Material Removal Mechanisms in Monopolar Electrosurgery

The underlying mechanisms that cause the observed tissue differences in monopolar electrosurgery under different electrical excitation conditions have not been accurately identified to date. Without an understanding of the mechanisms behind the observed differences in tissue effect, advances in electrosurgical technology are reduced to empirical trial and error. The numerical method we present herein allows single arc events and two ensuing vaporization mechanisms and thermal damage to surrounding tissues to be modeled. It also allows for a realistic prediction of the effect of different electrical waveforms employed in monopolar electrosurgery. The method presented here models both explosive boiling and confined boiling as mechanisms for observed material removal. It uses an Arrhenius damage calculation to predict both tissue cutting rates and adjacent thermal damage to peripheral tissue. All results agree with experimentally observed results. To our knowledge this agreement has not been accomplished with previous models. While not a complete description of the physical events surrounding tissue division and coagulation in electrosurgery, modeling single arc events is the initial step towards understanding the mechanisms of monopolar electrosurgery.