant problem with bipolar electrodes is tissue sticking. This can be reduced or eliminated by irrigation of the bipolar electrodes at the time of activation. This concept, originally introduced by Malis (34) for neurosurgery, has the added and potentially significant advantage that it reduces lateral thermal damage. In essence, the irrigant not only cools the electrodes but also the tissue, thereby minimizing conducted thermal injury. Although any solution, including saline, can be used, non-electrolytic solutions such as glycine or weakly electrolytic solutions work best (41). This ability to irrigate particularly with water or saline while activating differentiates bipolar from monopolar surgery as well. The reason it is possible is that the tissue to be coagulated is between the jaws of the device and does not interfere with current flow. In contrast, saline does not allow for electrosurgical effect in a monopolar circuit because it disperses the current before it reaches the tissue.

The principle tissue effect achieved with bipolar electrosurgery is tissue coagulation through the process of desiccation. Clearly, contact of the tissue with the electrodes is necessary by squeezing, but not with excessive pressure, the tissue between the pads of the device. Recently, bipolar cutting devices have been introduced clinically and are gaining popularity (Figure 28.). Essentially, they provide bipolar coagulation with mechanical cutting but not true electrosurgical cutting described earlier. Mechanical cutting is provided either as a scissors or with a sharp blade that passes though the center of the bipolar electrodes (Figure 29.). The latter devices have been termed "tripolar" which is erroneous (Figure 30.). These so called, tripolar devices are actually bipolar electrodes that coagulate the tissue followed by deployment of a sharp blade that cuts the tissue. This method is successfully used to divide short gastric blood vessels during laparoscopic Nissen fundoplication and similar caliber blood vessels without the need for multiple instrument changes. It should also be noted that true tripolar devices are under investigation that combine 3 electrodes to produce cutting and coagulating but are not clinically used at present.

 

II. UTRASONIC ENERGY

A. Introduction

Ultrasound is alternative to electrosurgery for cutting and coagulating. The use of ultrasonic energy in surgery has increased dramatically since the introduction of ultrasonic cavitational dissection in 1972 (45) and ultrasonic cutting and coagulation in 1991 (46). Today virtually all laparoscopic procedures can be performed safely and efficiently without electrosurgery by using ultrasound. Furthermore, ultrasonic surgery can also replace mechanical surgical clips and scissors in many laparoscopic procedures.

B. Physics of Ultrasound

The basic mechanism for ultrasonic cutting and coagulating depends on the mechanical propagation of sound (pressure) waves from an energy source through a medium to an active blade element. Sound waves are longitudinal mechanical waves that can be propagated in solids, liquids or gases (47). Mechanical waves are characterized by the transport of energy through matter by the motion of a disturbance in the matter without any corresponding bulk motion of the matter itself (47). Earthquakes, ocean waves and audible sound waves are examples. There are a large range of frequencies of longitudinal mechanical waves. Audible sound waves, which stimulate the human ear to the sensation of hearing, are confined to the frequency range of 20 cycles per second (hertz) to about 20,000 cycles per second. A longitudinal wave with a frequency below 20 cycles per second, such as an earthquake wave, is an infrasonic wave. One whose frequency is above the audible range is an ultrasonic wave.

Ultrasonic waves may be produced by applying electromagnetic energy to either piezoelectric (also termed electrostrictive) or magnetostrictive transducers, that create mechanical vibration in response to electric or magnetic fields, respectively. The piezoelectric effect is the elastic vibration of a quartz crystal induced by resonance with an applied electric or magnetic field. Resonance is the phenomena in which a driving force near that of the natural frequency of the crystal is applied to cause the crystal to vibrate with a larger amplitude at that same frequency (47). If there was no resonance, the oscillations would gradually die out because the motion of the crystals would be damped out by dissipation of energy at the ends and by the resistance of air to motion. This concept can be visualized by considering a guitar string. The string vibrates when it is plucked. This vibration will continue as long as it is continuously plucked. However, if the guitar string is left alone once its vibration is started it will rapidly stop because of loss of energy at the fixed ends and resistance to vibration from the surrounding air. In this example, the guitarist is the resonator. The wave produced in the guitar string is an example of a transverse mechanical wave rather than a longitudinal wave because the motion of the string is perpendicular to the direction the wave is propagated (Figure 31). In contrast, the motion of the particles in a longitudinal wave is parallel to the direction of the wave. Examples of this type of wave include a spring or a piston acting on an air filled tube (Figure 31).

When ultrasonic waves are applied at low power levels no tissue effect occurs. This is the case for diagnostic ultrasound imaging. However, higher power levels and power densities can be harnessed to produce surgical cutting, coagulation, and dissection of tissues. Two examples of this energy form currently exist in the surgical armamentaria: the ultrasonic cavitational aspirators and the ultrasonically activated cutting and coagulating devices. The former harness the ultrasonic energy for cavitational fragmentation of tissue whereas the latter use the ultrasonic energy to cut and coagulate tissue.

Ultrasonically activated devices that cut and coagulate tissues, (Harmonic Scalpel®, Ethicon Endo-Surgery, Inc., Cincinnati, Ohio; AutoSonix®, US Surgical Corporation, Norwalk, Conn.; SonoSurg®, Olympus Corp, ) will henceforth be referred to as ultrasurgical devices in order to differentiate them from those that only cavitate. The Harmonic Scalpel® (Figure 32) and the AutoSonix® (Figure 33) systems operate at a frequency of 55.5 kHz, while the SonoSurg® (Figure 34) system uses a frequency of 23.5 kHz. Ultrasurgical devices are composed of a generator, hand piece and blade (46). The hand piece houses the ultrasonic transducer, a stack of piezoelectric crystals sandwiched under pressure between two metal cylinders (Figure 35). The transducer is attached to a mount which is then attached to the blade extender and blade. Heat is generated in the handpiece when these crystals are activated by electromagnetic current. The Harmonic Scalpel cools the hand piece with air. The AutoSonix® and SonoSurg® systems rely principally on a large diameter handpiece made of heat dissipating materials to remove the heat and prevent heat build up. Heat dissipation is important, because the crystals will not function properly if they get too hot and the overall function of the device will decay.

The generator of all these systems is a microprocessor controlled, high frequency switching, power supply that pulses the acoustic system in the hand piece with AC current. The electrical pulsing of the crystals results in vibration of the transducer at the natural harmonic frequency of the crystals which is at 55.5 kHz in the case of the Harmonic and AutoSonix systems and at 23.5 kHz in the case of the SonoSurg system. The microprocessor senses changes in the acoustic system to maximize power and alerts the user of system faults (46). System faults may result from; a microscopic crack in the blade; too much exerted pressure (high impedance), contact against an object such as metal which will not allow blade vibration (high impedance) or overheating of the blade. System faults of any type result in no pulsing of the crystals and therefore no vibration of the blade. The mechanical vibration established in the handpiece is conducted to a blade via an extending rod which is necessary for laparoscopic use. In the case of the Harmonic System, this rod is housed either in a 10 mm hollow stainless steel tube (Figure 32), permanently sheathed with metal to produce a 5 mm diameter (Figure 32), housed in a 10 mm stainless steel tube whose end has a shear configuration (Figure 32), housed in a 5 mm metal sheath whose end has a shear configuration (Figure 32) or as a short blade without sheath for open surgical applications (Figure 32). The AutoSonix and SonoSurg systems, at the present time, provide only the scissors configuration with the AutoSonix system limited to a 5mm shaft and the SonoSurg system limited to a 10 mm reusable shaft (Figures 33, 34).

The extender shaft must be kept in isolation from the laparoscopic cannula or the oscillations will be dampened by contact with the cannula. This, in turn, will generate heat at the cannula. Furthermore, the active extending rod must be sheathed to prevent transmission of any energy to tissue at sites other than where it is in contact with the blade. This is accomplished by silastic rings that are placed at the nodes of the extender. The mechanical wave traveling down the shaft is longitudinal and travels as a plane down the shaft. Furthermore the wave is a standing wave rather than a traveling wave. That is, the wave travels down the shaft and then returns to the origin rather than traveling down the shaft and exiting out the end and stopping. For example, a wave created in dangling string by snapping it will move down the string and exit at the end without further vibration of the string. In contrast, if a spring is anchored to a weight and the weight is released, the wave will return from the end towards the hand that started the motion. The amplitude of waves is algebraic. Therefore, as waves travel in both directions, they cancel each other out where they are not in phase and add algebraically where they are in phase (Figure 36,37). This so call principle of superposition results in a standing wave with definable nodes that occur one wavelength apart. These nodes represent points where there is no motion. In addition, antinodes are identifiable where the motion is greatest in amplitude (Figure 38. Antinodes are also periodic and located one wavelength apart and one half wavelength from the node (Figure 39). Thus, by placing the silastic rings at the nodes, the extending rod is mechanically isolated from the sheath. Although the wave suffers some loss of energy as it propagates down the shaft to the blade, the loss is negligible.

Although the frequency of displacement in any of these systems is constant, the amplitude of displacement of the tip of the blade is variable among systems and within a given ultrasurgical system. The Harmonic system which vibrates at a frequency of 55.5 kHz has a maximum longitudinal displacement of 80 m (46). The AutoSonix system which also vibrates at a frequency of 55.5 kHz has a maximum longitudinal displacement of 110 m. The SonoSurg system which vibrates harmonically at a frequency of 23.5 kHz has a maximum longitudinal displacement of 200 m. Differences in the amplitude of displacement are varied in any given system by altering the power provided to the crystals that causes them to vibrate. Remember that resonance or application of an electric current to the crystals causes them to vibrate with a large amplitude at their natural frequency. The higher the driving force, the higher the amplitude. However, an upper limit does exist for the driving force the crystals can withstand without shattering.

Differences in blade mass and geometry appear to make the cutting and coagulating properties similar among the various ultrasurgical devices despite differences in the amplitude of displacement and frequency of vibration. The only data available to date is derived from the Harmonic Scalpel®. As a result, the remainder of the discussion will be limited to the Harmonic Scalpel ®system. Only inferences can be made to instruments from the other instruments since no comparative data exist as of this time.

The initial displacement of the crystals by the application of electrical energy causes the crystals to expand approximately 8 microns in the case of the Harmonic scalpel. However as noted previously, the displacement at the end of the blade is up to 80 microns in the case of the Harmonic Scalpel® and 200 microns for the SonoSurg® system. This increase in the amplitude of displacement as the longitudinal, mechanical wave travels down the shaft of the device is the result of amplification. Amplification of the amplitude of displacement occurs whenever there is a reduction in the mass of the shaft transporting the wave (Figure 40). As the mass of the device is decreased, the velocity of the particles in the shaft must increase to conserve energy. This results in greater amplitude of displacement of the particles for a given unit time(so called acoustic horn). In general, all the ultrasurgical devices have 2 to three areas of reduction in mass that include; the transition from the handpiece to the extension shaft, the transition of the extension shaft to the blade: and the blade itself (Figure 41).

Extensive experimentation in animals has shown that the desired surgical effect of the ultrasonically activated scalpel in different tissues and conditions of surgery require different blades (48) (Figure 42). Although the end of the instrument is referred to as the blade it need not cut nor be sharp. These blades or tips would ideally vary from a pure cutting blade to a pure, coaptive, coagulating blade. Maximum cutting is achieved with a sharp edged blade, such as one resembling a modified #15 blade. Unfortunately, hemostasis is poor with a sharp edge because cutting occurs prior to coagulation. Maximum hemostasis is achieved with a blade of large, flat surface area, with a blunt edge. A blade of small surface area with a blunt edge applies the vibrational force to such a small area that it causes cavitational fragmentation and cavitational cutting rather than coagulation. Therefore, the blades for the scalpel configuration exist in two basic shapes: a hook-spatula type configuration and a ball coagulator. These devices require pressure exerted against or tension applied to the structures to be coagulated or coagulated, respectively. Although this tissue support is readily available when working on the liver or uterus, other tissues are cut or coagulated with difficulty because they lack a surface to apply pressure on, the surface available is not safe or the structure can not easily be put on tension. For example, it is difficult to apply tension to a transected mesenteric vessel. Furthermore, application of pressure to this structure would risk injury to underlying structures such as the ureter, duodenum, kidney or aorta. In these situations, an ultrasurgical scissors type device can be used that is capable of grasping, cutting and coagulating unsupported tissue such as the mesentery of viscera . These devices have a double edged or round blade and a fixed pad. When the pad is closed on the vibrating blade, mechanical energy is concentrated between the blade and the pad. This allows both pressure and tension on the tissue to be controlled by the device without the need to use surrounding tissue structures for support.

Based on initial work in animals (48) and confirmed in human laparoscopic cholecystectomies (49), the hook-spatula configuration appears to be the optimum blade for laparoscopic use in that it provides an excellent balance of cutting and coagulating. The inner radius of the hook is sharp thereby offering maximum cutting. Furthermore, the curved inner radius allows the tissues to be placed under tension by hooking them thereby facilitating cutting. The outer, non-sharp radius, and relatively large surface area provided by the spatula configuration offer excellent coagulation. The ball tip is used when coagulation is not easily obtained with the hook-spatula because of an awkward angle of application. The author has performed over 1250 laparoscopic cholecystectomies using these blades with the need for supplemental electrosurgical coagulation in only two of the initial 100 patients (49). Furthermore, there has been only one patient requiring transfusion for postoperative bleeding.

C. Ultrasonic Cutting, Coagulation and Cavitation

The basic mechanism for coagulating bleeding vessels ultrasonically is similar to that of electrosurgery or lasers. Vessels are sealed by tamponading and coapting with a denatured protein coagulum. The manner in which protein is denatured, however, is different for each of these modalities. Electrosurgery uses electrons and lasers use photons to excite molecules in the tissue. The kinetic energy expended in the motion of these molecules is released as heat. The coagulum is formed by heating tissues to denature protein (4). Water molecules are not excluded from this process. As the temperature rises, the water in cells is turned to steam and evaporated. Once all water is excluded from an area of tissue the process of desiccation is complete. A continued increase in the temperature of the tissue is possible only after all the water has been eliminated from the tissue. At this point the tissue temperature rises more steeply. Temperatures are subsequently reached at which the tissues oxidize producing the characteristic charring seen with electrosurgery and lasers. However, complete desiccation is not necessary for tissue coagulation. Tissues coagulate at 60 to 80 degrees centigrade whereas desiccation is complete at 100 degrees (Figure 43)(50).

Ultrasurgical devices denature protein by the transfer of mechanical energy to the tissues which is sufficient to break tertiary hydrogen bonds, and by the generation of heat from internal tissue friction that results from the high frequency vibration of the tissue. While convenient to consider the generation of heat with ultrasurgery as proportional to the force of friction that occurs between the blade and the tissue, such a depiction is inaccurate. Vibration occurs not only on the surface but also within the tissue. Thus, frictional forces exist both on the surface and internally. Furthermore, the metal used to transmit the energy has heat capacity that allows it to accumulate heat. This augments the effect of ultrasurgical cutting by providing an external as well as an internal source of heat. As a result, time is required for the tissue to heat, since not only is tissue heating important but also blade heating at the site of contact with the tissue. Large vessels bleed when cut by the sharp edge of the Harmonic Scalpel®, but not when pressure is applied to them with the broad side of the blade, and the blade vibrated for 2-3 seconds. As a general rule, experimental studies have proven the ability of the hook-spatula blade to coagulate blood vessels in the 2 mm diameter range without difficulty and the scissors configuration to coagulate vessels up to 5 mm in diameter (51). It is important to remember that these data are only available from work with the Harmonic Scalpel® system and may or may not apply to the other systems.

Initial thermal studies indicated that heat generated as a result of stress and friction in the tissues with the Harmonic Scalpel® is limited to temperatures below 80 degrees. Modifications in the initial Harmonic Scalpel® system to its present day configuration now allow greater temperatures to be achieved during prolonged activation. However, the overall temperatures achieved by the Harmonic Scalpel system remain well below the 250 to 400 degree centigrade temperatures achieved with electrosurgery and laser surgery. The lower maximal temperatures achieved with the Harmonic Scalpel® result in a reduced tissue charring and desiccation. The limited heat generated also minimizes the zone of thermal injury. Animal studies at the University of Pittsburgh show that skin incisions made with the ultrasonically activated scalpel or cold steel scalpel heal almost identically and are superior to electrosurgical incisions (24). Animal studies in our laboratory comparing seromyotomies performed in pigs with either electrosurgery or the ultrasonically activated scalpel noted four times less lateral thermal damage with the ultrasonically activated scalpel (1.2 versus 5 mm)(52). This minimal thermal damage may explain the marked reduction in postoperative adhesions to the liver bed following laparoscopic cholecystectomy with the ultrasonically activated scalpel (22%) when compared to electrosurgery 66%) or laser surgery (77%) in experiments performed in pigs (53).

It is important to recognize that coagulation produced by ultrasonic surgery is slower that that observed with either electrosurgery or laser surgery. Nonetheless it is as effective or more effective with regards to hemostasis than that observed with the other modalities. Studies comparing the depth and lateral thermal damage of ultrasurgery and electrosurgery show the same depth of thermal damage achieved with both modalities but maximal depth of coagulation is achieved with electrosurgery in less than three seconds while ultrasurgery requires 10 seconds to achieve the same effect (Figure 44)(54). This results in a more gradual coagulation effect by ultrasurgery which makes it easier to provide the right amount of coagulation needed and not char or desiccate tissue. Overall, there is a gradual tissue blanching that is easily visible with ultrasurgery that allows the user to stop the process of coagulation prior to reaching temperatures at which the tissue chars. The slower rate of coagulation should not be confused with less coagulation. In fact, these studies also demonstrate a greater depth of thermal injury with ultrasurgery than electrosurgery if activation persists more than 10 seconds. In this regard, it is important to recognize that even though minimal amounts of lateral and depth of thermal damage are achieved with ultrasurgery under normal usage and short periods of activation, deeper injury can be obtain. Therefore, the user should not be lulled into a false sense of security that deep structures can not be injured with ultrasound and that only 1 mm of damage is always achieved. The amount of injury achieved with ultrasound is proportional to the duration of activation and the pressure or tension exerted on the tissues.

It is also important to realize that despite the slower rate of tissue coagulation, the entire process of tissue coagulation combined with transection, the ultimate goal of surgery, is faster with the LCS or hook scalpel than with other energy modalities. While this may seem paradoxical, the LCS has been shown in two randomized trials to reduce the time necessary for division of the short gastric blood vessels during laparoscopic Nissen fundoplication and to reduce cost when compared to the alternative use of clips, scissors and electrosurgery (55,56). The principal reason for this advantage in time is the dramatic reduction in instrument changes required when an ultrasonic scissors is compared to clips, scissors and electrosurgical techniques. Recently, the LCS was compared to bipolar electrosurgery for division of the short gastric vessels (57). No differences were noted in operative time or bleeding.

The mechanisms of coagulation offer an advantage for ultrasonic surgery over electrosurgery when coagulating the side wall of a blood vessel. Blood vessel are usually not coapted significantly with electrosurgery because of the concomitant reduction in power density as the surface area of contact between the tissue and the electrode increases with coaptation (4). Furthermore, the blood within the vessels has a high heat capacity and acts as a heat sink. This allows one side to coagulate prior to the other with resultant bleeding from a hole in the wall of the vessel that was in contact with electrosurgery (4). In contrast, the ultrasonically activated scalpel relies on pressure and coaptation of the vessel walls for maximum energy transfer to the tissue. Thus, the vessel is sealed together without bleeding from the surface closest to the blade. To some extent, the process of ultrasonic coagulation represents a tissue weld in which two layers of tissue are heated to the ideal temperature necessary for them to meld together and produce a seal.

The absence of coagulated tissue sticking to the active element is a unique feature of ultrasurgical coagulation compared to other energy modalities. This is the result of two separate mechanisms. The first, and probably most important, is the vibration of the blade on the tissue which prevents the tissue from sticking to the blade. The second mechanism is related to the lower amount of heat generated at the interface of the tissue with the active element during coagulation with ultrasurgery. Tissue sticking can also be reduced or eliminated with monopolar electrosurgery by using Teflon coated electrodes or with bipolar electrosurgery by irrigation.

Pressure and coaptation are of paramount importance to the coagulative ability of ultrasonic surgery. As previously noted, unsupported tissue such as a transected bleeding blood vessel in a mesentery that can not be compressed against a firm surface, such as the liver, can not be coagulated effectively with the hook-spatula blade or blade configuration. Scissors type devices obviate this problem by providing a vibrating blade and a passive (not ultrasonic) tissue pad with which tissue is pressed against the active, vibrating blade. This allows unsupported tissue to be grasped and coagulated without difficulty, or cut and coagulated like a scissors. Animal work with the Harmonic LCS device has shown this device to reproducibly coagulate vessels up to 5 mm in diameter (51). Spivak and colleagues have found the Harmonic LCS to be equal to clips for small vessels less than 0.5 mm and to be near the efficacy seen with clips for vessels in the 2 to 3.5mm diameter range when a 300 mm Hg pressure is applied to the sealed vessels (58). In addition, lateral thermal damage with this device at power settings used in clinical practice consistently produces significantly less lateral thermal damage than that seen using monopolar electrosurgery with cutting or coagulation current or bipolar electrosurgery when power settings evaluated are equivalent to those used in clinical practice (20-30 watts). For example, one study examining the lateral thermal damage associated with transection of uterine horns of pigs found 1mm lateral thermal damage for the LCS, 9 mm lateral thermal damage for 30 watts monopolar electrosurgery and 7.5 mm for bipolar electrosurgery (59).

