Confusion Around Therapeutic Temperature Management Hypothermia After In-Hospital Cardiac Arrest?

Abstract

Over the past 15 years, therapeutic temperature management (TTM) has become an increasingly important goal of care in critically ill patients with acute brain injury. TTM (initially defined as cooling to 32oC−34oC) was used with increasing frequency to treat patients with postanoxic/hypoxic encephalopathy caused by catastrophic events such as neonatal asphyxia or cardiac arrest (CA). In the case of CA, using TTM was supported by the results of 2 randomized controlled trials and 45 nonrandomized (mostly before/after) studies. Guidelines from the American Heart Association and European Resuscitation Council have recommended the use of TTM for postanoxic injury after witnessed CA since 2003, and after an initially slow uptake, especially in the United States, application and implementation of these guidelines increased significantly in recent years, with growing consensus on the importance of TTM. However, this trend is currently under threat. In 2013, a large randomized controlled trial by Nielsen and coworkers reported that outcomes in patients with CA cooled to 33oC were not better than in patients cooled to 36oC, leading to a highly contentious debate in the TTM field. Strong opinions on this issue range from accepting the results of the Nielsen study and changing the target temperature to 36oC to staying with a target of 32oC−33oC because of perceived problems with the trial. We support the latter view and have criticized the Nielsen study in these pages for possible selection bias, up to 4-hour delays in initiation of cooling, prolonged (average 10 hours) time …