Measurements of Temperature Distributions at Electro-Surgical Dispersive Electrode Sites

Abstract

The superficial temperature distribution for various types of dispersive electrodes applied to human subjects and a surrogate medium are presented. Typical temperature distributions on the human thigh display a high temperature perimeter and cooler central area, with the temperature extremes and contours peculiar to the electrode design. These patterns persist for several minutes after electrode removal. A series of experiments was conducted on a surrogate medium to determine the extent of volumetric (ohmic) heating, to evaluate influence of media properties on the temperature distribution, and to evaluate the use of the medium for simulation of the human system. It was found that volumetric heating is appreciable and that appropriate alteration of the medium resistivity with depth produced patterns having similar characteristics to those obtained with the same electrode on a human thigh. A simplified model to analytically predict the temperature distribution is presented and the results are similar to those observed on human subjects.