Impact of irrigation systems on stone migration

Purpose: To evaluate forces exerted on a stone with different ureteroscopic irrigation systems that could impact stone migration during ureteroscopy. Materials and Methods: A 3-mm steel simulated stone was welded to a 3F stone basket. The basket wire was then backloaded into the working channel of a 4.5F Wolf semirigid ureteroscope. The basket shaft was attached to a 50 g load cell. The ureteroscope was placed in a ureteral model (14F silicon tubing). Simulated blood was dripped adjacent to the stone at 12 drops/min. Endo-irrigation devices were attached to the ureteroscope, and irrigation was applied at a rate sufficient to maintain visualization of the stone. Force on the stone was measured with the following endo-irrigation systems: Gravity (183 cm H2O); pressurized irrigation (150 mm Hg, 300 mm Hg); Kosin Technology Universal Piggyback Irrigation System (UPIS) at gravity (183 cm H2O),150 mm Hg and 300 mm Hg; EMS Medical Peditrol Foot Pump; Cook Ureteroscopy Irrigation System; ACMI Irri-Flo Irrigation Delivery System; and Boston Scientific Single-Action-Pump System (SAPS). Results: SAP required the least number of pumps (0.35/sec) to maintain a clear endoscopic field while the Peditrol device required the most (1.88/sec). Pulse duration was longest for the ACMI (1.6 see) and shortest for pressurized gravity and UPIS (<0.3 see). The average total maximum impulse during a pump was significantly greater with the Cook (0.017 Ns) and ACMI (0.027 Ns) systems. On average, gravity-based systems applied the least amount of force, <= 0.0006 Ns, maximum impulse at any given time. Conclusions: Gravity-based systems exert less force than hand-held and foot-pump devices. Of the hand-held devices, the SAP exerted the least average maximum impulse on the stone.