The
literature regarding cooling of comatose survivors of cardiac arrest is mixed. But even more controversial is the role of therapeutic hypothermia in
the group of patients with non-shockable rhythm.
Enter the HYPERION trial published in the high impact New England Journal of Medicine.
This mammoth
effort was an open-label pragmatic RCT comparing hypothermia
(33 degrees) vs normothermia (37 degrees) in comatose survivors
of cardiac arrest with non-shockable rhythms (PEA or asystole).
As if PEA
and asystole were not bad enough, they excluded the sicker patients who
would have highly likely died anyway- regardless of cooling or no cooling. These
were patients who had no CPR for >10 minutes, CPR for more than 60 minutes, those
with high vasopressor requirements etc.
The primary
outcome was a good one; survival with a favorable day-90 neurologic outcome. This was defined as independent & able to perform ADL’s (CPC score 1-2). Unfortunately, it was possibly poorly determined by a single blinded psychologist by phone interview.
Results?
Over 4
years, 581 patients were included from 25 French ICU’s. On day 90, 10.2% of
the hypothermia group vs. 5.7% of the normothermia had a good
outcome (difference 4.5% 95%CI 0.1 to 8.9; P=0.04 and a NNT of 22.) Overall mortality
did not differ between the groups at 80%.
Cooling
wins!?
Despite the
results, I am a bit less enthusiastic about this one.
The
literature is still conflicting, and this is far from overwhelming data.
The primary
result has a fragility index of 1. If only one of the patients that did well in
the hypothermia group were reclassified as unfavorable at 90 days, the results
would not have been statistically significant… we would be talking about a negative
trial.
There are other
issues with the measurement of the primary outcome, external validity
and a few other things.
In the end,
it is probably fine if your ICU wants to cool these patients. But please make sure
it does not distract & get in the way of providing adequate resuscitation and supportive
care. Stay cool (or not) and do the right things first.
Covering:
Lascarrou
JB, Merdji H, Le Gouge, A, et al. Targeted Temperature Management for Cardiac
Arrest with Non-Shockable Rhythm. New Engl J Med; 2019: 381:2327-2337. [link to article]
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