1. Tucker, Robert PhD, MD

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To the Editor,


Having recently read the article, "Clinical Applications of Argon Plasma Coagulation in Endoscopy" by K. Jane Malick (Gastroenterology Nursing, 29[5], 386-393), I believe it is necessary to correct several inaccuracies that the author has presented in the Nursing Implications section.


First, the author states that all "jewelry, including pierced ornaments, should be removed to avoid the risk of electrical injury." I certainly agree that the majority of jewelry should be left at home, not because of the potential of electrical injury, but rather for commonsense safekeeping.


Electrosurgical injuries can occur from the active electrode, cables, capacitive coupling or radiofrequency leakage currents, the return electrode (often inappropriately called the grounding pad), or the monopolar current path leading to the return electrode. If an energized active electrode is placed on the patient outside the operative site, an unintended burn will occur whether the patient is wearing jewelry or not. Burns can occur even if the electrode is not energized but hot from a prolonged activation. It is important that active electrodes not be placed on patients when not in use, but rather returned to a stand.


Any break in the insulation on electrosurgical cables, either active or dispersive, that touches the patient will result in a burn and also has the potential to set fire to drapes. This problem exists without jewelry present, and for this reason, the staff must examine all cables before the procedure to ensure their integrity.


Capacitive coupling and leakage currents are physical properties of radiofrequency currents and cannot be eliminated. A capacitor consists of two metal conductors separated by an insulator. Radiofrequency current flow in one of the conductors induces current flow in the second conductor across the insulation even if the insulation is intact. An example of this is an active electrode cable (one conductor and insulation) wrapped around a towel clamp (second conductor). Every time current flows in the active electrode cable, current is induced in the towel clamp. If the towel clamp touches the patient, a burn results. I have seen several burns occur by this mechanism, and operating room staff should not use towel clamps to hold excess active electrode cable. I have not seen a similar injury mechanism occur in gastrointestinal procedures.


Several factors potentiate the capacitive coupling effect: high voltage (coagulation mode), high-power procedures, long activation times, and a small separation between the conductors (on the order of a few millimeters). This phenomenon could possibly be a concern with pierced jewelry such as a metal tongue stud during a tonsillectomy or a genital piercing during a gynecologic or a urologic procedure. However, in gastrointestinal procedures, even a genital piercing is sufficiently far from the active electrode contained in the endoscope to be of no concern. Gastrointestinal procedures also occur at low voltage, low power, and short activation times, which also minimizes any capacitive coupled currents.


Burns can occur under the return electrode, but with the advent of return electrode monitoring and split return electrodes, this problem has virtually been eliminated. It is, however, a well-known fact that metal objects in the path of current flow can concentrate radiofrequency current. This effect is the reason that staff should not place return electrodes over metal implants such as artificial hips because this would place the metallic hip directly in the current path from the surgical site to the return electrode. Jewelry is simply not in the radiofrequency current path during gastrointestinal procedures and not a risk for burns.


Also in the same section, the author states that "patients should be clear of any electrical conductive objects" such as bedside rails. This advice would have been important before the 1970s, when many generators were ground referenced (i.e., the return electrode was physically connected to ground [the earth]). With these generators, if a patient touched a grounded metal object, the radiofrequency current could return to ground by the generator or by the metal object. This caused many alternate site burns.


Modern generators are typically isolated, separated from ground by a resistance. The radiofrequency current, therefore, does not flow to ground (a high-resistance path) but rather flows to the generator (low-resistance path). Isolated generators have virtually eliminated alternate burns in electrosurgical procedures. Currently, a few ground-referenced generators are produced, but these generators compare the active current supplied to the surgical site with the return current, and if they are not the same, the generator is disabled. Such a safety feature also eliminates the alternate site burns from patient contact with grounded objects in grounded generators.


The author continues by recommending that "padding be placed between any skin-to-skin contact sites." Although this suggestion may be followed for patient comfort, it is not important for the prevention of electrosurgical burns. Because radiofrequency current will follow the paths of least resistance, current will flow in low-resistance internal tissue such as blood vessels rather than cross high-resistance skin to high-resistance skin in its path to the return electrode.




Robert Tucker, PhD, MD


University of Iowa Hospital and Clinics, Iowa City