The association of prehospital advanced airway management time and outcome in out-of hospital cardiac arrest patients

Currently, there is limited evidence regarding the optimal duration of advanced airway management (AAM) with endotracheal intubation in out-of-hospital cardiac arrest (OHCA), particularly in the complex setting of prehospital on-scene management. The current study examined the association between the AAM time (≤ 2, 2–4, 4–6, and > 6 min) provided by the emergency medical service (EMS) team and patient outcomes. We attempted to replicate the chest compression assessment cycle, performing evaluations every 2 min. The primary outcome was survival to hospital discharge. The secondary outcome was sustained return of spontaneous circulation (ROSC) at the scene, defined as continuous ROSC for > 20 min. Data on all adult patients aged > 18 years who experienced non-traumatic out-of-hospital cardiac arrest (OHCA) and met the eligibility criteria were collected from EMS patient care reports. Data on survival to hospital discharge were obtained from the electronic medical records. The association between AAM time and survival to hospital discharge and sustained ROSC at the scene was examined via univariable and multivariable analyses. Approximately 50% of patients received AAM within ≤ 2 min, 16.05% within 2–4 min, 9.74% within 4–6 min, and 24.21% after > 6 min. Sustained ROSC at the scene occurred in 39.7% of patients. When classified by AAM time, sustained ROSC rates were 36.2%, 42.6%, 41.2%, and 44.3%, while survival to hospital discharge was 4.2%, 3.3%, 4.1%, and 8.7%, respectively. There was no significant difference in sustained ROSC by AAM time. Among patients with shockable rhythms, AAM at 4–6 and > 6 min was associated with 1.23-fold and 1.28-fold increased ROSC likelihood compared to ≤ 2 min; for non-shockable rhythms, the likelihoods were 1.11, 1.15, and 0.95, respectively. Regarding survival to discharge, shockable-rhythm patients receiving AAM at 4–6 and > 6 min had 1.3-fold and 1.86-fold increased likelihoods compared to 2–4 min. For non-shockable rhythms, AAM at 2–4, 4–6, and > 6 min was associated with 0.48, 1.89, and 3.44-fold likelihoods of survival, respectively, compared to ≤ 2 min. In this retrospective cohort, patients with non-shockable rhythms appeared to have higher survival among those who received AAM later (> 6 min); however, this pattern may largely reflect survivorship bias and residual confounding rather than any beneficial effect of delaying AAM. In contrast, earlier AAM did not show a clear survival advantage in patients with shockable rhythms. These associations should therefore not be interpreted as causal or as evidence that AAM timing is a modifiable determinant of outcomes. Instead, the findings are exploratory and hypothesis-generating, underscoring the need for prospective studies with appropriate adjustment for time-dependent confounding to clarify the true relationship between AAM timing and survival.