Influence of Saline on Temperature Profile of Laser Lithotripsy Activation

Abstract

Purpose: We established an ex vivo model to evaluate the temperature profile of the ureter during laser lithotripsy, the influence of irrigation on temperature, and thermal spread during lithotripsy with the holmium:yttriumaluminum-garnet (Ho:YAG) laser. Materials and Methods: Two ex vivo models of Ovis aries urinary tract and human calcium oxalate calculi were used. The Open Ureteral Model was opened longitudinally to measure the thermal profile of the urothelium. On the Clinical Model, anterograde ureteroscopy was performed in an intact urinary system. Temperatures were measured on the external portion of the ureter and the urothelium during lithotripsy and intentional perforation. The lithotripsy group (n = 20) was divided into irrigated (n = 10) and nonirrigated (n = 10), which were compared for thermal spread length and values during laser activation. The intentional perforation group (n = 10) was evaluated under saline flow. The Ho:YAG laser with a 365 lm laser fiber and power at 10W was used (1J/Pulse at 10 Hz). Infrared Fluke Ti55 Thermal Imager was used for evaluation. Maximum temperature values were recorded and compared. Results: On the Clinical Model, the external ureteral wall obtained a temperature of 37.4°C -2.5°and 49.5°C -2.3°(P = 0.003) and in the Open Ureteral Model, 49.7°C and 112.4°C with and without irrigation, respectively (P < 0.05). The thermal spread along the external ureter wall was not statically significant with or without irrigation (P = 0.065). During intentional perforation, differences in temperatures were found between groups (opened with and without irrigation): 81.8°-8.8°and 145.0°-15.0°, respectively (P < 0.005). Conclusion: There is an increase in the external ureteral temperature during laser activation, but ureteral thermal values decreased when saline flow was applied. Ureter thermal spread showed no difference between irrigated and nonirrigated subgroups. This is the first laser lithotripsy thermography study establishing the framework to evaluate the temperature profile in the future.

Holmium:yttrium-aluminum-garnet laser induced lithotripsy: in-vitro investigations on fragmentation, dusting, propulsion and fluorescence

“…Innovations in laser development resulted in the introduction of high power Ho:YAG lasers on the market, providing an average power around 100W, which can be very efficient in stone destruction [35][36][37]. Furthermore, attention should in particular also be dedicated to heat generation inside the urinary tract when using such high power laser devices [38][39][40][41][42]. Fluorescence-assisted endoscopic laser lithotripsy should be introduced in particular in connection with high power laser devices.…”

Two‐year‐old girl with impacted ureteral stone successfully treated with a single session of combined percutaneous nephrostomy and ureteroscopy

“…For the present patient, because ureteroscopy revealed significant ureteral edema, we used retrograde irrigation with a single action pumping system to ensure sufficient visibility. As the external ureteral temperature increases during Ho:YAG activation, we took care to fragment the stone near its center, minimizing laser‐induced damage to the ureter . In an effort to limit operating within the ureter, we pushed the stone fragments proximally to the renal pelvis and collected them from there.…”

Collateral damage to the ureter and Nitinol stone baskets during thulium fiber laser lithotripsy

“…Another potential safety concern is collateral thermal damage to the ureter during TFL lithotripsy . TFL kidney stone ablation rates have been observed to scale linearly with pulse rate, and when operated at pulse rates up to 500 Hz, the TFL is capable of rapid stone ablation .…”