The cutting mechanism for the ultrasonically activated scalpel is different from that observed with electrosurgery or laser surgery. Cutting during ultrasonic surgery results from the actual "power cutting" offered by a relatively sharp blade vibrating 23, 500 or 55,500 times per second over a distance of 50 to 200 m. This effect is best observed in high protein density areas such as collagen or muscle rich tissues which have an inherent high internal tissue tension. In contrast, cutting with electrosurgery or lasers occurs when the temperature of cells increases to such a point that the concomitant increase in gas pressure explodes the cells (4).

Animal studies have demonstrated the ultrasonically activated scalpel similar in efficacy to an electrosurgical unit with no difference in operative time, complications or bleeding (53). The ultrasonically activated scalpel is superior with respect to avoidance of inadvertent gallbladder perforation (46,49) and is able to cut and coagulate tissue without the generation of smoke. Although there is atomization of fluid which creates a transient mist, this does not accumulate, and does not significantly impair the visual field as the droplets rapidly settle out. This mist is capable of carrying tissue fragments but no living cells have been found in this mist (59,60). Furthermore, the amount of tissue fragments created appears similar to that produced with electrosurgery (60). It is unknown at the present time if this mist carries live viral particles or DNA as has been observed with laser surgery (60).

The handpiece of ultrasurgical devices is electrically grounded. This eliminates electric injury to the user or patient from the handpiece. The ultrasonically activated scalpel also eliminates the risks of electrical injury to the patient and surgeon, since there is no current flow through the patient. As a result, problems with sparking, capacitance and injury away from the visual field are eliminated. Finally, because there is little or no cutting ability with the blade in an inactivated situation, the blunt side of the ultrasonically activated scalpel can also be used as a blunt dissector.

A second mechanism for cutting tissue with ultrasound is cavitation, a process that is not as prominent in ultrasonic surgical devices, such as the Harmonic Scalpel, because of the geometry of the blade. However, ultrasonic dissecting devices, the so called ultrasonic cavitational aspirators (CUSA? System, Valley Labs, or Ultra? Ultrasonic Aspirator, Sharplan Lasers, Inc.) harness the ultrasonic energy to primarily if not solely produce cavitational fragmentation. These ultrasonic cavitational devices operate in the range of 23 kHz (45) and produce the cavitational effect by propagating the mechanical wave to a tapering, hollow, small diameter tip. As is the case for ultrasurgical devices, ultrasonic cavitational aspirators are composed of a generator, hand piece and tip. The generator is a microprocessor controlled, high frequency switching, power supply that provides electrical energy to the hand piece (Figure 45). The hand piece houses the ultrasonic transducer which, vibrates at its natural harmonic frequency of 23 kHz. This vibrational energy is then conducted via a hollow, 10 to 12 mm, circular, titanium tube (resonator) to a 3mm, conical, hollow tip, such that the tip vibrates in an axial direction 23,000 times per second with a longitudinal displacement of 200 to 300 m (62) (Figure 46). The tube and tip are encased in a protective flue which provides irrigation and aspiration.

The longitudinal vibrational activity of the narrow hollow tip when combined with suction allows fragmentation and aspiration of collagen sparse tissue. The mechanism of this cavitational action is controversial. However, it is generally believed that the extremely rapid, forward and backward motion of the tip in contact with the tissue results in the generation of increasing and decreasing internal tissue pressures. When the internal tissue or cellular pressure falls below the vapor pressure of tissue and cellular fluid, vapor filled vacuoles form within the cell. These vacuoles expand and contract with each excursion of the aspirator tip, generating forces that fragment cells or expands tissue planes. By aspirating the tissue at the same time, tissue debris from fragmentation is cleared to allow further cavitational fragmentation and the tissue is held in better contact with the vibrating source to allow more optimal tissue coupling with the energy.

Tissue damage is confined to an area of about 1 to 2 mm next to the tip (45). Despite this small distance, heat is dissipated within the blade and the tissue during the vibration of the tip that is of sufficient intensity to burn through a surgical glove. In fact, given the lower operating frequency and the geometry of the blade of ultrasonic cavitational devices, more heat is produced in the tissue and at the blade than with ultrasurgical devices. However, there is little denaturization of protein and heat damage in tissues because the device is cooled with saline. A reduction in the irrigant flow can allow an increase in the temperature of the tip and produce a better coagulation effect but it is not equivalent in degree to that obtained with electrosurgery.

The ultrasonic cavitational aspirator is tissue selective because the fragmentation of tissue depends on the water and fat content of the tissue. Low water content tissues such as those that are collagen rich (blood vessels, nerves, ureters) require considerable more energy to fragment than high water content tissues such as liver, tumors and spleen. The tissue selectivity provided by the ultrasonic cavitational aspirator combined with minimal thermal damage result in an excellent dissection device that provides safe dissection of tissues with preservation of nerves, arteries and other collagenous structures.

The ultrasonic cavitational aspirator represents the evolution of the phaco-emulsifier used extensively in cataract surgery (63). In the late 1970's the phaco-emulsifier was modified to provide more power, such that it could fragment tissues such as liver and, therefore, rendering it more useful in open surgical procedures (64). Extensive work by Hodgson et.al..(45), and others (64-68) has proven the usefulness and safety of this device is open surgery such as tumor debulking, neurosurgery, and liver surgery.

The evolution of laparoscopic surgery has brought with it an appreciation of the need for adequate exposure and precise bloodless dissection. Application of the ultrasonic aspirator to laparoscopic surgery has arisen from this realization. Mounting clinical and experimental evidence supports the use of ultrasonic cavitational devices in this setting. Wetter, et.al.(69) reported the use of ultrasonic cavitational aspirators facilitates laparoscopic cholecystectomy in certain circumstances. In their randomized, comparative study of 73 patients using laser surgery, electrosurgery or the ultrasonic cavitational aspirator, the ultrasonic cavitational aspirator was particularly useful for dissecting Calot's triangle, especially when the cystic duct and artery were enveloped by adipose tissue or acute inflammation (edema). Dissection of a fibrous gallbladder from the liver bed, however, was not simplified by the ultrasonic cavitational aspirator and required either electrosurgery or lasers for completion of this stage of the dissection. In addition, because of the absence of coagulating and cutting with the ultrasonic cavitational aspirator, either electrosurgery or clips are necessary for complete hemostasis and scissors are preferred for separation of tissue planes. At least one model, the CUSA® CEM?, now incorporates electrosurgery. This should reduce the number of instrument changes required during ultrasonic cavitational dissection to completely free the structure.

The laparoscopic ultrasonic cavitational aspirator has been successfully used in the treatment of endometriosis (62), and in advanced gynecologic endoscopic procedures such as presacral neurectomy and laparoscopically assisted vaginal hysterectomy (69). Another exciting area for application of the ultrasonic cavitational aspirator is in laparoscopic colectomy. Initial clinical experience with this device has shown it to speed dissection by allowing for more rapid and precise skeletonization of the mesentery. This should result not only in facilitation of the procedure but in a reduction in overall cost as less time, clips, and staples are necessary. This can also be achieved rapidly with an ultrasurgical scissors and should be more rapid than the ultrasonic cavitational device due to the reduction in instrument changes need to accomplish the procedure.

The tissue selectively demonstrated by the ultrasonic cavitational aspirators should not lead the surgeon to a false sense of security that injury of vital structures is not possible with the device. The small diameter tip of the cavitational aspirator creates a very high power density, particularly when the tip is placed perfectly perpendicular to a structure. This high power density combined with any reduction in irrigant flow can lead to a tremendous build of heat in the tissue and significant thermal damage to tissue. This is illustrated in the report by Kato and colleagues (71) of a pinhole occurring in the common duct during cavitational dissection in the hepato-duodenal ligament in 91 laparoscopic cholecystectomies.

A final action of ultrasonic surgical devices in general and ultrasurgical instruments in particular that is rarely considered by surgeons is tissue drilling. Ultrasurgical devices particularly with a ball tip can drill a coagulated channel though soft tissue if constant pressure is applied to a site over a long period of activation. This feature is currently used by dentists to repair dental cavities and has is under evaluation for ablation of atheromatous plaques in blood vessels. The use of this action in general surgery is likely to find most usefulness in the coring of tumors in hollow structures such as the esophagus and in creating channels for placement of other devices such as cryoprobes. Although there is some animal research in this area, this action has not been reported clinically.

 

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7. Thompson BH and Wheeless CR. Gastrointestinal complications of laparoscopic sterilization. Obstet Gynecol. 1975; 41: 669-76.

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10. Odell RC. Electrosurgery: Principles and safety issues. Clin Obstet Gynecol. 1995; 38: 610-21.

11. Ata AH, Bellemore TJ, Meisel A et al. Distal thermal injury from monopolar electrosurgery. Surgical Laparoscopy and Endoscopy 1993; 3: 323-7.

12. Saye, WB, Miller W and Hertzmann, P Electrosurgical Thermal Injury. myth or misconception. Surgical Laparoscopy and Endoscopy. 1991; 1: 223-228.

13. Tucker RD, Voyles CR and Silvis SE. Capacitive coupled stray currents during laparoscopic and endoscopic electrosurgical procedures. Biomedical Instrumentation and Technology 1992; 26; 303-11.

14. Voyles CR and Tucker RD. Unrecognized hazard of surgical electrodes passed through metal suction-irrigation devices. Surg Endosc 1994; 8: 185-87.

15. Tucker RD and Ferguson S. Do surgical gloves protect staff during electrosurgical procedures? Surgery 1985; 110; 892-95.

16. Leavitt MD, Bond JH. Volume, composition and source of intestinal gas. Gastroenterology. 1970; 59:921.

17. Neuman GG, Sidebotham G, Negoianu, et al. Laparoscopic explosion hazards with nitrous oxide. Anesthesiology 1992; 78: 875-9.

18. Ott D Smoke production and smoke reduction in endoscopic surgery: Preliminary report. End. Surg 1993;1:230-32..

19. Esper E, Russell TE, Coy B et al. Transperitoneal absorption of thermocautery-induced carbon monoxide formation during laparoscopic cholecystectomy. Surgical Laparoscopy and Endoscopy 1994; 4: 333-335.

20. DesCoteaux, Picard P Poulin EC and Baril M. Preliminary study of electrocautery smoke particle produced in vitro and during laparoscopic procedures. Surg Endoc 1996; 10: 152-58

21. Wu JS, Luttmann DR Meininger TA and Soper NJ. Production and systemic absorption of toxic byproducts of tissue combustion during laparoscopic surgery. Surg Endosc 1997; 11: 1075-9.

22. Nezhat C, Seidman DS, Vreman, HJ et al The risk of carbon monoxide poisoning after prolonged laparoscopic surgery. Obstet Gynecol. 1996; 88: 771-4.

23. Rappaport WD, Hunter GC, Allen R et al. Effect of electrocautery on wound healing in midline laparotomy incisions. Am J. Surg 1990; 160: 618-620.

24. Hambley, R, Hebda PA, Abell E, Cohen, B., Jegasothy BV. Wound healing of skin incisions produced by ultrasonically vibrating knife, scalpel, electrosurgery, and carbon dioxide laser. J. Dermatol Surg. Oncol 1988;14:11.

25. Kim K, Brunner E, Ritter E et al. Relevance of methods of skin incision technique on development of wound infection. Am. Surg. 1991; 88: 129-30.

26. Soballe PW, Nimbkar NV, Hayward I et al. Electric cautery lowers the contamination threshold for infection of laparotomies. Am J Surg 1998; 175; 263-66.

27. Porter KA, O'Connor S Rimm E and Lopez M. Electrocautery as a factor in seroma formation following mastectomy. Am J Surg 198; 176; 8-11.

28. Peterson HB, Ory HW, Greenspan JR and Tyler CW. Deaths associated with laparoscopic sterilization by unipolar electrocoagulating devices, 1978 and 1979, am J Obstet Gynecol 1981; 139: 141. 1981.

29. Phillips JM, Keith D, Hulka JF et al. Gynecologic laparoscopy in 1975. J Reprod. Med 1975; 16:105-10.

30. Levy BL and Soderstrom RM. Bowel injuries during laparoscopy: Gross anatomy and histology. J Reprod Med 1085; 30: 168-75.

31. DiGiovanni M, Vasilenko P and Belsky D. Laparoscopic tubal sterilization. The potential for thermal bowel injury. J. Reprod. Med. 1990; 35: 951-4.

32. Stewart KS, Pearson JF, Docker et al. A possible hazard of laparoscopic sterilization. Am. J. Obstet. Gynecol. 1973; 115: 1154-57.

33. Greenwood J Two point or interpolar coagulation. A new principle and instrument for applying current in neurosurgery. Am J Surg 1940; 50: 267-70.

34. Malis L Electrosurgery. J Neurosurgery 1996; 85: 970-75.

35. Corson SL, Patrick H and Hamilton T. Electric consideration of laparoscopic sterilization. J Reprod Med 1973; 11: 159-64.

36. Rioux JE, Cloutier D. A new bipolar instrument for laparoscopic tubal sterilization. Am J Obstet Gynecol 1974; 119: 737-9.

37. Moore JP, Silvis SE, and Vennes, JA. Evaluation of bipolar electrocoagulation in canine stomachs. Gastrointestinal endoscopy. 1978; 24: 148-151.

38. Riedel HH, Cortis-Kleinwort G, and Semm K. Various coagulation techniques tested in a rabbit model. Endoscopy 1984; 16: 47-52.

39. Baggish MS and Tucker RD. Tissue actions of bipolar scissors compared with monopolar devices. Fertility and Sterility 1995; 63: 422-6.

40. Tucker RD, Benda JA, Marden A and Engel T. The interaction of electrosurgical bipolar forceps and generators on an animal model of fallopian tube sterilization. Fertility and Sterility. 1995; 63: 422-6.

41. Ramsay JWA, Shepard NA Butler M et al. A comparison of bipolar and monopolar diathermy probes in experimental animals. Urol Res 1985; 13: 95-102.

42. Papp JP, State of the art: endoscopic electrocoagulation of actively bleeding upper gastrointestinal lesions. Am J. Gastroent 1979: 71: 516-21.

43. Tucker RD and Hollenhorst MJ. Bipolar electrosurgical devices. End Surg. 1993: 1: 110-114.

44. Ayers JWT, Johnson RS, Ansbacher R, et al. Sterilization failures with bipolar tubal cautery. Fertil Steril 1984; 42: 526-30.

45. Hodgson, WJ, Poddar, PK, Mencer, EJ, et.al. Evaluation of ultrasonically powered instruments in the laboratory and clinical setting. Am. J. Gastroent. 1979;72: 133-140.

46. Amaral JF Laparoscopic application of an ultrasonically activated scalpel. Gastrointest. Clin No. Am. 1993; 3: 381-392.

47. Halliday, D and Resnick, R Fundamentals of Physics John Wiley & Sons New York, 1974.

48. Amaral JF. The experimental development of an ultrasonically activated scalpel for laparoscopic use. Surg. Endo Laparosc. 1994;4:92-99.

49. Amaral JF Laparoscopic cholecystectomy in 200 consecutive patients using an ultrasonically activated scalpel. Surg Laparosc & Endo 1995;5: 255-62.

50. Mueller W. The advantages of laparoscopic assisted bipolar high frequency surgery. End Surg. 1993;1: 96-96.

51. Hoenig DM, Chrostek CA and Amaral JF Laparosonic Coagulating Shears: Alternative Method of Hemostatic control of unsupported tissue. J Endourology 1996; 10: 431-3.

52. Meltzer RC, Hoenig DM, Chrostek C and Amaral, JF. Porcine seromyotomies using an ultrasonically activated scalpel. Surg Endosc 1994;8: 253.

53. Amaral JF and Chrostek C. Comparison of the ultrasonically activated scalpel to electrosurgery and laser for laparoscopic surgery. Min Invas Ther & Allied Technol. 1997; 6: 324-31.

54. Amaral JF and Chrostek C. Depth of thermal injury: Ultrasonically activated scalpel versus electrosurgery. Surg Endosc. 1995; 9: 226.

55. Swanstrom LL and Pennings JL. Laparoscopic control of short gastric vessels. J Am Coll Surg 1995; 181: 347-51.

56. Laycock WS, Trus TL and Hunter JG. New technology for division of short gastric vessels during laparoscopic Nissen fundoplication. A prospective randomized trial. Surg Endosc. 1996; 10: 71-3

57. Underwood RA, Dunnegan DL and Soper NJ. Prospective randomized trial of bipolar electrosurgery v3rsus ultrasonic coagulation for division of short gastric vessels during laparoscopic Nissen fundoplication. Surg Endosc 1998; 12:509.

58. Spivak H, Richardson WS and Hunter JG. The use of bipolar cautery, laparosonic coagulating shears, and vascular clips for hemostasis of small and medium sized vessels. Surg Endosc. 1998; 12: 183-5.

59. Marinkovic, S, Chrostek, CA and Amaral, JF. Surgical Laparoscopic Energy and Lateral Thermal Damage. Minimally Invasive Therapy, 1994; 4: 333.

60. Ott DE, Moss E and Martinez K. Aerosol exposure from an ultrasonically activated (Harmonic) device. J Am Assoc Gynecol Laparosc 1998; 5: 29-32.

61. Nduka CC, Poland N, Kennedy M, et al. Does the ultrasonically activated scalpel release viable airborne cancer cells? Surg Endosc 1998; 12: 1031-34.

62. Vasquez, JM, Eisenberg, E, O'Steen, KG et.al. Laparoscopic ablation of endometriosis using the cavitational ultrasonic surgical aspirator. J. Am.Assn Gyn Laparoscopists 1993;1:36-42.

63. Kelman, CD. Phaco-Emulsification and aspiration-Report of 500 consecutive cases. Am. J. Opth. 1973; 75: 764-768.

64. Flamm, ES, Ransohoff, J., Wunchinich, et.al. Preliminary experience with ultrasonic aspiration in neurosurgery. Neurosurgery 1978; 2:240-256.

65. Hodgson, WJ, Morgan, J, Byrne, D, and DelGuercio, LR. Hepatic resections for primary and metastatic tumors using the ultrasonic surgical dissector. Am. J. Surg. 1992; 163: 246-250.

66. Fasano, VA, Zemi, S, Frego, L et.al. Ultrasonic aspiration in the surgical treatment of intracranial tumors. J. Neurosurg. Sci. 1981; 25: 35-40.

67. Chopp RT, Shah BB, Addonizio JC. Use of ultrasonic surgical aspirator in renal surgery. Urology 1983; 22: 157-9.

68. Transberg KG, Rigotti P, Brackett KA, et. al. Liver Resection: a comparison using the Nd-YAG laser, an ultrasonic surgical aspirator or blunt dissection. Am. J. Surg. 1986; 151;368-73.

69. Wetter, LA, Payne, JH, Kirschenbaum, G, et.al. The ultrasonic dissector facilitates laparoscopic cholecystectomy. Arch. Surg. 1992; 127: 1195-1199.

70. Grochmal SA, Weekes A, Garratt D, et.al. Applications of the laparoscopic ultrasonic aspirator for advanced gynecologic operative endoscopic procedures. J. Am. Assn Gyn Laparoscopists 1993;1:43-47.

71. Kato, et al. J. Laparo Endo. Surg. 1995; 5: 31-6

 

FIGURES

Figure 1. DC and AC current

DC current is the unidirectional flow of electrons. AC current involves the rapid reversal polarity as shown here.

Figure 2. Radiofrequency spectrum

Figure 3. Monopolar circuit

Injury occurs at the active electrode because the site of contact is small. Injury does not occur at the indifferent electrode has a large surface area. This large surface area means the current density is low at any given site on it

Figure 4. Monopolar indifferent electrode placement.

The pathways to the indifferent electrode will be more direct as the indifferent electrode gets closer to the operative site

Figure 5. Bipolar electrode

Figure 6. Electrosurgical actions: Cut, fulguration and desiccation

Figure 7. Electrosurgical waveforms

Open circuits are associated with higher peak voltages and more variability than closed circuits.

Figure 8. Blend currents

The blend current is a cutting current in which the duty cycle has been reduced.

Figure 9. Valley Lab and ConMed electrosurgical generators

Figure 10. ERBE Generator

Figure 11. Ground pad burn

(Courtesy of Valley Lab)

Figure 12. Alternate site burn

Figure 13. Insulation failure zones

From: Voyles CR and Tucker RD. Education and engineering solutions for potential problems with laparoscopic monopolar electrosurgery. Am. J. Surg. 1992; 57-62.

