Work

Suction Sheaths Attenuate Both Intrarenal Temperature and Pressure During Pulsed Tm:YAG Laser Lithotripsy: A Bench-Top Study Using a Flexible Ureteroscope with Integrated Tip Sensors

Year: 2026

Type: preprint

Abstract: Background Laser lithotripsy during retrograde intrarenal surgery (RIRS) carries potential risks of thermal accumulation and elevated intrarenal pressure (IRP). This study aimed to compare the effects of different p-Tm:YAG laser settings and ureteral access sheath (UAS) configurations on intrarenal temperature (IRT) and IRP. Methods This in vitro study utilized a simulation model to evaluate four distinct pulsed Thulium:YAG (p-Tm:YAG) laser configurations: 1.0 J × 10 Hz, 10 W;0.6 J × 20 Hz, 12 W;1.0 J × 20 Hz, 20 W;0.4 J × 50 Hz, 20 W. These settings were cross-tested using C-UAS (conventional ureteral access sheaths; UAS; Cook, 10.7/12.7 Fr and 12/14 Fr) and FANS (Flexible and Navigable Suction ureteral access sheath, Innovex, 10/12 Fr and 11/13 Fr). Both IRT and IRP were continuously monitored using a flexible ureteroscope equipped with distal-tip sensors, and measurements were recorded at 10-second intervals throughout the lasing process. Results Active suction substantially mitigated both IRT and IRP elevation compared to conventional UAS. Temperature-time regression lines showed the 20-W settings produced faster temperature increases than the 10-W settings. Among all tested configurations, the larger suction sheath (FANS; 11/13 Fr) consistently maintained the most stable thermal and pressure environments, whereas smaller sheath diameters amplified both responses across all lasing conditions. Furthermore, under active suction, IRP showed no consistent time-dependent cumulative trend; instead, intermittent pressure fluctuations may have been more closely related to transient outflow obstruction during fragment evacuation than to elapsed experimental time. Conclusion In this in vitro RIRS model, smaller sheath diameters were associated with higher intrarenal temperature and pressure, while suction sheaths effectively reduced both IRT and IRP. Thermal elevation was more evident at higher laser power, and different energy–frequency settings produced distinct thermal profiles despite equivalent total power. IRP showed no consistent time-dependent cumulative trend under standardized conditions with a non-restrictive lumen. These findings highlight the importance of simultaneous IRT and IRP monitoring and suggest that suction sheaths, particularly when combined with pressure- and temperature-sensing ureteroscopes, may enhance the safety of flexible ureteroscopy.

Source: Research Square

DOI: 10.21203/rs.3.rs-10513542/v1