The electrosurgery: - A story of controversies and discrepancies

Though it has been known for decades, there are still controversies on how Electro-surgery physically really works.The known electro- and thermodynamical models of RF-electrsurgery are summarized and discussed. Especially their discrepancies and thermodynamical inadequacy (regarding pressure, temperature and power / energy) are emphasized. Thermodynamically the assumptions in the literature assume atmospheric pressure and range between two extremes:a) all the water of the cut volume has to evaporate to achieve cutting b) less than 1% of this water ought to evaporate to achieve cutting; which leads to an energy density discrepancy of nearly one to ten. It is improbable, that cutting of the tissue in electrotomy would succeed due to a pressure equal to atmospheric pressure, since conventional “mechanical” cutting success is due to exercising a mechanical pressure on tissue much greater than atmospheric pressure.Electrodynamically, the points of view can be summarized in essentially two different models. 1) “the conventional field model” and 2) “the arcs-model”. In the first one a solid (mechanical) contact between tissue and electrode is assumed, so that conventional field theory calculations can be applied to estimate power density configurations. In the second model, instead of solid contact, a “riding” of the electrode on a vapor film during cutting is assumed; with the result of formation of arcs. Arcs are considered in this model as essential, making the cutting electrode more effective. By some authors it is even mentioned that cutting in electrosurgery is only possible when the voltage between cutting electrode and tissue is high enough to produce arcs, or in other words: no arcs no cutting.Based on a qualitative proof of an “overpressure hypothesis” using “schlieren” photography, and depending on the thermodynamical similarity between electrosurgery and laser surger- - y, and using a biphasic system a new, more realistic model of electrotomy is introduced to overcome those discrepancies Controversies. The major features of this model are: 1- Cutting is due to partial evaporation under overpressure followed by pressure waves after tissue rupture. 2- Coagulating effect during cutting is due to coagulating arcs over the vapor layer, their frequency probability correlates positively with crest factor. 3- The specific resistance of tissue is no longer invariant. It is temporal and spatial variant; It seems, according to our model, that maximum power of electrosurgical units are oversized which could affect, if true, patient´s safety negatively.