[In vitro studies of 2 µm laser treatment of benign prostatic hyperplasia].

OBJECTIVE: To compare the speed of vaporization of human prostatic tissue with benign prostatic hyperplasia (BPH) and depth of tissue damage using 70 and 120 W 2 µm laser devices.

METHODS: Fresh prostatic tissue specimens were obtained from 5 patients by open prostatectomy and divided into separate groups (70 and 120 W) based on the energy of laser output (70 and 120 W respectively). Trials were performed in acryl basin containing 0.9% saline at 37 °C. And then each prostate gland in vitro was vaporizated similarly as routine transurethral 2 µm laser vaporesection. 70 W and 120 W power were applied for prostatic vaporesection. The 2 µm laser vaporization proportion and vaporesection speed were calculated postoperatively. Prostatic tissue was embedded for histological evaluation. After hematoxylin and eosin (H & E) staining and nicotinamide adenine dinucleotide-reduced (NADH) measurement, depth of coagulation zone and necrotic tissue layer were measured. The results of prostatic tissue between two groups were compared.

RESULTS: With increasing output power, the speed (mean ± SD) of vaporesection of human prostatic tissue increased from (5.21 ± 0.66) g/5 min at 70 W to (10.84 ± 1.23) g/5 min at 120 W. Significant differences existed in the speed of vaporesection, resection and vaporization between 120 W and 70 W devices (P = 0.000). The proportion of vaporization mode was 81% at 70 W and 87% at 120 W during prostatic vaporesection. There was a stable penetration/coagulation depth with increasing power output for (0.98 ± 0.13)/(0.30 ± 0.09) mm at 70 W and (0.99 ± 0.12)/(0.31 ± 0.08) mm at 120 W. There were no significant differences in penetration and coagulation depth between 120 W and 70 W (P > 0.05).

CONCLUSIONS: Both 120 and 70 W 2 µm Laser devices yield excellent performance and security in vaporizated human prostate tissue. The 120 W 2 µm laser offers significantly higher vaporesection rates than 70 W power. And vaporization mode is a predominant procedure of prostatic vaporesection.