Presentation Authors: Brenton Winship*, Daniel Wollin, Evan Carlos, Chloe Peters, Durham, NC, Jingqiu Li, Singapore, Singapore, Russell Terry, Kohldon Boydston, Glenn Preminger, Michael Lipkin, Durham, NC
Introduction: Moses technology is a Holmium:YAG laser pulse delivery system shown to minimize stone retropulsion. This may allow laser lithotripsy at higher power, however power and heat production are proportional and temperatures over 43C - the threshold for cellular death - may be achieved during ureteroscopic lithotripsy. While prior in vitro studies have shown the importance of irrigation and laser activation time, the impact of laser pulse type on temperature has not been evaluated.
Methods: A flexible ureteroscope was placed in a 36cm, 13Fr ureteral access sheath inserted into a full 250mL bag of saline to simulate a normal caliber ureter, renal pelvis reservoir, and antegrade irrigant flow. A thermocouple was placed adjacent to the tip of a 365Âµm laser fiber fired for 30 sec at 0.6J/6Hz, 0.8J/8Hz, 1J/10Hz, 1J/20Hz, and 0.2J/80Hz at constant irrigation pressure of 100mmHg. We tested 2 runs per setting at short pulse (500Âµs), long pulse (1200Âµs), Moses-contact and Moses-distance. The mean temp change was recorded with 6Â°C above baseline as a threshold for potential injury (as body temp is 6Â° below 43Â°C).
Results: The mean temp change from baseline at 0.6J/6Hz remained under 6Â° and was similar across all pulse types. Long pulse created significantly greater temp increases relative to all pulse types at 0.8J/8Hz and 1J/10Hz. Both Moses settings produced temp changes similar to short pulse at these settings. At 1J/20Hz, long pulse and Moses-contact produced greater temp increases relative to short pulse. At 0.2J/80Hz, all pulse types produced similar temps relative to short pulse, however Moses-contact was significantly warmer than Moses-distance. Long pulse and both Moses settings achieved temp changes over 6Â° significantly faster than short pulse at 0.8J/8Hz, 1J/10Hz, and 1J/20Hz. At 0.2J/80Hz all pulse types surpassed 6Â° over baseline at similar rates. (Figure)
Conclusions: Laser pulse type impacts the production of potentially dangerous intraureteral temps during lithotripsy. Long pulse produced the greatest and fastest temp increases. Moses settings produced similar temp increases to short pulse at 0.8J/8Hz and 1J/10Hz, although time to surpass 6Â° above baseline was similar to long pulse. Both long pulse and Moses have been shown to reduce stone retropulsion. Moses may confer this advantage with decreased heat production.