Effect Of The Operation Parameters Of Electrosurgical Unit On Tissue Lesions

Electrosurgical units(ESUs)are used to separate,cut and coagulate targeted tissue through the thermal effect of high frequency alternating current.However,the thermal effect inevitably leads to thermal damage of adjacent tissue,then affecting the quality of surgery and prolonging patients' recovery.Most previous studies on tissue damage caused by ESUs'thermal effect were clinical case statistics.At present,the clinic operation of ESUs mainly relies on doctors' experiences,while there is no specific standard or direction for the selection of operation parameters ESUs.The relationship between operation parameters and tissue damage is still unclear.In addition,in order to alleviate tissue adhesion on the surface of ESU's active electrode during surgery,electrodes with surface coating have been studied recently and some of them have been used clinically.However,the thermal damage of adjacent tissues caused by these electrodes was rarely reported.Therefore,it is necessary to systematically study the influence of ESU's operation parameters on tissue damage,clarify the relationship between them,and then provide valuable insights into the clinic usage of ESUs.In this study,electrosurgical cutting test was performed on tissue samples of ex vivo freshly porcine liver under blend mode using a monopolar electrosurgical unit.The influences of output power and cutting depth on tissue thermal damage were studied using in vitro simulation and finite element analysis.Moreover,the tissue thermal damages resulted from PTFE-coated electrode and tungsten-coated electrode were also investigated.The relationship between the cutting efficiency of PTFE-coated electrode and tissue thermal damage were explored.The influence of tungsten-coating thickness on tissue thermal damage was also investigated.Main results and conclusions were drawn as follows:(1)The cutting efficiency,hemostatic effect,and tissue thermal damage of ESU were closely associated with its power.Under a low power,the cutting efficiency was low.The tissue damage was mainly characterized with "white condensate",however,the white condensate area was narrow so that its hemostasis effect was not enough.With the power increasing,the white condensate area was increased,tissue carbonization occurred on the marginal region of incision,and thus both the hemostasis effect and cutting efficiency were improved.Under a same power,the increase in cutting depth resulted in a decrease in the maximum temperature of the adjacent tissue but non-linear increases in the lesion area and degree of tissues.(2)PTFE-coated electrode exhibited an effective anti-tissue adhesion effect,accompanied with slight tissue damage,only at the early stage of electrosurgical cutting,when its cutting efficiency was significantly lower than that of traditional 304 stainless steel electrode.Increasing output power could effectively improve the cutting efficiency of PTFE-coated electrode,but its tissue damage was significantly aggravated.With the cutting time increasing,the failure of PTFE coating occurred gradually and then resulted in the loss of anti-stick effect.As a result,the cutting efficiency was increased,and the tissue damage was aggravated.(3)The nano-scale tungsten-coating on the surface of 304 stainless steel electrode had no significant effect on the thermal damage of adjacent tissue.