Prehospital Advanced Cardiac Life Support for Out-of-hospital Cardiac Arrest: A Cohort Study.

Objectives: Out-of-hospital advanced cardiac life support (ACLS) has not consistently shown a positive impact on survival. Extracorporeal cardiopulmonary resuscitation (E-CPR) could render prolonged on-site resuscitation (ACLS or basic cardiac life support [BCLS]) undesirable in selected cases. The objectives of this study were to evaluate, in patients suffering from out-of-hospital cardiac arrest (OHCA) and in a subgroup of potential E-CPR candidates, the association between the addition of prehospital ACLS to BCLS and survival to hospital discharge, prehospital return of spontaneous circulation (ROSC), and delay from call to hospital arrival.

Methods: This cohort study targets adult patients treated for OHCA between April 2010 and December 2015 in the city of Montreal, Canada. We defined potential E-CPR candidates using clinical criteria previously described in the literature (65 years of age or younger, initial shockable rhythm, absence of ROSC after 15 minutes of prehospital resuscitation, and emergency medical services-witnessed collapse or witnessed collapse with bystander cardiopulmonary resuscitation). Associations were evaluated using multivariate regression models.

Results: A total of 7,134 patients with OHCA were included, 761 (10.7%) of whom survived to discharge. No independent association between survival to hospital discharge and the addition of prehospital ACLS to BCLS was found in either the entire cohort (adjusted odds ratio [AOR] = 1.05 [95% confidence interval {CI} = 0.84-1.32], p = 0.68) or among the 246 potential E-CPR candidates (AOR = 0.82 [95% CI = 0.36-1.84], p = 0.63). The addition of prehospital ACLS to BCLS was associated with a significant increase in the rate of prehospital ROSC in all patients experiencing OHCA (AOR = 3.92 [95% CI = 3.38-4.55], p < 0.001) and in potential E-CPR candidates (AOR = 3.48 [95% CI = 1. 76-6.88], p < 0.001) compared to isolated prehospital BCLS. Delay from call to hospital arrival was longer in the ACLS group than in the BCLS group (difference = 16 minutes [95% CI = 15-16 minutes], p < 0.001).

Conclusions: In a tiered-response urban emergency medical service setting, prehospital ACLS is not associated with an improvement in survival to hospital discharge in patients suffering from OHCA and in potential E-CPR candidates, but with an improvement in prehospital ROSC and with longer delay to hospital arrival.