title: Feasibility of extended use of an electromagnetic lithotripter beyond the manufacturer's recommended maintenance schedule.
abstract: OBJECTIVE
  The study evaluates the effect of chronic usage, beyond the recommended maintenance schedule, on the efficacy of electromagnetic lithotripter. To our knowledge, there is no publication investigating the effect of chronic usage on the electromagnetic lithotripter, despite the maintenance schedule established by the manufacturers. Our goal is to verify if the acoustic parameters of the shock wave changed with usage, and if this change could be associated with change in clinical efficacy.
  
  
  METHODS
  This study lasted 18 months. Every 6 months the lithotripter's efficacy was evaluated in two ways: objectively and clinically. Objective efficacy was measured using a piezoelectric hydrophone and artificial stones to capture the acoustic parameters and the crater of fragmentation, respectively. Clinical efficacy data was collected by studying the rate of successful extracorporeal shock wave lithotripsy treatment in patients with urolithiasis. The changes in clinical efficacy, acoustic parameters, and craters of fragmentation were compared and analyzed with appropriate statistical methods.
  
  
  RESULTS
  Five hundred twenty five patients participated in the study. The clinical efficacy remained stable throughout the three observation periods (55.7%, 66.2% and 55.5%; p = 0.11). The focal head of the lithotripter was used three times the recommended schedule. There was no obvious change in the acoustic parameters of the shock waves, and the focal zone remained stable.
  
  
  CONCLUSIONS
  The clinical efficacy of the electromagnetic lithotripter appears to be stable despite usage beyond the recommended maintenance schedule. More studies are needed to validate the safety of this practice.
authors.affiliation: Division of Urology, Sherbrooke University Hospital Centre, Fleurimont, Quebec, Canada.
authors.forename: Tony Y H
authors.initials: TY
authors.lastname: Chen
authors.forename: Yves
authors.initials: Y
authors.lastname: Ponsot
authors.forename: Martin
authors.initials: M
authors.lastname: Brouillette
authors.forename: Jean-Píerre
authors.initials: JP
authors.lastname: Tétrault
authors.forename: Le Mai
authors.initials: le M
authors.lastname: Tu
mesh_terms: D000162:Acoustics; D016009:Chi-Square Distribution; D055590:Electromagnetic Phenomena; D004868:Equipment Failure; D005240:Feasibility Studies; D006801:Humans; D008096:Lithotripsy / Q000295:instrumentation* / Q000592:standards*; D011786:Quality Control; D012189:Retrospective Studies; D013997:Time Factors; D052878:Urolithiasis / Q000628:therapy*