HOLMIUM-YAG LITHOTRIPSY - PHOTOTHERMAL MECHANISM CONVERTS URIC-ACID CALCULI TO CYANIDE

Purpose: Holmium:YAG lithotripsy fragments stones through a phototherm al mechanism. Uric acid when heated is known to be converted into cyan ide, We test the hypothesis that holmium: YAG lithotripsy of uric acid calculi produces cyanide. Materials and Methods: Human calculi of kno wn uric acid composition were irradiated with holmium:YAG energy in wa ter. Stones received a total holmium:YAG energy of 0 (control), 0.1, 0 .25, 0.5, 0.75, 1.0 or 1.25 kJ. The water in which lithotripsy was per formed was analyzed for cyanide concentration. A graph was constructed to relate holmium:YAG energy to cyanide production. Results: Holmium: YAG lithotripsy of uric acid calculi in vitro produced cyanide consist ently. Cyanide production correlated with total holmium:YAG energy (p <0.001). Conclusions: Holmium:YAG lithotripsy of uric acid calculi ris ks production of cyanide. This study raises significant safety issues.