The effect of prolonged laser activation on irrigation fluid temperature: an in vitro experimental study

Abstract

To investigate the effect of prolonged laser activation on irrigation fluid temperature by varying the power settings flow rate (10-30ml/min). An experimental study using a 20ml syringe, 12/14 ureteral access sheath, a dual-lumen catheter and a thermocouple was performed. The laser was fired with 12W (0.3J × 40Hz), 40W (1J × 40Hz), 60W (1.5J × 40Hz) using Quanta Ho 150W (Quanta System, Samarate, Italy). All trials were performed with fluid outflow rate of 10, 20 and 30ml/min with the fixed fluid volume at 10ml. Continuous laser activation for 10min with the outflow rate of 10ml/min using only 12W resulted to continuous temperature rise to as high as 83°C. Similar rise of temperatures were observed for 40W and 60W with 10ml/min outflow rate with intermittent laser activation. With 20 and 30ml/min outflow rates the maximum temperatures for all power settings were below the threshold (< 43°C). However, the time to reach the same total emitted energy was 60% and 40% shorter 60W and 40W, respectively. Our study found that continuous laser activation with as less as 12W using 10ml/min outflow rate increased the irrigation fluid temperature above the threshold only after 1min. In the current experimental setup, with the fluid outflow rate of 20 and 30ml/min safe laser activation with 60W and 40W (temperature < 43°C) can be achieved reaching the same total emitted energy as with 12W in significantly shorter time period.