Use of Targeted Temperature Management after Out-of-hospital Cardiac Arrest: A Meta-Analysis of Randomized Controlled Trials

Background Individual randomized trials have yielded variable results regarding the benefits of targeted temperature management in patients encountering out-of-hospital cardiac arrest. This study aimed to systemically determine if targeted temperature management initiated after an out-of-hospital cardiac arrest was associated with improved outcomes. Methods Electronic databases were searched for published randomized trials that compared targeted temperature management (core body temperature 32-34°C) vs control (core body temperature ≥36°C) after an out-of-hospital cardiac arrest. The main outcomes assessed were all-cause mortality and poor neurological outcome. Results Six trials with 1391 patients were included in the analysis. Compared with the control group, targeted temperature management was associated with a nonsignificant reduction in all-cause mortality (relative risk [RR] 0.90; 95% confidence interval [CI], 0.77-1.04; P =.15, I² = 34%), which was similar among those with a shockable rhythm (RR 0.89; 95% CI, 0.74-1.08, P =.25, I² = 46%). All-cause mortality was significantly reduced with targeted temperature management after exclusion of one trial that allowed for mild hypothermia in the control arm (RR 0.83; 95% CI, 0.71-0.96; P =.01, I² = 0%). There was a nonsignificant reduction in poor neurological outcome with targeted temperature management compared with control (RR 0.87; 95% CI, 0.74-1.03, P =.10, I² = 54%), which was similar among those with a shockable rhythm (RR 0.87; 95% CI, 0.70-1.07, P =.19, I² = 63%). Poor neurological outcome was significantly reduced with targeted temperature management after exclusion of one trial that allowed for mild hypothermia in the control arm (RR 0.82; 95% CI, 0.70-0.95; P =.01, I² = 19%). Conclusion Targeted temperature management initiated after successful resuscitation in patients who encountered an out-of-hospital cardiac arrest was associated with a nonsignificant reduction in mortality and poor neurological outcome. Lack of benefit was strongly influenced by inclusion of one study that used mild hypothermia in the control arm. These results indicate that only mild hypothermia may be needed to improve outcomes among patients presenting with an out-of-hospital cardiac arrest.