MP38-04 IMPACTED STONE MODEL USED TO COMPARE HYDROPHILIC GUIDEWIRE EFFICACY

Abstract

INTRODUCTION AND OBJECTIVES: Guide wire passage beyond impacted stones is the first step of either stone treatment or decompression of infected obstructed systems. The optimal guidewire for use with impacted ureteral stones has not been previously determined. The purpose of this study was to develop an in-vitro impacted ureteral stone model and to use this model to compare efficacy between several commercially available guide wires. METHOD(S): An in-vitro impacted ureteral stone model was constructed to simulate actual ureteral diameter, length, and angulation. Next, a calcium oxalate monohydrate stone was placed into the ureter and impacted to resist passage of fluid at 300 mm Hg. A ureteral catheter was positioned 2 cm below the impacted stone. In a randomized single blinded fashion, five attending urologists tested the model using 0.038 inch versions of the angle-tipped ZIPwire (Boston Scientific), angle-tipped Glidewire (Terumo), angle-tipped Hiwire (Cook), straight-tipped Roadrunner hydrophilic PC (Cook), and the straight-tipped Standard Teflon coated wire (Cook). In addition, in a separate benchtop trial the force required to pass the impacted stone was measured. Outcomes included time for wire passage (sec), number of attempts, force required for wire passage and attending blinded subjective preference ratings. An Independent-Samples Kruskal-Wallis test was used for statistical analysis, with p<0.05 considered significant. RESULT(S): The mean pound force (lbf) for wire passage (with comparison to Glidewire) was; Glidewire =0.025, ZIPwire (0.036; p=0.08), Hiwire (0.2; p=0.01), Standard wire (0.6; p<0.01), and the Roadrunner did not pass. Pairwise comparisons showed significant differences between the ZIPwire and Hiwire (p=0.01), and ZIPwire vs. standard wire (p <0.01), standard Teflon coated guidewire (23.3 sec; p=<0.01) and the Roadrunner did not pass. The mean number of attempts to pass each wire was Glidewire (1.9), ZIPwire (2.5), Hiwire (3.5), Standard teflon coated (4.1), and the Roadrunner did not pass (trend not significant). The attending staff reported the order of preference for wires as Glidewire, ZIPwire, Hiwire, Standard Teflon coated wire, and the Roadrunner in this impacted stone model. CONCLUSION(S): The guidewire employed may have a significant effect upon the ease of passage beyond a tightly impacted ureteral stone. This may have significant implications upon operative time, surgical ease, and safety.