Optimized generator modes for bipolar vessel sealing

Bipolar electrothermal vessel sealing is a widely used method for the sealing of blood vessels and tissue of up to several millimeters diameter. Despite their wide-spread usage, instruments and generator modes are often traditionally developed and enhanced. A systematic investigation of the thermofusion process and the subsequent derivation of new model-based control strategies have the potential to improve the vessel sealing process and reduce unwanted side-effects. Based on a previously developed mathematical model of bipolar vessel sealing, optimization based control strategies are developed that could possibly reduce the thermal damage to the lateral tissue. Assuming that it is sufficient to ensure a certain tissue temperature for successful thermofusion, it is shown that the lateral damage could be significantly reduced by optimizing the generator voltage. Furthermore it is shown, that an optimized voltage trajectory may still reduce the lateral damage to some extent if it is assumed that tissue desiccation is required. Additionally, optimally pulsed voltage strategies are presented and compared to currently employed typical generator modes. The results illustrate that optimized control strategies can potentially reduce the thermal damage to the lateral tissue and thus make bipolar vessel sealing more suitable for surgical procedures in the vicinity of sensitive structures, particularly nerves.