Degree of vaporization in bipolar and monopolar resection.

PURPOSE To compare the in vitro degree of vaporization in bipolar and monopolar resection. MATERIALS AND METHODS Using either a bipolar system or a monopolar system, samples of chicken muscle and lamb kidney were resected in an isolated basin and then desiccated in an incubator. The percentual degree of vaporization for each sample was obtained as a difference between the total fresh weight of the sample and the calculated fresh weights of the resected tissue and remains. RESULTS Reference samples showed that the water content was 73% in muscle and 77% in kidney. More muscle (mean 52%) than kidney (32%; P<0.0001) tissue was vaporized. The fraction of vaporized tissue was significantly higher in the bipolar technique. In muscle, the differences between monopolar and bipolar were 17% (P<0.05) and 26% (P<0.001), respectively, depending on the type of irrigation used. For kidney, the differences were 27% (P<0.01) and 34% (P<0.01), respectively. Further exploration of the degree of vaporization when using the bipolar resection showed that the choice of loop (P<0.0001), fluid (P<0.03), and tissue (P<0.0001) were all independently associated with the degree of vaporization. CONCLUSIONS This study indicated that vaporization removes 50% more tissue than the weight of the resected tissue during conventional tissue resection. Bipolar standard loop resection resulted in a significantly higher degree of vaporization in both muscle and kidney than did monopolar technique. Bipolar resection worked satisfactorily in Ringer's acetate.