Figure 14. Insulation breaks in instruments

Figure 15. Insulation failure from instrument

(Courtesy of Valley Lab)

Figure 16. Active electrode monitoring system

(Courtesy of Valley Lab)

Figure 17. Current concentration in spermatic cord

From Schellhammer PF Electrosurgery: Principles, hazards and precautions. Urology 1974; 3:261-8.

Figure 18 Current concentration on duodenum

Figure 19 AC and DC current capacitors

Figure 20 Capacitive coupling: cut, coagulation and blend circuit

From: Voyles CR and Tucker RD. Education and engineering solutions for potential problems with laparoscopic monopolar electrosurgery. Am. J. Surg. 1992; 57-62.

Figure 21 Capacitive coupling: 2 vs 11 mm cannula

From: Voyles CR and Tucker RD. Education and engineering solutions for potential problems with laparoscopic monopolar electrosurgery. Am. J. Surg. 1992; 57-62.

Figure 22 Capacitive coupling from cannula

(Courtesy of Valley Lab)

Figure 23 Capacitive coupling: current dispersement

Figure 24 Argon beam coagulator

(Courtesy of Conmed)

Figure 25 Bipolar vs monopolar current density

From Ramsay JWA, Shepard NA Butler M et al. A comparison of bipolar and monopolar diathermy probes in experimental animals. Urol Res 1985; 13: 95-102.

Figure 26 Bipolar vs monopolar heat conduction

From Ramsay JWA, Shepard NA Butler M et al. A comparison of bipolar and monopolar diathermy probes in experimental animals. Urol Res 1985; 13: 95-102.

Figure 27 Bipolar coagulation with Klepinger forceps

(Courtesy of Valley Lab)

Figure 28 Bipolar cutting devices

(Courtesy of Everest Medical)

Figure 29 Bipolar cutter - Everest Medical

(Courtesy of Everest Medical)

Figure 30 Sietzinger Tripolar device

(Courtesy of Circon)

Figure 31 Longitudinal versus mechanical wave

From Halliday, D and Resnick, R Fundamentals of Physics John Wiley & Sons New York, 1974.

Figure 32 Ethicon-Ultracision System

(Courtesy of the Ethicon Endosurgery Division of Johnson and Johnson)

Figure 33 USSC-AutoSonix system

(Courtesy of the USSC division of Tycos)

Figure 34 Olympus - SonoSurg system

(Courtesy of Olympus Corporation)

Figure 35 Schematic of handpiece

Figure 36 Principle of superposition

From Halliday, D and Resnick, R Fundamentals of Physics John Wiley & Sons New York, 1974.

Figure 37 Principle of superposition

From Halliday, D and Resnick, R Fundamentals of Physics John Wiley & Sons New York, 1974.

Figure 38 Standing wave

From Halliday, D and Resnick, R Fundamentals of Physics John Wiley & Sons New York, 1974.

Figure 39 Standing wave - photo

This photo of a constantly vibrating string shows the sinus wave pattern that is left in a standing wave after a steady state is reached.

From Halliday, D and Resnick, R Fundamentals of Physics John Wiley & Sons New York, 1974.

Figure 40 Acoustic horn

The first reduction in mass of the device causes amplification of displacement from 8 to 25 microns.

Figure 41 Acoustic horn

The second reduction in mass of the device causes amplification of the displacement to 80 microns.

Figure 42 Blades

The top left blade with sharp edges cuts well but coagulates poorly. The top right blade with its large mass and dull edges coagulates well but cuts poorly. The bottom left blade has characteristics for both to provide cutting and coagulating. The ball coagulator in the bottom left panel has geometry that provides coagulation in various positions.

Figure 43 Temperature versus tissue effect

From: Mueller W. The advantages of laparoscopic assisted bipolar high frequency surgery. End Surg. 1993;1: 96-96.

Figure 44 Depth of thermal injury

Figure 45 CUSA generator

(Courtesy of Valley Lab)

Figure 46 CUSA handpiece-tip

(Courtesy of Valley Lab)

 

Table Electrocautery versus Electrosurgery

	Electrocautery	Electrosurgery
Current travels through the tissues	No	Yes
The effect is proportional to the electrical resistance of the tissues	No	Yes
Cuts and coagulates tissues	No	Yes
Can produce effects distal to the site of contact	No	Yes

 

Electrosurgical Injuries and Risks

Grounding failures

Alternate Site Injuries

Demodulated currents

Insulation failure

Tissue injury at a distal site

Sparking

Direct coupling

Capacitive coupling

Surgical glove injury

Explosion

Toxic aerosols

 

Table 3: Performance Specifications

Force 2 Valley Lab Electrosurgical Generator

Max Open Rated Load Max Power at Crest factor
Circuit P-P voltage Ohms rated load

 

CUT 3000 300 300 1.9

Blend1 3500 300 250 2.4

Blend 2 3500 300 200 2.7

Blend 3 4000 300 150 3.0

Coag 7000 300 120 9.0

Low Volt Coag 3500 300 99 3.0

Bipolar

Cut 1200 150 70 1.9

 

Conmed Excalibur plus PC

Max Open Rated Load Max Power at Crest factor

Circuit P-P voltage Ohms rated load

Monopolar

Pure cut 2,000 300 300 1.8

Blend 1 2,000 300 180 2.4

Blend 2 2,200 300 120 3.1

Blend 3 2,400 300 80 3.8

Coag Standard 6,500 300 120 6.4

Coag Spray 10,500 500 80 8.5

Bipolar

Cut 400 50 50 1.7

Coag 400 50 50 1.5-12

 

4. Conversion: When, how and why?

Univ. Prof. Dr. Wolfgang Wayand, MD, F.A.C.S.

AKh- Academic teaching Hospital, 2nd Surgical department and, Ludwig Boltzmann Institut für operative Laparoskopie; Krankenhausstr. 9, A-4020 Linz

 

The Latin word "conversio" stands for change of attitude.

In our context "conversion" usually is used as a technical term for switching from a laparoscopic to a traditional surgical procedure. Before starting a laparoscopic procedure, surgeons must have the patients informed consent, that he would agree to this conversion whenever necessary. We have to keep in mind, that laparoscopy is one option, but it is never the patients right to have it performed this way. This will give the surgeons the option to convert the procedure whenever necessary and it must never be taken as a failure.

However there are no prospective randomised trial for when, how and why to convert, but the following reasons may lead to it:

 

Technical reasons:

Insecurity at the application of the pneumoperitoneum.
Camera failure, breakdown of electricity, inadequate instruments, etc. ...

Anatomical reasons:

Adhesions, unsecurity to identify vital structures (common bile duct, ureter, etc.)

Unacceptable long operation time:

If after 30 minutes no progress is achievable, conversion is recommended.

Complications:

Bleeding, perforation, possible damage of vital structures, anaesthesiological problems, etc.

 

The surgeon should always consider the possibility of conversion. So the trocars should be placed in such a way, that the trocar sites could be included in a traditional laparotomy, when required.

The patients individual risk of facing a conversion should be estimated preoperatively. For the example of a laparoscopic cholecystectomy we found in a prospective study on 300 patients that the following parameters will increase the individual patients probability to have his operation converted:

right upper quadrant pain (p < 0.01) rigidity in right upper abdomen (p < 0.01), previous upper abdominal surgery (p < 0.01), biliary colic within the last 3 weeks

(p < 0.05), white blood cell count > 10 x 10 (9)/1 (p < 0.05), thickening of the gallbladder wall (p < 0.05), hydroptic gallbladder (p < 0.05), pericholecystic fluid (p < 0.01), shrunken gallbladder (p < 0.01).

In dubio - incisio (whenever in doubt, incise!) A laparotomy must never be considered as being a failure, the avoidance of a laparotomy might be one.

 

 

Literature:

1. A diagnostic score to predict the difficulty of a laparoscopic cholecystectomy from preoperative variables.

Schrenk P, Woisetschläger R, Rieger R, Wayand WU.

Surg Endosc 1998 Feb; 12 (2):148-50

2. Management of Major Biliary Complications After Laparoscopic Cholecystectomy

G. Branum, M.D., C. Schmitt, M.D., J. Baillie, M.D., P. Suhocki, M.D., M. Baker, M.D., A. Davidoff, M.D., S. Branch, M.D., R. Chari, M.D., G. Cucchiaro, M.D., E. Murray, R.N., T. Pappas, M.D., P. Cotton, M.D., W.C. Meyers, M.D.

Annals of Surgery 1993, Vol. 217, No. 5: 532-541

3. Mechanism, management, and prevention of laparoscopic bowel injuries

P. Schrenk, M.D., R. Woisetschläger, M.D., R. Rieger, M.D., W. Wayand, M.D.

Gastrointestinal Endoscopy 1996, Vol. 43, No. 6: 572-574

4. Fatal and life-threatening complications in antireflux surgery: analysis of 5502 operations

T.K. Rantanen, J.A. Salo and J.T. Sipponen

British Journal of Surgery 1999, 86: 1573-1577

5. Trocar Injuries in Laparoscopic Surgery

Sunil Bhoyrul, M.D., FRCS, Mark A Vierra, M.D., FACS, Camran R Nezhat, M.D., FACS, Thomas M Krummel, M.D., FACS, Lawrence W Way, M.D., FACS

J Am Coll Surg 2001, Vol. 192, No. 6: 677-683

 

---

C. Daniel Smith, MD

 

Why perfrom hernia repairs laparrscopically?

More comforatble and rapid recovery

Mechanically superior

Ideal for bilateral and recurrent hernia

 

Why NOT perfrom hernia repair laparoscopically?

Potential complications not typically seen in open hernia repair

Technically demands and difficult to learn

Potential increased cost of care

 

Avoiding problems during laparoscopic inguinal hernia repair

Know anatomy

Triangle of doom

Triangle of pain

Aberant obturator vessels

Minimize use of electrocautery

Correct dissection plans are avascular.

Electrocautery causes nerve injury

Limit number of points of fixation

Each point of fixation is potential nerve or vascular injury

Fixation into bone can cause chronic pain

Appropriate mesh placement

To keyhole or not to keyhole?

Can the mesh be too big?

Proper patient selection

Most difficult patient - large scrotal componenet, sliding hernia, recurrfent hernia
(especially prior laparoscopic repair), incarcerated hernia

 

Procedure specific problems

TEP

Hole in peritoneum

Epigastric vessels hanging in field

Bladder injury

Vascular injury (iliac vein or aberrant obturator artery/vein)

Sliding hernia or significant scrotal component

Postoperative urinary retention

Postoperative subcutaneous emphysema

Postoperative neuropraxia

Postoperative groin or scrotal seroma

TAPP

Bladder injury

Vascular injury (iliac vein or aberrant obturator artery/vein)

Bowel injury

Sliding hernia or significant scrotal component

Postoperative urinary retention

Postoperative bowel obstruction

Postoperative neuropraxia

Postoperative groin or scrotal seroma

Postopertive troca site hernia

 

Conversion strategies

TEP to TAPP

TEP or TAPP to Open

 

REFERENCES

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2. Ovroutski, S., et al., A rare complication of laparoscopic surgery: iatrogenic arteriovenous fistula with high-output cardiac failure. Surgical Laparoscopy, Endoscopy & Percutaneous Techniques, 2001. 11(5): p. 334-7.

3. Dalessandri, K.M., S. Bhoyrul, and S.J. Mulvihill, Laparoscopic hernia repair and bladder injury. Journal of the Society of Laparoendoscopic Surgeons, 2001. 5(2): p. 175-7.

4. Moreno-Egea, A., J.L. Aguayo, and M. Canteras, Intraoperative and postoperative complications of totally extraperitoneal laparoscopic inguinal hernioplasty. Surgical Laparoscopy, Endoscopy & Percutaneous Techniques, 2000. 10(1): p. 30-33.

5. Leibl, B.J., et al., Scrotal hernias: a contraindication for an endoscopic procedure? Results of a single-institution experience in transabdominal preperitoneal repair. Surgical Endoscopy, 2000. 14(3): p. 289-92.

6. Lau, H., et al., Laparoscopic totally extraperitoneal inguinal hernioplasty: an audit of the early postoperative results of 100 consecutive repairs. Annals of the Academy of Medicine, Singapore, 2000. 29(5): p. 640-3.

7. Jonsson, B. and N. Zethraeus, Costs and benefits of laparoscopic surgery--a review of the literature. European Journal of Surgery, 2000. Suppl(585): p. 48-56.

8. Duron, J.J., et al., Prevalence and mechanisms of small intestinal obstruction following laparoscopic abdominal surgery: a retrospective multicenter study. French Association for Surgical Research. Archives of Surgery, 2000. 135(2): p. 208-12.

9. Collaboration, E.H., Laparoscopic compared with open methods of groin hernia repair: systematic review of randomized controlled trials. British Journal of Surgery, 2000. 87(7): p. 860-7.

10. Stark, E., et al., Nerve irritation after laparoscopic hernia repair. Surgical Endoscopy, 1999. 13(9): p. 878-81.

11. Ramia, J.M., et al., Pneumomediastinum as a complication of extraperitoneal laparoscopic inguinal hernia repair. JSLS: Society of Laparoendoscopic Surgeons, 1999. 3(3): p. 233-4.

12. Lantis, J.C., 2nd and S.D. Schwaitzberg, Tack entrapment of the ilioinguinal nerve during laparoscopic hernia repair. Journal of Laparoendoscopic & Advanced Surgical Techniques. Part A, 1999. 9(3): p. 285-9.

13. O'Riordan, D.C. and L.F. Horgan, Intestinal obstruction following transabdominal pre-peritoneal laparoscopic inguinal hernia repair: comment. Australian & New Zealand Journal of Surgery, 1998. 68(1): p. 75.

14. Smith, C.D., G. Tiao, and T. Beebe, Intraoperative events common to videoscopic preperitoneal mesh inguinal herniorrhaphy. American Journal of Surgery, 1997. 174(4): p. 403-5.

15. Ferzli, G.S., et al., Pneumothorax as a complication of laparoscopic inguinal hernia repair. Surgical Endoscopy, 1997. 11(2): p. 152-3.

16. Ramshaw, B.J., et al., The effect of previous lower abdominal surgery on performing the total extraperitoneal approach to laparoscopic herniorrhaphy. Am Surg, 1996. 62(4): p. 292-4.

 

6. Complications Following Laparoscopic Ventral Hernia Repair

B. Todd Heniford, M.D., FACS

Carolinas Laparoscopic and Advanced Surgery Program, Department of General Surgery
Carolinas Medical Center, Charlotte, North Carolina

 

Introduction

An incisional hernia develops in 3% to 13% of laparotomy incisions, which necessitates approximately 90,000 ventral hernia operations per year (1). Unfortunately, primary repair of ventral hernias often yields unsatisfactory results; reported recurrence rates have ranged from 25% to 52% (2-4). The use of prosthetic materials to assist with ventral herniorrhaphy has decreased rates of recurrence, but important wound complications accompany mesh usage (4-7).

Laparoscopic incisional hernia repair has evolved to be feasible and safe. It has been shown to be as effective as the time-tested open repair, but is associated with possible post-operative complications. (8) Most of these are not unique to laparoscopic repair and are listed in Table 1.

 

Complications

Enterotomy

The incidence of small bowel enterotomy during laparoscopic ventral hernia repair has been reported to be from 1% to 6%. (8,9) When enterotomies are not identified intra-operatively, the outcome is often ominous. When an injury is identified, if it cannot be repaired laparoscopically, the patient must be converted to an open repair.

There are two main options when it comes to the management of a bowel injury and the placement of mesh. The safest measure may be to make the repair a two-stage operation. This entails repairing or resecting the injured bowel laparoscopically or in an open fashion, completing the adhesiolysis, and bringing the patient back for a second operation to repair the hernia defect from a few days to a few weeks later. The second option must be considered with caution. If there is no or minimal spillage associated with the enterotomy, and the enterotomy was in the small intestine, the injury may be repaired and the mesh placed at the same operation. This scenario has been reported in 5 patients within a single series, all of whom have done well, without mesh infection or other sequela. (8)

 

Seroma Formation

Seroma formation is not unique to the laparoscopic approach but since the hernia sac is not removed during laparoscopic ventral hernia repair, many patients develop a seroma at the hernia site. In the vast majority of patients, these seromas are palpable, but asymptomatic. Most will resolve spontaneously from to 10 weeks following surgery.

The treatment of seromas is somewhat controversial. Most surgeons will offer treatment only if the seroma becomes symptomatic, or has not resolved after a course of conservative management. Some authors advocate needle aspiration of a hernia site seroma. However, infection of the prosthesis must be considered as a possible complication associated with seroma aspiration. We have noted no long term complications from seromas following laparoscopic ventral hernia repairs regardless of whether they were aspirated early or allowed to persist for a maximum of 10 weeks.

 

Prolonged Suture Site Pain

After laparoscopic ventral hernia repair, patients will occasionally complain of persistent pain and point tenderness at a transabdominal suture site. The incidence of this complication long term is approximately 2%. (8) While this pain will resolve in most patients a percentage of them will require intervention. The first line of treatment can be a course of oral non-steroidal anti-inflammatory therapy or just additional time. If the pain persists, we have found that a one time injection of bupivacaine and lidocaine into the muscular fascia at the suture site can result in long-term relief of the discomfort in 85% of patients. (11) The procedure may be repeated if necessary. The mechanism of action of this technique is not well delineated but it is a useful clinical tool in the management of this problem. Should local injection fail to provide permanent relief of suture site pain, the suture at fault can be removed.

 

Recurrence

The recurrence rate after laparoscopic ventral hernia repair was reported to be <10% in early series (9,10), and more recently has been shown to be <4%. (8) While patient selection, infection, and other factors can contribute to recurrence, the underlying factor in many reported recurrences is lack of trans-abdominal suture fixation. Though hernia tacks or staples are routinely used to fix the edge of the mesh they should not serve as the primary source of attachment. Tack and staples do not provide a firm "purchase" on the fascia, and the result is mesh migration. Large, nonabsorbable sutures should be used to provide strong and reliable fixation of the mesh prosthesis.

Complication	No. ( % ) of Patients (n=407)
Prolonged ileus	9 (2.21)
Seroma > 6 wk	8 (1.97)
Suture site pain > 8 wk	8 (1.97)
Intestinal injury	5 (1.23)*
Cellulitis of trocar site	5 (1.23)
Mesh infection	4 (0.98)
Hematoma or postoperative bleeding	3 (0.74)
Urinary retention	3 (0.74)
Fever of unknown origin	3 (0.74)
Respiratory distress	2 (0.49)
Intraabdominal abscess	1 (0.25)
Trocar site herniation	1 (0.25)
Total	53 (13.0)

* Six patients in our total experience had enterotomies, but only 5 are listed here because the other patient required conversion to an open repair and was therefore not included in the data analysis.

 

References

1. Mudge M, Hughes LE. Incisional hernia: a 10-year prospective study of incidence and attitudes. Br J Surg 1985;72:70-71.

2. Hesselink VJ, Luijendijk RW, de Wilt JHW, et al. An evaluation of risk factors in incisional hernia recurrence. Surg Gynecol Obstet 1993;176:228-234.

3. Linden van der FT, Vroonhoven van TJ. Long-term results after surgical correction of incisional hernia. Neth J Surg 1988;40:127-129.

4. Stoppa RE. The treatment of complicated groin and incisional hernias. World J Surg 1989;13:545-554.

5. Temudom T, Siadati M, Sarr MG. Repair of complex giant or recurrent ventral hernias by using tension-free intraparietal prosthetic mesh (Stoppa technique): lessons learned from our initial experience (fifty patients). Surgery 1996;120:738-744.

6. White TJ, Santos MC, Thompson JS. Factors affecting wound complications in repair of ventral hernias. Am Surg 1998;64:276-280.

7. Leber GE, Garb JL, Albert AI, et al. Long-term complications associated with prosthetic repair of incisional hernias. Arch Surg 1998;133:378-382.

8. Heniford BT, Park A, Ramshaw BJ, Voeller G. Laparoscopic ventral and incisional hernia repair in 407 patients. J Am Coll of Surg 2000;190:645-50.

9. LeBlanc KA, Booth WV, Whitaker JM, et al. Laparoscopic incisional and ventral herniorraphy in 100 patients. Am J Surg 2000;180:193-7.

10. Holzman MD, Purut CM, Reintgen K, et al. Laparoscopic ventral and incisional hernioplasty. Surg Endosc 1997;11:32-5.

11. Pollinger HS, Harold KL, Nelms CD, Matthews BD, Kercher KW, Sing RF, Heniford BT. Local injection for the treatment of suture site pain after laparoscopic ventral hernia repair. Abstract submitted to the American Hernia Society, 2002.

 

7. Appendectomy

A. Fingerhut, MD

 

SYLLABUS NOT AVAILABLE

 

8. Colectomy

Antonio M. Lacy, M.D. Ph.D.

