Comparison of the Degree of Fragmentation according to the Various Levels of Shock Wave Power in the Same Storage with EDAP LT-01 Plus

Park, Jin Oh; Kim, Dong Sun

Abstract

PURPOSE: Many patients complains of pain during shock wave lithotripsy(SWL). For this reason, SWL frequently is performed in decreased power setting of the shock wave and it could result in decreased fragmentation rate. We evaluated the fragmentation rates at different shock wave power in the same storage that resulted in the same amount of energy delivered.
MATERIALS AND METHODS
From 1995 to 1997, a total of 97 renal stones less than 2cm in diameter were treated at the same sessional storage of 90 with various shock wave power(46%,54%,64%,74%,87%,100%). In case of EDAP device the energy delivered to disintegrate the stone is expressed as storage, that is calculated by power x duration x rate. The patients were treated by a power of 46 to 100 per cent at 10 impulses per second during the various treatment time to deliver the same storage. Complete fragmentation was defined as no residual fragments or fragments less than 3mm on KUB films at 2 weeks after treatment, otherwise another session was delivered. At 3 months after first session incomplete fragmentation was regarded as failure. Data were collected retrospectively and included the size of stones, the number of treatments and complete fragmentation rate. The results were compared between low power group at 46, 54, 64 per cent and high power group at 74, 87, 100 per cent of shock wave power setting. Statistical comparison were performed by the student`s t-test.
RESULTS
The complete fragmentation rate was 74.2 per cent in 97 renal stones. The mean size of stones was 1.04+/-0.52cm and the mean number of treatments was 3.6 sessions. For low and high power group the mean size of stones were 1.10+/-0.62cm, 1.02+/-0.54cm, respectively(p>0.05) and the complete fragmentation rate was 50.0 per cent and 86.4 per cent, respectively(p<0.05). The mean numbers of session were 5.4+/-2.5 and 2.8+/-1.7, respectively(p<0.05). In cases of the complete fragmentation of stones the mean numbers of session between low and high power group were 5.2+/-2.3 and 2.3+/-0.6, respectively(p<0.05). Posttreatment complications, such as prolonged gross hematuria, perirenal hematoma or steinstrasse, was not seen in both groups.
CONCLUSIONS
The above results indicate that the shock wave power is more important in fragmentation of urinary stone than the number of shock wave, even at same storage.