title: Airway scope laryngoscopy under manual inline stabilization and cervical collar immobilization: a crossover in vivo cinefluoroscopic study.
abstract: BACKGROUND
  Direct laryngoscopy along with manual inline stabilization (MIS) is currently the standard care for patients with suspected neck injuries. However, cervical collar immobilization is more commonly performed in the prehospital environment, and its early removal is necessary before intubation. We hypothesized that if usability of Airway Scope (AWS) in a difficult airway could also bring merits to intubation under cervical collar immobilization, unnecessary risk caused by the removal of a neck collar may be prevented.
  
  
  METHODS
  In this crossover study, 30 consenting patients presenting for surgery were assigned to undergo intubation using AWS. Neck was stabilized manually and by a neck collar in a random order before laryngoscopy was performed by the same anesthesiologist. Measurements include interincisor distance (IID), success rate, intubation time, and fluoroscopic examination of the upper and middle cervical spine.
  
  
  RESULTS
  IID was notably narrower after application of a neck collar (mean ± SE: MIS, 19 mm ± 1 mm; collar, 10 mm ± 1 mm; p < 0.01). One and 9 failures were encountered in MIS and collar groups, respectively (p = 0.012). Intubation time proved no statistical significance. Extension of craniocervical junction was observed in both groups, but occipitoatlantal joint was significantly more extended in collar group (median [range]: AWS, 10-degree angle [-1 to 20-degree angle]; collar, 14-degree angle [5 to 26-degree angle]; p < 0.01).
  
  
  CONCLUSIONS
  AWS laryngoscopy under cervical collar immobilization fails to meet our expectation. Intubation failed in 30% of the cases in collar group whereas only 3.3% of the cases in MIS group. Significant difference of mouth opening limitation is probably the major reason, as 7 of 9 failed cases in collar group had IID <10 mm. This was insufficient to insert the 18-mm blade of AWS. In addition, occipitoatlantal joint suffered a greater extension when wearing a neck collar. Differences in the method to stabilize the neck may be the reason.
  
  
  CONCLUSIONS
  When compared with cervical collar immobilization, AWS laryngoscopy along with MIS seems to be a safer and more definite method to secure airway of neck-injured trauma patients because it limits less mouth opening and upper cervical spine movement.
authors.affiliation: Department of Anesthesiology and Critical Care Medicine, Yokohama City University School of Medicine, Yokohama, Kanagawa, Japan. yoshibird@hotmail.com
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Aoi
authors.forename: Gaku
authors.initials: G
authors.lastname: Inagawa
authors.forename: Kozo
authors.initials: K
authors.lastname: Hashimoto
authors.forename: Hideo
authors.initials: H
authors.lastname: Tashima
authors.forename: Sayaka
authors.initials: S
authors.lastname: Tsuboi
authors.forename: Takeshi
authors.initials: T
authors.lastname: Takahata
authors.forename: Kyota
authors.initials: K
authors.lastname: Nakamura
authors.forename: Takahisa
authors.initials: T
authors.lastname: Goto
mesh_terms: D000328:Adult; D000368:Aged; D002574:Cervical Vertebrae / Q000000981:diagnostic imaging / Q000293:injuries*; D002933:Cineradiography / Q000379:methods*; D018592:Cross-Over Studies; D004867:Equipment Design; D005260:Female; D006801:Humans; D007103:Immobilization / Q000379:methods*; D007442:Intubation, Intratracheal / Q000295:instrumentation*; D020704:Laryngoscopes; D007828:Laryngoscopy / Q000379:methods*; D008297:Male; D008875:Middle Aged; D013124:Spinal Injuries / Q000175:diagnosis / Q000628:therapy*; D016896:Treatment Outcome