Factors influencing electrovaporization in the treatment of benign prostatic hyperplasia

Electrovaporization refers to the process of vaporizing tissue using electrical energy. Proposed as a new treatment method for benign prostatic hyperplasia (BPH), this technique allows removal of prostatic tissue with simultaneous coagulation, thereby minimizing blood loss. The recent increase in popularity of electrovaporization in the treatment of BPH warrants a quantitative assessment of the process, including an objective evaluation of its influencing factors. In this study, the effects of power, mechanical loading, and excursion rate on tissue removal by electrovaporization were examined in fresh skeletal muscle. A monopolar electrode was attached to the weighted arm of a linear motion system and rolled across the tissue surface while activated by a radio-frequency generator. The tissue samples were frozen and cut longitudinally to allow visualization and measurement of the vaporized groove using an optical imaging technique. The volume of tissue removed increased significantly when power was increased from 120 to 150 W (46 to 119 mm3, p = 0.006), when the load was increased from 20 to 50 gm (20 to 119 mm3, p = 0.002), and when the excursion rate was decreased from 25 to 15 mm/s (29 to 69 mm3, p < 0.05) and from 15 to 10 mm/s (69 to 137 mm3, p < 0.05). There was no significant gain in volume removed when power was increased to 180 W or when the load was increased to 70 gm, indicating that these factors are constrained with regard to optimal tissue removal. Using a novel method to quantitatively assess tissue removal by electrovaporization, this study has demonstrated that greater tissue removal can be achieved by increasing power, increasing the load, or decreasing the excursion rate, but only within limits.