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

Two different regimens of SWL delivery for treating urinary stones were compared.

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.

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.

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.