Electrosurgical Complications in Laparoscopic Surgery
Unlike open surgery where hemostasis (control of bleeding) is accomplished by pressure and careful application of fine clamps and ligatures, laparoscopic surgery must rely on electrosurgery to achieve hemostasis. Excessive use of energy can burn a hole in the wall of the organ involved. Current can also cause injury to adjacent organs, and even distant organs. Complications of electrosurgery occur secondary to thermal injury from one of three basic causes. The first is thermal trauma from unintended or inappropriate use of the active electrode(s). The second from current diverting to another, undesirable path, causing injury remote from the immediate operative field. Third is injury at the site of the “return” or dispersive electrode. Active electrode injury can occur with either unipolar or bipolar instruments, while trauma secondary to current diversion or dispersive electrode accidents only occurs with the unipolar technique. Complications of electrosurgery are reduced with strict adherence to safety protocols coupled with a sound understanding of the circumstances that can lead to undesirable effects on tissue.
Active Electrode Trauma
Unintended activation in open space without touching the tissue is one of the more common mechanisms by which the active electrode causes complications. Such a complication frequently occurs when an electrode, left untended within the peritoneal cavity, is inadvertently activated by compression of the hand switch or depression of the foot pedal. Control of the electrosurgical unit or generator (ESU) by someone other than the operating surgeon is also a source of accidental activation of the electrode.
A direct extension is another mechanism by which the active electrode(s) cause complications. The zone of vaporization or coagulation may extend to involve large blood vessels or vital structures such as the bladder, ureter, or bowel. Bipolar current reduces, but does not eliminate, the risk of thermal injury to adjacent tissue. Consequently, care must be taken to isolate blood vessels prior to desiccation, especially when near vital structures, and to apply appropriate amounts of energy in a fashion that allows an adequate margin of non-injured tissue.
Diagnosis
During minimal access surgery the diagnosis of direct thermal visceral injury may be suspected or confirmed intraoperatively. Careful evaluation of nearby intraperitoneal structures should be made if unintended activation of the electrode occurs. The visual appearance will depend upon a number of factors including the type of the electrode, its proximity to tissue, the output of the generator, and the duration of its activation. High power density activations will often result in vaporization injury, and will be more easily recognized than lower power density lesions that result in desiccation and coagulation. The diagnosis of visceral thermal injury is often delayed until the signs and symptoms of fistula or peritonitis present. This will be particularly true with desiccation injury. Because these complications may not present until two to at least ten days following surgery, long after discharge, both the patient and the physician must be made aware of the possible consequences. Consequently, patients should be advised to report any fever or increasing abdominal pain experienced postoperatively.
Prevention
Electrosurgical injuries are largely prevented if, (a) the surgeon is always in direct control of electrode activation, and (b) all electrosurgical hand instruments are removed from the peritoneal cavity when not in use. When removed from the peritoneal cavity, the instruments should be detached from the electrosurgical generator or they should be stored in an insulated pouch near to the operative field. These measures prevent damage to the patient’s skin if the foot pedal is accidentally depressed.
Management
Once diagnosed thermal injury to bowel, bladder, or ureter, recognized at the time of laparoscopy, should immediately be managed appropriately, considering the potential extent of the zone of coagulative necrosis. The extent of thermal trauma will depend upon the characteristics of the energy transferred to tissue. An electrosurgical incision made with the focused energy from a pointed electrode will be associated with a minimal amount of surrounding thermal injury, and may be repaired in a fashion identical to one created mechanically. However, with desiccation injury created as a result of prolonged contact with a relatively large caliber electrode, the thermal necrosis may extend centimeters from the point of contact. In such instances, wide excision or resection will be necessary.
Remote Injury
Remote injury due to current diversion can occur when an electrical current finds a direct path out of the patient’s body via grounded sites other than the dispersive electrode. Alternatively, the current can be diverted directly to other tissue before it reaches the tip of the active electrode. In either instance, if the power density becomes high enough, unintended and severe thermal injury can result. These injuries can only occur with ground-referenced ESUs because they lack an isolated circuit. In such generators, when the dispersive electrode becomes detached, unplugged, or otherwise ineffective, the current will seek any grounded conductor. If the conductor has a small surface area, the current or power density may become high enough to cause thermal injury. Examples include electrocardiograph patch electrodes or the conductive metal components of the operating table.
