Assessing the Impact of Prehospital Intubation on Survival in Out-of-Hospital Cardiac Arrest

There is a developing body of literature documenting adverse survival outcome of out-of-hospital endotracheal intubation for critical multiple trauma and head injury patients. Objective. To compare the rates of survival to hospital admission and discharge of nontraumatic out-of-hospital cardiac arrest (OHCA) patients who received successful out-of-hospital endotracheal intubation and those who were not intubated. Methods. We conducted a retrospective analysis from an ongoing database of OHCA patients brought to a large suburban tertiary care emergency department by paramedic services between 1995 and 2006. We dichotomized patients by whether they were successfully endotracheally intubated or not prior to hospital arrival. Utstein style cardiac arrest variables were abstracted for all cases. All survivors to hospital admission were reviewed to exclude those patients in whom intubation was not attempted or unnecessary, such as those who had successful first-shock recovery of spontaneous circulation. We used chi square and logistic regression techniques for analysis, using survival to discharge as the primary outcome and survival to admission as a secondary outcome. Results. There were 1,515 total cases with 33 early survivors excluded. Overall, 1,220 (86.2%) were intubated; of those intubated, 270 (20.2%) survived to admission and 93 (7.0%) survived to discharge. Upon univariate analysis, there was no difference in survival between intubated and non intubated groups (6.5% vs 10.0%, OR = 0.63, 95% CI 0.37,1.08). For patients initially in ventricular fibrillation/ventricular tachycardia (VT/VF), in a multivariate Logit model, intubation significantly decreased survival to discharge, adjusted odds ratio (OR) = 0.52 (95% confidence interval 0.27, 0.998). Intubated non-VF patients were more likely to survive to admission, adjusted OR 2.96 (1.04, 8.43), but not to discharge (1.8% vs. 1.0%, p = 1.0). Conclusion. This observational study in an unselected population shows that patients in VF/VT arrest who underwent out-of-hospital intubation were less likely to survive to discharge than those not intubated. Out-of-hospital intubation of patients with non-VF arrest was associated with an increased rate of survival to admission, but not survival to discharge. Future prospective studies are needed to define the role of out-of-hospital endotracheal intubation in cardiac arrest patients.