Consultant surgeon and Asst. Proffessor, Gastrointestinal Surgery
Institute of Digestive Diseases, Hospital Clínic. University Of Barcelona
Villarroel 170, 08036 Barcelona. Spain
e-mail: alacy@medicina.ub.es alacy@clinic.ub.es

 

Laparoscopic surgery has represented a great progress in the treatment of many gastrointestinal diseases. Early reports on laparoscopic-assisted colectomy (LAC) in patients with colorectal diseases suggested that it minimises surgical trauma, decreases perioperative complications and leads to more rapid recovery. However, development of complications such as port-site metastases in colorectal cancer patients in some cases questioned this approach. Gastrointestinal surgeons experienced in colon and rectal procedures are understandably concerned about the problems of treating colorectal lesions by laparoscopic means. The rapid adoption by some surgeons of laparoscopic techniques in colorectal surgery could suggest some impulsiveness by some authors. However, the role of laparoscopic surgery will require acritical examination of risks-benefits balance: "evidence-based medicine" ("From promising report to standard procedure: seven stages in the career of a medical innovation". JB McKinlay, 1981).

Laparoscopic colorectal surgery presents some important differences with other surgical procedures by laparoscopic approach. This is a multi-quadrant technique, that it means the surgeon has to require advanced two-hand surgical skills. These procedures require labour intensive and time consuming. The surgeon should to control of named vascular structures and usually needs bowel anastomosis. In our hands, more than 80% of our surgery in colorectal diseases is performed for malignancy. However, there are still some controversies:

-current standard of care for the treatment of colorectal carcinoma

-local wound recurrence of tumour cells in port sites and incisions

-resections of T4 lesions

-cost-benefit

-length of hospitalization

-intraoperative laparoscopic complications (related to the technique and lack of tactile sensation)

 

General surgeons have demonstrated clear advantages of the technique on laparoscopic cholecystectomy. Will this scenario be repeated for the use of LAC?. Laparoscopic colorectal resection is still in the early stages of clinical evaluation worldwide. Before accepting the laparoscopic technique as the standard procedure to treat colorectal diseases, those questions need to be addressed:

-Is colorectal resection technically feasible by the laparoscopic approach?

-Is the morbidity of colorectal resection affected by the laparoscopic technique?

-Is the laparoscopic approach oncologically safe?

-Is the laparoscopic approach a technique in the current resident training programs around the world?

-Should LAC be performed by all surgeons or only by specially qualified surgeons who are adept in laparoscopic procedures or colorectal surgeons?

 

This relatively new technology must be analyzed by well-trained, experienced laparoscopic and colorectal teams, because the surgical indication is colon and rectal cancer in many cases. Perhaps there is less controversy with regard to benign disease. However, it is very important to know the real incidence of morbidity related to the laparoscopic technique defined as a complication caused by the laparoscopic approach. This report analyzed the complications of the a quite large experience with more than 800 patients who underwent laparoscopic assisted colectomies at the Gastrointestinal Surgery Unit of the Institut of Digestive Diseases (IDD) of Barcelona. The results of IDD based in a modification of the grading system described by Clavien et al. This system allowed stratification by medical acuity:

Class I :none

Class II :intraoperative complication without conversion

Class III :conversion because of intraoperative complication

Class IV :relaparotomy after conversion because of intraoperative complication

Class V :complications associated with mortality

 

In this report was also included:

Intraoperative complications (enterotomies, colostomies, bleeding, anastomotic complications, localization of the lesions, other...)

Postoperative surgical complications

Postoperative non-surgical complications

 

Moreover, the complications related to LAC of colorectal malignancies are more important in a technical point of view. In a recent paper published by the Australian's group, they analysed 52 studies, after exclusions, and only 15 papers had a correct level of evidence (level 2 and 3-2). That it means the lack of papers with a high level of evidence published in the English literature about this controversial topic. It would be very interesting to know the complications related to oncological factors (lymph nodes recovered, tumor margins, ports site metastases, recurrence rate and survival).

This review found no significant differences in terms of overall complications rates. The disadvantages for LAC appear to group together around the trend toward increased duration of surgery. Of the total reported complication for laparoscopic colectomies only less than 10% are related to laparoscopic approach (that include hemorrhage, small bowel perforations, port site herniation, hematoma, etc...).

 

We discuss the results of a cohort of patients treated by laparoscopic colorectal surgery in our unit. We describe a prospective clinical study that includes patient operated upon laparoscopic approach. The period of study was a six year experience after more than 300 colorectal patients operated on laparoscopic technique. Results are studied according the above mentioned modified Clevian's classification comparing with open techniques.

We also present our results of Barcelona's trial (randomised controlled trial in laparoscopic colon cancer). In summary, the short-term results are: Operative time was significantly longer and intraoperative blood losses significantly lower with laparoscopic surgery. Patients of the LAC group recovered significantly faster than those of the OC group with shorter peristalsis detection and oral intake times, and shorter duration of hospitalization. Overall morbidity was significantly lower in patients treated with LAC (relative risk, 0·49; 95 percent confidence interval, 0·30 to 0·82). Postoperative complications are detailed in the table. One patient from the LAC group and three from the OC group died within 30 days of the surgical procedure (relative risk of perioperative mortality, 0·49; 95 percent confidence interval, 0·09 to 2·68).

 

Data related to surgical intervention and morbidity.

	Laparoscopic-assisted colectomy (n= 111)	Open colectomy (n = 108)	P value
Duration of the intervention (minutes)	142 ± 52	118 ± 45	0·001
Blood loss (mL)	105 ± 99	193 ± 212	0·001
Initiation of peristalsis (hours)	36 ± 31	55 ± 40	0·001
initiation of oral intake (hours)	54 ± 42	85 ± 67	0·001
Duration of hospital stay (days)	5·2 ± 2·1	7·9 ± 9·3	0·005
Morbidity (patients)	12	31	0·001
Postoperative complications wound infection persistent ileus evisceration intraperitoneal haemorrhage intraluminal haemorrhage anastomotic leak intraabdominal collection pneumonia acute renal failure hepatic cirrhosis decompensation infection of the urinary tract	8 3 - - - - - 2 - - 1	18 9 2 1 1 2 1 - 1 2 -

 

Despite that the first report on LAC in colon cancer was published in 1991, this procedure is currently used by very few groups. This contrasts to what it has occurred with cholecystectomy, for which laparoscopic surgery is the treatment of choice. Several features may explain this different attitude. First, LAC is technically a difficult procedure that requires intensive training. Second, there is few published randomised clinical trials comparing LAC to conventional open surgery in colorectal diseases. Therefore, there is no data to counteract the non-substantiated traditional view that appropriated oncological surgery requires an open approach. Finally, early reports suggested that LAC in colon cancer may favour tumour dissemination.

Our results clearly demonstrate that postoperative recovery is faster and complications fewer in patients treated by LAC. However, the most interesting result of the trial is that LAC appears to improve the long-term outcome obtained by conventional surgery in patients with colon cancer.

 

References

1. Lacy AM, García-Valdecasas JC, Delgado S, Grande L, Fuster J, Tabet J, Ramos C, Pique JM, Cifuentes A, Visa J. Postoperative complications of laparoscopic-assisted colectomy. Surg Endosc 1997; 11:119-22.

2. Milsom JW, Bohm B, Hammerhofer KA, Fazio V, Steiger E, Elson P. A prospective, randomised trial comparing laparoscopic versus conventional techniques in colorectal cancer surgery: a preliminary report. J Am Coll Surg 1998; 187:46-54.

3. Poulin EC, Mamazza J, Schlachta CM, Gregoire R, Roy N. Laparoscopic resection does not adversely affect early survival curves in patients undergoing surgery for colorectal adenocarcinoma. Ann Surg 1999; 229:487-92.

4. Franklin ME, Kazantsev B, Abrego D, Diaz EJ, Balli J, Glass L. Laparoscopic surgery for stage III colon cancer: long term follow up. Surg Endosc 2000; 14:612-6.

5. Berends FJ, Kazemier G, Bonjer HJ, Lange JF. Subcutaneous metastases after laparoscopic colectomy. Lancet 1994; 344:58.

6. Vukasin P, Ortega AE, Greene FL, Steele GD, Simons AJ, Anthone GJ, Weston LA, Beart RW Jr. Wound recurrence following laparoscopic colon cancer resection. Results of the American Society of Colon and Rectal Surgeons Laparoscopic Registry. Dis Colon Rectum 1996; 39:S20-S23.

7. Chapman AE, Levitt MD, Hewett P, Woods R, Sheiner H, Maddern GJ.Laparoscopic-assisted resection of colorectal malignancies: a systematic review.AnnSurg.2001;234:590-606.

8. Schiedeck TH, Schwandner O, Baca I, Baehrlehner E, Konradt J, Kockerling F, Kuthe A, Buerk C, Herold A, Bruch HP. Laparoscopic surgery for the cure of colorectal cancer: results of a German five-centre study.
Dis Colon Rectum 2000; 43:1-8.

9. Hartley JE, Mehigan BJ, Mac Donald AW, Lee PW, Monson JR. Patterns of recurrence and survival after laparoscopic and conventional resections for colorectal carcinoma. Ann Surg 2000; 232:181-6.

---

Bernard Dallemagne, M.D.

 

Since laparoscopic fundoplication was first described in 1991, it has become clear that laparoscopic antireflux surgery is associated with a small but significant incidence of complications and adverse outcomes. Some of these complications are common with open antireflux operations, some, unique to the laparoscopic approach, are particularly significant from the medico legal point of view.

Reported complications following laparoscopic antireflux surgery are diverse. TABLE 1

 

Pneumothorax

Intraoperative pneumothorax is reported in < 2% of patients: it's usually associated with an injury to the left pleural membrane during esophageal lateral dissection; it may occur also more frequently in "giant"hiatal hernia and redo operations.

Intraoperativley, it resulted in the following pathophysiologic changes: decrease in total lung thorax compliance, increase in airway pressures, and increase in CO2 absorption. Consequently, PACO2 and PETCO2 also increased. Spo2, however, remained normal. The use of PEEP largely corrected these respiratory changes.

It does not require the placement of chest drain, since carbon dioxid gas is rapidly reabsorbed. Early postoperative chest X ray may demonstrate a pneumothorax that will not be present one hour later.

 

Pneumomediastinum

Pneumomediastinum and subcutaneous emphysema are usually of little consequence and do not affect gaz exchanges.

 

Vascular Injury

Besides the "typical" vascular injuries associated with the laparoscopic access, there have been reports of more specific "antireflux" associated vascular injuries: to the inferior vena cava, the abdominal or thoracic aorta, the diaphragmatic vessels. These injuries are probably related to the experience of the surgeon.

Bleeding from the short gastric vessels is not rare and usually easily managed with the modern devices, cauthery, clips, ultrasonic dissectors. Bleeding from a laceration of the left liver lobe is usually managed by compression with a surgical sponge hold by the liver retractor.

The incidence of splenic injury and splenectomy is dramatically reduced by the laparoscopic approach: from 1-8 % in open operations to almost zero in laparoscopic surgery. It is more common following gastric mobilisation and short gastric vessels division and is due to wrong manipulation of the gastro-splenic ligament and/or instruments.

 

Perforation of the gastrointestinal tract

Unrecognized perforation of the gastrointestinal tract is the leading cause of death after laparoscopic antireflux operation.

Perforation of the small bowel, the colon or the duodenum are related to laparoscopic access in general.

Esophageal and gastric perforations are specific risks. Esophageal injury occurs during dissection of the retroesophageal space, during passage of a calibrating tube or even during suturing. Perforation of the stomach is usually due to the use of inappropriate instruments or traction on the tissues.

All of these injuries can be repaired by sutures.

Schauer et al. have analysed the sequences of these injuries and their consequences. They are related to the experience of the surgeon. If unrecognised, the morbidity and mortality rate increases dramatically. If recognised and repaired, they usually do not lead to complications.

 

Morbidity - Mortality

In recent years, the reported mortality rate after open fundoplication has ranged from 0 to 1.3 %; that after laparoscopic fundoplication has ranged from 0 to 1.4%.

In a review of 5502 antireflux operations performed in Finland between 1987 and 1996, Rantanen et al. reported 0.2% mortality rate after open fundoplication and 0.1% after laparoscopic approach. The prevalence of life-threatening complications was significantly greater after laparoscopic surgery (1.2%) than after open surgery (0.3% ). Table 2

There were considerable delays between the beginning of alarming symptoms and decision of intervention: 6 days after laparoscopic operation. The most frequent complication in both the open (16/23) and laparoscopic(10/15) was perforation of the esophagus or fundus. Recommendation is that if esophageal or gastric perforation is suspected, a water-soluble contrast swallow should be obtained without delay.

 

Conclusions

Over the last decade, it has become apparent that the laparoscopic approach is associated with an increased risk of some complications, and as well as the occurrence of new complications specific to the laparoscopic approach. More life-threatening complications were perceived after laparoscopic than after open fundoplication.

The incidence of some of these complications decreases as surgeons gain experience; others can be minimized by using an appropriate operative technique.

 

Table 1: Reported complications following laparoscopic antireflux surgery

(from Watson DI et al. Surg Endosc 15:344-352 )

Pneumothorax	Pneumomediastinum
Obstruction to bronchus	Pulmonary embolism
Cardiac laceration and tamponade	Pleuropericarditis
Injury to major vessels	Mesenteric thrombosis
Paraesophageal hiatus hernia	Hiatal stenosis
Bilobed stomach	Gastroparesis
Esophageal perforation	Gastric perforation
Duodenal perforation	Bowel perforation
Late diaphragmatic rupture	Delayed gastric perforation
Necrotizing fasciitis

 

Table 2: Life-threatening and fatal complications in antireflux surgery

(from Rantanen et al. Br J Surg 86 :1999 ;1573-1577)

	Open fundoplication (n =22)	Laparoscopic fundoplication (n =15)	Other antireflux procedure (n =6)
Oesophageal perforation	7 (2)	4	2 (1)
Gastric perforation	8 (4)	6 (1)	1 (1)
Intra-abdominal abscess	3 (1)	0	0
Oesophageal obstruction	0	3	0
Intestinal complications*	3 (2)	0	1 (1)
Intra-abdominal haemorrhage	0	2	0
Mediastinitis	1	0	0
Pneumonia	0	0	1 (1)
Heart failure	0	0	1 (1)

 

References

1. D. Pohl, T. R. Eubanks, P. E. Omelanczuk, and C. A. Pellegrini. Management and outcome of complications after laparoscopic antireflux operations. Arch.Surg. 136 (4):399-404, 2001.

2. D. I. Watson and A. C. de Beaux. Complications of laparoscopic antireflux surgery. Surg.Endosc. 15 (4):344-352, 2001.

3. G. Zaninotto, D. Molena, and E. Ancona. A prospective multicenter study on laparoscopic treatment of gastroesophageal reflux disease in Italy: type of surgery, conversions, complications, and early results. Study Group for the Laparoscopic Treatment of Gastroesophageal Reflux Disease of the Italian Society of Endoscopic Surgery (SICE). Surg.Endosc. 14 (3):282-288, 2000.

4. T. K. Rantanen, J. A. Salo, and J. T. Sipponen. Fatal and life-threatening complications in antireflux surgery: analysis of 5,502 operations. Br.J.Surg. 86 (12):1573-1577, 1999.

5. M. T. Viljakka, M. E. Luostarinen, and J. O. Isolauri. Complications of open and laparoscopic antireflux surgery: 32-year audit at a teaching hospital. J.Am.Coll.Surg. 185 (5):446-450, 1997.

6. J. D. Urschel. Complications of antireflux surgery. Am.J.Surg. 166 (1):68-70, 1993.

 

10. Management of New and Recurrent Symptoms Following Laparoscopic Fundoplication

John G. Hunter, M.D.

 

When performed through a laparotomy or thoracotomy, between 9% and 30% of patients develop recurrent symptoms or new troublesome symptoms that result as a side effect of fundoplication. 1-3 Reported failure rates with laparoscopic fundoplication range from 2% to 17% depending on how failure is defined. 4-8 That these failure rates are indeed lower than those reported for open fundoplication probably reflects the fact that laparoscopic fundoplication is a relatively new technique, not that laparoscopic fundoplication is intrinsically better.

The taxonomy of failure can be symptom based (e.g., heartburn, dysphagia, gas bloat) or it may be anatomically based, using a description of how the current anatomy deviates from the ideal. From a mechanistic and therapeutic standpoint, the latter definition is preferable. The anatomy of failure includes four common types of fundplication failure previously described with open surgery. These are (1) slipped or misplaced fundoplication, (2) disrupted fundoplication, (3) herniated fundoplication, and (4) fundoplication that is too tight or too long. 9 To this list of four can be added two new anatomic problems--the "two-compartment stomach" and the twisted fundoplication. 10

Early Postoperative Symptoms (<3 months)

In the early postoperative period (less than 3 months), the presence of certain symptoms is extremely common and no treatment other than reassurance is necessary.

The most common postoperative symptom is solid food dysphagia. Because distal esophageal edema (with or without hematoma) and transient esophageal dysmotility are common sequelae of fundoplication, it is no wonder that most patients have difficulty swallowing solid foods after a loose, floppy fundoplication is performed. We generally recommend that the patient stay on a full liquid diet for a week after surgery and then maintain a soft diet for the next 3 weeks following the operation. This protocol has dramatically reduced the incidence of postoperative food impaction, nausea, and vomiting seen when a regular diet is begun too soon after the operation. When patients complain of postoperative dysphagia, we urge them to return to a liquid diet until swallowing is easy, and then advance to a soft diet. If a patient has difficulty tolerating a full liquid diet, early intervention may be necessary. Options for early intervention include esophageal dilation and/or placement of a gastrointestinal feeding tube. We have used nasal enteric tubes and gastrostomy tubes when early postoperative dysphagia or nausea becomes so severe as to cause weight loss and dehydration.

Recurrent Symptoms (> 3 months)

When recurrent or new symptoms of GERD develop in the late postoperative period, investigation is warranted. For individuals who return with symptoms identical to those for which they underwent surgery, a diagnostic trial of antireflux medication is appropriate. In addition, we generally order a barium swallow, as we have determined that at least 90% of all fundoplication abnormalities can be seen with this study. 10 If the barium swallow is normal, it is unusual for patients to respond to proton pump inhibitor therapy. Because respiratory symptoms and atypical gastroesophageal reflux symptoms are so often intertwined, it may take the performance of a fundoplication to determine once and for all which supraesophageal symptoms are related to reflux and which are not. Frequently the typical symptoms of reflux (heartburn, dysphagia, regurgitation) will be eliminated by fundoplication, but the supra-esophageal symptoms in the same patient (globus, cough, hoarseness, wheezing) will not be eliminated. The best preoperative predictors of supraesophageal symptom relief after a fundoplication are the response of the symptom to proton pump inhibition and/or the correlation of supraesophageal symptoms with reflux events on a 24-hour pH study.

If preliminary evaluation with a postoperative barium swallow does not reveal any abnormalities, and a trial of medical therapy fails, further investigation is unlikely to bear fruit but should be done nevertheless. In 10% of our patients referred for postoperative symptoms, esophagogastroduodenoscopy (EGD) revealed an anatomic problem missed by barium swallow. 10 The most common anatomic problem discovered on EGD, when the barium swallow looked normal, was a slipped or misplaced Nissen fundoplication. Although the gastroesophageal junction may be difficult to define on barium swallow, an EGD demonstrating the prescence of gastric folds above a fundoplication indicates a Nissen valve that has been misplaced or slipped onto the stomach. Also, a partially disrupted flundoplication will be visable on EGD in the reteroflexed position, demonstrated by a gastroesophageal junction that is patulous (does not hug the scope), but this finding may be missed on barium swallow. When the results of EGD are normal and the barium swallow is normal, the 24-hour pH study (the fourth test) is almost always normal, as well.

Persistent Postoperative Dysphagia

In contradistinction to the patient with recurrent reflux symptoms, the patient with new-onset dysphagia represents a different problem. In the patient with dysphagia that persists past 3 months, we confirm that an anatomic abnormality exists by performing a video barium swallow with a 12.5 mm barium pill. If the pill passes the gastroesophageal junction readily, one must suspect that the dysphagia is a result of an esophageal motility disturbance or is of psychogenesis nature. Thus the normal barium swallow is followed by an esophageal motility study in patients with significant dysphagia. If the barium swallow demonstrates an anatomic abnormality near the gastroesophageal junction, a motility study is necessary, but only in preparation for a "redo" operation. The decision to reoperate at this point must be individualized based on the patient's nutritional status and the severity of the dysphagia. A patient who is still confined to liquids 3 months postoperatively, or a patient who is losing weight because of dysphagia, should be offered early elective reoperation. If the solid food dysphagia is mild or moderate, dietary restrictions are few, and weight loss is not present, we prefer a conservative course of management for the first year postoperatively. If, at that time, the barium tablet still hangs in the distal esophagus and the patient is bothered by the dietary restrictions that are necessary, a second operation is offered. The last scenario is one in which the postoperative barium swallow demonstrates an obvious anatomic problem, such as a slipped or herniated fundoplication. Most of these problems will require reoperation.