Modem ESUs are designed and built with isolated circuits and impedance monitoring systems or active electrode monitoring system. Consequently, if any part of the circuit is broken, an alarm sounds, and/or the machine “shuts down,” thereby preventing electrode activation. Since the widespread introduction of such generators, the incidence of burns to alternate sites has become largely confined to cases involving the few remaining ground referenced machines.
Insulation Failure
Failure in the insulation coating the shaft of a laparoscopic electrosurgical electrode can allow current diversion to adjacent tissue. The high power density resulting from such small points of contact fosters the creation of a significant injury. During laparoscopic surgery, bowel is frequently the tissue near to, or in contact with, the shaft of the electrode, making it the organ most susceptible to this type of electrosurgical injury. The fact that the whole shaft of the electrode is frequently not encompassed by the surgeon’s visual field at laparoscopy makes it possible that such an injury can occur unaware to the operator.
Prevention of complication of insulation failure starts with the selection and care of electrosurgical hand instruments. Loose instrument bins should be replaced with containers designed to keep the instruments from damaging each other. The instruments should be examined prior to each case, searching for worn or obviously defective insulation. When found, the damaged instrument should be removed and repaired or replaced. Despite all efforts, unobserved breaks in insulation may rarely occur. While the use of disposable instruments is often claimed as a way of reducing the incidence of insulation failure, there is no guarantee that this is the case, as invisible defects may occur in the manufacturing process. Furthermore, the insulation on disposable electrodes is thinner and more susceptible to trauma. Consequently, when applying unipolar electrical energy, the shaft of the instrument should be kept free of vital structures and, if possible, totally visible in the operative field.
Direct Coupling
During minimal access surgery direct coupling occurs when an activated electrode touches and energizes another metal conductor such as a laparoscope, cannula or other instrument. If the conductor is near to, or in contact with, other tissue, a thermal injury can result. Such accidents often happen following unintentional activation of an electrode. Prevention of direct coupling is facilitated by removal of the electrodes when not in use and visually- confirming that the electrode is not in inappropriate contact with other conductive instruments prior to activation.
Capacitive Coupling
Many capacitive coupling of diathermy current have been reported as causes of occult injury during surgical laparoscopy. Capacitance reflects the ability of a conductor to establish an electrical current in an unconnected but nearby circuit. An electrical field is established around the shaft of any activated laparoscopic unipolar electrode, a circumstance that makes the electrode a capacitor. This field is harmless if the circuit is completed via a dispersive, low power density pathway. If capacitive coupling occurs between the laparoscopic electrode and a metal cannula positioned in the abdominal wall, the current without any complication returns to the abdominal wall where it traverses to the dispersive electrode. However, if the metal cannula is anchored to the skin by a nonconductive plastic retaining sleeve, or anchor (a hybrid system), the current will not return to the abdominal wall because the sleeve acts as an insulator. Instead, the capacitor will have to search elsewhere to complete the circuit. Consequently, bowel; or any other nearby conductor, can become the target of a relatively high power density discharge. The risk is greater with high voltage currents, such as the coagulation output on an electrosurgical generator. This mechanism is also more likely to occur when a unipolar electrode is inserted through an operating laparoscope that, in turn, is passed through a plastic laparoscopic port. In this configuration, the plastic port acts as the insulator. If the electrode capacitively couples with the metal laparoscope, nearby bowel will be at risk for significant thermal injury.
During minimal access surgery prevention of capacitive coupling can largely be accomplished by avoiding the use of hybrid laparoscope cannula systems that contain a mixture of conductive and nonconductive elements. Instead, it is preferred that all plastic or all-metal cannula systems be used. When and if operating laparoscopes are employed, all metal cannula systems should be the rule unless there is no intent to perform unipolar electrosurgical procedures through the operating channel.
Risk of this injury is very much minimized if low voltage radiofrequency current (cutting) is used, and when the high voltage outputs are avoided.
