Choosing a powerful lithotriptor.

Clinicians have no yardstick to help them choose the most efficient lithotriptor. Their leading priority is a system allowing complete disintegration of the stone with the minimum number of shocks and a low re-treatment rate. One of the prerequisites of this system is a powerful shock wave generator. "Power" is as yet ill defined in lithotripsy. Therefore clinicians' choice depends upon other factors. Acoustic output measurements were recorded on 3 commercial lithotriptors representing the 3 main shock wave generating systems. These were the Dornier MPL 9000 (standard and X-155 electrodes), the Siemens (Lithostar, Lithostar Plus and System C) and the Wolf Piezolith 2300. The shock wave measurements were correlated to the capability of the lithotriptors to disintegrate standard stone models in vitro. Two factors were identified. The pulse intensity integral in the focus and the size of the focal zone proved to be the most important factors to assess and compare the efficacy or "power" of different lithotriptors. Together they can help clinicians to identify and choose the most efficient shock wave generating systems.

Ureteric stone management using a second generation lithotriptor.

A series of 209 consecutive patients with ureteric calculi underwent 296 extracorporeal shock wave lithotripsy treatments on the Siemens Lithostar over a 25-month period; 123 stones were upper ureteric, 30 mid-ureteric and 56 lower ureteric; 46.9% were right-sided stones, 53.6% were left-sided and 0.5% (1 patient) were bilateral. On referral, 60 patients had stents and 15 had nephrostomies for obstruction. All treatments were performed without anaesthesia except for 9 patients in whom stent insertion or ureteroscopic manipulations were attempted concomitant to ESWL. The average number of treatments was 1.42, with 27.5% of patients requiring more than 1 treatment. The average number of shocks per treatment was 3995 and the average hospital stay was 1.79 days. Complete clearance of the stone was achieved in 82% of upper ureteric stones, 89% of mid-ureteric and 80% of lower ureteric stones. The facility for X-ray localisation of stones allows a high proportion of ureteric calculi to be treated successfully by ESWL, including the more taxing middle and lower ureteric calculi.

Extracorporeal shock wave lithotripsy for renal calculi in children.

Fifteen children (8 male and 7 female) with an age range of 18 months to 15 years were treated with extracorporeal shock wave lithotripsy (ESWL) using the Siemens Lithostar. Two children had a history of metabolic stone disease and 1 child had previously undergone open stone surgery. Four children were treated with a ureteric stent in place and 1 nephrostomy was inserted before treatment. All children were treated under general anaesthesia and all of the stones treated were confined to the kidney and ranged in size from 5 mm to a complete staghorn. The number of treatments ranged from 1 to 6 and generator voltage ranged from 16 to 19 kV with a maximum number of 30,000 shocks to a complete staghorn. Complications were minimal, with 3 children presenting with colic, 1 child requiring a stent and none requiring a nephrostomy after treatment. The overall stone clearance rate at 3 months was 65%. ESWL provides an effective treatment for selected calculi in children. In the short term, complications are minimal but the long-term effects on children need to be monitored.