 

ANATOMIC FAILURE OF NISSEN FUNDOPLICATION

Fundoplication Herniation

The most frequent anatomic problem we have encountered in our patients following laparoscopic fundoplication has been herniation of the fundoplication across the diaphragm. 10 This has occurred in four settings. The first is the patient who strains or retches in the early postoperative period. Occasionally the patient will feel something pop, and usually patients have severe chest pain after herniation of the fundoplication. This is a surgical emergency and should be confirmed with water-soluable contrast radiography, followed by rapid return to the operating room for a laparoscopic or open reduction of the herniated stomach.

The second scenario is the patient who has a similar event, remote from the time of surgery. Although these patients may develop severe acute pain after herniation of the fundoplication, it is more usual for the event to be followed by heartburn, new onset of dysphagia, or development of postoperative chest pain resulting from gas or food distending the mediastinal portion of the herniated fundoplication. These patients should be evaluated by means of a barium swallow and esophagogastroscopy.

The third scenario is more insidious yet. It involves the patient who has a slow onset of recurrent or new symptoms (chest pain, dysphagia, heartburn) in the absence of a precipitating event. Reflection on the preoperative status of these patients usually demonstrates the presence of a paraesophageal hernia, esophageal structure, or Barrett's esophagus before the first operation. In these patients the herniation has occurred because esophageal foreshortening was not detected and adequately treated at the first operation or because the hiatus has stretched to allow cephalad migration of the stomach. Elective re-repair should include a Collis gastroplasty when esophageal foreshortening is discovered intraoperatively, along with re-repair of the esophageal hiatus.

The fourth group of patients who have herniation of their fundoplications and the vast majority of patients with small herniations are asymptomatic. Nearly half of the patients who develop fundoplication herniation will be truly asymptomatic. This group most commonly includes patients whose first operation was for a paresophageal hiatal hernia. 11 If the patient is asymptomatic, is not anemic, and has no evidence of ulceration in the herniated fundoplication, we would usually not recommend a reoperation.

In summary, patients with acute herniation need an emergency operation, those with an "event induced" recurrence should undergo elective reoperation, those with a recurrent secondary to esophageal foreshortening should undergo Collis gastroplasty and repeat fundoplication, and those with asymptomatic recurrence need not undergo reoperation.

Slipped Nissen Fundoplication

Patients with a "slipped" Nissen fundoplication represent a different challenge. Those with a gastric pouch above the fundoplication that is either long or bulbous will suffer the most severe symptoms of reflex and regurgitation. Not only is food trapped in this pouch during swallowing, it serves as a trap for acid-rich refluxate immediately below an incompetent sphincter. These patients are extremely grateful when the fundoplication is placed in the correct location on the esophagus. The challenge with this deformity is to determine whether the fundoplication slip is related to a repair under tension around a short esophagus or represents a gastroesophageal junction that was never reduced into the abdominal cavity. Reoperation in patients with a misplaced fundoplication often reveals a virgin segment of mediastinal esophagus just above the gastroesophageal junction, evidence that the esophagus was never adequately mobilized during the first operation. The operative principles for management of this problem will be discussed later.

Disrupted Fundoplication, Twisted Fundoplication, and Two-Compartment Stomach

The disrupted fundoplication is perhaps the easiest to diagnose and repair. The operative evaluation of these patients will usually include a 24-hour pH study as well as esophageal motility testing, barium swallow, and EGD. In the absence of erosive esophagitis or Barrett's esophagus, it is important to document gastroesophageal reflux with a pH study before reoperating on a patient with a disrupted fundoplication.

The new defects, which are unique to laparoscopic surgery, are the twisted fundoplication and the two-compartment stomach. The twisted fundoplication results from failure to mobilize the greater curvature of the stomach from the spleen and diaphragm (Rosetti-Nissen). A portion of the anterior wall of the stomach is pulled from the left around the esophagus to the right and sutured in this position. This creates tension at the gastroesophageal junction, which can result in rotation of the distal esophagus and a spiral-type deformity seen in retroflection of the endoscope. This deformity is usually associated with symptoms of dysphagia and severe postoperative gas bloat. This defect is very resistant to esophageal dilation and requires reoperation to correct it. Occasionally individuals who undergo this Rosetti modification of the Nissen fundoplication will have an additional problem--the two-compartment stomach. This occurs when a point on the greater curvature too far from the fundus is pulled up to the gastroesophageal junction to form the fundoplication. The result is a two-compartment stomach; the fundic compartment resides against the posterior left hemidiaphragm and the distal compartment (the antrum) lies below the septation. The proximal compartment is filled preferentially and will create early satiety, upper gastric distress, nausea, and retching. The hyper-competent valve will usually prevent vomiting in these patients. They are extremely uncomfortable and require urgent reoperation once the diagnosis is made. Barium swallow and upper endoscopy usually reveal the septated nature of the stomach establishing the diagnosis.

Bloating, Nausea, and Epigastric Pain

A small subset of patients who undergo laparoscopic Nissen fundoplication will be plagued by persistent bloating, nausea, and epigastric pain postoperatively. These patients fall into two groups: those with functional problems and those with delays in gastric emptying, which may be a result of inadvertent vagal injury. In the early postoperative period, treatment with antiemetics is the best therapy. When nausea persists beyond the usual 3-month postoperative period, however, investigation is warranted. Initially we believed that these symptoms might represent gastritis, but found little benefit from proton pump inhibition and little EGD evidence of gastritis in these patients. Ifs the EGD is normal, it is usually sufficient to treat these patients with antiemetic medications including ondansetron, Phenergan, and etc. In contrast, when the EGD demonstrates food in the stomach after a 12-hour fast, one must postulate that gastroparesis has occurred postoperatively or was overlooked on the preoperative evaluation. Significant amounts of food in the stomach are strong evidence of gastroparesis. There is probably little need for a gastric emptying study in these patients, but we generally perform this study to quantify the amount of gastric retention. If gastric emptying cannot be normalized on prokinetic agents (and it rarely is), we recommend that pyloroplasty be performed. If the patient is losing weight, a feeding jejunostomy is added. Following these two procedures, we prefer to wait for a year to determine whether gastric emptying will return. If there is no appreciable improvement in gastric emptying after a 12-month follow-up period, subtotal gastrectomy with Roux-en-Y gastrojejunostomy is appropriate.

Reoperation for Failed Fundoplication

In addition to our study mentioned earlier, there have been a number of others that have addressed redo laparoscopic fundoplication. 12-15 Some surgeons attempt all redo fundoplications laparoscopically, some will perform all redo fundoplications through a thoracotomy, and some perform all redo fundoplications through a laparotomy. We generally tailor our redo operations according to the method used for the previous operation(s). When the first operation was performed through a thoractomy or with laparoscopy, our preferred approach is a laparoscopic approach. When the first operation was performed through a laparotomy, our preferred operative approach is through a laparatomy. When we have approached this latter group through a thoractomy, the intra-abdominal adhesions make redo surgery difficult. When we have performed the redo operation in this latter group with laparoscopy, we have found, as did the Austrian investigators, 14 that intra-abdominal adhesions made the laparoscopic procedure quite lengthy. Whether the redo operation is performed laparoscopically or through a laparotomy, the principles are the same.

 

Exposure for Laparoscopic Redo Fundoplication

We use the same five-trocar technique that was used for the primary operation. Because there will frequently be adhesions between the fundoplication and the liver, it may be necessary to adjust the liver retractor several times as the adhesions are taken down. Adhesiolysis is best performed with electrosurgical scissors or ultrasonic shears. Dissection then proceeds by identifying the diaphragmatic crura. This is generally easiest on the left side of the fundoplication. If the short gastric vessels have been previously mobilized, it is easy to follow the left hemidiaphragm down to its base. The right diaphragm is best approached by identifying the caudate lobe of the liver and proceeding superiorly and to the left until the right crus is encountered. If the hepatic branch of the vagus has not been divided during the first operation, it is usually necessary to do so at the second operation to facilitate dissection and repair. If the short gastric vessels were not taken down during the first operation, this is performed. A 360-degree dissection of the diaphragmatic crura allows a Penrose drain to be placed behind the esophagus. This drain is held in place with clips or with an endoloop. The surgeon should note that if the fundoplication has become herniated, the Penrose drain will be around the stomach and not around the esophagus. Inferior traction on the drain allows the surgeon to reduce the herniated fundoplication back into the abdomen. Again, the dissection is kept close to the stomach to avoid causing a penumothorax. If a pneumonthorax does occur, generally the intra-abdominal pressure is decreased to 8 to 10 mm Hg, and dissection proceeds without physiologic difficulty. Once the fundoplication has been reduced from the chest, the next step is to take the old fundoplication apart. This is performed with sharp dissection by identifying the stitches on the anterior portion of the fundoplication and dividing them sharply. The fundus of the stomach is then peeled to the left and to the right from the midposition to take down the fundoplication circumferentially. Again, sharp dissection without the use of electrosurgery or a harmonic scalpel is preferred to ensure that the vagal nerves are not damaged in the course of this dissection. Generally, the vagal trunks will be found within the prior fundoplication. The posterior vagus can usually be preserved if it was previously left inside the fundoplication, but it is more difficult to preserve if it was left outside the fundoplication. The anterior vagus nerve should and can be preserved if it has not been encased in scar tissue at the level of the diaphragm. Once the fundoplication has been entirely taken down, an assessment of intra-abdominal length is performed by pulling the crura together with a grasper and letting go of the drain. If 2 cm of tension-free esophagus exists in the abdomen, the esophagus is not foreshortened and a Collis procedure need not be done. If the gastroesophageal junction lies within 2 cm of the closed hiatus, a Collis gastroplasty is performed as previously described.16 Occasionally patients appear to have adequate intra-abdominal length but will have had a herniated fundoplication twice previously without known diaphragmatic stressors. Under these circumstances we advocate performing a Collis gastroplasty regardless.

We have reported that the results of redo fundoplications deteriorate with each successive operation. 10 Whereas success for the first operation ranges between 90% and 95%, second operations are successful between 80% and 90% of the time, and third operations are successful between 50% and 66% of the time. Because fourth operations are rarely successful at all, many individuals suggest that esophageal resection be performed after three failed fundoplications. This is generally our policy when all other conservative measures have failed.

 

REFERENCES

1. DeMeester TR, Bonivina L., Albertucci M. Nissen fundoplication for gastroesophageal reflux disease: Evaluation of primary repair in 100 consecutive patients. Ann Surg 1986; 204:9-20.

2. Hiebert CA, O'Mara CS. The Belsey operation for hiatal hernia: A twenty-year experience. Am J Surg 1979; 137:532 535.

3. Shirazzi SS, Schulze K, Soper RT. Long-term follow-up for treatment of complicated chronic reflux esophagitis. Arch Surg 1987; 122:548-552.

4. Hinder RA, Filipi CJ, Wetscher G, Neary P, DeMeester TR, Perdikis G. Laparoscopic Nissen fundoplication is an effective treatment for gastroesophageal reflux disease. Ann Surg 1994; 220:472-483.

5. Hunter, JG, Trus TL, Branum GD, Waring JP, Wood WC. A physiologic approach to laparoscopic fundoplication for gastroesophageal reflux disease. Ann Surg 1996; 223:673687.

6. Peters JH, Heimbucher J, Kauer WK, Incarbone R, Bremner CG, DeMeester TR. Clinical and physiologic comparison of laparoscopic and open Nissen fundoplication. J Am Coll Surg 1995; 180:385-393.

7. Jamieson GG, Watson DI, Britten-Jones R, Mitchell PC, Anvari M. Laparoscopic Nissen fundoplication. Ann surg 1994; 220: 137-145.

8. Cushieri A, Hunter JG, Wolfe B, Swanstrom LL, Hutson W. Multicenter prospective evaluation of laparoscopic antireflux surgery. Surg Endosc 1995; 7:505-510.

9. Hinder RA, Klingler PJ, Perdikis G, Smith SL. Management of the failed antireflux operation. Surg Clin North Am 1997; 77:1083-1098.

10. Hunter JG, Smith CD, Branum GD, Waring JP, Trus TL, Cornwell M, Galloway K. Laparoscopic fundoplication failures: Patterns of failure and response to fundoplication revision. Ann Surg 1999; 230:595-606.

11. Watson DI, Jamieson GG, Devitt PG, Mitchell PC, Game PA. Paraesophageal hiatus hernia: An important complication of laparoscopic Nissen fundoplication. Br J Surg 1995; 82: 521-523.

12. Soper NJ, Dunnegan D. Anatomic fundoplication failure after laparoscopic antireflux surgery. Ann Surg 1999; 229:669-677.

13. Cures MJ, Josloff RK, Schoeb O, Zucker KA. Laparoscopic reoperation for failed antireflux procedures. Arch Surg 1999; 134:559-563.

14. Pointner R, Bammer T, Then P, Kamolz T. Laparoscopic refundoplications after failed antireflux surgery. Am J Surg 1999; 178:541-544.

15. Horgan S, Pohl D, Bogetti D, Eubanks T, Pellegrini C. Failed antireflux surgery: What have we learned from reoperations? Arch Surg 1999; 134:809-817.

16. Johnson AB, Oddsdottir M, Hunter JG. Laparoscopic Collis gastroplasty and Nissen fundoplication: A new technique for the management of esophageal foreshortening. Surg Endosc 1998; 12:1055-1060.

 

11. GASTRIC BY PASS

Jean Mouiel, MD, FACS

Professor of surgery, Chairman of the Department of Digestive Surgery and Laparoscopy, Obesity Center University of NICE - SOPHIA ANTIPOLIS, 40 bld Victor Hugo NICE - FRANCE

 

Morbid obesity leads to high risk factors in surgical achievement of Roux en Y gastric by pass (RYGBP) due to :

- excess of fat increasing operative difficulties,

- major comorbidities increasing specific complications especially cardiovascular and respiratory,

- masked symptomatology making diagnosis of major complications often difficult to recognize.

 

The NIH consensus conference (1) had assessed the procedure in open surgery and the first publications in laparoscopy (2,3,4) revealed an improvment in results with a better ratio risk-benefit, so that minimal access approach can be recommended in bariatric surgery.

 

PERSONAL EXPERIENCE.

Among a series of 564 morbid obese patients operated from June 97 to December 2000 according to 4 laparoscopic procedures : adjustable silicone gastric banding, vertical banded gastroplasty, Roux en Y gastric by pass (RYGBP) and duodenal switch with bilio-pancreatic diversion, a cohort of 100 RYGBP with a follow up of 12 months at least was studied.

 

Technique used was the technique described by Higa (3) with retrocolic Roux en Y loop, vertical calibrated gastroplasty, hand sewn gastro jejunal anastomosis.

Among the 100 patients :

- 87 were operated by laparoscopy (82 primary, 5 redos for gastric banding failure),

- 13 were operated by open surgery (6 redos for gastric banding failure, 7 redos for vertical banded gastroplasty).

 

Indications concerned superobese patients or morbid obese patients with large hiatal hernia, sweet eater, binge eater or after failure of restrictive procedures.

 

Demographics were as follow :

- age : 47 (22 - 67),

- sex : 82 females, 18 males,

- BMI : 53 (38 - 68),

- ASA II 92,

- ASA III 8,

- comorbidities 135 ( mainly diabetes 21, hypertension 37, sleep apnea 16).

 

Results : the operative time was 180 mm in average (90 - 300). There was no conversion, no per op complication, no mortality. Hospital length of stay was 8 days in average (5 - 45). Mean excess loss was 64.5 % in 6 months and 70.5 % in 12 months. Most of comorbidities were cured (GERD, sleep apnea or hypoventilation syndrome) or improved (hypertension, diabetes, arthrosis).

 

Early complications :

5 early complications were observed :

- 1 ulcer perforation resolved by open surgery PO day 1,

- 2 small bowel obstructions resolved by laparoscopy PO day 5 and 18,

- 1 subphrenic abcess (leak?)resolved by prolonged drainage,

- 1 phlebitis in spite of anticoagulotherapy.

 

Late complications :

6 late complications were observed :

- 5 stenosis resolved by endoscopic dilatation,

- 1 non compliance resolved by reversal whereas the result was excellent (BMI 50 down to 28).

 

COMMENTS.

Comparison restrictive vs combination procedures shows the same percentage (3.5 ± 1%) of complications listed according to a meta analysis (5).

 

 

COMPLICATIONS	RESTRICTIVES PROCEDURES n = 3568 %	COMBINATION PROCEDURES n = 3626 %
PERI-OP DEATHS	0.14	0.39
BLEEDING	0.45	0.88
DUMPING SYNDROME	0.28	14.64
INFECTION	3.11	5.27
SPLENIC INJURY	0.22	0.8
STOMAL STENOSIS	2.21	2.68
GASTRIC POUCH DILATATION	2.41	0.47
STAPLE LINE FAILURE	1.54	5.96
STOMACH EROSION-ULCERATION	1.21	1.16
VIT-MIN- DEFICIENCY	1.63	10.98
VOMITING	8.49	2.56

In bold type = high %

 

Complications of open RYGBP :

 

 Surgical complications according to 7 authors (series of more 100 patients BMI 42-62, follow up 6-168 months) (6,7,8,9,10,11,12).

 

1. OUT COMES FOR OPEN GBP

	n	+ %	Leak %	Hernia %
GRIFFEN 1981	402	0.75	5.47	3.5
LINNER 1982	174	0.57	0.57	0
SUGERMAN 1989	182	1	1.6	18
PORIES 1995	608	1.5		23.9
CAPELLA 1996	560	0
FOBI 1998	944	0.4	3.1	4.7
MAC LEAN 1999	243	0.41		16

 

 Nutritional complications (13,14)

 

STUDY	IRON	B12	FOLATES	ANEMIA	Follow up months
AMARAL 1985 n=150	49%	70%	18%	35%	33
BROLIN 1998 n= 348	47%	37%	35%	54%	42

 

It has been firmly established that these deficiencies were common and daily prophylactic vitamines/minerals supplements are highly recommanded. Symptomatic gallbladder lithiasis can be added to these complications with an incidence ranging from 3 to 30%. There is a discussion regarding its prophylaxy, some surgeons having recommended systematic cholecystectomy at the time of bariatric surgery. Actually most of surgeons recommend URSODIOL at doses of 600 and 1200 mg per day during 6-12 months after RYGBP (15).

 

 

 

Complications of laparoscopic RYGBP :

 

 

 Surgical complications according to Higa (16) Schauer (17) Wittgrove (18).

 

 

	HIGA n = 1040	SCHAUER n = 275	WITTGROVE n = 500	TOTAL %
DEATH	1*	1*	0	0 - 0.3
LEAK	12	5	9	1 - 2
BLEEDING	6	9	4
SB.OBSTRUCTION	26	3	3
PULMONARY	1	16	7
INFECTION	1	13	4
STENOSIS	51	13	8	4 - 5

 

* Pulm. Embolism.

 

Most of these complications happened during the learning curve and decreased with experience.

 

 Comparison of surgical complications lap vs open RYGBP

 

	LAPAROSCOPY	OPEN SURGERY
MORTALITY	0.1 - 0.5 %	0.3 - 1.5 %
MORBIDITY short	6 %	12 %
MORBIDITY late	11 %	16 %

Besides the well known advantages of laparoscopy with less pain, rapid recovery, minimal incisions, real advantages can be underlined in RYGBP with no ventral hernia, few abdominal sepsis, less general complications.

 

 Nutritional complications had been studied by Schauer in a series of 275 patients.

 

IRON DEFICIENCY	27	10 %
ANEMIA	22	8 %
HYPOKALEMIA	14	5 %
HYPO MAGNESEMIA	2	0.7 %
PROTEIN MALNUTRITION	1	0.3 %

 

In this series the rate of cholecystectomy for symptomatic cholelithiasis was low (4/275).

 

CONCLUSIONS.

RYGBP is an advanced lap procedure feasible by trained surgeons in a multidisciplinary bariatric center. The procedure is very efficient to improve major co-morbidities with acceptable risks to be compared to the natural evolution of a very severe disease responsible of 55 000 deaths/year in France and 300 000 deaths/year in USA.

 

REFERENCES

1. Gastrointestinal surgery for severe obesity : National Institutes of Health Consensus Development Conference Statement. Am J Clin Nutr 1992;55:615S-619S.

2. Wittgrove A, Clark GW, Tremblay LJ. Laparoscopic gastric by pass, Roux en Y : preliminary report of five cases. Obes Surg 1994;4:353.

3. Higa KD, Boone KB, Ho T, et al. Laparoscopic Roux en Y gastric by pass for morbid obesity : technique and preliminary results of our first 400 patients. Arch Surg 2000 135,9:1029-1033.

4. Lonroth H, Dalenback J, Haglind E, Lundell L. Laparoscopic gastric by pass. Another option in bariatric surgery. Surg Endosc 1996; 10:636-638.

5. Monteforte M.J., Turkelson C.M., Meta analysis - Bariatric surgery for morbid obesity Ober Surg 2000, 10:391-401.

6. Griffen WO, Bivins BA, Bell RM, Jackson KA. Gastric by pass for morbid obesity. World J Surg 1981;5:817-822.

7. Linner JH. Comparative effectiveness of gastric by pass and gastroplasty. Arch Surg 1982;117:695-700.

8. Sugerman HJ, Londrey GL, Kellum JM, et al. Am J Surg 1989;157:93-102.

9. Pories WJ, Swanson MS, MacDonald KG, et al. Who would have thought it? An operation proves to be the most effective therapy of adult-onset of diabetes mellitus. Ann Surg 1995;222:339-352.