Dispersive Electrode Burns
The use of isolated circuit generators with return electrode monitors has all but eliminated dispersive electrode related thermal injury. Return electrode monitoring (REM) is actually accomplished by measuring the impedance (sometimes called resistance) in the dispersive electrode, which should always be low because of the large surface area. To accomplish this, most return electrode monitors, actually are divided into two electrodes, allowing the generator to compare the impedance from the two sides of the pad. If the overall impedance is high, or if there is a significant difference between the two sides, as is the case with partial detachment, the active electrode cannot be activated. Without such devices, partial detachment of the patient pad could result in a thermal injury because reducing the surface area of the electrode raises the current density. It is important for the surgeon to establish what type of ESU is being used in each case. Absence of a REM system is a reason for increased scrutiny of the positioning of the dispersive electrode, both before the surgery begins, and as the operation progresses.
Electrode Shields and Monitors
A United States-based company, (Electroscope Inc.) markets a system that helps to reduce further the chance of direct or capacitive coupling. A reusable shield is passed over the shaft of the laparoscopic electrode prior to its insertion into the peritoneal cavity. This shield protects against insulation failure and detects the presence of significant capacitance. Should an insulation break occur, or when capacitance becomes threatening, the integrated monitoring system automatically shuts down the generator. The shield enlarges the effective diameter of the electrode by about 2 mm, making it necessary to use larger caliber laparoscopic ports.
Despite perceptions to the contrary, electrosurgery has been rendered a safe modality for use in surgical procedures. However, safe and effective application of electrical energy requires an adequate understanding and implementation of basic principles as well as the availability of modern electrosurgical generators and appropriate education of medical and support staff. Care and prudence must be exercised when utilizing electricity within the peritoneal cavity. The zone of significant thermal injury usually extends beyond that of the visible injury, a feature that must be borne in mind when operating in close proximity to vital structures such as bowel bladder, ureter, and large and important blood vessels. It is equally important to impart the minimal amount of thermal injury (if any) necessary to accomplish the task at hand, even around nonvital structures, by using the ideal power output and the appropriate active electrodes.
Unlike open surgery where hemostasis (control of bleeding) is accomplished by pressure and careful application of fine clamps and ligatures, laparoscopic surgery must rely on electrosurgery to achieve hemostasis. Excessive use of energy can burn a hole in the wall of the organ involved. Current can also cause injury to adjacent organs, and even distant organs. Complications of electrosurgery occur secondary to thermal injury from one of three basic causes. The first is thermal trauma from unintended or inappropriate use of the active electrode(s). The second from current diverting to another, undesirable path, causing injury remote from the immediate operative field. Third is injury at the site of the “return” or dispersive electrode. Active electrode injury can occur with either unipolar or bipolar instruments, while trauma secondary to current diversion or dispersive electrode accidents only occurs with the unipolar technique. Complications of electrosurgery are reduced with strict adherence to safety protocols coupled with a sound understanding of the circumstances that can lead to undesirable effects on tissue.
Active Electrode Trauma
Unintended activation in open space without touching the tissue is one of the more common mechanisms by which the active electrode causes complications. Such a complication frequently occurs when an electrode, left untended within the peritoneal cavity, is inadvertently activated by compression of the hand switch or depression of the foot pedal. Control of the electrosurgical unit or generator (ESU) by someone other than the operating surgeon is also a source of accidental activation of the electrode.
A direct extension is another mechanism by which the active electrode(s) cause complications. The zone of vaporization or coagulation may extend to involve large blood vessels or vital structures such as the bladder, ureter, or bowel. Bipolar current reduces, but does not eliminate, the risk of thermal injury to adjacent tissue. Consequently, care must be taken to isolate blood vessels prior to desiccation, especially when near vital structures, and to apply appropriate amounts of energy in a fashion that allows an adequate margin of non-injured tissue.
