Moderate hypothermia not superior to mild hypothermia following out-of-hospital cardiac arrest

Among patients who had experienced an out-of-hospital cardiac arrest (OHCA), inducing moderate therapeutic hypothermia (cooling to 31°C) did not result in better neurological or mortality outcomes than inducing mild hypothermia (cooling to 34°C) in the CAPITAL CHILL trial [1].

While current guidelines for the management of patients who have experienced OHCA recommend targeted temperature management, it remains unclear what the optimal target temperature should be to achieve the most favourable outcomes. A pilot study of 36 patients suggested that better outcomes may be achieved by inducing hypothermia below the guideline-prescribed range of 32–34°C [2]. The CAPITAL-CHILL trial (NCT02011568), presented by Dr Michel Le May (University of Ottawa, ON, Canada), was the first randomised controlled trial to explore outcomes achieved by cooling OHCA patients to 31°C.

CAPITAL-CHILL was a prospective, single-centre, randomised, double-blinded clinical trial that randomised 367 comatose survivors of OHCA to be cooled using an endovascular cooling device to a temperature of either 34° (n=183) or 31° (n=184) for 24 hours following OHCA. The primary outcome measure was the number of patients who experienced either a poor neurological outcome (as judged by a rehabilitation medicine specialist) or death at 6 months. The Disability Rating Scale (DRS) was used to rate the neurological outcome.

At 6 months, the primary outcome was met by 48.4% of the participants in the moderate hypothermic group and 45.4% of the participants in the mild hypothermic group (relative risk [RR] 1.07; 95% CI 0.86–1.33; P=0.56). In the mild hypothermic group, 41.0% of the patients died compared with 43.5% of the patients in the moderate hypothermic group (RR 1.06; 95% CI 0.83–1.35; P=0.63).

The researchers concluded that their findings do not support changing current guidelines regarding post-OHCA therapeutic hypothermia.

1. 
   
   1. Le May M. Therapeutic Hypothermia Following Out-Of-Hospital Cardiac Arrest: A Randomised Trial Comparing Mild and Moderate Therapeutic Hypothermia (CAPITAL-CHILL Trial). Abstract 411-08, ACC 2021 Scientific Session, 15–17 May.
   2. Lopes-de-Sa E, et al. Circulation 2012;126(24):2826–2833.

 

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Posted on 9 July, 202129 July, 2021