In vivo comparison of electrosurgical vaporization electrodes.

To determine the acute tissue effects of endoscopic electrosurgery using different electrodes, smooth ball, smooth bar, vertically grooved bar, and horizontally fluted bar electrodes were applied to the epithelial surface of porcine bladders in vivo with electrosurgical cutting current supplied at 100, 150, and 200 W. A single pass was made on the surface of the tissue under endoscopic control with sorbitol irrigation using an excursion rate of 5 mm/sec. Each electrode was tested five times at each setting. The depths of electrosurgical vaporization and coagulation were measured by a pathologist blinded to the electrode and power setting. Depth of vaporization increased with the power setting of the generator and was greater with the non-smooth electrodes than the smooth electrodes. The depth of coagulation likewise was greater using the non-smooth electrodes but increased only minimally with increasing power settings. There were no differences in vaporization or coagulation depth between the small ball and smooth bar electrodes. The differences between the vertically grooved bar and horizontally fluted bar also were insignificant, except that in one-third of cases, the horizontally fluted bar created clefts undermining otherwise-undamaged areas of tissue. Non-smooth electrosurgical electrodes produce more vaporization and coagulation than smooth electrodes at a given power setting and therefore may be preferred for endoscopic applications. For use in tissues where precise control is required, the vertically grooved bar may be superior to the horizontally fluted bar because it provides similar vaporization and coagulation with a more uniform tissue effect.