Spectral distribution of current during electrosurgery

A spectrum analysis of current in axial body structures during electrosurgery, utilizing a canine model in a simulated transurethral resection, has revealed a shift to lower frequency peaks as the power levels of the generator were increased. The authors verified prior investigations in the time domain, where greater collective current levels were observed in arteries, followed sequentially by vein, muscle, and nerve. Arterial/venous current ratios were in the range of 2:1 in the extremities. The levels of current in cylindrical structures were proportional to cross-sectional area and appeared to be conduit dependent. Great vessels, such as the aorta and the heart, appear to act as sinks for large amounts of current, sometimes exceeding 500 mA total with 3000 mA noted at peaks 40 Hz separate from the generator center frequency at 680 kHz. The cardiac muscle, likewise, contains substantial current at practically all frequencies measured within a 100 kHz range of center, and even beyond.<>