Thermal-Electric Finite Element Analysis and Experimental Validation of Bipolar Electrosurgical Cautery

Cautery is a process to coagulate tissues and seal blood vessels using heat. In this study, finite element modeling (FEM) was performed to analyze temperature distribution in biological tissue subject to a bipolar electrosurgical technique. FEM can provide detailed insight into the tissue heat transfer to reduce the collateral thermal damage and improve the safety of cautery surgical procedures. A coupled thermal-electric FEM module was applied with temperature-dependent electrical and thermal properties for the tissue. Tissue temperature was measured using microthermistors at different locations during the electrosurgical experiments and compared to FEM results with good agreement. The temperature- and compression-dependent electrical conductivity has a significant effect on temperature profiles. In comparison, the temperature-dependent thermal conductivity does not impact heat transfer as much as the temperature-dependent electrical conductivity. Detailed results of temperature distribution were obtained from the model. The FEM results show that the temperature distribution can be changed with different electrode geometries. A flat electrode was modeled that focuses the current density at the midline of the instrument profile resulting in higher peak temperature than that of the grooved electrode (105 versus $96°C$⁠).