title: [In vitro studies of 2 µm laser treatment of benign prostatic hyperplasia].
abstract: 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.
authors.affiliation: Department of Urology, Guizhou Provincial People's Hospital, Guiyang 550002, China.
authors.forename: Guang-heng
authors.initials: GH
authors.lastname: Luo
authors.forename: Xiu-shu
authors.initials: XS
authors.lastname: Yang
authors.forename: Jun
authors.initials: J
authors.lastname: Liu
authors.forename: Zhao-lin
authors.initials: ZL
authors.lastname: Sun
authors.forename: Shu-jie
authors.initials: SJ
authors.lastname: Xia
mesh_terms: D000368:Aged; D006801:Humans; D066298:In Vitro Techniques; D053685:Laser Therapy / Q000379:methods*; D008297:Male; D011467:Prostate / Q000473:pathology; D011470:Prostatic Hyperplasia / Q000601:surgery*; D016896:Treatment Outcome