How to Do Electrosurgery Safely

The horrific result of a patient plate burn. A generator equipped with return electrode monitoring might have avoided this injury.

Surgeons have been using electrosurgery, which uses high-frequency alternating current to cut and coagulate tissue, since the beginning of this century. However, minimally invasive procedures, especially laparoscopic and other endoscopic techniques, have made electrosurgery much riskier than when it was used in traditional open procedures.

There are two basic principles of electricity: 1) electrical current flows to ground and 2) it follows the path of least resistance. Monopolar electrosurgery creates a complete electrical circuit from the active electrode, to the target tissue, to the dispersive return electrode, and back to the generator. Because surgeons now work through keyhole incisions and manipulate electrodes and instruments through long, narrow channels, it is more difficult than ever to prevent the electricity from traveling outside this path and burning or vaporizing non-targeted tissue. Another electrosurgery hazard is the risk of inhaling toxic chemicals, mutagenic particles, and bacterial and viral DNA particles (possibly including HIV).

Fortunately, there are simple ways that you can avoid these hazards. In this article, I'll discuss five risks associated with electrosurgery, and present some techniques that I use to reduce the risk in my OB-GYN practice.

Insulation failure can result in an unintended burn to non-targeted tissue.

1. Direct Coupling
If the active electrode touches a non-insulated metal instrument within the abdomen, it will convey energy to the second instrument, which may in turn, if the current density is high enough, transfer it to surrounding tissues and cause a thermal burn. For example, the active electrode could come in contact or in close proximity (less than 2 mm) to a laparoscope, creating an arc of current between the two. The laparoscope could then brush against surrounding tissue, causing a severe burn to the bowel and other structures. The burns may not be in the visual field of the surgeon and therefore will not be recognized and dealt with in a timely fashion.

Solution:
To prevent direct coupling, first make sure the active electrode is not in close proximity to or touching another metal instrument before you activate the generator. Check that the electrode is touching the targeted tissue, and only that tissue, before you activate the generator. Note that when targeted tissue is coagulated (desiccated) the impedance increases and the current may arc to adjacent tissue, following the path of least resistance.

Also, make sure you place all metal instruments, such as laparoscopes, through conductive metal trocars. This way, if the active electrode touches the instrument, the current will simply flow from the instrument to the metal trocar. As long as the trocar is in contact with a relatively large portion of the abdominal wall, the current will not be able to concentrate; instead, it will dissipate harmlessly from the trocar through the abdomen and back through adjacent tissue to the return electrode. If the trocar is completely or partially constructed of plastic, however, the energy may not be able to dissipate back through the body. The metal within the trocar will build up a charge, which could eventually arc to adjacent tissue and back to the return electrode, but at a harmful level of current. In doing so, it may travel through the bowel, skin, or even the operator's hands, causing burns.

2. Insulation Failure
Continued regular use or cleaning and sterilization can cause the layer of insulation covering the shaft of the active electrode to break down. Tiny, visually undetectable tears are actually more dangerous than large cracks, since the current escaping from these miniscule breaks is more concentrated, and therefore capable of causing sparks (averaging 700?? ? C). These sparks can cause severe burns and even ignite fires, especially in oxygen-rich environments.

Unfortunately, many surgeons unknowingly contribute to the problem. Routine use of the high voltage "coagulation" current may actually compromise insulation integrity. The higher the voltage, the greater the risk that the current will break through weak insulation.

Solution:
First, encourage surgeons to always use the lowest voltage they can. All electrosurgery systems will allow you to use a "coagulation" or "cutting" waveform of current. Coagulation current is released in rapid (40,000 Hz), high-voltage bursts to desiccate tissue and cause hemostasis; cutting current comes out in a lower-voltage, uninterrupted flow to dissect tissue.

In most cases, you should try to use the cutting current for both cutting and coagulation. The coagulation mode is really only necessary when you need to fulgurate, or stop diffuse bleeding on highly vascularized tissue. Using the lowest voltage may reduce the wear on the insulation and minimize the chance that the current can escape through hairline cracks.

Keep in mind, however, that using the cutting current minimizes, but does not eliminate, the risk of insulation failure. To really be sure that the insulation is not compromised, I recommend implementing an electrosurgical unit that employs active electrode monitoring technology (AEM). This technology is called "Electro-Shield" (ElectroScope Inc., Boulder, Colo.) and it virtually eliminates these type of electrical burns.

Active electrode monitoring protects against thermal burns in two ways. First, it encases the insulated electrode in a protective metal shield that is connected to the generator; the entire probe is also covered with an extra layer of insulation. The extra conductive and insulating layers ensure that stray current is contained and flows right back to the generator. Second, the system monitors the electrical circuit so if stray energy reaches dangerous levels, the unit shuts off automatically and sounds an alarm before a burn can occur. Electroscope's AEM system operates on a principle similar to Ground Fault Interrupt (GFI) outlets in our home. It protects against insulation breaks by grounding electricity's unpredictable elements, eliminating stray burns to the patient. This is presently considered the standard of care in endoscopic electrosurgery.

