• In adults that suffer an out-of-hospitals (OOH) cardiac arrest of presumed cardiac cause, does induced therapeutic hypothermia targeting 36°C compared to 33°C reduce mortality or reduce neurological deficit?

• Randomised, controlled clinical trial
• Single blinded

• 36 intensive care units
• Europe and Australia
• November 2010 and January 2013

• Inclusion: adult patients who were unconscious (GCS < 8) on admission to hospital after OOH cardiac arrest of presumed cardiac cause.
• Exclusion: > 6 hours from ROSC to enrolment screening, unwitnessed arrest with systole, hypothermia < 30°C, suspected or known intracranial haemorrhage.
• 950 patients enrolled

• 28 hours of temperature management with a target of 36°C using invasive or surface cooling, followed by gradual warming to 37°C at 0.5°C per hour and avoidance of pyrexia for 72 hours from randomisation.
  • 4 patients did not receive this intervention as assigned

• 28 hours of temperature management with a target of 33°C using invasive or surface cooling, followed by gradual warming to 37°C at 0.5°C per hour and avoidance of pyrexia for 72 hours from randomisation
  • 3 patients did not receive this control as assigned

• Primary outcome: There was no difference in all-cause mortality through to the end of the trial (mean follow-up period was 256 days).
  • 48% had died in the 36°C group and 50% had died in the 33°C group.
  • The hazard ratio for death was 1.06 for cooling to 33°C (CI 0.89 to 1.28; p=0.51)
• Secondary outcome: There were no differences between the groups regarding their neurological status (modified Rankin scale or Cerebral Performance Category).

• This trial does not provide evidence that targeting a body temperature of 33°C confers any benefit for unconscious patients admitted to the hospital after out-of-hospital cardiac arrest, as compared with targeting a body temperature of 36°C.

• Not generalisable to arrests with long or unknown ‘down-time’
  • Unwitnessed arrests with systole as initial rhythm were excluded
  • 90% had bystander witness; 73% had bystander CPR
  • Median time to basic life support was 1 minute!
  • Median time to advanced life support was 9 and 10 minutes
  • Median time to ROSC was 25 minutes
• Follow-up was relatively short-term; unclear if 36°C confers long-term neurological benefit or harm.
• Wide confidence intervals: with 95% certainty, true hazard ratio for 33°C could be anywhere between 0.89 (strong benefit) and 1.28 (strong harm).

The Bottom Line

Links

Full text pdf not available without subscription / abstract / doi: 10.1056/NEJMoa1310519

Editorial or Commentaries

Metadata

Summary author: @DuncanChambler
Summary date: 1 May 2014
Peer-review editor: @stevemathieu75 (DOI: at local institution we have opted for 36°C)