Don’t Touch the Bed! Capacitive Coupling in Electrosurgery Causes Current Loss During Pinch Burning

Background: The commonly used "pinch burn" technique in electrosurgery involves applying current to forceps while grasping tissues for hemostasis. The authors of this study have noticed a reduction in efficacy of pinch burning while touching the surgical table, suggesting that current may be lost through the surgeon's body. Intuitively, surgical gloves should insulate the current, however a phenomenon called capacitive coupling may explain the losses. An experiment was devised to determine if this effect could be measured. Study Design: A circuit was created to measure the voltage across tissue represented by a 2kΩ resistor. The circuit was shorted with forceps held by a gloved hand. The voltage was measured when holding the forceps in isolation versus touching the table at the waist or forearm. Results: The measured voltage was 14.4+0.1V but decreased to 12.2+0.1V (16%) when the surgeon touched the table with the waist and to 10.7+0.2V (26%) touching at the forearm (p<0.0001). This corresponded to a 1.1 and 1.8mA current drop, and power loss of 28.5mW (29%) and 43.9mW (45%) respectively. Conclusion: When pinch burning in the OR, the circuit can be shorted from body into the table. Despite the insulating properties of surgical gloves, electrosurgery allows this effect to occur via a phenomenon called capacitive coupling. In a simulated setting this can result in current losses up to 26% and power losses up to 45%. In difficult technical situations where hemostasis is paramount, one strategy to improve pinch burning efficacy is to avoid contact with the surgical table.