Effect of therapeutic hypothermia on survival and neurological outcome in adults suffering cardiac arrest: a systematic review and meta-analysis.

INTRODUCTION: The aim of this review was to determine current evidence for the effect of therapeutic hypothermia (TH) on survival and neurological outcome in adults suffering cardiac arrest (CA).

EVIDENCE AQUISITION: We searched the Cochrane Controlled Trials Register, MEDLINE, EMBASE and NLM databases from 2000 to 2017 using the following terms: hypothermia, cooling, therapeutic, cardiac arrest, resuscitation, cardiopulmonary, CPR. Studies were eligible if they compared TH versus normothermic management in adult humans sustaining CA. Randomized controlled trials (RCT), pilot studies and observational trials were included.

EVIDENCE SYNTHESIS: Ten studies involving 3259 patients were included in meta-analysis. Pooling all eligible studies showed a favorable effect for TH on survival and neurological recovery. However, sensitivity analysis for RCTs showed no benefit on either outcome, while observational trials showed benefit for neurological recovery with just marginally significant benefit regarding survival. Studies including patients with shockable rhythms demonstrated benefit for both outcome measures, while those including patients with any rhythms demonstrated benefit for neurological recovery but not for survival. TH did not benefit patients with non-shockable rhythms. Trials using external cooling favored TH regarding survival and neurological outcome but those using systemic cooling with or without external cooling did not show such benefit. When the overall incidence of complications was pooled, there was a statistically significant shift in odds ratio favoring normothermic management over TH.

CONCLUSIONS: Evidence from RCTs suggests TH does not improve survival or neurological outcome, while observational trials favor TH over normothermia. TH may be attended with higher risk for complications.