Correlation of simultaneously monitored intrarenal and irrigation pressures during ureteroscopy: an in vivo pilot study.

PURPOSE: This study aimed to evaluate the relationship between irrigation pressure and intrarenal pressure during ureteroscopy and to assess whether intrarenal pressure trends could be inferred via the flexible ureteroscope working channel using the pump release technique, with antegrade percutaneous measurement as the reference. PATIENTS AND METHODS: Pressures were recorded during ureteroscopic lithotripsy in nineteen patients undergoing endoscopic combined intrarenal surgery. Intrarenal pressure was continuously measured via an antegrade Chiba needle placed, whenever feasible, into the lower posterior calyx or otherwise into the calyx nearest to the stone, and connected to a pressure transducer. Irrigation pressure was continuously and concurrently recorded from the proximal irrigation line of the ureteroscope using a second transducer. Correlation analyses were performed. We also assessed whether intrarenal pressure could be estimated using the pump release technique, in which sudden release of the irrigation pump interrupts flow and creates a transient static column approximating intrarenal pressure. RESULTS: A total of 3 h and 53 min of pressure data were recorded. Mean irrigation (PIrr) and intrarenal pressures (IRP, measured via the Chiba needle) were 56.6 mmHg and 34.1 mmHg, respectively. Moderate correlations were identified between PIrr and IRP during gravity irrigation (r = 0.506) and between their peak values (r = 0.49). During PRT, a significant correlation was observed between PIrr and simultaneous IRP over brief intervals (r = 0.602–0.613). CONCLUSIONS: Using external pressure transducers on irrigation lines to estimate intrarenal pressure trends during ureteroscopy is feasible. Larger studies are needed to validate this method and to account for factors that may influence pressure accuracy.