Laser Lithotripsy Induces Dose-Dependent Temperature Elevation During Retrograde Intrarenal Surgery

Area of Science:

• Urology
• Medical Engineering
• Laser Medicine

Background:

• Laser lithotripsy is a common procedure for kidney stone removal.
• Real-time temperature monitoring during laser lithotripsy is essential to prevent thermal injury.

Purpose of the Study:

• To assess calyceal and tissue temperatures during laser lithotripsy using thulium fiber laser (TFL) and holmium:YAG (Ho:YAG) lasers.
• To determine if laser settings and types influence thermal effects.

Main Methods:

• A prospective study involving 20 patients undergoing endoscopic combined intrarenal surgery.
• Temperature measurements were taken at 5, 15, 25, and 35 mm from the laser fiber tip using a multipoint thermal sensor needle.
• Temperatures were recorded during fragmentation, dusting, and pop-dusting with TFL and Ho:YAG lasers, with a pause if temperatures exceeded 43°C.

Main Results:

• During fragmentation, temperatures remained below 41°C.
• During dusting, calyceal temperatures exceeded 43°C in 4 patients per laser type; one Ho:YAG patient had tissue temperature reach 49°C.
• During pop-dusting, calyceal temperatures exceeded 43°C in most patients, with significantly higher average maximum temperatures for TFL (52.9°C) compared to Ho:YAG (45.1°C). Tissue temperatures exceeded 43°C in three patients for each laser type.

Conclusions:

• High-powered laser lithotripsy, particularly during pop-dusting, can rapidly elevate calyceal temperatures above 43°C.
• Temperatures exceeding 43°C pose a risk of permanent tissue injury.
• Real-time temperature monitoring is critical during laser lithotripsy to mitigate thermal damage risk.