The efficacy and safety of prehospital therapeutic hypothermia in patients with out-of-hospital cardiac arrest: A systematic review and meta-analysis

Abstract Background The benefit of therapeutic hypothermia (TH) to patients suffering out-of-hospital cardiac arrest (OHCA) has been well established. However, the effect of prehospital cooling remains unclear. We aimed to investigate the efficacy and safety of prehospital TH for OHCA patients by conducting a systematic review of randomised controlled trials (RCTs). Methods The MEDLINE, EMbase and CENTRAL databases were searched for publications from inception to April 2015. RCTs that compared cooling with no cooling in a prehospital setting among adults with OHCA were eligible for inclusion. Random- and fixed-effect models were used depending on inter-study heterogeneity. Results Eight trials that recruited 2379 participants met the inclusion criteria. Prehospital TH was significantly associated with a lower temperature at admission (mean difference (MD) −0.94; 95% confidence interval (CI) −1.06 to −0.82). However, survival upon admission (Risk ratio (RR) 1.01, 95%CI 0.98–1.04), survival at discharge (RR 1.02, 95%CI 0.91–1.14), in-hospital survival (RR 1.05, 95%CI 0.92–1.19) and good neurological function recovery (RR 1.06, 95% CI 0.91–1.23) did not differ between the TH-treated and non-treated groups. Prehospital cooling increased the incidence of recurrent arrest (RR 1.23, 95%CI 1.02–1.48) and decreased the PH at admission (MD −0.04, 95%CI −0.07 to −0.02). Pulmonary oedema did not differ between the arms (RR 1.02, 95%CI 0.67–1.57). None of the potentially controversial issues (cooling methods, time of inducing TH, the proportion of continuing cooling in hospital, actual prehospital infusion volume and primary cardiac rhythms) affected the efficacy. Conclusion Evidence does not support the administration of prehospital TH to patients with OHCA.