Changing the window of shock wave application : how it improves the results of ESWL for renal calculi

ABSTRACT

Objectives: The aim of this work is to study the impact of using multiple windows of shock wave application on the results of ESWL therapy for renal calculi. Patients and Methods: Between January 1996 and October 2002; 676 patients with single pelvic stones ? 2.5 cm and either no or mild back pressure changes were treated by lithotripsy using the Dornier MPL 9000 with ultrasonic localization. Our patients were divided into two groups according to the total stone burden (15 mm and 15 - 25 mm) Every group was divided into two subgroups the first subgroup was treated by a single window of shock wave coupling and the second subgroup by changing the window of shock wave coupling every 500 SW from the posterior to the postero-lateral and to the lateral side of the patient. The results were recorded and statistically evaluated. Results: For stones 15 mm we found no difference between the two subgroups regarding the total SW energy; number of sessions; pattern of disintegration and the complication and clearance rate. But the need for additional doses of analgesia was significantly decreased for the patients who were treated by multiple windows. For stones sized 15 - 25 mm; we found a statistically significant decrease in the total SW number; in the number of sessions and the need for additional doses of analgesia when multiple windows of coupling were adopted. Changing the window of coupling also resulted in a statistically significant improvement in the pattern of disintegration of the stones. The rate of complication; clearance and auxiliary measures was comparable in all subgroups. Conclusion: Changing the window of SW application improves the pattern of disintegration; reduces the number of shock waves necessary for effective treatment; decreases the number of sessions and the need for additional doses of analgesia when ESWL is done for renal pelvic stones 15 mm