10. Capella JF, Capella RF. The weight reduction operation of choice: vertical banded gastroplasty or gastric by pass. Am J Surg 1996;171:74-79.

11. Fobi MAL, Lee H, Holness R, Cabinda D. Gastric by pass operation for obesity. World J Surg 1998;22:925-935.

12. MacLean LD, Rhode B, Nohr CW. Late outcome of isolated gastric by pass. Ann Surg 2000;231:524-528.

13. Amaral JF, Thompson WR, Caldwell MD, et al. Prospective hematologic evaluation of gastric exclusion surgery for morbid obesity. Ann Surg 1985, 201:186-193.

14. Brolin RE, Gorman JH, Gorman RC et al. Prophylactic iron supplementation after Roux en Y gastric by pass : a prospective, double-blind, randomized study. Arch Surg 1998, 133:740-744.

15. Sugerman HJ, Brewer NH, Shiffman ML, et al. Prophylactic Ursodiol acid prevents gallstone formation following gastric by pass induced rapid weight loss: a multicenter, placebo controlled, randomized, double-blind prospective trial. Am J Surg, 1994, 169:91-96.

16. Higa KD, Boone KB, Ho T. Complications of the laparoscopic Roux en Y gastric by pass : 1040 patients. What have we learned? Obes Surg 2000, 10:509-513.

17. Schauer PR, Ikramuddin S, Gourash W et al. Outcomes after laparoscopic Roux en Y gastric by pass for morbid obesity. Ann Surg 2000, 232,4:515-529.

18. Wittgrove AC, Clark GW, Schubert KR. Laparoscopic gastric by pass Roux en Y, the results in 500 patients with 5 year follow up. Obes Surg 2000, 10:233-239.

 

12. Splenectomy

Adrian Park, MD

 

Laparoscopy Splenectomy (LS) has become one of the most commonly performed laparoscopic solid organ procedures. It is now considered the procedure of choice for normosplenic patients requiring splenectomy for various benign indications. (Refine) As with most laparoscopic procedures, there is a learning curve associated with mastery of the technique. The focus of this presentation will be upon the avoidance of complications in performing LS once the basic learning curve has been ascended.

 

It is difficult to compare complication rates of LS reported among various authors, because categorization of complications and indications for splenectomy vary widely. It is not appropriate to compare morbidity from a series of normosplenic ITP patients with those from series of lymphoma or leukemia patients. Similarly it is important, in comparing complications arising from open splenectomy (OS) with those from LS that the patients are well matched with regard to underlying pathologies. Most sizeable LS series report complication rates ranging from 4% to 23% with an average of about 10%. Comparable series of open splenectomy report complication rates extending to 40% but averaging closer to 20%.

 

Complications of LS can be broadly categorized as relating to laparoscopic procedures in general or relating more specifically to the technique of LS. They can also be categorized as major and minor complications. (see Table 1).

 

 

Table 1

Laparoscopic Splenectomy Complications

SAGES Postgraduate Course I, 14 March 2002

 

I. Intraoperative Complications

a. Laparoscopic technique-related

i. Trocar injury

1. Vascular

2. Hollow Viscus injury

ii. CO2 Retention

iii. Air embolism

iv. Port site bleeding

v. Staple mis-fire

vi. Conversion

b. Splenectomy-related

i. Splenic injury

ii. Hilar injury

iii. Colon injury

iv. Gastric Injury

v. Pancreatic injury

vi. Diaphragmatic injury

vii. Pneumothorax

c. Anesthesia

i. Airway complications

ii. Aspiration

iii. Drug reaction

1. Prolonged neuromuscular blockade

2. Malignant Hyperthermia

 

II. Postoperative Complications

a. Major

i. Local/Procedural

1. Postoperative bleeding

2. Subphrenic Abscess

3. Post-splenectomy Sepsis

ii. Distant site

1. Pneumonia

2. DVT

3. Pulmonary Embolism

4. Pleural Effusion

5. Cardiac

6. Bowel injury

7. Neurologic

a. Peripheral nerve injury

b. CNS event

iii. Recurrent Disease

1. Splenosis

2. Missed Accessory Spleen

b. Minor

i. Urinary Tract Infection

ii. Surgical site superficial infection

iii. Trocar site hematoma

iv. Gastroparesis

v. Atelectasis

 

Independent of any complications inherent to laparoscopic surgery in general (e.g., related to pneumoperitoneum, injuries from trocars), LS is associated with several potential perioperative complications that the surgeon should be aware of and be able to treat. The greatest potential problem is hemorrhage, which can be from three sources: a small caliber vessel (short gastric or polar vessels), a larger vessel of the hilum, or the splenic parenchyma. The first type of hemorrhage, though not life-threatening, can become quite a hindrance to the operation, as rapidly accumulating blood may impair vision. However, it can also easily be stopped with the use of clips, electrocoagulation, or the ultrasonic dissector. Hemorrhage from a larger vessel may be an indication for immediate conversion to laparotomy. The best means for its prevention is delicate dissection of the artery and vein to prevent rupture of smaller splenic and pancreatic blood vessels. The dissected artery and vein should then be ligated prior to any movement of the spleen. Hemorrhage originating in the parenchyma is less dangerous and can be managed by clamping the artery or by applying direct pressure.

 

Another potential complication of LS is injury to the tail of the pancreas. Proper dissection and placement of the endostapler can avoid this problem. The use of the lateral approach to LS lengthens the splenic hilum, which permits the endostapler to be used without risk of causing harm to the pancreatic tail. Another possible complication of LS is perforation of the diaphragm during dissection of the superior pole of the spleen. A small puncture may be quickly amplified by the presence of pneumoperitoneum, causing a pneumothorax. This can be controlled laparoscopically and by the use (occasionally) of a pleural drain.

 

Deep vein thrombosis, pulmonary embolus, and wound infection have also been described as complication of LS. It is interesting to note that particularly in the largest series of LS, there is remarkably low incidence of deep surgical infection or subphrenic abcess.

 

Table 2

Postoperative complications in authors experience of over 240 LS.

 

Bleeding complications (4.5%)

Intraoperative bleeding (requiring transfusions)

Postoperative bleeding

Abdominal wall hematoma

Hemothorax

Pulmonary complications (3.5%)

Atelectasis

Pneumonia and upper respiratory tract infections

Pulmonary embolus

Pneumothorax

Pleural effusion

Septic complications (1%)

Wound infection

Deep line sepsis

Urinary tract infection

Others (2%)

Deep venous thrombosis

Gout flare

Myocardial infarction

Vocal cord damage

Postoperative ileus

Hypophyseal insufficiency

Urinary retention

Overall Complication Rate (11%)

 

In this presentation technical "pearls" will also be offered to counter the potential pitfalls of the procedure. Strategies for avoiding complications in the following areas will be addressed:

Establishing pneumoperitoneum; Trocar placement; exposing and dividing (splenic) ligamentous attachments; the splenic hilum and hemorrhage; the big spleen; specimen retrieval.

 

It will be demonstrated that LS is both safe and feasible in patients of all ages and for a wide range of splenic pathologies. Evolution and refinement of LS techniques have made this procedure effective even in patients with massive spleens and previous abdominal surgery.

 

References

1. Kathkouda N, Hurtwitz MB, Rivera RT, Chandra M, Waldrep DJ, Gugenheim J, Mouiel J (1998) Laparoscopic splenectomy. Outcome and efficacy in 103 consecutive cases. Ann Surg 228:568-578

2. Poulin E. Mamamzza J (1998) Laparoscopic splenectomy: lessons from the learning curve. Can J Surg 41:28-36

3. Park A, Marcaccio M. Sternbach M, Witzke D, Fitzgerald P (1999) Laparoscopic versus open splenectomy. Arch Surg 134:1263-1269

4. Park AE, Birgisson G, Mastrangelo MJ Jr., Marcaccio MJ, Witzke DB (2000) Laparoscopic splenectomy: outcome and lessons learned from over two hundred cases. Surgery 128:660-667

5. Gigot JF, Lenegele B, Gianello P, Etienne J, Claeys N (1998) Present status of laparoscopic splenectomy for hematologic disease: certitudes and unresolved issues, Semin Laparoscopic Surg 5:147-167

6. Targarona EM, Espert JJ, Bombuy E, Vidal O, Cerdan G, Artigas V, et al. (2001) Complications of laparoscopic splenectomy, Arch Surg (in press)

 

 

13. Strategies to Prevent and Treat Bile Duct Injuries During Laparoscopic Cholecystectomy

Nathaniel J. Soper, M.D., F.A.C.S.

Washington University School of Medicine

660 S. Euclid, Campus Box 8109

St. Louis, Missouri 63110

 

General surgeons who perform laparoscopic cholecystectomies should know how to avoid bile duct injuries and understand the principles of their intraoperative management, the former being much more important than the latter. This discussion will cover the causes, avoidance, and intraoperative recognition and management of biliary injury.

 

Causes of laparoscopic bile duct injury

 

Biliary injury occurs either due to anatomical misidentification of the cystic duct or due to technical problems, especially the misuse of cautery. Misidentification is the most common cause of serious injuries. The two structures which are misidentified as the cystic duct are the common bile duct or an aberrant right hepatic duct.

 

Misidentification of the common bile duct as the cystic duct leads to the "classical injury". The common bile duct is clipped and divided usually just below the cystic/common bile duct junction. In order to free the specimen the biliary tree must be divided again. This is done across the common hepatic duct or at an even higher level. In fact, by traction on the gallbladder, hepatic ducts may be pulled down so that the point of division is well above the bifurcation. Injuries to the right hepatic artery often accompany this injury.

 

An important contributor to misidentification is the direction of traction of the gallbladder during its dissection. When Hartmann's pouch is pulled superiorly rather than laterally, the common bile duct and cystic duct come into alignment, appearing to be a single duct. Other proposed

contributing factors to duct misidentification are inflammation, especially acute inflammation, a short cystic duct, and a large stone in the infundibulum. The latter, as well as thick-walled or distended gallbladders, which are often present in acutely inflamed gallbladders, make retraction and display of the cystic duct difficult. Misidentification may also be more common when adhesive bands tether the gallbladder to the common bile duct.

 

In the second misidentification scenario an aberrant right hepatic duct, which is present in 2% of cases, is mistaken as the cystic duct. The segment of an aberrant right hepatic duct, between the point that the cystic duct enters it and the point that the aberrant duct joins the common hepatic duct, looks very much like a cystic duct. The misidentified segment is clipped and usually cut. In order to remove the gallbladder the aberrant duct must be cut again at a higher level.

 

The main technical causes of laparoscopic ductal injury are failure to occlude the cystic duct securely, too deep a plane of dissection when taking the gallbladder off the liver bed, and thermal injuries to the bile duct. Clips are less reliable than ligatures or suture ligatures, the standard methods of securing the cystic duct during open cholecystectomy. The main problem is inappropriate use of clips instead of another occlusion device on a thick or attenuated cystic duct. Injury to ducts in the liver bed may occur with dissection in too deep a plane when excising the gallbladder, usually when the dissection is difficult as when acute or severe chronic inflammation are present or when the gallbladder is intrahepatic. This is much more likely to cause bile leaks from the gallbladder bed than injury to a duct of Luschka. Cautery-induced injuries are more likely to occur in the presence of severe inflammation which may lead to the use of excessively high cautery settings to control hemorrhage. Injury to the bile duct may also occur during laparoscopic common duct exploration. These injuries are usually avulsions of the cystic duct or perforation of the common duct.

 

Prevention of bile duct injuries

 

General . Laparoscopic cholecystectomy should be performed only by surgeons trained and proctored in the operation. Laparoscopic cholecystectomy is more difficult in the presence of acute inflammation and biliary injury is more likely under these circumstances. It is also more difficult when the patients are males, elderly, or when there have been repeated attacks of pain. A previous attack of acute cholecystitis also is a significant contributing factor to operative difficulty. Laparoscopic cholecystectomy during an attack of acute cholecystitis should be considered to be an advanced laparoscopic technique and it is desirable that an experienced laparoscopic surgeon be a member of the operating team.

 

Avoidance of ductal misidentification. Misidentification is due to failure to identify the cystic structures conclusively. The cystic duct and artery are the only structures which require division during a cholecystectomy, and the objective of dissection is to identify these structures conclusively. Furthermore, only these structures need to be identified. The key phrase is "conclusive identification". Such a method is available during open cholecystectomy, by tentatively identifying of the cystic structures in the triangle of Calot followed by dissection of the gallbladder off the liver bed. After complete detachment of the gallbladder conclusive identification of the cystic structures as the only two structures entering the gallbladder can be made. In 1995 we introduced a technique for conclusive identification of the cystic structures at laparoscopic cholecystectomy based on a "critical view of safety". In this technique the hepatocystic triangle is cleared of all fat and investing tissue. At this point only two structures are connected to the lower end of the gallbladder, and the lowest part of the gallbladder attachment to the liver bed has been exposed. Once the critical view is attained cystic structures may be occluded, as they have been conclusively identified. Failure to achieve the critical view is an absolute indication for conversion or possibly cholangiography to define ductal anatomy.

 

Whether anatomical identification by routine operative cholangiography (RIOC) prevents biliary injury is debated. A recent population study in Australia found that RIOC reduced the incidence of injury. Other studies suggest that the severity but not the incidence of biliary injury is reduced by RIOC. Operative cholangiography is best at detecting a misidentification of the common bile duct as the cystic duct and will prevent excisional injuries of bile ducts, provided that the cholangiogram is interpreted properly. RIOC is poor at detecting aberrant right ducts which unite with the cystic duct before joining the common duct.

 

Avoidance of technical errors. Clips should be placed so that the tips can be seen projecting beyond the duct, free of extraneous material. Clips should not be manipulated in the subsequent dissection. Clips should not be used when the cystic duct is thick or attenuated. Instead, a preformed ligature loop should be applied to occlude the cystic duct. Applying extra clips is not the answer and may lead to a tenting injury of the bile duct.

 

Avoidance of ductal injury in the liver bed depends upon staying in the correct plane of dissection. Use of the cautery dissector combined with irrigation to keep the field clear of blood is helpful, but there is no substitute for meticulous technique and experience in this dissection.

 

Cautery should not be used or used with great care in the triangle of Calot. Great care means low cautery settings, coagulation of small pieces of tissue at one time and that tissue must be lifted off adjacent tissue. Low cautery settings are mandatory as higher settings may lead to arcing of current to ducts. Cautery should not be used to divide the cystic duct since this may lead to thermal necrosis of the cystic duct stump or adjacent bile duct. Bleeding should not be controlled by blind application of clamps, clips or cautery. Brisk bleeding is an indication for conversion.

 

Elective conversion to open surgery is not a complication. Conversion to avoid injury is indicated when the dissection is not progressing, when the surgeon is unsure of anatomical position after a trial of dissection, when the laparoscopic instruments are ineffective in retraction or separation of tissue planes or when there is a suggestion of injury.

 

Intraoperative identification of biliary injury

 

Intraoperative identification of injury may occur by recognition of bile in the field, indicating a cut bile duct, by cholangiographic findings, or rarely by direct observation of a divided duct. At other times the actual diagnosis of biliary injury is made after conversion for bleeding or inability to proceed in a difficult dissection.

 

Management of injuries recognized intraoperatively

 

There is little written about what should be done once a biliary injury is suspected during laparoscopic cholecystectomy. The following is based on the authors' experience with referred biliary injuries. It is also predicated on highly suggestive evidence that repair of difficult biliary injuries frequently fail when performed by surgical teams inexperienced in upper biliary tree surgery, such as liver resections and bile duct reconstructions.

 

In the unlikely event that a major bile duct injury is recognized laparoscopically and the surgeon does not feel comfortable managing the injury, a closed-suction drain should be inserted and the patient transferred to a biliary referral center for definitive management. Intraoperative recognition of biliary injury, however, is usually an indication for conversion. The following two guidelines are suggested when laparotomy is undertaken for suspected injury: 1) A repair should be attempted only if the techniques of dissection or reconstruction required for repair are commonly used by the operating team. 2) The injury should not be worsened by attempting a dissection for the purpose of making an exact diagnosis. Repair of minor injuries to the lateral wall of the bile duct or to the common bile duct near the duodenum normally require techniques commonly practiced by most general surgeons. Injuries of aberrant ducts and those at or above the confluence of hepatic ducts require operative techniques more likely to be available at specialized hepatobiliary units. When such expertise is not available at the time of injury, closed suction drains should be placed in the right upper quadrant and the patient referred.

 

Lateral injuries of the bile duct are repaired by closure of the defect using fine absorbable sutures over a T-tube and placement of a closed suction drain in the vicinity of the repair. Nonabsorbable sutures are contraindicated as they may form a nidus for stone formation. The T-tube should be brought out through a separate incision in the duct, if possible. Complete transection of a bile duct should be repaired with a Roux-en-Y hepaticojejunostomy. The principles of repair are that the anastomosis be tension free, with good blood supply, mucosa-to-mucosa and of adequate caliber. Hepatico-jejunostomy is used in preference to either choledocho-choledochotomy or choledocho-duodenostomy, since a tension free anastomosis is always possible with hepaticojejunostomy. Choledocho-choledochotomy has the additional disadvantage that blood supply to the anastomosis may be poor, and frequently results in stricture.

Suggested Reading

1. Russell JC, Walsh SJ, Mattie AS, Lynch JT. Bile duct injuries, 1989-1993. A statewise experience. Connecticut Laparoscopic Cholecystectomy Registry. Archives of Surgery 1996;131(4):382-8

2. Sanabria JR, Gallinger S, Croxford R, Strasberg SM. Risk factors in elective laparoscopic cholecystectomy for conversion to open cholecystectomy. Journal of the American College of Surgeons 1994;179(6):696-704

3. Strasberg SM, Hertl M, Soper NJ. An analysis of the problem of biliary injury during laparoscopic cholecystectomy [see comments]. [Review] [111 refs]. Journal of the American College of Surgeons 1995;180(1):101-25

4. Fletcher DR, Hobbs MS, Tan P, et al. Complications of cholecystectomy: risks of the laparoscopic approach and protective effects of operative cholangiography: a population-based study. Annals of Surgery 1999;229(4):449-57

5. Stewart L, Way LW. Bile duct injuries during laparoscopic cholecystectomy: Factors that influence the results of treatment. Arch Surg 1995;1995:1123-1129

---

Stephanie B. Jones, MD

Assistant Professor, Department of Anesthesiology and Pain Management,
Southwestern Center for Minimally Invasive Surgery
The University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX 75390-9068

 

 

Morbidity and mortality directly attributable to anesthesia has decreased remarkably over the past two decades, while patient expectations have increased. No longer do patients just want to make sure they Awake up@ when the surgical procedure has ended. They now expect to be comfortable, free of nausea, and ready to leave the hospital in a minimum amount of time. The addition of laparoscopy to the scene has set the bar even higher, as operations that previously required long inpatient stays become ambulatory procedures. Consequently, the most common anesthetic complications are those that have the potential to prolong the hospital stay or necessitate readmission, namely postoperative nausea and vomiting (PONV), and persistent pain.

 

Laparoscopic procedures in general tend to have a high risk of PONV, with figures as high as 70% routinely quoted, especially for gynecologic laparoscopy. Emesis can result in dehydration, electrolyte imbalance, venous hypertension and bleeding, or increased tension on sutures. One study of planned outpatient laparoscopic tubal ligations showed a 12.1% admission rate, 61% of which were to due to PONV. The etiology of PONV is multifactorial: non-anesthetic factors such as the operative site and patient gender, choice of anesthetic technique or agent, residual gastric or abdominal distention, pain, and the use of opioids. This list is by no means exhaustive. Nonetheless, a multitude of studies has tried to pinpoint what variables can be changed to decrease the incidence of PONV. General anesthesia certainly increases the risk. Omitting nitrous oxide from a general anesthetic has been shown to decrease vomiting, but only in groups of patients at high risk for PONV. The use of propofol as a maintenance agent instead of inhaled anesthetics may help as well. This can be an expensive approach for longer procedures. Reversal of neuromuscular blockade with anticholinesterase agents has been shown to increase PONV, so one might try to use shorter acting relaxants and avoid reversal. This may be difficult with laparoscopic procedures, as relatively profound muscle relaxation is often needed until late in the case to help achieve a good surgical view with pneumoperitoneum. The risks inherent to residual paralysis outweigh omission of reversal agents in most cases.

 

Alternatives to general anesthesia do exist for laparoscopy. The impetus to try different techniques has been particularly prevalent for inguinal hernia repair. One group combined a subarachnoid block (spinal) with insufflation of nitrous oxide in extraperitoneal hernia repairs. The use of nitrous oxide prevented the shoulder pain that can often plague awake patients during laparoscopy due to carbon dioxide irritation of the diaphragm. Another group published a series of ten patients who underwent the same procedure with local anesthesia, and little to no sedation. For most procedures and the majority of patients, however, a general anesthetic is still preferred. The question then becomes whether, and how, a patient should receive antiemetic prophylaxis.

