Effect of Extracorporeal Shock Wave Lithotripsy on Renal Function

Abstract

The effect of extracorporeal shock wave lithotripsy and its possible effect on renal function has not been fully investigated. We evaluated renal function using the quantitative scintillation gamma camera. Preoperative estimated renal plasma flow (ERPF) was compared with immediate (1 to 7 days) and long-term postoperative (over 3 months)ERPF. Twelve patients undergoing simultaneous bilateral treatment had mean preoperative total ERPF of 609 ± 90 ml/min and immediate mean postoperative total ERPF of 557 ± 104 ml/min (p = 0.0006). There was no significant correlation between the number of shock waves administered and the change in ERPF. Sixty-two patients given unilateral treatment showed mean preoperative and postoperative ERPF on the treated side of 296 ± 72 and 273 ± 74 ml/min, respectively (p = 0.0001). The contralateral values were 324 ± 73 and 314 ± 71 ml/min (p = 0.018). However, with fewer than 1500 shocks, there were no significant differences, whereas with more than 1600 shocks, both the treated and the nontreated sides were significantly different: p = 0.0001 and p = 0.0391, respectively. The correlation coefficient between number of shocks and postoperative minus the preoperative ERPF on the treated side was -0.2504. The difference between postoperative and preoperative ERPF could be predicted from the number of shocks and started falling beween 650 and 700 shocks. Although there is some eventual improvement, our short-term data suggest that one should limit the number of shocks given per kidney per treatment, and we caution against casual overtreatment.