Concerning therapeutic hypothermia (targeted temperature management, TTM) post-cardiac arrest, the landmark TTM2 trial (2021) changed practice by showing:
- A There was no significant difference in mortality or neurological outcome between TTM at 33°C and normothermia (< 37.8°C) in comatose survivors of out-of-hospital cardiac arrest ✓
- B Cooling to 33°C significantly improved survival compared to 37°C (normothermia)
- C TTM at 36°C was superior to 33°C for all patients
- D Cooling to 33°C was harmful and significantly increased mortality
Correct answer: A. There was no significant difference in mortality or neurological outcome between TTM at 33°C and normothermia (< 37.8°C) in comatose survivors of out-of-hospital cardiac arrest
Explanation
The TTM2 trial (939 patients, NEJM 2021) found no significant difference in all-cause mortality at 6 months between targeted hypothermia at 33°C and normothermia (actively preventing fever > 37.8°C) in unconscious survivors of out-of-hospital cardiac arrest. This contradicted earlier smaller trials (TTM1 at 33°C vs 36°C). Current AHA 2022 ACLS guidelines state that while cooling to 32–36°C may still be performed, active prevention of fever (normothermia protocol) is a reasonable alternative. Fever (>37.7°C) should always be actively prevented post-arrest.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
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Written and medically reviewed by the StethoPrep medical team.