Understanding the Association Between Physiologically Difficult Airways and Right Mainstem Intubation in Children

Physiologically difficult airways describe patients undergoing tracheal intubation with physiologic derangements, putting them at higher risk for hemodynamic collapse during intubation. Prior studies have shown lower first pass intubation success rates in patients with physiologically difficult airways. Right mainstem intubation (RMSI) occurs in up to 16% of pediatric intubations, contributes to hypoxemia, and has the potential to worsen physiologic derangements. We evaluated the association between physiologically difficult airways and RMSI and assessed relevant adverse outcomes.

We performed a retrospective, video-based observational study of pediatric intubations in a pediatric emergency department. Our main exposure was the presence of a physiologically difficult airway defined by hypoxemia despite supplemental oxygen, persistent hypotension, severe primary metabolic acidosis, cardiac dysfunction, status asthmaticus, or patients that were post–return of spontaneous circulation. The primary outcome was RMSI. Secondary outcomes included changes in oxygen saturation, post-intubation hypotension, peri-intubation cardiac arrest, and mortality. We compared RMSI rates using generalized linear mixed models, controlling for proceduralist specialty/level of training, patient age, indication for intubation, and number of attempts. Pre- and post-intubation physiologic changes were analyzed using a difference-in-differences (DID) approach. Inverse probability of treatment weighting with regression modeling assessed associations between RMSI, cardiac arrest, and mortality.

Of 467 intubations, 127 patients (27.3%) met criteria for a physiologically difficult airway. RMSI occurred in 66 patients (14%) overall, including 27 patients with physiologically difficult airways (21%). Physiologically difficult airways were associated with higher odds of RMSI (OR 2.48, 95% CI 1.45–4.24). Younger age also increased RMSI risk (OR 0.95, 95% CI 0.91–0.99). Patients with physiologically difficult airways and RMSI experienced significantly greater post-intubation hypoxemia (DID estimate = −7.7%, p=0.01).

The presence of a physiologically difficult airway, along with younger age, was associated with increased risk of RMSI. These findings highlight the need for targeted airway strategies in this patient population.