Diagnosis
During minimal access surgery the diagnosis of direct thermal visceral injury may be suspected or confirmed intraoperatively. Careful evaluation of nearby intraperitoneal structures should be made if unintended activation of the electrode occurs. The visual appearance will depend upon a number of factors including the type of the electrode, its proximity to tissue, the output of the generator, and the duration of its activation. High power density activations will often result in vaporization injury, and will be more easily recognized than lower power density lesions that result in desiccation and coagulation. The diagnosis of visceral thermal injury is often delayed until the signs and symptoms of fistula or peritonitis present. This will be particularly true with desiccation injury. Because these complications may not present until two to at least ten days following surgery, long after discharge, both the patient and the physician must be made aware of the possible consequences. Consequently, patients should be advised to report any fever or increasing abdominal pain experienced postoperatively.
Prevention
Electrosurgical injuries are largely prevented if, (a) the surgeon is always in direct control of electrode activation, and (b) all electrosurgical hand instruments are removed from the peritoneal cavity when not in use. When removed from the peritoneal cavity, the instruments should be detached from the electrosurgical generator or they should be stored in an insulated pouch near to the operative field. These measures prevent damage to the patient’s skin if the foot pedal is accidentally depressed.
Management
Once diagnosed thermal injury to bowel, bladder, or ureter, recognized at the time of laparoscopy, should immediately be managed appropriately, considering the potential extent of the zone of coagulative necrosis. The extent of thermal trauma will depend upon the characteristics of the energy transferred to tissue. An electrosurgical incision made with the focused energy from a pointed electrode will be associated with a minimal amount of surrounding thermal injury, and may be repaired in a fashion identical to one created mechanically. However, with desiccation injury created as a result of prolonged contact with a relatively large caliber electrode, the thermal necrosis may extend centimeters from the point of contact. In such instances, wide excision or resection will be necessary.
Remote Injury
Remote injury due to current diversion can occur when an electrical current finds a direct path out of the patient’s body via grounded sites other than the dispersive electrode. Alternatively, the current can be diverted directly to other tissue before it reaches the tip of the active electrode. In either instance, if the power density becomes high enough, unintended and severe thermal injury can result. These injuries can only occur with ground-referenced ESUs because they lack an isolated circuit. In such generators, when the dispersive electrode becomes detached, unplugged, or otherwise ineffective, the current will seek any grounded conductor. If the conductor has a small surface area, the current or power density may become high enough to cause thermal injury. Examples include electrocardiograph patch electrodes or the conductive metal components of the operating table.
Modem ESUs are designed and built with isolated circuits and impedance monitoring systems or active electrode monitoring system. Consequently, if any part of the circuit is broken, an alarm sounds, and/or the machine “shuts down,” thereby preventing electrode activation. Since the widespread introduction of such generators, the incidence of burns to alternate sites has become largely confined to cases involving the few remaining ground referenced machines.
Insulation Failure
Failure in the insulation coating the shaft of a laparoscopic electrosurgical electrode can allow current diversion to adjacent tissue. The high power density resulting from such small points of contact fosters the creation of a significant injury. During laparoscopic surgery, bowel is frequently the tissue near to, or in contact with, the shaft of the electrode, making it the organ most susceptible to this type of electrosurgical injury. The fact that the whole shaft of the electrode is frequently not encompassed by the surgeon’s visual field at laparoscopy makes it possible that such an injury can occur unaware to the operator.
Prevention of complication of insulation failure starts with the selection and care of electrosurgical hand instruments. Loose instrument bins should be replaced with containers designed to keep the instruments from damaging each other. The instruments should be examined prior to each case, searching for worn or obviously defective insulation. When found, the damaged instrument should be removed and repaired or replaced. Despite all efforts, unobserved breaks in insulation may rarely occur. While the use of disposable instruments is often claimed as a way of reducing the incidence of insulation failure, there is no guarantee that this is the case, as invisible defects may occur in the manufacturing process. Furthermore, the insulation on disposable electrodes is thinner and more susceptible to trauma. Consequently, when applying unipolar electrical energy, the shaft of the instrument should be kept free of vital structures and, if possible, totally visible in the operative field.
Direct Coupling
During minimal access surgery direct coupling occurs when an activated electrode touches and energizes another metal conductor such as a laparoscope, cannula or other instrument. If the conductor is near to, or in contact with, other tissue, a thermal injury can result. Such accidents often happen following unintentional activation of an electrode. Prevention of direct coupling is facilitated by removal of the electrodes when not in use and visually- confirming that the electrode is not in inappropriate contact with other conductive instruments prior to activation.
