FLEXIBLE ENDOSCOPE DEFLECTABILITY - CHANGES USING A VARIETY OF WORKING INSTRUMENTS AND LASER FIBERS

To measure the effects of different working instruments and holmium la ser fibers on the deflectability in a variety of actively deflectable flexible endoscopes, a benchtop study was performed, The endoscopes st udied were the Storz 7.5 flexible ureteroscope, the AUR-7 and AUR-9 fl exible ureteroscopes (Circon-ACMI), a prototype Mitsubishi flexible ur eteroscope (Mitsubishi Optics, Inc.), the ACN flexible cystoscope (Cir con-ACMI), and the Storz flexible cystoscope, Working instruments incl uded 1.6F (Wolf) and 1.9F (Microvasive) electrohydraulic lithotripsy ( EHL) probes, 1.9F two-prong graspers and Bagley baskets, 2.4F Segura a nd helical baskets (Microvasive), 3.0F Segura basket, and 200- and 365 -mu m holmium laser fibers (Xintec), In ureteroscopes, the effect of 1 .6F and 1.9F EHL probes ranged from having no effect in the Xintec 6,0 00, to decreasing deflection by 30 degrees in the AUR-7, Working instr uments that were 2.4F or greater reduced deflection from 33 degrees to 93 degrees, Better deflectability was noted with the 200-mu m holmium laser fiber than with the 365-mu m fiber, The diameter of the working instrument did not affect deflectability as severely in cystoscopes, No significant differences in deflection existed between the 365-mu m and 200-mu m fibers in the flexible nephroscopes tested, In general, w orking instruments less than 2.4F and the 200-mu m laser fiber have li ttle effect on deflectability compared with working instruments 2.4F o r larger and the 365-mu m fiber, Flexible cystoscopes, with their larg er working channels and stronger deflection cables, are affected less by working instrument diameter than are flexible ureteroscopes.