In the Feb 21, 2002 NEJM, two trials of what came to be known as therapeutic hypothermia (or HACA - Hypothermia after Cardiac Arrest) were simultaneously published: one by the HACA study group and another by Bernard et al. During the past decade, I can think of only one other therapy which has caused such a paradigm shift in care in the ICU: Intensive Insulin Therapy (ill-fated as it were). Indeed, even though the 2002 studies specifically limited enrollment to out of hospital (OOH) cardiac arrest with either Ventricular Tachycardia (VT) or Ventricular Fibrillation (VF), the indications have been expanded at many institutions to include all patients with coma after cardiac arrest regardless of location or rhythm (or any other original exclusion criterion), so great has been the enthusiasm for this therapy, and so zealous its proponents.Readers of this blog may know that I harbor measured skepticism for HACA even though I recognize that it may be beneficial. From a pragmatic perspective, it makes sense to use it, since the outcome of hypoxic-ischemic encephalopathy (HIE) and ABI (Anoxic Brain Injury) is so dismal. But what did the original two studies actually show?
- The HACA group multicenter trial randomized 273 patients to hypothermia versus control and found that the hypothermia group had higher rates of "favorable neurological outcome" (a cerebral performance category of 1 or 2 - the primary endpoint) with RR of 1.40 and 95% CI 1.08-1.81; moreover, mortality was lower in the hypothermia group, with RR 0.74 and 95% CI 0.58-0.95
- The Bernard et al study randomized 77 patients to hypothermia versus control and found that survival (the primary outcome) was 49% and 26% in the hypothermia and control groups, respectively, with P=0.046
