Hypothermia versus normothermia after out-of-hospital cardiac arrest: A systematic review and meta-analysis of randomized controlled trials

Dhan Bahadur Shrestha; Yub Raj Sedhai; Pravash Budhathoki; Suman Gaire; Anurag Adhikari; Ayusha Poudel; Barun Babu Aryal; Wasey Ali Yadullahi Mir; Khagendra Dahal; Markos G Kashiouris

doi:10.1016/j.amsu.2022.103327

Hypothermia versus normothermia after out-of-hospital cardiac arrest: A systematic review and meta-analysis of randomized controlled trials

Ann Med Surg (Lond). 2022 Jan 29:74:103327. doi: 10.1016/j.amsu.2022.103327. eCollection 2022 Feb.

Affiliations

¹ Department of Internal Medicine, Mount Sinai Hospital, Chicago, IL, USA.
² Department of Internal Medicine, Division of Hospital Medicine, Virginia Commonwealth University, School of Medicine, Richmond, VA, USA.
³ Department of Internal Medicine, Bronxcare Health System, Bronx, NY, USA.
⁴ Department of Emergency Medicine, Palpa Hospital, Palpa, Nepal.
⁵ Department of Emergency Medicine, Nepal National Hospital, Kathmandu, Nepal.
⁶ Department of Emergency Medicine, Alka Hospital, Kathmandu, Nepal.
⁷ Nepalese Army Institute of Health Sciences, Kathmandu, Nepal.
⁸ Department of Internal Medicine, Division of Cardiology, Creighton University School of Medicine, Omaha, NE, USA.
⁹ Department of Internal Medicine, Division of Pulmonary Disease and Critical Care Medicine, VCU School of Medicine, Richmond, VA, USA.

Abstract

Background: The current guidelines recommend targeted temperature management (TTM) as part of the post-resuscitation care for comatose patients following out-of-hospital cardiac arrest. These recommendations are based on the weak evidence of benefit seen in the early clinical trials. Recent large multicentered trials have failed to show a meaningful clinical benefit of hypothermia, unlike the earlier studies. Thus, to fully appraise the available data, we sought to perform this systematic review and meta-analysis of randomized controlled trials.

Methods: We searched four databases for randomized controlled trials comparing therapeutic hypothermia (32-34 °C) with normothermia (≥36 °C with control of fever) in adult patients resuscitated after out-of-hospital cardiac arrest. Independent reviewers did the title and abstract screening, full-text screening, and extraction. The primary outcome was mortality six months after cardiac arrest, and secondary outcomes were neurological outcomes and adverse effects.

Relevance for patients: Six randomized controlled trials were included in this review. There was no significant difference between the hypothermia and normothermia groups in mortality till 6 months follow up after out-of-hospital cardiac arrest (OR 0.88, 95% CI 0.67-1.16; n = 3243; I² = 51%), or favorable neurological outcome (OR 1.31, 95% CI 0.93-1.84; n = 3091; I² = 68%). Rates of arrhythmias were notably higher in the hypothermia group than the normothermia group (OR 1.43, 95% CI 1.20-1.71; n = 3029; I² = 4%). However, odds for development of pneumonia showed no significant differences across two groups (OR 1.13, 95% CI 0.98-1.31; n = 3056; I² = 22%). Therefore, targeted hypothermia with a target temperature of 32-34 °C does not provide mortality benefit or better neurological outcome in patients resuscitated after the out-of-hospital cardiac arrest when compared with normothermia.

Keywords: AHA, American Heart Association; CI, Confidence interval; ESC, European resuscitation council; IHCA, In-hospital cardiac arrest; Induced Hypothermia; OHCA, Out-of-hospital cardiac arrest; OR, Odds ratio; Out-of-hospital cardiac arrest; PRISMA, Preferred Reporting Items for Systematic Review and Meta-Analysis; RCTs, Randomized controlled trials; ROSC, Return of spontaneous circulation; TH, Therapeutic hypothermia; TTM, Targeted temperature management; Temperature.

Publication types

Review