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Nov. 17th saw the on-line publication of two important therapeutic hypothermia trials in the setting of cardiac arrest. These studies were well covered by several of the top intensive care blogs. Below is an organized (selected) summary, including Scott Weingart’s (emcrit.org) recent interview with Dr. Stephen Bernard who is one of the original protocol-establishing trial’s authors. Taken together, these studies are changing practice world-wide.

Overall, the message is that we should continue to cool patients, likely 36 deg C is sufficient for most patients, and probably, what is more important is the avoidance of fever. Some patients may still benefit from deeper cooling. Also very interesting that the PEA/Asystole group, now included Nielsen et al.’s study, did not see benefit (some say PEA is different than asystole in terms of perfusion and may respond differently to cooling).

Some commentators suggest that a brain “dose-response” curve exists – such that those with a suspected greater degree of neuronal injury may benefit from lower temperatures and/or longer cooling times – however, I think this will be difficult to show definitively while controlling for confounders. The post-arrest brain injury (and it’s extent) occurs acutely in a short amount of time and there are physiologic parameters that govern the secondary injury that ensues over the coming days – it will be challenging to assess those parameters in the acute setting. We likely need a focused physical exam (perhaps augmented by objective instruments such as pupillometry), brain imaging, and continuous EEG as parameters to study acutely that may provide us future insight on how to stratify patients.

Review/Commentary

Rittenberger and Callaway’s NEJM commentary on Nielsen et al.’s article

Interesting blogs

Medical Evidence Blog

  • Intensive Care Network interview with Dr. Nielsen

  • Original research articles:*

  • Update [27 Dec. 2013]:* Excellent panel discussion by several leaders in ED/CCM on new perspectives on TTM. See the new [RAGE Podcast]{https://ragepodcast.com/rage-session-one/)

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