Temperature profiles of calyceal irrigation fluids during flexible ureteroscopic Ho:YAG laser lithotripsy.

Abstract

To evaluate calyceal irrigation fluid temperature changes during flexible ureteroscopic Ho:YAG laser lithotripsy. Between May 2019 and January 2020, patients with kidney stones undergoing flexible ureteroscopic Ho:YAG laser lithotripsy were enrolled. A K-type thermocouple was applied for intraoperative temperature measurement. Laser was activated at different power (1J/20Hz and 0.5J/20Hz) and irrigation (0ml/min, 15ml/min and 30ml/min) settings, temperature-time curve was drawn and time needed to reach 43°C without irrigation was documented. Thirty-two patients were enrolled in our study. The temperature-time curve revealed a quick temperature increase followed by a plateau. With 15ml/min or 30ml/min irrigation, 43°C was not reached after 60s laser activation at both 1J/20Hz and 0.5J/20Hz. At the power setting of 1J/20Hz and irrigation flow rate of 15ml/min, the temperature rise was significantly higher than other groups. Without irrigation, the time needed to reach 43°C at 1J/20Hz was significantly shorter than that at 0.5J/20Hz (8.84 ± 1.41s vs. 13.71 ± 1.53s). Ho:YAG laser lithotripsy can induce significant temperature rise in calyceal fluid. With sufficient irrigation, temperatures can be limited so that a toxic thermal dose is not reached, when irrigation is closed, the temperature increased sharply and reached 43°C in a few seconds.