The incidence of difficult airways in an Australian adult tertiary–quaternary hospital: a retrospective observational study of 5,293 episodes of anesthesia

PURPOSE: In this study, we aimed to evaluate the incidence and anticipation rate of difficult airways in adult nonobstetric patients undergoing general anesthesia at a single tertiary-quaternary Australian hospital, and to review the predictors of difficult airways and the impact of videolaryngoscopy (VL) on glottic visualization in unanticipated difficult airway cases. METHODS: We conducted a retrospective observational study over a 6-month period. We included 5,293 adult patients who underwent general anesthesia with airway instrumentation. Data was extracted from anesthetic records. Difficult airways were defined according to the Canadian Airway Focus Group criteria. Cases of difficult airways were classified as anticipated or unanticipated on the basis of preoperative airway assessments. RESULTS: Of 5,293 patients, 207 (4%) had a difficult airway, with 71% (146/207) deemed unanticipated. The incidence of unanticipated difficult airways was 3% (146/5,293). Significant predictors of difficult airways included reduced thyromental distance, restricted neck extension, and high Mallampati scores (P < 0.05 for all). Videolaryngoscopy was more commonly used in anticipated difficult airways (odds ratio [OR], 3.8; 95% confidence interval [CI], 2.0 to 7.0) and significantly reduced the incidence of Cormack-Lehane grade 3 and 4 glottic views compared with direct laryngoscopy (OR, 0.3; 95% CI, 0.2 to 0.6). CONCLUSIONS: The incidence of difficult airways in this contemporary cohort was low and aligned with published estimates. As most difficult airways were unanticipated, routine VL use is supported to optimize glottic visualization and enhance the management of unexpected airway difficulty.