Does the Heat Generation by the Thulium:Yttrium Aluminum Garnet Laser in the Irrigation Fluid Allow Its Use on the Upper Urinary Tract? An Experimental Study.

INTRODUCTION: The current experimental study aimed into evaluating the temperature raise of the irrigation fluid caused by the use of the Thulium:Yttrium aluminum garnet (Tm:YAG) laser. The study setting was designed to replicate conditions of upper urinary tract (UT) surgery. MATERIALS AND METHODS: An experimental setting was designed for the investigation of differences in the temperature of the irrigation fluid in different flow rates, laser power settings, and laser activation times and modes. The experimental configuration included a burette equipped with a micrometric stopcock, a thermocouple, and a modified 40-mL vessel. A Tm:YAG and Holmium:Yttrium aluminum garnet (Ho:YAG) laser devices were used. RESULTS: The Tm:YAG in the continuous mode and in power settings of 5, 10, and 20 W showed similar temperature changes during the 10-minute observation period. The temperatures of the Tm:YAG in the pulsed mode tended to range within similar levels (46.8°C-61°C) with the continuous mode (47.8°C-68°C) when power settings up to 20 W were considered. When the higher power settings (50 and 100 W) were investigated, the temperatures reached were significantly higher in both pulsed and continuous modes. The Ho:YAG showed similar temperatures in comparison to the Tm:YAG in all the flow rates and power settings. The temperatures ranged between 45.6°C and 68.7°C. CONCLUSION: The Tm:YAG in the pulsed and continuous mode with power settings up to 20 W seemed to have potential for UT use. By combining a power setting at the above limit and a low flow rate (as low as 2 mL/minute), it is possible to use the Tm:YAG with safety in terms of temperature.