Shockwave lithotripsy with renoprotective pause is associated with vasoconstriction in humans

A pause early in shock wave lithotripsy (SWL) increased vasoconstriction as measured by resistive index (RI) during treatment and mitigated renal injury in an animal model. The purpose of our study was to investigate whether RI rose during SWL in humans. Prospectively recruited patients underwent SWL of renal stones with a Dornier Compact S lithotripter. The renal protective protocol consisted of treatment at 1 Hz and slow power ramping for the initial 250 shocks followed by a 2 min pause. RI was measured using ultrasound prior to treatment, after 250 shocks, after 750 shocks, after 1500 shocks, and after SWL. A linear mixed-effects model was used to compare RI at the different time points and to account for additional covariates in fifteen patients. RI was significantly higher than baseline for all time points 250 shocks and after. Age, gender, body mass index, and treatment side were not significantly associated with RI. Monitoring for a rise in RI during SWL is possible and may provide real-time feedback as to when the kidney is protected. [Work supported by NIH DK043881, NSBRI through NASA NCC 9-58, and resources from the VA Puget Sound Health Care System.]