High-power potassium-titanyl-phosphate laser fibres for endovaporization of benign prostatic hyperplasia: how much do they deteriorate during the procedure?

OBJECTIVE: • To assess the residual power delivered at the tip of a high-power (80 W) potassium-titanyl-phosphate (KTP) laser (80 W Green Light PV(TM), Laserscope(®); American Medical Systems, Minnetonka, MN, USA) at the end of a photoselective vaporization of the prostate (PVP) procedure, as well as the deflection angle of the laser beam. MATERIALS AND METHODS: • In total, 65 laser fibres were collected at the end of PVP procedures indicated for symptomatic benign prostatic hyperplasia over a period of 17 months. PVP was performed by two senior urologists. • The power of laser beam at tip exit was measured for each fibre at the end of the procedures using a photodiode whose signal was amplified, and then quantified by a volt multimeter. • The deflection angle was measured using a graduated sphere. RESULTS: • Approximately 70% of fibres delivered less than 40 W at the end of the procedure, which is less than the vaporization threshold. • Some 9% of fibres had lost their diffraction capacity with a significant alteration of laser beam angulation. These values were not operator dependent. CONCLUSIONS: • The data show that a large proportion of laser fibers deliver a significantly underpowered beam at the end of the procedures. • This seems to be caused by peroperative destruction of the fibers, which results in a progressive loss of efficacy of PVP during procedures.