Critical Analysis of a New Generation Electrohydraulic Lithotripter: A Single Institution Experience with the Medispec E3000

Abstract

The Medispec E3000(™) is a new generation electrohydraulic lithotripter with a wider focal width comparable to the Dornier HM3(™). We evaluate the efficacy of this machine for management of urinary stones at our institution by shockwave lithotripsy (SWL). There were 168 urinary calculi managed using the Medispec E3000 lithotripter over a 14-month period (10/2010-12/2011). During the first 6 months (10/2010-6/2011), a low power ramping protocol of 11-12-17 kV was used, and for the remaining 6 months (6/2011-12/2011), stones were managed with a higher power ramping protocol of 15-17-22.5 kV. A subanalysis of these groups was performed, as well as for stone location. The major end point was stone-free rate (SFR), defined as fragments <4 mm on follow-up imaging. Data were analyzed using the Fisher exact test and two-tailed Student t test. The study included 102 males and 66 females with an average age of 52.8 years. Mean stone size was 6.9 × 7.2 mm, which was significantly associated with SFR (P<0.0010). The overall SFR was 64.9%, with no significant difference between stones managed with the low power protocol (61.3%) and the high power protocol (70%). SFR varied by location across the upper pole (64.9%), midpolar area (57.1%), lower pole (68.4%), renal pelvis (79.2%), proximal ureter (66.6%), midureter (83.3%), and distal ureter (53.8%), but these differences were not significant (P=0.59). Efficiency quotient for the Medispec E3000™ was 54%. Overall, we achieved SFR of 64.9% in our initial experience with the Medispec E3000™. Optimizing treatment parameters may further improve success rates, and further outcomes follow-up may allow a more comprehensive evaluation of the lithotripter's overall efficacy.