An in vitro study evaluating the internal pressure during RIRS of suction ureteral access sheath versus traditional...

Flexible ureteroscopy (fURS) remains the gold standard for managing ureteral and renal calculi. The integration of vacuum suction ureteral access sheaths has demonstrated improved stone clearance rates. Through an in vitro fURS model, this study systematically validates the sheath's efficacy in regulating intraluminal pressure across diverse operational parameters, providing mechanical insights for clinical optimization.

An 8.6Fr disposable flexible ureteroscope was utilized to measure intraluminal pressure within a silicone urinary tract model fabricated using 3D printing technology. The experiment was conducted under three configurations of ureteral access sheaths (UAS): (1) conventional UAS, (2) negative pressure suction sheath with an open vent, and (3) negative pressure suction sheath with a fully closed vent. Intraluminal pressure and irrigation flow rate were recorded for various UAS sizes under irrigation pressures ranging from 10 to 240 mmHg.

Under varying infusion pressure conditions, the negative pressure sheath with an open vent exhibited slightly lower intraluminal ureteral pressure compared to the traditional sheath; however, this difference was not statistically significant (p = 0.56). In contrast, when using the closed vent method, the negative pressure aspiration sheath demonstrated a significantly distinct change in intraluminal pressure compared to both the traditional sheath and its open vent mode (p < 0.01). Additionally, the choice of ureteral sheath size had a profound impact on intraluminal pressure, with larger sheath sizes associated with lower pressure levels under the same infusion pressure (p < 0.01).

During ureteroscopy procedures, intraluminal pressure within the ureter increases proportionally with irrigation pressure. However, the application of negative pressure using a closed vent can effectively mitigate this rise in intraluminal pressure.