CHICAGO, IL, USA (UroToday.com) - Shockwave lithotripsy (SWL) is an efficacious minimally invasive therapy for a majority of renal stones. The optimal voltage treatment protocol to ensure stone communition has not been determined.
In this study, Lambert and colleagues from Columbia University in New York report a prospective randomized trial to determine whether fixed voltage or escalating voltage shockwave lithotripsy results in higher stone free rates with less morbidity. Forty patients (median age 47y) were enrolled over two years. The study used the Dornier Doli 50 lithotripter. Patients were randomized to receive an escalating strategy of 500 shocks at 14 kV, 1000 shocks at 15 kV, and 1000 shocks at 16 kV or the fixed strategy consisting of 2500 shocks at 16 kV. Plain abdominal radiographs were used for follow up at 1 month. Beta-2-microglobulin and microalbumin pre-SWL, immediately after SWL, and 1 week post-SWL were used to evaluate renal damage. Median stone size was 8mm.
Their results showed that 89% of patients in the escalating group were stone free compared to 48% in the fixed group (p<0.01). Beta-2-microglobulin and microalbumin levels were not significantly different between the treatment groups, although there were decreased levels in the escalating group. These results along with the other recent data that comminution improves with slower shockwave frequency means “low and slow” with SWL treatment will result in improved stone-free outcomes.
Presented by Erica H. Lambert, MD, et al. at the Annual Meeting of the American Urological Association (AUA) - April 25 - 30, 2009 - McCormick Place Convention Center - Chicago, Illinois, USA.