VARIATION IN OUTPUT POWER OF LASER PROSTATECTOMY FIBERS - A NEED FOR POWER MEASUREMENTS

Objectives. The aim of tills study was the assessment of the duality o f side-firing fibers that are being used for laser prostatectomy, eith er by a laser light transmission measurement or by visual inspection. Methods. A power meter (Aquarius) was developed to measure the actual power transmitted through a side-firing fiber and delivered to the pro static tissue. The power measurements were performed under clinical co nditions, that is, under water and at relatively high input power. Fur thermore, a protocol was developed for visual inspection of the fibers . Eight types of side-firing fibers were measured before use, Before a nd after a procedure, three fiber types were measured: ProLase II (28 samples), UltraLine (23 samples), and UroLase (44 samples). Ail these fibers were used in standard treatment protocols. Results. At 60 W the transmission ai new fibers (not used) ranged between 49% and 83% when compared to a bare fiber. After use, a large variation was found in t ransmitted power between different samples of one device. A correlatio n with total transmitted power was not present. At higher power input, vapor bubbles are generated at the tip of the fibers. Depending on th e fiber design, these bubbles have a major impact on the transmission. Only for the UroLase fiber was there a significant correlation betwee n visual inspection and the transmission of used samples at 10, 20, an d 40 W. Conclusions. The transmission strongly varies between fibers a nd between different samples of one fiber during clinical use. Moreove r, the transmission does not correlate with visual inspection, A power measurement during a clinical treatment will contribute to a more con trolled procedure and to a better comparison of clinical laser prostat ectomy studies.