Capacitive Coupling
Many capacitive coupling of diathermy current have been reported as causes of occult injury during surgical laparoscopy. Capacitance reflects the ability of a conductor to establish an electrical current in an unconnected but nearby circuit. An electrical field is established around the shaft of any activated laparoscopic unipolar electrode, a circumstance that makes the electrode a capacitor. This field is harmless if the circuit is completed via a dispersive, low power density pathway. If capacitive coupling occurs between the laparoscopic electrode and a metal cannula positioned in the abdominal wall, the current without any complication returns to the abdominal wall where it traverses to the dispersive electrode. However, if the metal cannula is anchored to the skin by a nonconductive plastic retaining sleeve, or anchor (a hybrid system), the current will not return to the abdominal wall because the sleeve acts as an insulator. Instead, the capacitor will have to search elsewhere to complete the circuit. Consequently, bowel; or any other nearby conductor, can become the target of a relatively high power density discharge. The risk is greater with high voltage currents, such as the coagulation output on an electrosurgical generator. This mechanism is also more likely to occur when a unipolar electrode is inserted through an operating laparoscope that, in turn, is passed through a plastic laparoscopic port. In this configuration, the plastic port acts as the insulator. If the electrode capacitively couples with the metal laparoscope, nearby bowel will be at risk for significant thermal injury.
During minimal access surgery prevention of capacitive coupling can largely be accomplished by avoiding the use of hybrid laparoscope cannula systems that contain a mixture of conductive and nonconductive elements. Instead, it is preferred that all plastic or all-metal cannula systems be used. When and if operating laparoscopes are employed, all metal cannula systems should be the rule unless there is no intent to perform unipolar electrosurgical procedures through the operating channel.
Risk of this injury is very much minimized if low voltage radiofrequency current (cutting) is used, and when the high voltage outputs are avoided.
Dispersive Electrode Burns
The use of isolated circuit generators with return electrode monitors has all but eliminated dispersive electrode related thermal injury. Return electrode monitoring (REM) is actually accomplished by measuring the impedance (sometimes called resistance) in the dispersive electrode, which should always be low because of the large surface area. To accomplish this, most return electrode monitors, actually are divided into two electrodes, allowing the generator to compare the impedance from the two sides of the pad. If the overall impedance is high, or if there is a significant difference between the two sides, as is the case with partial detachment, the active electrode cannot be activated. Without such devices, partial detachment of the patient pad could result in a thermal injury because reducing the surface area of the electrode raises the current density. It is important for the surgeon to establish what type of ESU is being used in each case. Absence of a REM system is a reason for increased scrutiny of the positioning of the dispersive electrode, both before the surgery begins, and as the operation progresses.
Electrode Shields and Monitors
A United States-based company, (Electroscope Inc.) markets a system that helps to reduce further the chance of direct or capacitive coupling. A reusable shield is passed over the shaft of the laparoscopic electrode prior to its insertion into the peritoneal cavity. This shield protects against insulation failure and detects the presence of significant capacitance. Should an insulation break occur, or when capacitance becomes threatening, the integrated monitoring system automatically shuts down the generator. The shield enlarges the effective diameter of the electrode by about 2 mm, making it necessary to use larger caliber laparoscopic ports.
Despite perceptions to the contrary, electrosurgery has been rendered a safe modality for use in surgical procedures. However, safe and effective application of electrical energy requires an adequate understanding and implementation of basic principles as well as the availability of modern electrosurgical generators and appropriate education of medical and support staff. Care and prudence must be exercised when utilizing electricity within the peritoneal cavity. The zone of significant thermal injury usually extends beyond that of the visible injury, a feature that must be borne in mind when operating in close proximity to vital structures such as bowel bladder, ureter, and large and important blood vessels. It is equally important to impart the minimal amount of thermal injury (if any) necessary to accomplish the task at hand, even around nonvital structures, by using the ideal power output and the appropriate active electrodes.
