Hot off the press from NEJM.org, comes a study from the Scandinavian lands. There, a rigorous well conducted study involving almost a thousand post-cardiac arrest patients were randomized to two temperature management groups; 33 versus 36 degree Celsius.
What do you know, there is NO difference in mortality between the 2 groups (primary outcome), or neurologic function (secondary outcomes).
Is this history repeating itself? The medical literature contains numerous examples of study interventions where initial small(er) studies claim benefit, get trumpeted by the medical community, and later large randomized trials debunk the initial findings. Therapeutic hypothermia may be one such example. In fact, critics of hypothermia often cite the small sample sizes of the initial landmark studies as a reason for potential biases.
Does this then spell the end for induced therapeutic hypothermia after cardiac arrest? This is difficult to answer, and may even raise more questions with this latest trial. It's been more than ten years since the first landmark trials were published in 2002, and a lot have changed since then. Care of the post-arrest patients is bound to have improved with time and recognition of the post-arrest syndrome.
But this study does highlight a few points:
- Hyperthermia after ROSC is probably bad. The early trials did not control for the temperature of the control groups and that may account for the difference in outcomes.
- In this study, every patient got CPR very quickly and the median pulseless intervals were less than 30 minutes in both groups (you'd expect that in a Scandinavian country). Therefore, the majority were VF collapses, and the patients got ACLS in 10 minutes. We do know that people tend to do better the less time they spend in arrest so this in itself may contribute to better outcomes in any group regardless.
- The study was praised for standardising an algorithm to withdrawal of life-sustaining care - a first, and very well thought out.
- Targeted temperature PROBABLY works, just keep to under 37 degrees. We still do not know which is best.
Read the article and the accompanying editorial below; what do you think?