Thermography-Based Comparison of Irrigation Temperatures Between Moses Mode and Virtual Basket Mode: An In Vitro Phantom Study

Abstract

Objectives:

This study aims to evaluate changes in irrigation fluid temperatures during laser activation by using thermography, with comparison between Moses mode (MM) and virtual basket mode (VBM).

Materials and Methods:

Experiments were performed using an unroofed pyelocaliceal model. The laser was fired for 60 seconds at 0.4 J/60 Hz. Three runs were tested per setting using short pulse mode, long pulse mode, MM contact, and VBM. The time to reach threshold of thermal injury (43°C) was evaluated using thermometer and thermography, both with and without saline irrigation (25 mL/min). These outcomes were compared between laser pulse modes.

Results:

In measurement of time to reach the threshold, thermography-based time was significantly shorter than thermometer-based time in all laser modes under the condition of no irrigation. Thermography measurement results indicate that the speed of temperature rise depends on laser pulse modes, and the time to reach the threshold in MM was significantly shorter than that in VBM (9.0 seconds vs 14.3 seconds, p = 0.03). When 25 mL/min saline irrigation was used, the peak temperatures by both thermometer and thermography measurements did not exceed the threshold during laser activation.

Conclusions:

Thermography-based evaluation suggests that irrigation temperatures near mucosa around stones can rapidly elevate during laser lithotripsy when the irrigation condition is poor. Temperature rise speed in MM may be more rapid than that in VBM. To prevent thermal injury, laser pulse modes must be used selectively according to the condition of irrigation.