Endoscopic Valves and Irrigation Devices for Flexible Ureteroscopy: Is There a Difference?

Background And Purpose: A variety of ureteroscopic irrigation systems are available, ranging from gravity-driven pressure bags to hand-operated pumps. Endoscopic valves maintain a watertight seal during ureteroscopy (URS) while facilitating passage of instruments. The clinical utility and ergonomics of such devices have not been established. We systematically compare the mechanical properties and usability of select valve devices and hand-operated irrigation systems in an in vitro setting.

Materials And Methods: In vitro testing of four different endoscopic valves: UroSeal adjustable endoscopic valve (US Urology), adjustable biopsy port seal (Gyrus ACMI), Blue Silicone Seal ACMI CS B612 (Gyrus ACMI), and REF ABP Biopsy Port Seal (ACMI Corporation) was performed. Usability was evaluated via insertion/extraction forces and insertion time for instruments, including a straight tip sensor wire, 0.035″, (Boston Scientific), a laser fiber (Flexiva 200, Boston Scientific), and an Ngage Nitinol Stone Extractor 1.7F (Cook Urological) through a flexible ureteroscope (Olympus URF P5, Olympus). Flow rate, flow time, and user fatigue were tested for two irrigation systems: The single action pumping system (SAP, Boston Scientific) and the Pathfinder Plus (PP, Utah Medical Products).

Results: The US needed the shortest time for both wire insertion and basket insertion (P=0.005, and P<0.001, respectively), while the BSS needed the greatest time for laser fiber insertion (P<0.005). The REF ABP needed the greatest force for withdrawal of the Ngage basket, the laser fiber, and the Captura stone grasper through a closed seal, while the US took the least amount of force for both laser fiber withdrawal and insertion via analysis of variance. Leak point pressure assessment demonstrated that the US was leak free at irrigation pressures up to 200 mm Hg, while the ABP, BSS, and the REF ABP devices demonstrated leaks ranging from 30 to 200 mm Hg. The average and peak flow of the SAP were significantly higher than that of the PP. Mean grip strength decreased significantly after operation of the SAP for 10 minutes, while no loss of grip strength was observed after use of the PP.

Conclusions: The US valve has the advantage of facile manipulation of wires and baskets while maintaining a watertight seal, while other devices may be more cost-effective and secure. The PP has the advantage of less operator hand fatigue and ease of use, but the SAPS may allow for greater on-demand pressures. Further studies are needed to evaluate the effect of these irrigation systems on outcomes.