Difficult airway predictors were associated with decreased use of neuromuscular blocking agents in emergency airway management: a retrospective cohort study in Thailand

Background It is recommended that difficult airway predictors be evaluated before emergency airway management. However, little is known about how patients with difficult airway predictors are managed in emergency departments. We aimed to explore the incidence, management and outcomes of patients with difficult airway predictors in an emergency department. Methods We conducted a retrospective study using intubation data collected by a prospective registry in an academic emergency department from November 2017 to October 2018. Records with complete assessment of difficult airway predictors were included. Two categories of predictors were analyzed: predicted difficult intubation by direct laryngoscopy and predicted difficult bag-mask ventilation. The former was evaluated based on difficult external appearance, mouth opening and thyromental distance, Mallampati score, obstruction, and limited neck mobility as in the mnemonic “LEMON”. The latter was evaluated based on difficult mask sealing, obstruction or obesity, absence of teeth, advanced age and reduced pulmonary compliance as in the mnemonic “MOANS”. The incidence, management and outcomes of patients with these difficult airway predictors were explored. Results During the study period, 220 records met the inclusion criteria. At least 1 difficult airway predictor was present in 183 (83.2%) patients; 57 (25.9%) patients had at least one LEMON feature, and 178 (80.9%) had at least one MOANS feature. Among patients with at least one difficult airway predictor, both sedation and neuromuscular blocking agents were used in 105 (57.4%) encounters, only sedation was used in 65 (35.5%) encounters, and no medication was administered in 13 (7.1%) encounters. First-pass success was accomplished in 136 (74.3%) of the patients. Compared with patients without predictors, patients with positive LEMON criteria were less likely to receive neuromuscular blocking agents (OR 0.46 (95% CI 0.24–0.87), p = 0.02) after adjusting for operator experience and device used. There were no significant differences between the two groups regarding glottic view, first-pass success, or complications. The LEMON criteria poorly predicted unsuccessful first pass and glottic view. Conclusions In emergency airway management, difficult airway predictors were associated with decreased use of neuromuscular blocking agents but were not associated with glottic view, first-pass success, or complications.