We evaluate the time to awakening after out-of-hospital cardiac arrest in patients treated with targeted temperature management and determine whether there was an association with any patient or event characteristics.

This was a prospective, observational cohort study of consecutive adult survivors of out-of-hospital cardiac arrest of presumed cardiac cause who were treated with targeted temperature management between January 1, 2008, and March 31, 2014. Data were obtained from hospitals and emergency medical services agencies responding to approximately 90% of Arizona’s population as part of a state-sponsored out-of-hospital cardiac arrest quality improvement initiative.

Among 573 out-of-hospital cardiac arrest patients who completed targeted temperature management, 316 became responsive, 60 (19.0%) of whom woke up at least 48 hours after rewarming. Eight patients (2.5%) became responsive more than 7 days after rewarming, 6 of whom were discharged with a good Cerebral Performance Category score (1 or 2). There were no differences in standard Utstein variables between the early and late awakeners. The early awakeners were more likely to be discharged with a good Cerebral Performance Category score (odds ratio 2.93; 95% confidence interval 1.09 to 7.93).

We found that a substantial proportion of adult out-of-hospital cardiac arrest survivors treated with targeted temperature management became responsive greater than 48 hours after rewarming, with a resultant good neurologic outcome.