Outcomes using a fourth-generation lithotripter: a new benchmark for comparison?

Abstract

To evaluate the efficacy of a fourth-generation lithotripter, the Sonolith Vision (Technomed Medical Systems, Vaulx-en-Velin, France) for treating single previously untreated renal calculi, and to compare the results with the reference standard HM-3 (Dornier MedTech Europe GmbH, Wessling, Germany) in the same population originally studied by the USA Cooperative Study Group in 1986. The Sonolith Vision uses an innovative electroconductive shock-wave generator with an elliptical reflector specially designed to give the maximum concentration of energy on the stone. We reviewed the treatment sessions from our prospectively maintained database of the first 1000 consecutive patients with urinary stone disease who were treated with the Sonolith Vision between September 2004 and March 2006. Patients with previously untreated solitary renal calculi in anatomically normal kidneys were included. The outcome was assessed by plain films for radio-opaque stones, and renal ultrasonography for radiolucent stones, at 1 and 3 months after lithotripsy; the results were analysed according to stone size and location. Data from 309 patients who had a complete follow-up and with 373 renal calculi that matched the above criteria were analysed. The initial fragmentation rate was 94%. The stone-free rate for stones of <10 mm was 77%, for 11-20 mm was 69% and for >20 mm was 50%. The overall stone-free rate 3 months after lithotripsy was 75%. Within a month of lithotripsy, 221 patients (59%) became stone-free. Additional procedures to render patients stone-free after lithotripsy were needed in only 22 cases (7%). The overall efficiency quotient was 62%. The stone-free rates for lower, upper, middle calyceal and renal pelvic calculi were 74%, 70%, 78.5% and 75%, respectively. There were no serious complications. When similar populations of stone formers were assessed the Sonolith Vision achieved a high success rate, comparable with that using the HM-3 machine but with lower analgesia requirements and very low re-treatment rates. This method of comparison belies the commonly held view that newer lithotripters are less effective than the original spark-gap machines.