Experimental and Finite Element Analysis of the Thermal-Electric Process in Monopolar Electrosurgical Thermal Management

This study develops a thermal management system for the most commonly used energy-based surgical instrument: the monopolar electrosurgical device. Monopolar electrosurgery, using the same principle as the electrical discharge machining, is widely used to cut or remove tissue by sparks during surgical operations. This study develops a thermal management system consists of cooling channels placed around the active electrode to reduce the thermal damage to the tissue. Finite element modeling (FEM) was performed to analyze temperature distribution in biological tissue subject to heat generation by a commonly used monopolar electrosurgical device. The mathematical model was verified by comparing FEM predicted temperature distribution with experimental measurements. Exvivo experiments were performed with bovine liver tissue heated by a monopolar pencil electrode. The experimental data for 1 mm distance from the electrode is seen to fit within 1% of the predicted temperature values by the FEM simulation. The accuracy of the model decreases at further distances from the electrode. The inaccuracies are believed to be due to unaccounted temperature-dependent thermal conductivity. The addition of the cooling channels shows a reduction of the radial thermal damage of the tissue in both FEM simulations and ex-vivo experimental procedures.Copyright © 2008 by ASME