The mechanism analysis of bipolar vessel sealing in vitro using EDM model

Vessel sealing (VS) is an advanced hemostasis in electrosurgery; however, there is still great potential for improvement because the mechanism of the thermal process has yet to be fully understood. Based on key factors influencing VS effect, the tissue fusion mechanism of bipolar VS was discussed in this work from the view of an engineering machining method: electrical discharge machining (EDM). Vessel lumen contact modality and lumen wall micro-discharge modality were proposed in this study. Lumen contact modality corresponds to the impedance sealing mechanism and the lumen wall micro-discharge modality means an EDM fusion mechanism. In micro-discharge modality, heat is generated inside of vessel and tissue is fused with the advantages of less collateral thermal damage. Ex vivo experiments validated the analysis of lumen micro-discharge modality with rabbit arteries using a self-made low output power generator and device. Experimental results showed that a higher burst pressure (BP) was achieved with diameter of 2.0 mm at a gap of 0.7 mm than that of diameter of 4.0 mm at a gap of 0.2 mm. A histological examination showed that the lateral thermal damage in the micro-sparkle modality extends less from the edge of the electrode. The analysis may contribute to further understand physical essence of bipolar VS, and might contribute to improve VS tissue effect.