title: A dual-channel flexible ureteroscope: evaluation of deflection, flow, illumination, and optics.
abstract: OBJECTIVE
  Despite the evolution and progressive improvements of ureteroscopes, problems related to visibility and maneuverability can still hinder the goals of surgical intervention. We evaluate the attributes of a dual-channel flexible ureteroscope compared with a single-channel device and discuss the implications for expanded techniques afforded by this new technology.
  
  
  METHODS
  In vitro measurements of active deflection, irrigant flow through the working channel, luminescence, and optical resolution were performed between the single-channel Wolf Viper and the dual-channel Wolf Cobra ureteroscopes. Characteristics were obtained with the working channels both empty and with combinations of a 200 μ holmium aser fiber, 3.0F biopsy forceps, and 1.5F, 2.4F, and 2.8F nitinol basket. Luminescence from each scope was measured using a commercial luminometer. Three blinded physicians rated the optical resolution captured electronically using a standard test image.
  
  
  RESULTS
  The single-channel scope has improved upward deflection both empty and with all but the largest single tools, with an improved range of 4 to 15 degrees. The dual-channel scope has superior downward deflection across all comparisons (average increase of 24.5 degrees) and superior upward deflection with large or multiple instruments in the working channel. Baseline flows through each individual-channel of the dual-channel scope were slower than the larger single-channel ureteroscope. Because flow can be provided through a dedicated port in the dual-channel configuration, however, overall flow, depending on instrumentation, can be up to 37 times faster than the single-channel (range 1.5-37×). Optical resolution and luminescence are comparable between the two scopes.
  
  
  CONCLUSIONS
  The dual-channel flexible ureteroscope provides similar deflection characteristics to the current single-channel scope. Deflection and flow characteristics are superior, however, when larger or multiple simultaneous instruments are used in the working channel. These benefits may facilitate the development and implementation of novel endoscopic procedures.
authors.affiliation: Department of Urologic Surgery, University of Minnesota, Minneapolis, Minnesota, USA.
authors.forename: Ken
authors.initials: K
authors.lastname: Haberman
authors.forename: Omar
authors.initials: O
authors.lastname: Ortiz-Alvarado
authors.forename: Ekkarin
authors.initials: E
authors.lastname: Chotikawanich
authors.forename: Manoj
authors.initials: M
authors.lastname: Monga
mesh_terms: D049449:Luminescence; D018583:Pliability; D012212:Rheology; D020709:Ureteroscopes