That whole hypothermia treatment for cardiac arrests? Not so fast…

Despite the best claims of tv shows, the actual survival rates of people in cardiac arrest is in the one percent rate. Or worse. There’s been lots of continuing research to try to improve the figures.
One new treatment that’s been getting a lot of hype, hope, and publicity is induced hypothermia, namely taking the patients and quickly cooling them down, in the hope that this will reduce brain damage and give the patient a better chance at recovery.
The New England Journal of Medicine just reported on a study that casts, err, cold water on this:
Conclusions
In unconscious survivors of out-of-hospital cardiac arrest of presumed cardiac cause, hypothermia at a targeted temperature of 33°? C[91.4 F] did not confer a benefit as compared with a targeted temperature of 36 C [96.8 F].

http://www.nejm.org/doi/full/10.1056/NEJMoa1310519

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5 responses to “That whole hypothermia treatment for cardiac arrests? Not so fast…

  1. In an area of uncertainty like brain damage after survival from cardiac arrest, post resuscitation care is plagued by sampling and methodology problems that cannot be overcome.

    It is true that cardiac arrest has a low rate of survival after all, but this study is of the small percentage of survivers. Then they were put in two arms to prevent the post cardiac arrest fever that causes more metabolic brain damage.

    If comparable patients could undergo controlled hypoxemic events and get hypothermia treatment, no doubt there would be some benefits because cooling tissues reduces metabolism and the generation of free radicals and such–THEORETICALLY.

    This debate on hypothermia would be better resolved in controlled animal studies than with humans and the varability and uncertainties of cardiac arrest.

  2. I think the hypothermia concept for treatment of cardiac arrest stems from the cold-water drowning observations. Since the mechanisms of cold-water drowning and sudden cardiac arrest are very different, it seems unlikely that one could reliably extend the concept. Worth a try, heaven knows — anything that may improve brain recovery after cardiac arrest, and that is not known to be seriously dangerous, is worth a crack. The opportunities for trying different modalities are very few and I would expect it would take years of observations and analysis before we knew if we had learned anything.
    Ethically, we’re not going to induce cardiac arrest and then use different modalities to study the outcomes, not in humans at least. Given the rare opportunities to try these for human benefit, I’d want some strong justification before I called for animal experimentation. The animals would have to be higher-order mammals for the results to be valid guides to therapy.

  3. The reported survival rate for out of hospital Cardiac arrest was 0.5% with and without any resuscitation. In 25 years of ER practice, I never successfully resuscitated anyone in full arrest. So, by that testimonial, ACLS and CPR, appeared to be “junk science”. The causes of cardiac arrest are diverse. The patients health stats were diverse. And animals don’t get fat or get heart disease like humans. This is a treatment I think will never be proven.

  4. There’s actually a double digit survival rate (with “walk out of the hospital” criteria) for “sudden cardiac death” for witnessed arrests in public facilities with AEDs (automatic external defibrillators) and fast responding attentive personnel. The classic example of this is… (drumroll) casinos.
    - the distinction between these cases and the cardiac arrests in a hospital are that the person walking down the hallway tends to be healthier and younger, and “something goes wrong” (that’s a big scientific term) causing their heart to go into fibrillation and stop.
    If they get a defibrillation shock quickly, there’s a realistic chance everything will reset ok.
    - folk in cardiac arrest in a hospital or who’re getting an EMS response tend to be older, sicker, and (if it’s an EMS run) wait a lot longer than someone who gets zapped right then and there.
    - I’ll readily concede, based on my experience as a paramedic with a near zilch cardiac arrest “save” rate, that I thought “public access defibrillation” (“PAD”) was a complete waste of resources. It’s nowhere near as great a panacea as the press releases claim, but it’s doing a fair amount of good.

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