Impact of preoperative haemoglobin concentrations on the efficiency of KTP-laser vaporization of the prostate

Abstract

The potassium-titanyl-phoshate laser (KTP laser) device produces light (wavelength of 532 nm) that is absorbed by haemoglobin, thus releasing thermal energy. This reaction causes vaporization of the tissue. We tested whether preoperative haemoglobin concentrations (Hb) affect the efficiency of the 80 W KTP laser, thus affecting the energy applied. We assessed 164 patients undergoing KTP-laser vaporization for benign prostate hyperplasia from January 2005 to July 2006 at Heidelberg University Hospital. We prospectively collected data on patients' demographics, urodynamics, Hb, prostate volume, and energy applied. We calculated the correlation between preoperative Hb and surgery energy applied and we adjusted it for prostate volume. We further compared the postoperative urinary flow and residual volume results in non-low-Hb and in low-Hb patients. The mean age was 68.8 (+/-8.8 years), the median prostate volume 50.0 mL (interquartile range 40-80), the median preoperative urinary flow 10.1 mL/s (interquartile range 7.1-14.0), the median surgery duration 70.0 min (interquartile range 50-92.75), the median preoperative Hb 144.5 g/L (interquartile range 132-151), and the median applied energy 209.5 kJ (interquartile range 156.5-272.75). The unadjusted correlation between preoperative Hb and applied energy was -0.089 (P < 0.05). After adjustment for prostate volume this correlation was not significant (Pearson r = -0.180, P > 0.05). Functional results did not differ between low-Hb and non-low-Hb patients (P > 0.05 for urinary flow and postvoid volume). Haemoglobin concentrations, in the range of clinically encountered values, do not affect the efficiency of 80 W KTP-laser vaporization of the prostate. This laser technique is thus applicable in patients with low haemoglobin concentrations without concerns about efficiency.