title: A comparison of tracheal tube tip designs on the passage of an endotracheal tube during oral fiberoptic intubation.
abstract: BACKGROUND
  The design of an endotracheal tube has been shown to influence the passage of the tube through the glottis during fiberoptic intubation. Difficulty in passing the endotracheal tube can occur if the aryepiglottic folds obstruct the passage of the bevel. The relevant aspects of endotracheal tube design include the shape of the bevel, the material used by the manufacturer, and the ability of the tube to conform to the shape of the fiberscope. The aim of the current study was to compare the ease of passage through the glottis of two different tubes. One tube was a wire reinforced polyvinyl chloride tube with a standard bevel and the other was a newly designed tube with a bevel of different shape and made of silicone rubber. The new design is for use with the a commerical intubating laryngeal mask.
  
  
  METHODS
  The authors studied a population of 30 patients who received a standard anesthetic. In all cases, oral fiberoptic intubation was attempted. Anesthetic was administered to each patient using both tubes, and before the study the order of the tubes was randomized. The difficulty in passing the tube was assessed by a blinded observer and graded using a three-point scale (grade 1: no difficulty passing the tube; grade 2: obstruction to passing the tube relieved by withdrawal and a 90 degrees anticlockwise rotation; grade 3: obstruction necessitating more than one manipulation or external laryngeal manipulation).
  
  
  RESULTS
  In 27 patients, no difficulty was shown by use of the silicone-tipped tube. In only three patients was there difficulty that necessitated a 90 degrees anticlockwise twist. With the wire-reinforced tube, no difficulty was experienced on 14 occasions. Grade 1 difficulty was experienced eight times and difficulty necessitating more than one maneuver, head movement, or external laryngeal manipulation was seen on eight occasions. Statistical significance was achieved at P = 0.0002 (Wilcoxon signed rank test).
  
  
  CONCLUSIONS
  The authors conclude that the use of the silicone-tipped tube with the new bevel design may provide an advantage in the clinical situation of fiberoptic intubation.
authors.affiliation: Department of Anaesthesia, Manchester Royal Infirmary, United Kingdom. jonessmith13@compuserve.com
authors.forename: J R
authors.initials: JR
authors.lastname: Greer
authors.forename: S P
authors.initials: SP
authors.lastname: Smith
authors.forename: T
authors.initials: T
authors.lastname: Strang
mesh_terms: D000328:Adult; D005336:Fiber Optic Technology; D006801:Humans; D007442:Intubation, Intratracheal / Q000295:instrumentation*; D012828:Silicones
chemical_list: D012828:Silicones