Intrarenal pressure response to suction during ureteroscopy with a flexible and navigable suction sheath: in vivo porcine studies
摘要
Use of flexible and navigable suction ureteral access sheaths (FANS) can improve stone clearance during ureteroscopy but activation of suction for too long lowers intrarenal pressure (IRP) and can induce collapse of the collecting system. The appropriate time to activate suction and the IRP at which the collecting system collapses have not been defined. We sought to activate suction for varying lengths of time and quantify IRP in an in vivo porcine model. Ureteroscopy was performed in anesthetized porcine subjects using an 11/13Fr, 46 cm FANS and a 9.5 Fr pressure measuring flexible ureteroscope. Irrigation pressure was adjusted to provide baseline IRP of 40 or 70 cmH2O. Suction of -204 or -272 cmH2O (-150 or -200 mmHg) was activated for 1, 2, or 5 s while IRP was recorded. Longer periods of suction were also applied to allow complete collapse of the collecting system and correlation of endoscopic visual appearance with IRP. Trials with 1, 2, or 5 s of vent occlusion produced a drop in intrarenal pressure from 40 cmH2O baseline to values of 18.3, 3.7, and − 14.7 cmH2O respectively and from 70 cmH2O baseline IRP to 27.3, 2.7, and − 9.3 cmH2O respectively. The collecting system began to visibly collapse when IRP decreased below 10.7 cmH2O and appeared completely collapsed at 0.3 cmH2O. Upon release of suction IRP immediately increased to 7.3 cmH2O and then required 35.2 s to return to baseline IRP. Activation of suction during ureteroscopy produced a rapid drop in IRP and visual contraction of the collecting system below 11 cmH2O. The time required to refill the collecting system was much longer than the period of suction activation. These findings illustrate limitations of suction as currently used clinically and provide insights for further refinement of suction technology.