Therapeutic hypothermia does not improve arrest outcome

November 18, 2013 by  
Filed under Acute Med, All Updates, EMS, Guidelines, ICU, Resus

A paper published today represents to me what’s great about science.

I am impressed with those investigators who had the wherewithall to subject previous therapeutic hypothermia studies to skeptical scrutiny and then design and conduct a robust multicentre trial to answer the question.

One of the criticisms of the original two studies was that those patients who were not actively cooled did not have their temperature tightly controlled, and therefore some were allowed to become hypERthermic, which is bad for brains.

This latest study showed no difference in survival or neurological outcome after cardiac arrest between target temperatures of 33°C and 36°C.

So controlling the temperature after cardiac arrest is still important, but cooling down to the recommended range of 32-4°C is not.

Cool.

Read the full study at the NEJM site.

Targeted Temperature Management at 33°C versus 36°C after Cardiac Arrest

NEJM November 17, 2013 Full text


BACKGROUND Unconscious survivors of out-of-hospital cardiac arrest have a high risk of death or poor neurologic function. Therapeutic hypothermia is recommended by international guidelines, but the supporting evidence is limited, and the target temperature associated with the best outcome is unknown. Our objective was to compare two target temperatures, both intended to prevent fever.

METHODS In an international trial, we randomly assigned 950 unconscious adults after out-of-hospital cardiac arrest of presumed cardiac cause to targeted temperature management at either 33°C or 36°C. The primary outcome was all-cause mortality through the end of the trial. Secondary outcomes included a composite of poor neurologic function or death at 180 days, as evaluated with the Cerebral Performance Category (CPC) scale and the modified Rankin scale.

RESULTS In total, 939 patients were included in the primary analysis. At the end of the trial, 50% of the patients in the 33°C group (235 of 473 patients) had died, as compared with 48% of the patients in the 36°C group (225 of 466 patients) (hazard ratio with a temperature of 33°C, 1.06; 95% confidence interval [CI], 0.89 to 1.28; P=0.51). At the 180-day follow-up, 54% of the patients in the 33°C group had died or had poor neurologic function according to the CPC, as compared with 52% of patients in the 36°C group (risk ratio, 1.02; 95% CI, 0.88 to 1.16; P=0.78). In the analysis using the modified Rankin scale, the comparable rate was 52% in both groups (risk ratio, 1.01; 95% CI, 0.89 to 1.14; P=0.87). The results of analyses adjusted for known prognostic factors were similar.

CONCLUSIONS In unconscious survivors of out-of-hospital cardiac arrest of presumed cardiac cause, hypothermia at a targeted temperature of 33°C did not confer a benefit as compared with a targeted temperature of 36°C.

Comments

4 Responses to “Therapeutic hypothermia does not improve arrest outcome”

  1. Christopher on November 18th, 2013 13:58

    Now this is profoundly interesting.

  2. Christopher on November 18th, 2013 14:45

    And apparently Seattle/King County came to a similar conclusion for prehospital TH today as well!

    Conclusion and Relevance: Although use of prehospital cooling reduced core temperature by hospital arrival and reduced the time to reach a temperature of 34°C, it did not improve survival or neurological status among patients resuscitated from prehospital VF or those without VF.

    http://jama.jamanetwork.com/article.aspx?articleid=1778673

  3. Cliff on November 18th, 2013 14:46

    Thanks Christopher!

  4. Michael Busch on November 25th, 2013 07:54

    That therapeutic hypothermia does not improve outcome after OHCA – as you state- is false. The study by Nielsen and colleagues did not negate the therapeutic effect of TH, it just adjusted the target temperature!
    It might be the case that normothermia and fever prevention after OHCA are equally effective- but this needs to be tested in a RCT. Until then ….keep cool.