Survival, neurological and safety outcomes after out of hospital cardiac arrests treated by using prehospital therapeutic hypothermia: A systematic review and meta-analysis

Abstract

Survival after pre-hospital cardiac arrest (PHCA) remains low. Pre-hospital therapeutic hypothermia (PTH) is believed to improve patient's outcomes, but data on efficacy and safety remains scarce. Herein, we aimed to assess the influence of PTH on survival, neurological outcome, and adverse effects in patients with PHCA. A literature search of PubMed CENTRAL, EMBASE, and The Cochrane Central Register of Controlled Trials databases from inception to August 2019 was conducted and retrieved abstracts were independently assessed by two reviewers. The primary outcome was survival to hospital discharge with a favorable neurological outcome. Secondary outcomes were survival to hospital discharge and temperature upon hospital admission. The safety outcomes included pulmonary edema and recurrent arrest during transport to the hospital. We also considered a favorable neurological function to hospital discharge or longest post arrest follow-up. Eleven studies including 4891 patients were included into final analysis. The survival to hospital discharge did not differ between PTH and control group (RR 1.02; 95%CI 0.93 to 1.12). Among 4891 participants (2466 in PTH group and 2425 in control group), 1087 participants (564 vs. 523, respectively) had a favorable neurological outcome. Pulmonary edema occurred in 320 cases in PTH group and 273 in control group with significant heterogeneity (RR 0.90, 95%CI 0.59–1.38; I2 = 80%). The pooled results showed a significant difference in rearrests between the PTH and control group (RR 1.19; 95%CI 1.00 to 1.42). Our analysis demonstrates that PTH does not improve survival at discharge or neurological outcome.