Extracorporeal lithotripsy with low pressure shockwaves using a modified Dornier HM3 lithotriptor : preliminary results

Extracorporeal shock wave lithotripsy is a well established procedure for the treatment of the renal and ureteral calculi. The technical innovations of the low-pressure generator with a modified ellipsoid installed into the Dornier HM3 lithotripter leads to decrease the pressure in the second focus F2 lowering the painful sensation linked to the treatment and allowing to perform lithotripsy without general or epidural anae sthesia. From January to March 1988 132 patients underwent 144 treatment by modified Dornier Lithotripter HM3, we performed the treatments under a combination of anxiolytic and analgesic drugs in 125 patients (94.6%), only 7 patients needed the general or epidural anaesthesia, because of complex endoscopic pretreatment instrumentations. An average of 2150 Shock waves was applied with a range of 500 to 3800, the shock wave energy was administered at an average 20 Kvolts (16-26 Kv). Stone fragmentation had a success rate of 94.6%. The average postoperative stay was 4.5 days. After a month of follow-up 50.9% of the patients was free of stones, 27.8% had sand or spontaneously passable fragments and 11.1% had residual fragments larger than 4 mm. The treatment was judged as free of pain or with tolerable pain in 60% of the patients, 40% of the patients needed additional medication. The number of secondary treatment was, in our review, 9% but it could increase because we observed after a month of follow-up that 11% of the patients treated presents fragments larger than 4 mm.