Switching Monopolar Mode for RF-Assisted Resection and Superficial Ablation of Biological Tissue: Computational Modeling and Ex Vivo Experiments

Abstract

Radiofrequency (RF)-based monopolar (MM) and bipolar mode (BM) applicators are used to thermally create coagulation zones (CZs) in biological tissues with the aim of destroying surface tumors and minimizing blood losses in surgical resection. Both modes have disadvantages as regards safely and in obtaining a sufficiently deep coagulation zone (CZ). In this study, we compared both modes versus a switching monopolar mode (SMM) in which the role of the active electrode changes intermittently between the two electrodes of the applicator. In terms of clinical impact, the three modes can easily be selected by the surgeon according to the surgical maneuver. We used computational and experimental models to study the feasibility of working in MM, BM, and SMM and to compare their CZ characteristics. We focused exclusively on BM and SMM, since MM only creates small coagulation zones in the area between the electrodes. The results showed that SMM produces the deepest CZ between both electrodes (33% more than BM) and SMM did not stop the generator when an electrode lost contact with the tissue, as occurred in BM. Our findings suggest that the selective use of SMM and BM with a bipolar applicator offers greater advantages than using each type alone.