Monday, July 06, 2015

Temperature management post cardiac arrest: therapeutic hypothermia or strict normothermia?

Recent findings have raised this question, which is examined in a recent Circulation article:

Current guidelines from the American Heart Association recommend use of therapeutic hypothermia (TH) after witnessed cardiac arrest (CA) to mitigate posthypoxic injuries. This is based on results of 3 randomized, controlled trials (RCTs) enrolling 385 patients, 43 before–after studies enrolling 10 442 patients, and supporting evidence from the field of neonatal asphyxia where 7 RCTs enrolling 1329 patients also demonstrated neuroprotective effects of hypothermia. However, this has been called into question by a recently published RCT enrolling 939 patients, which found no benefit of cooling to 33°C compared with maintaining 36°C. In this article we review the literature, with extra attention for strengths and weaknesses of the recently published RCT. In view of potential weaknesses in the new study (including a possibility of selection bias, long delays before initiation of cooling, a time to target temperature of 10 hours, and a rapid rewarming rate), we conclude that there are sufficient grounds to continue using hypothermia in most patients with witnessed ventricular fibrillation (VF)/ventricular tachycardia (VT) arrest, pending results of further studies which should examine multiple temperature levels (32–36°C) and multiple treatment durations (24–72 hours).

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