title: Effect of output voltage distribution on stone comminution efficiency during shockwave lithotripsy in renal or ureteropelvic junction stones: a preliminary study.
abstract: OBJECTIVE
  This study evaluated stone comminution efficiency according to the distribution of the lithotripter output voltage during extracorporeal shockwave lithotripsy (SWL) of renal or ureteropelvic junction (UPJ) stones.
  
  
  METHODS
  Sixty-two patients with a single radiopaque renal or UPJ stone of surface area about 50-400 mm(2) were prospectively randomized to receive a total of 2400 shocks per session according to one of three shock protocols: group A, output voltage was increased from 25% to 35% to 45% with 800 shocks per voltage; group B, constant output voltage of 35%; group C, decreasing output voltage from 45% to 35% to 25%. SWLs were carried out using a fourth generation electroconductive lithotripter, the Sonolith Vision, without anesthesia. The stone-free (SF) and success (SF + clinically insignificant residual fragment) rates were assessed.
  
  
  RESULTS
  Patient demographics, body mass index, stone burden, laterality and stone locations were comparable among the three groups. There were no differences in the cumulative success rates (30%, 32% and 35% after the first session for groups A, B and C, respectively; 65%, 50% and 65% after the second session; and 80%, 68% and 75% after the third session). The cumulative SF rates and complications showed no differences among the three groups.
  
  
  CONCLUSIONS
  In this preliminary study, manipulation of the lithotripter output voltage distribution did not affect stone comminution efficiency for renal or UPJ stones. This finding should be confirmed by larger studies including more patients.
authors.affiliation: Department of Urology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, South Korea.
authors.forename: Dalsan
authors.initials: D
authors.lastname: You
authors.forename: Jinsung
authors.initials: J
authors.lastname: Park
authors.forename: Bumsik
authors.initials: B
authors.lastname: Hong
authors.forename: Hyung Keun
authors.initials: HK
authors.lastname: Park
mesh_terms: D000328:Adult; D004560:Electricity; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007669:Kidney Calculi / Q000628:therapy*; D008096:Lithotripsy / Q000009:adverse effects / Q000379:methods*; D008297:Male; D008875:Middle Aged; D010147:Pain Measurement; D011446:Prospective Studies; D016896:Treatment Outcome; D014514:Ureteral Calculi / Q000628:therapy*