Login to Access Video or Poster Abstract: MP62-08
Sources of Funding: "None"

Introduction

The Modulith SLK-F2 Electromagnatic lithotripter (Storz Medical AG, Tägerwilen, Switzerland) is the first lithotripter on the market with a unique design that allows for a dual focus system with the option of either a narrow or wide focal zone. Ex vivo data on the SLK-F2 lithotripter shows that the disintegration capacity and the renal vascular injury are independent of the focal diameter of the SW generator at the same peak positive pressure and disintegration power. We report on a subset of patients from our larger randomized trial for whom data on markers of renal injury were available. _x000D_ _x000D_

Methods

A subset of 134 patients (out of 263 total patients randomized in the trial) with previously untreated radio-opaque solitary stone located within the renal collecting system, measuring at least 5mm, were randomized to receive narrow or wide focus lithotripsy while maintaining a constant overall energy level, and also collected urinary markers of renal injury. Patients were followed with renal ultrasound at 2 weeks post lithotripsy to assess for the development of perinephric hematoma. Urinary markers of renal cellular damage (microalbulin, creatinine, beta 2-microglobulin, microalbumin/creatinine ratio and Beta 2-microglobulin/creatinine ratio) were measured pre-SWL, immediately post-procedure in the recovery room, 24 hours post-SWL and 7 days post-treatment. Data was analyzed using ANOVA and repeated measures ANOVA, Chi-square statistic and linear regression where appropriate, controlling for presence of diabetes as a confounder._x000D_ _x000D_

Results

68 patients were randomized to narrow focus lithotripsy versus 66 patients to wide focus. The groups were similar in baseline characteristics including age, gender, BMI, stone size and density, skin to stone distance and diagnosis of diabetes. Overall complication rates were comparable between the two groups (Narrow: 23.5% vs Wide: 12.1% P=0.085) including similar rates of perinephric hematoma (Narrow: 2.9% vs Wide: 4.5%; P = 0.624) and Steinstrasse (Narrow: 7.4% vs Wide: 4.5%; P = 0.493). Urinary markers of renal injury did change after SWL, and then normalized within 7days, however there were no differences in the magnitude, timing or degree of change between the narrow and wide focal zone groups.

Conclusions

The degree of renal injury as assessed by renal cellular markers and by ultrasound assessment of perinephric hematoma are comparable when using the narrow or wide focal zone of the Modulith SLX-F2.

Funding

"None"