Predictors of difficult endotracheal intubation in the emergency department: a single-center pilot study

Background: Identifying patients who are at risk of difficult endotracheal intubation is crucial in the emergency department. Therefore, this study evaluated the incidence and predictive factors of difficult tracheal intubation in the emergency department.

Methods: This was a 17-month prospective observational study. A difficult airway was defined as Cormack & Lehane classification grades III and IV at the first attempt of intubation. Patients who visited the emergency department, underwent traditional endotracheal intubation from participating physicians, and provided informed consent by themselves or via their delegates were enrolled in this study. Univariate associations between patient characteristics and difficult endotracheal intubation were identified, and statistically significant factors were included in a multivariate binary logistic regression model. A generalized association plot was used to show the relationships between variables.

Results: A total of 110 patients were enrolled in the study. The incidence of difficult intubation was 35.5% (39/110). In the difficult airway group, significantly higher body mass index (BMI), and incidence of double chin, thick short neck, Mallampati difficulty, small interincisor distance, small thyromental distance, and upper airway obstruction were noted on univariate analysis. A predictive formula for difficult tracheal intubation was successfully established by the combination of four independent predictors: BMI (odds ratio [OR] = 1.270), thyromental distance (OR = 0.614), upper airway obstruction (OR = 4.038), and Mallampati difficulty (OR = 5.163). A cutoff score of four maximized Youden’s index, providing sensitivity (79.5%) and specificity (81.7%) (95% CI: 0.794 to 0.938).

Conclusions: We used four predictors of difficult tracheal intubation, namely, BMI, thyromental distance, upper airway obstruction, and Mallampati difficulty, to create a predictive formula. This formula could help emergency physicians to quickly identify and carefully manage patients with difficult endotracheal intubation and consult experts early if necessary.

Difficult endotracheal intubation; Body mass index; Thyromental distance; Upper airway obstruction; Mallampati score

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