Capacitive coupled stray currents during laparoscopic and endoscopic electrosurgical procedures.

Capacitively coupled currents may not be appreciated during laparoscopic and endoscopic radiofrequency electrosurgery. Two specific problems are documented and quantified: coupling of current into metal trocar cannulas during laparoscopic surgery and coupling of current into a guide wire during endoscopic surgery. The examples can yield power levels in excess of 25 watts (laparoscopic) and 15 watts (endoscopic) on nearby metal conductors, which can in turn be dissipated into patient organs such as the bowel or the common bile duct. This capacitive coupling can be, in part, responsible for serious patient complications. Methods to minimize capacitive coupling, e.g., active electrode shielding, dispersive metal cannulas, sheathed guide wires, and bipolar active electrodes, are discussed for each example.