Temperature effect of Moses™ 2.0 during flexible ureteroscopy: an in vitro assessment

Abstract

Introduction: One of the main issues related to the use of high-power lasers is the associated rise in temperature. The aim of this study was to characterize temperature variations with activation of the Moses™ 2.0 laser.

Material and methods: An in vitro experimental study was designed using a high-fidelity uretero-nephroscope simulation model to assess changes in temperature during intracorporeal laser lithotripsy. Renal and ureteral temperature records were obtained from the treatment of BegoStones positioned in the renal pelvis. Different laser settings over three time periods and two possible irrigation flow speeds were evaluated. We considered 43°C as the threshold since it is associated with denaturation of proteins. The Wilcoxon-Mann-Whitney test was used to assess quantitative variables and the Kruskal-Wallis test for categorical variables.

Results: The highest increase in intrarenal temperature was reached with 30 seconds of laser activation at a laser setting of 0.5 J/100 Hz (50 W) and a flow of 10 mL/min. Only 15 seconds of activation was sufficient for most settings to exceed 43°C. The ureteral temperature did not increase significantly, regardless of the combination of laser setting, time, or irrigation flow, except when 30 W was used for a 30 second period. Multivariate analysis showed that an irrigation flow of 20 mL/min produced an intrarenal temperature decrease of 4.7-9.2°C (p <0.001).

Conclusions: Use of high-power lasers, both for the ureter and kidney, should involve consideration of temperature increases evidenced in this study, due to the potential biological risk entailed.

Keywords: kidney calculi; laser; retrograde intrarenal surgery; urolitiasis.

Figure 1

Experimental Setup: (1) Thermometer (2) Thermocouple at renal pelvis (3) Thermocouple at proximal ureter.

Figure 2

Maximum intrarenal temperature measured by thermocouple at a flow rate of 10 and 20 mL/min.