The optimization of laser prostatectomy. Part I: Free beam side fire coagulation.

ABSTRACT

OBJECTIVES: To study laser-tissue interaction and develop unifying principles for the optimization of free beam side fire neodymiumyttrium-aluminum-garnet (NdYAG) laser coagulation prostatectomy. METHODS: The heating patterns and coagulation volumes created by different right angle deflecting fibers were studied at different wattages and times in potato and canine models. RESULTS: In the potato, higher wattage resulted in deeper and more rapid heating. The high power density fibers created lesions of smaller volume which increased less with rising wattage than those fibers of lower power density. In the canine model, carbonization decreased heat penetration, and "popcorn" decreased superficial temperature without altering lesion size as long as it occurred without carbonization. As lasing progressed, smaller incremental increases in coagulation depth were achieved. CONCLUSIONS: To optimize coagulation laser prostatectomy, the surgeon should operate at the highest wattage which does not cause carbonization. The visualized intraoperative laser-tissue interaction allows the adjustment of laser power during the case as needed.