The following is a summary of “Thermal Safety Boundaries for Laser Power and Irrigation Rate During Ureteroscopy: In Vivo Porcine Assessment With a Ho:YAG Laser,” published in the October 2023 issue of Urology by Marom, et al.
For a study, researchers sought to map thermal safety boundaries during ureteroscopy (URS) with laser activation in two in vivo porcine subjects. They aimed to enhance the understanding of the relationship between laser power, irrigation rate, and fluid temperature in the collecting system.
Ureteroscopy was conducted in two in vivo porcine subjects using a prototype ureteroscope equipped with a thermocouple at its tip. Sixty-second laser activation trials were performed at various power settings and irrigation rates. Thermal dose calculations were made for each trial, and laser power-irrigation rate parameter pairs were categorized based on the number of trials exceeding a thermal dose of 120 equivalent minutes.
The study found that the collecting fluid temperature increased with higher laser power and slower irrigation rates. In the first porcine subject, the safe application of 25 W laser power required at least 15 mL/min irrigation, and 48 W needed at least 30 mL/min. With a larger calyx, the second subject showed that 15 W laser power required 9 mL/min irrigation and 48 W required 24 mL/min, with intermediate points following a near-linear curve.
The research validated prior bench studies and established a conceptual framework for selecting safe laser lithotripsy settings and irrigation rates during URS with laser lithotripsy. The findings also offered insights and guidance for future thermal mitigation strategies and devices developments.