Cluster Randomized Trial of Duration of Cooling in Targeted Temperature Management After Resuscitation for Cardiac Arrest

Background: The 2020 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care recommend that comatose patients with return of spontaneous circulation after cardiac arrest have targeted temperature management (TTM). However, the duration of TTM remains to be elucidated. Methods and Results: We conducted a cluster randomized trial in 10 hospitals to compare 12–24 vs. 36 h of cooling in patients with cardiac arrest who received TTM. The primary outcome was the incidence, within 1 month, of complications including bleeding requiring transfusion, infection, arrhythmias, decreasing blood pressure, shivering, convulsions, and major adverse cardiovascular events. Secondary outcomes were mortality and favorable neurological outcome (Cerebral Performance Categories 1–2) at 3 months. Random-effects models with clustered effects were used to calculate risk ratios (RR). Data of 185 patients were analyzed (12- to 24-h group, n=100 in 5 hospitals; 36-h group, n=85 in 5 hospitals). The incidence of complications within 1 month did not differ between the 2 groups (40% vs. 34%; RR 1.04, 95% confidence interval [CI] 0.67–1.61, P=0.860). Favorable neurological outcomes at 3 months were comparable between the 2 groups (64% vs. 62%; RR 0.91, 95% CI 0.72–1.14, P=0.387). Conclusions: TTM at 34℃ for 12–24 h did not significantly reduce the incidence of complications. This study did not show superiority of TTM at 34℃ for 12–24 h for neurologic outcomes.