CAPITAL CHILL RCT – Extreme Hypothermia in OHCA

December 3, 2021

Written by Clay Smith

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There was no benefit in 180-day mortality or neurological outcome in adults with out-of-hospital cardiac arrest (OHCA) when cooling to 31°C vs 34°C.

Why does this matter?
Therapeutic hypothermia is not better than normothermia, per the TTM trial. A range of temperatures, from 32-36°C, is acceptable according to the AHA and others. The authors note a pilot study and some animal studies that suggest the extreme hypothermia, 28-32°C may offer greater neuroprotection. Is this right?

How low can you go?
This was a single center RCT with 367 adults who were comatose after OHCA and were randomized to 31°C or 34°C. There was no difference in 180-day composite mortality and neurological outcome between the two temperatures; 48.4% at 31°C vs 45.4% at 34°C, RR 1.07 (95%CI, 0.86-1.33). No secondary outcomes were different, except ICU length of stay was longer in the 31°C group. There was no increase in adverse events in the cooler group. Take home: There is no benefit in going colder than 32°C.

Source
Effect of Moderate vs Mild Therapeutic Hypothermia on Mortality and Neurologic Outcomes in Comatose Survivors of Out-of-Hospital Cardiac Arrest: The CAPITAL CHILL Randomized Clinical Trial. JAMA. 2021 Oct 19;326(15):1494-1503. doi: 10.1001/jama.2021.15703.