Systematic evaluation of a novel foot-pump ureteroscopic irrigation system

To evaluate forces exerted on a stone with different ureteroscopic irrigation systems.

A 3 mm steel simulated stone was welded to a 3F stone basket and inserted into the working channel of a 4.5F Wolf semirigid ureteroscope. The basket shaft was attached to a 50 g load cell. The urterescope was placed in a ureteral model (14F silicon tubing). Simulated blood (McCormick™ Red Dye, 1 dye drop/15 mL H(2)O) was dripped adjacent to the stone at 12 drops/min. Endoirrigation devices were attached to the ureterscope and irrigation was applied at a rate sufficient to maintain visualization of the stone. Force on the stone was measured with the following endoirrigation systems: Boston Scientific™ Single-Action-Pump System (SAP) hand-pump and NuVista Medical™ Flo-Assist(®) foot-pump.

No significant difference (p=0.19) in the number of pumps required to maintain a clear endoscopic field was found between the SAP (0.20±0.075/second) and Flo-Assist device (0.25±0.056/second). The pump duration of the Flo-Assist was found to be less (1.12±0.40 seconds) than the SAP (1.35±0.31 seconds), but not significantly different (p=0.24). The average maximum impulse was significantly lower (p=0.0002) for the SAP (8.34×10(-5) Ns) than the Flo-Assist (1.96×10(-3) Ns). Total maximum impulse (2.02×10(-5) Ns) for the SAP and total average impulse (5.51×10(-6) Ns) were found to be lower than the Flo-Assist device. The Flo-Assist had a total maximum impulse of 4.49×10(-4) Ns and total average impulse of 8.85×10(-6) Ns, however, these differences were not statistically significant.

The hand-pump (SAP) and foot-pump (Flo-Assist) irrigation devices tested require comparable amounts of pumps for similar durations of time to maintain endoscopic visualization. Overall, the SAP device exerts less average maximum force on the stone than the Flo-Assist device.