Therapeutic hypothermia post cardiac arrest: an evidence-based guideline

Introduction

Recent studies have shown that induced hypothermia improves neurologic outcome in comatose survivors of cardiac arrest (CA). Our goal was to develop, implement and evaluate an evidence-based guideline for the management of comatose survivors of cardiac arrest.

Methods

A systematic review of the literature was conducted to identify potentially relevant randomized clinical trials and observational studies reporting on a strategy of therapeutic hypothermia in comatose survivors of out-of-hospital CA. The research design and methodologic quality of all studies meeting our inclusion criteria were evaluated independently and in duplicate.

Results

Three randomized clinical trials (RCTs) and six observational studies were evaluated. Pooling the RCT data of good neurologic outcome showed an odds ratio of 2.06 (95% confidence interval 1.34–3.15; P = 0.001) favoring therapeutic hypothermia strategy. Two RCTs support the use of a hypothermia strategy for the management of patients with witnessed CA due to ventricular fibrillation while one small RCT supports its use in patients with pulseless electrical activity or asystole. Although most studies used external cooling measures to induce and maintain mild hypothermia (32–34°C), one study used a 30 ml/kg bolus of cold (4°C) crystalloid during the induction of hypothermia. Duration of cooling ranged from few hours to about 3 days. Cointerventions in the evaluated studies were anesthetic agents, hemodynamic support, mechanical ventilation, glucose management and treatment of acute coronary syndrome. The evaluated trials were used to develop a practice guideline. The guideline was implemented during a pilot study to assess its feasibility. During this pilot phase, 16 patients were treated. The patients' characteristics and their outcomes data were comparable with the results of the clinical trials.

Conclusion

An evidence-based guideline for the management of comatose survivors of cardiac arrest is helpful to disseminate the strategy of induced hypothermia into clinical practice.