title: Does Stepwise Voltage Ramping Protect the Kidney from Injury During Extracorporeal Shockwave Lithotripsy? Results of a Prospective Randomized Trial.
abstract: BACKGROUND
  Renal damage is more frequent with new-generation lithotripters. However, animal studies suggest that voltage ramping minimizes the risk of complications following extracorporeal shock wave lithotripsy (SWL). In the clinical setting, the optimal voltage strategy remains unclear.
  
  
  OBJECTIVE
  To evaluate whether stepwise voltage ramping can protect the kidney from damage during SWL.
  
  
  METHODS
  A total of 418 patients with solitary or multiple unilateral kidney stones were randomized to receive SWL using a Modulith SLX-F2 lithotripter with either stepwise voltage ramping (n=213) or a fixed maximal voltage (n=205).
  
  
  METHODS
  SWL.
  
  
  METHODS
  The primary outcome was sonographic evidence of renal hematomas. Secondary outcomes included levels of urinary markers of renal damage, stone disintegration, stone-free rate, and rates of secondary interventions within 3 mo of SWL. Descriptive statistics were used to compare clinical outcomes between the two groups. A logistic regression model was generated to assess predictors of hematomas.
  
  
  CONCLUSIONS
  Significantly fewer hematomas occurred in the ramping group(12/213, 5.6%) than in the fixed group (27/205, 13%; p=0.008). There was some evidence that the fixed group had higher urinary β2-microglobulin levels after SWL compared to the ramping group (p=0.06). Urinary microalbumin levels, stone disintegration, stone-free rate, and rates of secondary interventions did not significantly differ between the groups. The logistic regression model showed a significantly higher risk of renal hematomas in older patients (odds ratio [OR] 1.03, 95% confidence interval [CI] 1.00-1.05; p=0.04). Stepwise voltage ramping was associated with a lower risk of hematomas (OR 0.39, 95% CI 0.19-0.80; p=0.01). The study was limited by the use of ultrasound to detect hematomas.
  
  
  CONCLUSIONS
  In this prospective randomized study, stepwise voltage ramping during SWL was associated with a lower risk of renal damage compared to a fixed maximal voltage without compromising treatment effectiveness.
  
  
  RESULTS
  Lithotripsy is a noninvasive technique for urinary stone disintegration using ultrasonic energy. In this study, two voltage strategies are compared. The results show that a progressive increase in voltage during lithotripsy decreases the risk of renal hematomas while maintaining excellent outcomes.
  
  
  BACKGROUND
  ISRCTN95762080.
authors.affiliation: Department of Urology, University of Bern, Bern, Switzerland.
authors.forename: Veronika
authors.initials: V
authors.lastname: Skuginna
authors.affiliation: Department of Urology, University of Bern, Bern, Switzerland.
authors.forename: Daniel P
authors.initials: DP
authors.lastname: Nguyen
authors.affiliation: Department of Urology, University of Bern, Bern, Switzerland.
authors.forename: Roland
authors.initials: R
authors.lastname: Seiler
authors.affiliation: Department of Urology, University of Bern, Bern, Switzerland.
authors.forename: Bernhard
authors.initials: B
authors.lastname: Kiss
authors.affiliation: Department of Urology, University of Bern, Bern, Switzerland.
authors.forename: George N
authors.initials: GN
authors.lastname: Thalmann
authors.affiliation: Department of Urology, University of Bern, Bern, Switzerland. Electronic address: urology.berne@insel.ch.
authors.forename: Beat
authors.initials: B
authors.lastname: Roth
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000419:Albuminuria / Q000209:etiology; D005260:Female; D006406:Hematoma / Q000000981:diagnostic imaging / Q000209:etiology*; D006801:Humans; D007668:Kidney / Q000293:injuries*; D007669:Kidney Calculi / Q000628:therapy*; D007674:Kidney Diseases / Q000000981:diagnostic imaging / Q000209:etiology*; D008096:Lithotripsy / Q000009:adverse effects* / Q000379:methods; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D016037:Single-Blind Method; D016896:Treatment Outcome; D014463:Ultrasonography; D001613:beta 2-Microglobulin / Q000652:urine
chemical_list: D001613:beta 2-Microglobulin
keywords: Extracorporeal shockwave lithotripsy; Randomized trial; Renal damage; Voltage ramping