Comparison between two shock wave regimens using frequencies of 60 and 90 impulses per minute for urinary stones

PURPOSE: Two different regimens of SWL delivery for treating urinary stones were compared. METHODS: Patients with urinary stones were randomly divided into two groups, one of which received 3000 shocks at a rate of 60 impulses per minute and the other of which received 4000 shocks at 90 impulses per minute. Success was defined as stone-free status or the detection of residual fragments of less than or equal to 3 mm three months after treatment. Partial fragmentation was considered to have occurred if a significant reduction in the stone burden was observed but residual fragments of 3mm or greater remained. RESULTS: A total of 143 procedures were performed with 3000 impulses at a rate of 60 impulses per minute, and 156 procedures were performed with 4000 impulses at 90 impulses per minute. The stone-free rate was 53.1% for patients treated with the first regimen and 54.8% for those treated with the second one (p = 0.603). The stone-free rate for stones smaller than 10 mm was 60% for patients treated with 60 impulses per minute and 58.6% for those treated with 90 impulses per minute. For stones bigger than 10 mm, stone-free rates were 34.2% and 45.7%, respectively (p = 0.483). Complications occurred in 2.3% of patients treated with 60 impulses per minute and 3.3% of patients treated with 90 impulses per minute. CONCLUSION: No significant differences in the stone-free and complication rates were observed by reducing the total number of impulses from 4000 to 3000 and the frequency from 90 to 60 impulses per minute.