Intrarenal pressure and flow rate profile using LithoVue™ elite: impact of different irrigation systems and working channel instruments.

PURPOSE: To report real-time IRP and FR while performing flexible ureteroscopy in porcine kidney model utilizing LithoVue™ Elite (Boston Scientific®) with different irrigation systems, including automated pumps. METHODS: Using an ex-vivo model of porcine kidney, IRPs were measured with LithoVue Elite. Ureteroscopic settings (US) were tested with all permutations of irrigation methods (IM), working channel occupant (WCO), and ureteral access sheaths (UAS). IMs included: Single Action Pumping System (SAPS™, Boston Scientific), Thermedx FluidSmart™ (Stryker®), and ENDOMAT™ (Karl Storz®). Pumps were tested at 50, 100, and 150 mmHg. WCOs included a 1.9Fr zero-tip basket, 200 µm, and 365 µm laser fibers. UASs utilized 11/13Fr and 12/14Fr 36 cm. RESULTS: 84 different US were tested (252 experiments). ENDOMAT had higher IRP but the same FR as Thermedx at the same US for 50 and 100 mmHg (p < 0.01). SAPS had higher IRP and FR than pumps in all US studies (p < 0.01). There was positive correlation between pressure set by the pump and both IRP and FR (rho > 0.9). As the diameter of the WCO increased, lower IRP and FR were observed with the pumps (p < 0.01). With SAPS, IRP was similar regardless of WCO, but FR was decreased with the increased diameter of WCO (p = 0.81 and p < 0.01, respectively). There was significantly higher IRP when using 11/13Fr UAS than 12/14Fr (p < 0.01). CONCLUSION: IRP was higher with SAPS than automated pumps. ENDOMAT showed higher IRP than Thermedx when under 150 mmHg. IRP and FR increase with higher pump pressure and decrease with larger diameter WCO. Likewise, a larger UAS significantly reduced IRP.

Intrarenal Pressure Measured Using a Novel Flexible Ureteroscope with Pressure Sensing Capabilities: A Study of the Effects of Ureteral Access Sheath, Irrigation, and Working Channel Accessories.

Introduction: Intrarenal pressure is emerging as an important monitoring parameter during flexible ureteroscopy (fURS). We measure how intraoperative conditions affect intrarenal pressure using a novel pressure sensing ureteroscope. Methods: The LithoVue Elite (LVE) single-use digital flexible ureteroscope (Boston Scientific) is the first commercial ureteroscope that senses pressure at its tip. LVE was used in a porcine model to measure intrarenal pressure with and without a ureteral access sheath (UAS) with various sizes and placement locations, irrigation methods, and working channel accessories. LVE pressure accuracy was measured in a bench model. This abstract shows the least-square means from multiway analysis of variances used for analysis. Results: Intrarenal pressures were the highest without a UAS (64 mm Hg), followed by the 11/13 UAS (51 mm Hg) and the 12/14 and 13/15, which were not statistically different (39-40 mm Hg). The pressures were highest with UASs placed at the ureteropelvic junction (61 mm Hg), and lowest if placed in the renal pelvis (24 mm Hg). Irrigation methods showed the highest pressures with syringe (57 mm Hg), while irrigation bags (pressurized at 150-300 mm Hg) produced 43 to 46 mm Hg and 25 mm Hg when applied with 80 cm of gravity. Placing a 200 µm laser fiber reduced pressures from 44 to 41 mm Hg. Finally, the bench model showed that LVE was 96% accurate up to 300 mm Hg. Conclusion: Intrarenal pressure significantly varied based on UAS sizes, placement, and irrigation methods. Accordingly, fURS with LVE is poised to be an invaluable tool for clinical decision-making and future studies of intrarenal pressure.