3. Capacitive Coupling
The phenomenon of "capacitance" is the ability of two conductors to transmit electrical flow even if they are separated by an intact layer of insulation. Capacitive coupling can occur even in the best-case scenario-that is, when the insulation around the active electrode is intact and the tip of the electrode isn't touching anything metal. If the active, insulated electrode is wrapped around a towel clamp, or placed inside a metal trocar sleeve, or comes in close contact with any conductive substance for an extended period of time, the current in the active electrode may induce a current in the second conductor.

As long as the induced current can dissipate easily through a large surface of tissue, it won't present a problem. The danger occurs if the second conductor contains some insulating material, as in the case of a metal cannula held in place by a plastic anchor. The plastic anchor will prevent the energy from dissipating and increase the likelihood of a thermal burn. Burns from capacitance current may occur when the surface area is less than 3 cm2 or the current density is approximately 7 w/cm2.

Solution:
As with direct coupling, the best way to prevent this phenomenon is to use the active electrode monitoring system that prevents current from capacitive coupling from building to dangerous levels. Also, you should avoid all plastic-metal hybrid instruments, including cannulas, trocars, and clamps, when doing electrosurgery.

4. Surgical Smoke
When an electrosurgical probe heats tissue and vaporizes cellular fluid, one byproduct is surgical smoke. We know that these fumes, which can contain carbon monoxide, DNA, bacteria, carcinogens, and irritants, are malodorous and can cause upper respiratory irritation. We do not yet know whether they are capable of causing cancer or spreading infectious disease. Surgical smoke can also obscure the operative site and cause the surgeon to inadvertently touch the electrode to non-targeted tissue.

Solution:
Surgical masks do not adequately filter surgical smoke; the particles are too small. A much better solution is a smoke evacuation system, a high-flow suction and filtering device that removes the particles from the air. Two kinds are available. One uses a hand-held nozzle, which is intended to be positioned at the surgical site. The system I use is attached directly to the electrosurgical probe; it whisks away.

the smoke at the point of creation before it can obscure the operative site or be inhaled by the staff.

A few tips from the Centers for Disease Control regarding use of these devices:
– Keep the nozzle of the suction device within two inches of the surgical site at all times;
– Be sure the device is on anytime the electrosurgical equipment is active;
– Dispose of all tubing, filters and absorbers after each use;
– Regularly inspect the system for leaks.

Energy can be transfered through intact insulation by means of capacitive coupling.

5. Detachment of Return Electrode
Return dispersive electrode pads range from 90 to 120 square centimeters, which is large enough to prevent dangerous current concentrations at the point where the current leaves the patient to go back to the generator. However, sometimes things go wrong. For instance, the electrode can become partially detached due to adhesive failure. Also, if the electrode contact isn't completely touching the skin because of excessive hair, a bony prominence, or any number of other possibilities, the contact impedance increases, and more electricity is forced through the area of the pad still in contact with the patient. The increased current concentration through the smaller contact area will cause heat to build, resulting in a severe burn.

Solution:
To ensure that the return electrode pad stays connected to the patient, make sure your electrosurgical system employs return electrode monitoring technology, or REM. REM-equipped generators continuously monitor the pad impedance level. If the monitor detects a dangerously high level of impedance, audible and visual alarms go off, and the system automatically deactivates before an injury can occur.

Here are a few more tips:
– Create an in-service for nurses and physicians on your generator's use and limitations;
– Maintain an in-house credentialing program for basic electrosurgery.
– Establish protocols designed to minimize risk.
– Always allow the generator to cool down before using it for another procedure.
– Avoid using conductive solutions (with electrolytes) such as saline or Ringers lactate. Conductive solutions dissipate the current, preventing any effect on the target tissue.
– Before starting a procedure, make sure that the tip of the active electrode is pushed all the way back into the electrosurgical pencil's handle to prevent arcing.
– If you use a TV monitor during electrosurgical endoscopy, pay attention to the picture quality. Interference or jerky movements may indicate that there is a spark present in the electrosurgical devices.

For certain ophthalmic, neurosurgical, ear, nose and throat procedures, and in more and more GYN procedures, bipolar electrosurgery is the technique of choice. All modern generators allow you to use both monopolar and bipolar modes. With bipolar technology, the surgeon grasps the targeted tissue between forceps tines that perform both the active electrode and return electrode functions. The grasped tissue is the only part of the patient included in the electrical circuit. Accordingly, a return electrode is no longer needed, and therefore there is no potential for a return electrode burn. Bipolar technology also eliminates the risk of current arcing, direct coupling, and capacitive coupling.

Unfortunately, bipolar electrosurgery works poorly with retracted blood vessels and thick tissue, and since the tissue to be coagulated needs to be grasped between the active and return electrodes, you can't use this technique to achieve hemostasis over a large area.

Dr. Vilos is a Professor of Obstetrics and Gynecology and the Director of Endoscopic Surgery at the University of Western Ontario in Canada.