 

In patients at high risk of PONV, prophylaxis does seems to make a difference with respect to the usual markers (incidence of nausea and/or vomiting), and outcome measures (admission rate, patient satisfaction scores). A variety of pharmacologic agents are available that function at several different receptor sites. Combinations of agents have been repeatedly shown to be useful in high-risk groups. Furthermore, when treating persistent nausea or emesis, changing to a different drug class that works at a different receptor tends to be much more effective than repeated doses of the same drug. Ondansetron and other serotonin (5HT3) receptor antagonists have received the most attention over the past decade. Most studies demonstrate greater efficacy when compared to other antiemetics and placebo. The side effect profile is limited primarily to an occasional headache, and they are non-sedating. An old favorite, metoclopramide, is really not very useful as an antiemetic, although it will stimulate gastric emptying. Droperidol, a butyrophenone, is nearly as effective as ondansetron, but can sometimes cause extreme dysphoria in awake patients. Administration of small doses (0.625 mg) given during surgery usually avoids this side effect while still providing effective PONV prophylaxis. Another inexpensive drug, dexamethasone, has been studied more recently as an antiemetic. Not only is a single 5-10 mg dose highly effective, side effects are minimal in otherwise healthy patients. The long half-life also results in prolonged efficacy -- antiemetic effects up to 24 hours after surgery have been documented. This is particularly attractive for outpatients. The timing of administration can be important. Dexamethasone is most effective when given at or before anesthetic induction, while ondansetron should be given near the end of the procedure.

 

Nonpharmacologic therapies have been tested as well. Interventions as simple as supplemental oxygen have been shown to be effective. Although the etiology of the positive effect is not clear, it has been suggested that higher inspired oxygen concentrations might prevent mild intestinal ischemia during surgery. The same mechanism (treatment of gut hypoperfusion) has been proposed as an explanation for the effectiveness of aggressive intravenous fluid resuscitation in preventing PONV. Stimulation of the P-6 acupuncture point is certainly met with some skepticism. However, use of transcutaneous acupoint electrical stimulation with the Reliefband7 device at P-6 has been shown to reduce nausea in a laparoscopic cholecystectomy population, and was as effective as ondansetron is a high risk plastic surgery population.

 

Another cause of both PONV and unplanned hospital admission is insufficient pain relief. Pain following laparoscopy arises from multiple sources: incisional, visceral, shoulder pain due to carbon dioxide insufflation, and procedure specific sources such as bile peritonitis after laparoscopic cholecystectomy, or tubal necrosis following tubal ligation. Successful pain management strategies use a variety of modalities to treat the different sources of pain. Local anesthetics can be used at port sites and intraperitoneal, opioids and NSAIDs treat visceral pain and inflammation. The concept of preemptive analgesia, although controversial, is important. The theory behind preemptive analgesia is that the presence of analgesia prior to the surgical stimulus prevents Awind-up@ or sensitization of nociceptors, reducing overall postoperative pain. Although the strongest evidence for preemptive analgesia exists in animal studies, several human studies do suggest the presence of such an effect. An argument can be made that negative study results might be due to incomplete pain coverage, as studies frequently evaluate only a single modality (e.g. local anesthetic injection at trocar sites).

 

Selective cyclo-oxygenase 2 inhibitors (COX-2) such as rofecoxib and celecoxib are receiving a great deal of attention within the context of preemptive analgesia, which will only increase when a parenteral form becomes available. When compared to non-selective NSAIDs such as ketorolac, COX-2 inhibitors are less likely to cause gastric erosion or platelet dysfunction. Rofecoxib 50 mg administered prior to surgery decreases opioid use and postoperative pain scores in patients undergoing arthroscopic knee surgery, ENT procedures, and lower abdominal surgery. Opioid sparing also reduces the incidence of opioid side effects such as nausea.

 

Surgeons may regard PONV and pain as relatively minor side effects rather than complications. However, both contribute significantly to the patient=s satisfaction after surgery, which is really the ultimate outcome measure. Cost effective, multimodal management of PONV and pain can be easily incorporated into standard practice, and should be considered routine for most laparoscopic procedures.

 

References:

 

1. Alexander JI. Pain after laparoscopy. Br J Anaesth 1997; 79:369-378.

2. Bisgarrd T, Klarskov B, Kristiansen VB, et al. Multi-regional local anesthetic infiltration during laparoscopic cholecystectomy in pateints receiving prophylactic multi-modal analgesia: a randomized couble-blinded, placebo-controlled study. Anesth Analg 1999; 89:1017-1024.

3. Bhopatkar SY, Reuben SS, Joshi W, Maciolek H. Preemptive analgesic effects of rofecoxib for ambulatory arthroscopic knee surgery. Anesthesiology 2001; 95:A34.

4. Ferzli G, Sayad P, Vasisht B. The feasibility of laparoscopic extraperitoneal hernia repair under local anesthesia. Surg Endosc 1999;13:588-590.

5. Hedayati B, Fear S. Hospital admission after day-case gynacological laparoscopy. Br J Anaesth 1999:83:776-779.

6. Michaloliakou C, Chung F, Sharma S. Preoperative multimodal analgesia facilitates recovery after ambulatory laparoscopic cholecystectomy. Anesth Analg 1996; 82:44-51.

7. Spivak H, Nudelman I, Fuco V, et al. Laparoscopic extrperitoneal inguinal hernia repair with spinal anethesia and nitrous oxide insufflation. Surg Endosc 1999; 13:1026-1029.

8. Tang J, Wang B, White PF, et al. The effect of timing of ondansetron administration on its efficacy, cost-effectiveness, and cost-benefit as a prophylactic antiemetic in the ambulatory setting. Anesth Analg 1998; 86:274-282.

9. Wang JJ, Ho ST, Liu YH, et al. Dexamethasone reduces nausea and vomiting after laparoscopic cholecystectomy. Br J Anaesth 1999; 83:772-775.

10. Watcha MF. The cost-effective management of postoperative nausea and vomiting. Anesthesiology 2000: 92:931-933.

11. Zarate E, Mingus M, White PF, et al. The use of transcutaneous acupoint stimulation for preventing nausea and vomiting after laparoscopic surgery. Anesth Analg 2001; 92:629-635.

 

 

15. Pharmacologic Therapies to Minimize Perioperative Problems

Steven D. Schwaitzberg, MD FACS

Dept. of Surgery New England Medical Center, Boston , MA

 

· Wound Infection

· Deep Venous Thrombosis

· Nausea and vomiting

· Pain

 

Wound Infection

The reduction of wound infection in Minimally Invasive Surgery (MIS) is one of the purported advantages of this technique. As such it becomes just as important to consider what opportunities there are to avoid the indiscriminate use of prophylactic antibiotics, as it is to consider what antibiotic to administer. The prototypical example of an MIS procedure is the laparoscopic cholecystectomy. The preponderance of data would indicate that prophylactic antibiotics are not indicated in low risk and elective laparoscopic cholecystectomy. Placebo controlled trials have failed to show a benefit for antibiotic therapy in this population. From this one can expect up to a 6% incidence of superficial infection at the umbilicus and zero to two percent incidence elsewhere at the remote trocar sites. Interestingly, the rate of umbilical infection falls in uncontaminated non-biliary tract surgery but prophylactic antibiotics do not apparently mitigate this. It seems that other local factor such as bile and stone spillage must pay a role in this as well. The role of prophylactic antibiotics is more robust in procedures for acute disease and high-risk patients. The basis of antibiotic therapy must be directed at the microbiology of the surgical target. Thus antibiotic therapy directed against E. Coli, Klebsiella sp. and enterococci, which are the three most likely organisms to be cultured in the bile, is appropriate. Unless there is specific clinical reason to think that a patient has the very rare emphysematous cholecystitis, therapy directed against anaerobes is not indicated. Certainly in any patient receiving prophylactic antibiotic therapy there is no data to support giving more than the one dose preoperatively in elective surgical patients. Consider the impact of giving just one extra dose of a $10 intravenous antibiotic to the 600,000 patients who undergo cholecystectomy in the US annually: 6 million dollars wasted! On the other hand open cholecystectomy is associated with a higher wound infection than laparoscopic cholecystectomy. In this day an age this is probably true because only the more difficult and high-risk procedure are done open. In the past this was probably true due to the large incision and opportunity for a substantial skin/subcutaneous tissue inoculum effect. Studies have shown a higher rate of variability in the prescribing habit of surgeons when it comes to prophylactic antibiotic therapy. A significant percentages of patients receiving drug therapy do so in the absence of specific clinical indication

Recommendation: Elective laparoscopic cholecystectomy - no antibiotics

High risk or open cholecystectomy one preoperative dose of
antibiotic therapy against top three biliary bacteria

 

Deep Venous Thrombosis

The use of pneumoperitoneum during laparoscopy decreases venous return to the heart. This increases the risk of venous stasis with subsequent deep venous thrombosis (.03% and pulmonary embolism (.06%). Graduated compression stocking are the standard therapy intraoperatively and post operatively to minimize DVT and have to be considered in all patients undergoing laparoscopy. The incidence of outpatient laparoscopic cholecystectomy is rising resulting in extremely early ambulation. The role of adjunctive pharmacologic therapy is unclear in routine patients. Attempts to quantify high risk patients with preoperative testing has been unrevealing since laboratory finding have translated poorly into clinical disease . Conversely certainly high risk populations can be identified. The increasing popularity of laparoscopic approaches to morbid obesity highlights this effect. Studies have shown the laparoscopic gastric bypass induces a hypercoagulable state similar to the open procedures. A recent survey of the American Society for Bariatric Surgery revealed a 2.6% incidence of DVT and a 1% incidence of pulmonary embolism which is much higher than that seen in the laparoscopic cholecystectomy series. As such pharmacologic therapy was frequently practiced in addition to graduated compression stockings. Low dose heparin therapy was most commonly used followed by low molecular weight heparin. Over 10% of bariatric surgeons discharged their patients on DVT prophylaxis.

Recommendation: Intraoperative graduated compression stocking for routine patients

Low dose heparin or low molecular weight heparin for high risk group with continuation postoperatively until fully ambulatory

 

Nausea and Vomiting

The cost effectiveness of laparoscopic surgery is in part due to minimizing postoperative in-hospital convalescence. The difference between an overnight admission and an outpatient procedure maybe in the success of the control of postoperative nausea and vomiting (PONV) observed in these patients. The cost of PACU medication is still less than the cost of overnight hospital admission in the US ( but not necessarily worldwide). The success of a program to reduce PONV seems to depend on its administration on a prophylactic basis. A variety of agents dramamine, metoclopramide, Compazine, ondansetron ( $235), and granisetron ( $177) +/- dexamethasone have evaluated with varying degree of success. In most but not all series ondansetron was found more effective than conventional antiemetic therapy but was still associated with substantial breakthrough PONV. Potentially exciting data from a European series demonstrating a high degree of success with a granisetron/dexamethasone combination has been reported in patients undergoing laparoscopic surgery. A variety of extrinsic factors may also play a role in the absolute magnitude of the PONV observed such as the choice of anesthetic or the use of heated insufflation gas. As such the surgeon needs to pay careful attention to the incidence of PONV in individual hospitals and perhaps even anesthesia personnel. The success of conventional antiemetics such as Dramamine and metoclopramide should be weighed prior to considering the more expensive alternatives on a programatic basis. However the more expensive antiemetics should be used if needed to complete a successful outpatient program.

Recommendation: Develop a consistent prophylactic approach to the reduction of PONV in concert with anesthesia personnel with escalation to the more expensive antiemetic schemes as clinically and financially indicated

 

Pain

The management of pain is the most common pharmacologic tool that the surgeon uses. In minimally invasive surgery, the approaches to pain management in the last ten years have been targeted at preoperative (preemptive) strategies, intraoperative approaches and post operative pain management. The preemptive strategies have focused on the administration of non-steroidal anti-inflammatory (NSAIDS), the use of dextromethorphan, and wound site management with local anesthetics. Although a few studies have failed to show a clear benefit of these approaches, most studies do demonstrate improved patient outcomes. The results often associated with the administration of ketorolac, which is somewhat costly, can seemingly be achieved less expensively by giving po ibuprofen or pr diclofenac preoperatively. The impact of local anesthetics seems to be limited to the first hour or two after surgery and while statistically significant, these benefits did little to alter overall outcome. On the other hand when it comes to pain, isn't any reduction worthy of consideration? The intraperitoneal administration of local anesthetic intraoperatively has been controversial, however several studies have demonstrated a benefit in laparoscopic cholecystectomy and in laparoscopic tubal ligation. Intra-preperitoneal administration of local anesthetic during hernia repair has been reported, but a benefit was not demonstrated. Normal saline as a drug has been instilled intra-abdominally in order to reduce shoulder pain following laparoscopically in combination with closed suction drainage and has been shown to be somewhat effective. The real impact of an effective preemptive analgesia program is realized by the reduction of needed postoperative medication. The three main choices in this arena are NSAIDS, narcotics, and centrally acting medications. Each of these groups has it advantages and disadvantages. The use of narcotics is associated with drowsiness, inability to operate heavy machinery (car) and perhaps worst of all in some ways - constipation. The use of NSAIDS to avoid this is often associated with gastric distress and increases the risk of gastrointestinal bleeding. Centrally acting drugs such as tramadol (+/- acetaminophen) have been recently approved for the treatment of acute pain post operatively. Some studies have shown a benefit when compared to NSAIDS with the additional benefit of reducing shivering and a somewhat more rapid discharge from the PACU.

Recommendation: Develop multimodal preemptive analgesic strategy incorporating the use of pharmacologic and local anesthesia therapy.

 

Summary

The rationale approach to the use of pharmacologic therapy should be aimed at maximizing patients safety and comfort while considering the expenditures in the face of available outcome related information.

1. De Witte J, Rietman GW, Vandenbroucke G, Deloof T. Post-operative effects of tramadol administered at wound closure. Eur J Anaesthesiol 1998; 15:190-5.

3. Dobay KJ, Freier DT, Albear P. The absent role of prophylactic antibiotics in low-risk patients undergoing laparoscopic cholecystectomy. Am Surg 1999; 65:226-8.

4. Elhakim M, Elkott M, Ali NM, Tahoun HM. Intraperitoneal lidocaine for postoperative pain after laparoscopy. Acta Anaesthesiol Scand 2000; 44:280-4.

5. Fiddes TM, Williams HW, Herbison GP. Evaluation of post-operative analgesia following laparoscopic application of Filshie clips. Br J Obstet Gynaecol 1996; 103:1143-7.

6. Frantzides CT, Sykes A. A reevaluation of antibiotic prophylaxis in laparoscopic cholecystectomy. J Laparoendosc Surg 1994; 4:375-8.

7. Fujii Y, Saitoh Y, Tanaka H, Toyooka H. Granisetron/dexamethasone combination for the prevention of postoperative nausea and vomiting after laparoscopic cholecystectomy. Eur J Anaesthesiol 2000; 17:64-8.

8. Fujii Y, Tanaka H, Kawasaki T. Prophylaxis with oral granisetron for the prevention of nausea and vomiting after laparoscopic cholecystectomy: a prospective randomized study. Arch Surg 2001; 136:101-4.

9. Garcia N, Kapur S, McClane J, Davis JM. Surgical infections and prophylactic antibiotics: 341 consecutive cases of gallbladder surgery in the era of laparoscopic surgery. J Laparoendosc Adv Surg Tech A 1997; 7:157-62.

10. Gharaibeh KI, Al-Jaberi TM. Bupivacaine instillation into gallbladder bed after laparoscopic cholecystectomy: does it decrease shoulder pain? J Laparoendosc Adv Surg Tech A 2000; 10:137-41.

11. Gillberg LE, Harsten AS, Stahl LB. Preoperative diclofenac sodium reduces post-laparoscopy pain. Can J Anaesth 1993; 40:406-8.

12. Harling R, Moorjani N, Perry C, MacGowan AP, Thompson MH. A prospective, randomised trial of prophylactic antibiotics versus bag extraction in the prophylaxis of wound infection in laparoscopic cholecystectomy. Ann R Coll Surg Engl 2000; 82:408-10.

13. Higgins A, London J, Charland S, et al. Prophylactic antibiotics for elective laparoscopic cholecystectomy: are they necessary? Arch Surg 1999; 134:611-3; discussion 614.

14. Illig KA, Schmidt E, Cavanaugh J, Krusch D, Sax HC. Are prophylactic antibiotics required for elective laparoscopic cholecystectomy? J Am Coll Surg 1997; 184:353-6.

15. Bradford TH, Robertson K, Norman PF, Meeks GR. Reduction of pain and nausea after laparoscopic sterilization with bupivacaine, metoclopramide, scopolamine, ketorolac, and gastric suctioning. Obstet Gynecol 1995; 85:687-91.

16. Byrne TK. Complications of surgery for obesity. Surg Clin North Am 2001; 81:1181-93, vii-viii.

17. Cabell CA. Does ketorolac produce preemptive analgesic effects in laparoscopic ambulatory surgery patients? Aana J 2000; 68:343-9.

18. Caprini JA, Arcelus JI, Laubach M, et al. Postoperative hypercoagulability and deep-vein thrombosis after laparoscopic cholecystectomy. Surg Endosc 1995; 9:304-9.

19. David AM, Swanson ML, Leve CM, Johnson JP, Dubin NH. Effect of lidocaine vs ketorolac tromethamine on postoperative laparoscopy pain control: a randomized study. Prim. Care Update Ob Gyns 1998; 5:196.

20. Ker CG, Hou MF, Chen JS, Lee KT, Sheen PC, Akbary MA. A comparative study of cefotaxime sodium versus a combination of cefapirin and gentamicin in the prophylactic treatment of patients undergoing cholecystectomy. Methods Find Exp Clin Pharmacol 1989; 11:711-5.

21. Koivuranta MK, Laara E, Ryhanen PT. Antiemetic efficacy of prophylactic ondansetron in laparoscopic cholecystectomy. A randomised, double-blind, placebo-controlled trial. Anaesthesia 1996; 51:52-55.

22. Koivuranta M, Ala-Kokko TI, Jokela R, Ranta P. Comparison of ondansetron and tropisetron combined with droperidol for the prevention of emesis in women with a history of post-operative nausea and vomiting. Eur J Anaesthesiol 1999; 16:390-5.

23. Kothari SN, Boyd WC, Bottcher ML, Lambert PJ. Antiemetic efficacy of prophylactic dimenhydrinate (Dramamine) vs ondansetron (Zofran): a randomized, prospective trial inpatients undergoing laparoscopic cholecystectomy. Surg Endosc 2000; 14:926-9.

24. Lindberg F, Bergqvist D, Rasmussen I. Incidence of thromboembolic complications after laparoscopic cholecystectomy: review of the literature. Surg Laparosc Endosc 1997; 7:324-31.

25. Mahatharadol V. A reevaluation of antibiotic prophylaxis in laparoscopic cholecystectomy: a randomized controlled trial. J Med Assoc Thai 2001; 84:105-8.

26. Mall JW, Schwenk W, Rodiger O, Zippel K, Pollmann C, Muller JM. Blinded prospective study of the incidence of deep venous thrombosis following conventional or laparoscopic colorectal resection. Br J Surg 2001; 88:99-100.

27. Michaloliakou C, Chung F, Sharma S. Preoperative multimodal analgesia facilitates recovery after ambulatory laparoscopic cholecystectomy. Anesth Analg 1996; 82:44-51.

28. Milford MA, Paluch TA. Ambulatory laparoscopic fundoplication. Surg Endosc 1997; 11:1150-2.

29. Mixter CG, 3rd, Meeker LD, Gavin TJ. Preemptive pain control in patients having laparoscopic hernia repair: a comparison of ketorolac and ibuprofen. Arch Surg 1998; 133:432-7.

30. Parlow JL, Meikle AT, van Vlymen J, Avery N. Post discharge nausea and vomiting after ambulatory laparoscopy is not reduced by promethazine prophylaxis. Can J Anaesth 1999; 46:719-24.

31. Putland AJ, McCluskey A. The analgesic efficacy of tramadol versus ketorolac in day-case laparoscopic sterilisation. Anaesthesia 1999; 54:382-5.

32. Raphael JH, Norton AC. Antiemetic efficacy of prophylactic ondansetron in laparoscopic surgery: randomized, double-blind comparison with metoclopramide. Br J Anaesth 1993; 71:845-8.

33. Saff GN, Marks RA, Kuroda M, Rozan JP, Hertz R. Analgesic effect of bupivacaine on extraperitoneal laparoscopic hernia repair. Anesth Analg 1998; 87:377-81.

34. Saleh A, Fox G, Felemban A, Guerra C, Tulandi T. Effects of local bupivacaine instillation on pain after laparoscopy. J Am Assoc Gynecol Laparosc 2001; 8:203-6.

