Airway Scope Laryngoscopy Under Manual Inline Stabilization and Cervical Collar Immobilization: A Crossover In Vivo Cinefluoroscopic Study

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 ± SEMIS, 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). DISCUSSION: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