Evaluation of the impact of ureteroscope, access sheath and irrigation system selection on intrarenal pressures in a porcine kidney model.

Introduction Elevated intrarenal pressure (IRP) during flexible ureterorenoscopy (FURS) is a predictor of postoperative complications. The aim of this study is to evaluate IRP during FURS in a porcine kidney model in order to determine the safest combination of irrigation device, ureteral access sheath (UAS) and ureteroscope. Methods Urinary tracts were harvested from Landrace pigs slaughtered for the food chain. Two flexible ureteroscopes, 8.7Fr and 9.5Fr were evaluated. Irrigation systems evaluated included; TraxerFlowTM (Rocamed, France), SAPSTM single action pumping system (Boston Scientific, USA), Pathfinder PlusTM (Utah Medical, USA), and a manual "bag squeeze". This experiment was conducted with no UAS, followed by an 11/13Fr UAS and then a 12/14Fr UAS. IRPs were measured in the prepared porcine kidney during all possible combinations of scope, UAS and irrigation system. Results Pressures were significantly reduced when using 12/14Fr UAS compared to 11/13Fr UAS (16.45 ± 5.3 cmH20 vs 32.73 ± 35.66 cmH20, p 0.006) and when using 11/13Fr UAS compared to no UAS (32.73 ± 35.66 cmH20 vs 49.5 ± 29.36 cmH20, p 0.02). Pressures were significantly reduced with the 8.7Fr scope compared to the 9.5Fr scope (24.1 ± 21.24 cmH20 vs 41.68 ± 34.5 cmH20, p 0.001). SAPSTM generates significantly greater IRP than TraxerFlowTM, Pathfinder PlusTM and a "bag squeeze" (p<0.05). The most dangerous combination was using the SAPSTM, no UAS and larger ureteroscope leading to an IRP of 100.6 ± 16.1 cmH20. The safest combination was using Pathfinder PlusTM with a 12/14Fr UAS and smaller ureteroscope giving an IRP of 11.6 ± 3.65 cmH20. Conclusion IRPs are reduced by selecting larger UAS and small ureteroscope. The SAPSTM generates significantly higher IRPs than other irrigation systems. In order to maintain safe IRPs during FURS urologists should use large UAS, narrow ureteroscopes and be cautious in selection of an irrigation device.