35. Salman MA, Yucebas ME, Coskun F, Aypar U. Day-case laparoscopy: a comparison of prophylactic opioid, NSAID or local anesthesia for postoperative analgesia. Acta Anaesthesiol Scand 2000; 44:536-42.

36. Sarac AM, Aktan AO, Baykan N, Yegen C, Yalin R. The effect and timing of local anesthesia in laparoscopic cholecystectomy. Surg Laparosc Endosc 1996; 6:362-6.

 

 

16. PREOPERATIVE SIMULATION STRATEGIES

Jacques Marescaux, MD, FRCS and Francesco Rubino, MD

IRCAD-European Institute of Telesurgery; 1 Place de l'Hopital; 67091 Strasbourg, France

 

Traditionally, preoperative planning of interventions has always taken place in the surgeons' mind, and it was not too long ago when surgeons derived most of their information from the physical examination of their patients. Besides the appropriate diagnosis precise preoperative planning of the surgical procedure is essential for the success of complex surgical procedures. Preoperative planning requires precise location of the lesions and their anatomical relation to the adjacent tissues and vessels.

The development of digitised medical images through CT scan and MRI has represented a major advancement in medicine, however, detection of lesions or localization of vessels is sometime difficult to process due to a variable image contrast between parenchimas and vessels as well as due to an important image anisotropy, the slice thickness being three times larger than the pixel width. Moreover, with conventional 2-D medical images is not easy to address important issues such as the spatial relationship of tumors with crucial structures, the evaluation of anatomic variants regarding vascular supply and a volumetric and functional analysis to predict the risk of organ failure after resections.

 

The advent of laparoscopic surgery and minimally invasive techniques have revealed the importance and potential danger of the learning curve, stressing the need for alternative training models and improvement of surgical education.

 

Recent advances in computer-technologies are creating the basis for the next surgical revolution. Computer-generated 3-D images that reconstruct anatomical and pathological structures and the possibility to translate medical information contained in images into a set of 3-D models allow to develop an actual interaction of virtual instruments with the virtual organs, and therefore potentially impact several aspects of medicine and surgery, including education and training, preoperative diagnostics, preoperative planning, intra- and post-operative applications, telemedicine and telesurgery as well as research.

 

Education and Training

The major technological advantage of virtual reality is the real-time interactivity in full 3D space and real-time changes of tissues in response to specific actions, which is the fundamental concept of surgical simulation.

Virtual reality provides a safe training environment where errors can be made without consequences to a patient and the learning process is based upon learning the cause of failure.

Just as military and commercial pilots who perform a considerable amount of their training in simulated environments and must be certified in their technical skills, the surgeons of the future may train with the aid of realistic surgical simulators and their skills assessed repeatedly and objectively.

This new way for surgical training has several possible advantages; in fact, in addition to improving educational opportunities, it may shorten residency training programs and lower educational expenses. The possibility to avoid the detrimental consequences of the early phases of the learning curve is perhaps the most important among the potential advantages.

 

Preoperative Diagnostics

Current applications of virtual reality in preoperative diagnostics include gastroscopy, bronchoscopy and colonoscopy. Some authors suggested that virtual colonoscopy may be better than barium enema for detection of colon polyps 1 . In addition, the virtual colonoscopy has the unique advantage to allow "navigation" in the lumen of the bowel and views of the mucosa from any angle, as well as the possibility to pass through stenosis and even cross the colonic wall into adjacent structures 1 . These advantages might render virtual colonoscopy especially suitable for use in screening programs for colorectal cancer.

At the European Institute of Telesurgery (EITS), we have developed systems based on the automatic reconstruction of anatomical and pathological structures from medical imaging such as CT-scan and MRI. These systems automatically delineate anatomical structures with high contrast by combining the use of thresholding, mathematical morphology and distance maps, for liver, upper airways, colon and biliary tracts. We are currently evaluating the clinical applicability and possible advantages of using such systems. Preliminary results of our 3-D virtual cholangiography system in twenty-six consecutive patients with suspected lithiasis of the common bile duct seem to indicate that this procedure is feasible and sufficiently accurate for non-invasive preoperative diagnosis of lithiasis of the biliary tract.

 

The development of systems for 3-D reconstruction of liver anatomy and hepatic lesions has been shown to improve tumor localization ability and to increase precision of operation planning. Lamade' and coworkers have reported a clinical study showing that the ability to adequately assign a tumoral lesion to a liver segment was significantly increased by 3-D reconstruction when compared with 2-D computed tomography scans. The target area of the resection proposal was also improved by up to 31% when using the 3-D model 2 .

 

At the European Institute of Telesurgery we have developed a fully automated software that from CT scan and MRI images provides, in less than 5 minutes, an accurate 3D reconstruction of anatomical and pathological structures of the liver as well as invisible functional information such as portal vein labelling and anatomical segment delineation according to the Couinaud definition. Using a mouse, the surgeon can select various segmental resections to determine the optimum procedure. After clinical application in more than 30 patients this methods shows that automated delineation of anatomical structures is more sensitive and more specific than manual delineation performed by a radiologist.

An important impact that virtual reality imaging can have on liver tumor resection is the calculation of risk. The calculation of remaining liver volumes subsequent to partial hepatectomies are considered to be essential in predicting the future development of postoperative liver failure. On the basis of the 3-D imaging and a patient-oriented risk analysis using objective parameters, virtual planning of hepatic resections could be helpful in improving patient selection, and reduce postoperative liver failure rates 3 .

 

 

Preoperative Planning

Although it has been nearly a decade since surgical simulation was first attempted, computer-assisted planning and simulation of operations have mostly been used in some subspecialties such as craniofacial surgery, neurosurgery and orthopedic surgery.

While in neurosurgery and orthopedic surgery firm bony reference frame is available, for most procedures in general surgery, the virtual operation planning on the basis of 3-D reconstruction of soft tissues has to overcome the obstacles of the inherent mobility and flexibility of the target organs.

However, more recent virtual reality systems that reconstruct in 3-D the patient specific anatomical structures and lesions as well as surgical anomalies help surgeons to better comprehend and practice the proposed procedure for each single patient, and be able to repeat individual steps to improve surgical technique. Whether or not this will result in the best surgical outcomes is not possible to state at the present status of researches, however the potential is huge. In craniofacial surgery, the use of three-dimension solid models for preoperative planning for craniosynostosis has been reported to reduce operating time and blood transfusion 4 .

 

Intraoperative Application; the concept of Augmented Reality

Usually surgeons use CT, US or MRI images to provide additional information reviewed during surgery; these images however cannot be readily integrated or overlayed into the surgical space. Augmented reality (AR) superimposes computed-generated images onto the real vision of the world in real-time. In surgery, the 3-D reconstruction can be superimposed onto the real patient for providing additional help to facilitate the operative procedure. For instance, with augmented reality 3-D reconstruction of the vessels can appear on the visible surface of the liver through a virtual transparency.

Augmented reality can be used to provide additional visual input, by labelling certain structures or allowing visualization of otherwise hidden structures.

At the EITS we have developed our own real-time augmented reality system for hepatic surgery. Two cameras provide a 3D video view of the physical model; by superimposing the virtual model we obtain a virtual transparency of the physical model.

 

Telemedicine and Telesurgery

Telemedicine could be considered an application of virtual reality in that it creates a virtual interface between physicians and patients. Teleproctoring, telementoring and teleconsultation have been highly developed at the EITS, where, integrated with computer-based data access and surgical education through the Internet constitute the Virtual University concept, realized in the Websurg.

Telesurgery, intended as the performance of a surgical operation from distance, requires application of robotic technologies. Since 1994 at EITS surgeons and computer scientists as well as telecommunication and robotic engineers have joined in a common effort aimed to verify the feasibility of surgery through long distances.

This project was articulated in several steps including:

1)verification of the feasibility and safety of robot-assisted cholecystectomy in 25 patients 5 ;

2)testing the effect of artificially introduced time delays between the surgeon's manipulations and the robotic effectors and the experimental performance of laparoscopic cholecystectomy from remote distance on a pig model 6 ;

3)performance a remote robot-assisted surgical operation on a human.

 

On September 7th 2001 our group has finalized this project performing, for the first time, a robot-assisted laparoscopic cholecystecomy in a human, between New York (surgeons) and Strasbourg (patient) 7 .

 

The feasibility of robotic surgeries from remote distances provide instant access to an expert in virtually any part of the world and could possibly result in more cost-effective and timely healthcare.

 

Future Developments

Virtual and augmented reality systems can be used not only to teach surgical skills and judgement or facilitate intraoperative maneuvers, but also to rehearse procedures before performing them. With more perfected surgical simulators, in the near future, surgeons may work out the best operative procedure for each single patient and being able to repeat individual steps to improve surgical technique. The procedures can also be recorded and replayed from a robot automatically and at a distance.

Combining AR with advanced robotics could guide the surgeons through technically challenging procedures and avoid injury to vital structures. The integration of physiology and anatomy in virtual 3D systems and simulators may also have a significant impact on research since new procedures could be performed in a virtual patient and functional consequences or possible complications anticipated.

 

Clinical Impact of New Technologies in Surgery and Costs

Outcomes of many surgical procedures still depend on the operator's skills and experience and on the learning curve. The problem of the costs of all the new technologies may be discouraging at a first glance, but at a more comprehensive evaluation of their possible clinical advantages they seem instead to be potentially cost-saving.

For instance, it has been estimated that between 44,000 and 98,000 deaths annually occur in USA due to errors in hospital care and that as much as 54% of surgical errors could be prevented 8 . Although not yet demonstrated in clinical trials, the potential of new technologies to reduce medical errors and complications related to the learning curve is reasonably huge. In fact, combining the possibility of obtaining active intervention and expert assistance even from remote distance with the possible improvement of surgical training and preoperative planning allowed by virtual and augmented reality, it is reasonable to expect a significant improvement of the standard of surgical care worldwide. This may well reduce the learning curve effect on errors, morbidity and its related costs. If this is the case, in our opinion, robotic surgery and virtual reality systems may be revealed to be cost-effective.

 

 

REFERENCES

 

1. Halligan S, Fenlon HM. Virtual colonoscopy. BMJ 1999; 319: 1249-1252

2. Lamade W, Glombitza G, Fischer L, Chiu P, Cardenas CE Sr, Thorn M, Meinzer HP, Grenacher L, Bauer H, Lehnert T, Herfarth C. The impact of 3-Dimensional reconstructions on operation planning in liver surgery. Arch Surg 2000; 135(11): 1256-1261

3. Rau HG, Schauer R, Helmberger T et al. Impact of virtual reality imaging on hepatic liver tumor resection: calculation of risk. Langenbeck's Arch Surg 2000; 385:162-170

4. Imai K, Tsujiguchi K, Toda C et al. Reduction of operating time and blood transfusion for craniosynostosis by simulated surgery using three-dimensional solid models. Neurol Med Chir (Tokyo) 1999; 39(6): 423-6

5. Marescaux J, Smith MK, Folscher D, Jamali F, Malassagne B, Leroy J. Telerobotic laparoscopic cholecystectomy: initial clinical experience with 25 patients. Ann Surg 2001; 234(1):1-7

6. Marescaux J, Leroy J, Gagner M, Rubino F, Mutter D, Vix M, Butner SE, Smith MK. Transatlantic robot-assisted telesurgery. Nature 2001; 413(6854):379-80

7. Marescaux J, Leroy J, Rubino F, Smith MK, Vix M, Simone M, Mutter D. Transcontinental robot-assisted remote telesurgery: feasibility and potential applications. Ann Surg 2002 (in press)

8. Kohn LT, Corrigan JM, Donaldson MS. Te err is human: building a safer health system. Washington, DC: National Academy Press, 1999.

 

 

17. Training and Determination of Outcomes and Competency

Gerald M. Fried, M.D.

Professor of Surgery, McGill University,Steinberg-Bernstein Chair of Minimally Invasive Surgery
McGill University Health Centre, 1650 Cedar Avenue, # L9.309
Montreal, Quebec, CANADA H3G 1A4

 

An important goal of our profession and our specialty societies should be ensuring quality of care, particularly when new procedures or technology are introduced. Ensuring competence in minimally invasive surgery requires several steps. First, there is the acquisition of knowledge, judgment and skills specific for this field. Once knowledge, judgment and skills have been learned, an evaluative program should verify this. Although courses can be provided to teach knowledge, judgment, and skills, verification that learning has been really acquired is essential. This talk will emphasize some of the tools used for formative evaluations (in-training assessments) and summative evaluations (credentialing or certifying assessments). Once privileges have been granted based on demonstration that an approved course has been taken and the knowledge, judgment, and skills acquired, the surgeon must demonstrate competence in the clinical use of the new technology in the course of clinical practice. This can be best achieved by outcomes measurement. This talk will address the learning process, the certification process and the measurement of appropriate outcomes.

 

Learning Process:

There is a vast amount of information in the surgical literature on Minimally Invasive Surgery (MIS). This includes the physiologic effects of pneumoperitoneum, risks, complications and their avoidance. A myriad of procedures have been described in detail, including methods of exposure and instrumentation. The surgeon must be familiar with this body of information and comfortable with the instrumentation before doing MIS procedures independently.

Judgment is more difficult to assess. For graduating residents the certification exam should include material to evaluate the topic of MIS. Oral exams are particularly useful to test judgment based on clinical scenarios. Other multimedia and printed material also teach judgment through the use of realistic scenarios. Specialty societies, individual authors, and for-profit companies are also preparing multimedia and text-based instructional materials to prepare the surgeon for decision making and using appropriate judgment in MIS.

Technical skills have traditionally been taught in the operating room through a process of progressive responsibility starting with observation, then assisting, and finally by operating first under guidance of an expert, and then independently. At this point in time it is neither cost-effective nor ethical to develop basic technical skills on patients. There is ample opportunity to develop specific skills using inanimate simulators (either physical or virtual-reality ones). Physical simulators have used endotrainer boxes and optical systems to reproduce the monocular vision associated with laparoscopic surgery. In these systems, actual surgical instruments can be utilized that have the same characteristics, feel, and haptic feedback that they are associated with in the O.R. It is an excellent opportunity to become familiar with instrumentation and to practice basic skills. Studies have shown that acquisition of skills using either physical or V-R simulators results in enhanced performance in the O.R. Similarly virtual reality systems provide objective assessment of performance and are particularly useful as a formative evaluation tool during training. Both physical and virtual training systems can provide useful objective measures of performance. Comparisons can be made with a peer group and a score can be determined that is associated with surgical competence.

 

Summative Evaluation

Once a surgeon has completed his/her educational program the next step is to measure the knowledge, judgment and skills that have actually been acquired. This should be tested using an evaluative process that has been shown to be objective, reliable, valid, sensitive and specific. Performance scores should be compared against a standard with the goal of ensuring that the surgeon meets the minimum standards associated with a group of competent surgeons in this field. This evaluation process is uncommon for practicing surgeons, but has been used in the area of trauma care as part of the ATLS program. The purpose of this evaluation is not to be exclusive but to give the surgeon the best opportunity to pass after appropriate learning has occurred. Such an evaluation can be administered through a national certifying organization e.g. American Board or Royal College, or by a national specialty society with credibility in the specific field. This should ideally be a voluntary process whereby the surgeon decides to take an exam to demonstrate that he or she has acquired the basic level of knowledge, judgment, and skills to provide surgical care for patients using MIS techniques.

 

Proctoring

Once a surgeon has undergone a learning experience and has demonstrated acquisition of knowledge, judgment, and skills through a summative assessment, these skills can be applied to the patient in a controlled and monitored environment. Where feasible it is appropriate that the surgeon be observed performing MIS procedures on his/her own patients. The observer should be a surgeon recognized by the surgeon and the institution as being competent in MIS surgery. The surgeon's skills should be appropriately evaluated and the proctor should agree that the surgeon has demonstrated familiarity with the basic principles of MIS, and has shown that he/she possesses the skills for either basic or advanced laparoscopic procedures. Once this has been accomplished the institution will usually give privileges for the surgeon to perform either basic or advanced MIS surgery. This should usually be accompanied by a recommendation that the surgeon measure outcomes of these procedures.

 

Outcomes Measurement

The primary purpose of outcomes measurement is to ensure that clinical care is delivered safely and effectively. It is also a useful source of feedback to the surgeon. This feedback can then be used to help provide better preoperative information to the patient regarding expectations of surgery. It can also help the surgeon identify areas where improvement can be made. When new technology or procedures are introduced it is necessary for the profession, not each individual surgeon, to demonstrate the benefit of the new technology through providing high-level evidence of its safety and efficacy. An example would be a randomized controlled trial comparing laparoscopic to open surgery for a given clinical problem.

Outcomes can evaluate surgical treatment from the perspective of the patient, the surgeon, and the health care system. An example is the use of laparoscopic antireflux surgery for treatment of gastroesophageal reflux disease. From the patient's point of view operative treatment may have been chosen to improve the quality of life. Outcomes to be measured should include effects of the surgery on the patient's symptoms, any side effects not present before surgery, quality of life (disease-specific and generic) and patient satisfaction.

From the surgeon's perspective, the goal is the "cure" of gastroesophageal reflux with minimal morbidity and mortality. Outcome measures might include postoperative physiological data (e.g. 24 pH, manometry), and monitoring of complications within 30 days.

The institution will usually also be interested in information regarding utilization of resources. Such data might include duration of surgery, length of stay, equipment costs. The insurer and employer would be interested in outcomes pertaining to duration of disability and loss of productive time after surgery.

 

Conclusions

If provision of safe and effective surgical care is our priority, then we should articulate a logical approach to the acquisition of the knowledge, judgment, and skills required to provide such care. When new procedures and technology are introduced, the technology should be assessed. Then, once the technology is proven to be safe and effective, there is a need to bring practicing surgeons to a level of competence in this new area so that it can be incorporated in their surgical practice. This outline provides an overview of how the knowledge, judgment, and skills required for performing MIS can be acquired and how an evaluation process can be put in place to ensure that surgeons practicing this form of surgical care are competent.

 

Bibliography:

1. Derossis AM, Fried GM, Abrahamowicz M, Sigman HH, Barkun JS, Meakins JL: Development of a model for training and evaluation of laparoscopic skills. American Journal of Surgery 1998; 175: 482-487

2. Derossis AM, Bothwell J, Sigman HH, Fried GM: The effect of practice on performance in a laparoscopic simulator. Surgical Endoscopy 1998; 12: 1117-1120

3. Fried GM, Derossis AM, Bothwell J, Sigman HH: Comparison of laparoscopic performance in vivo with performance measured in a laparoscopic simulator. Surgical Endoscopy 1999; 13:1077-1081

4. Darzi A. Datta V. Mackay S. The challenge of objective assessment of surgical skill.. American Journal of Surgery 2001. 181:484-6

5. Torkington J. Smith SG. Rees BI. Darzi A. The role of simulation in surgical training. Annals of the Royal College of Surgeons of England 2000. 82:88-94

6. Eyal R. Tendick F: Spatial ability and learning the use of an angled laparoscope in a virtual environment. Studies in Health Technology & Informatics. 81:146-52, 2001.

7. Haluck RS. Krummel TM. Computers and virtual reality for surgical education in the 21st century. Archives of Surgery 2000; 135:786-92

8. Scott DJ. Valentine RJ. Bergen PC. Rege RV. Laycock R. Tesfay ST. Jones DB. Evaluating surgical competency with the American Board of Surgery In-Training Examination, skill testing, and intraoperative assessment. Surgery 2000; 128:613-22

9. Rosser JC Jr. Rosser LE. Savalgi RS. Objective evaluation of a laparoscopic surgical skill program for residents and senior surgeons. Archives of Surgery. 1998; 133:657-61

10. Rosser JC. Herman B. Risucci DA. Murayama M. Rosser LE. Merrell RC.: Effectiveness of a CD-ROM multimedia tutorial in transferring cognitive

knowledge essential for laparoscopic skill training. American Journal of Surgery 2000;. 179: 320-4

11. Feldman LS, Mayrand S, Stanbridge D, Mercier L, Barkun JS, Fried GM: Laparoscopic fundoplication: a model for assessing new technology in surgical procedures. Surgery 2001; 130: 686-695

12. Barkun JS, Barkun AN, Samplais JS, Fried G, Taylor B, Wexler MJ, Goresky CA, Meakins JL: Randomised controlled trial of laparoscopic versus mini cholecystectomy. Lancet 1992; 340: 1116-1119

 

 

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A

Amaral, Joseph 11

D

Dallemagne, Bernard 57

Dutson, Erik 4

F

Fingerhut, A. 47

Fried, Gerald M. 93

H

Heniford, B. Todd 45

Henri, Margaret 4

Hunter, John G. 59

J

Jones, Stephanie B. 83

L

Lacy, Antonio M. 47

Leroy, Joel 4

M

Marescaux, Jacques 4, 89

Mouiel, Jean 65

P

Park, Adrian 70

S

Schwaitzberg, Steven D. 85

Smith, C. Daniel 43

Soper, Nathaniel 73

T

Talamini, Mark 9

W

Wayand, Wolfgang 36