Novel Flexible Ureteroscopic System for intrarenal pelvic and intracaliceal pressure measurement in porcine models

This study evaluates the consistency between intrarenal pelvic pressures (IPP) and intracaliceal pressures (ICP) and explores the impacts of irrigation flow rate (IFR) and ureteral access sheath (UAS) position on ICP using a novel Flexible Ureteroscope Pressure Measurement System. Six pigs with 12 kidneys were included in this study under general anesthesia. The IPP and ICP were measured using the Flexible Ureteroscopic Pressure Measurement System under varying UAS positions and IFRs. The 12/14Fr UAS was sequentially placed in the upper, middle, and lower segments of the porcine ureters. The irrigation pump was set to cumulative flow rates of 20, 30, 40, and 50 mL/min. Hemodynamic parameters were monitored using the Edwards Lifesciences monitoring system. The experiment was successfully completed in 10 kidneys. One kidney failed due to issues with UAS placement, and another was penetrated by the UAS. No significant difference was observed between the middle calyx ICP and IPP. ICP in the upper and lower calyces was higher than IPP, with the discrepancy being minor at 20 or 30 mL/min IFR but significant at higher IFRs of 40 and 50 mL/min. The ICP increased with higher IFRs and when the UAS was set in the low ureteral segment. Under the same IFR and UAS position, ICP varied among the three calyces (lower calyx > upper calyx > middle calyx). The Edwards Lifesciences monitoring system accurately measured hemodynamic parameters, which remained stable even at an IFR of 50 mL/min. The Flexible Ureteroscopic Pressure Measurement System can be used to measure the IPP and ICP. These pressures were not consistent across different IFRs and UAS positions. The highest ICP was observed in the lower calyx.