Therapeutic Hypothermia for Cardiac Arrest

Targeted temperature management is the key intervention for improving neurological outcomes after cardiac arrest. We discuss new data on the optimal timing and modalities of targeted temperature management. It took nearly half a century, from 1957 to 2002, for therapeutic hypothermia to acquire its current status as a key intervention for improving neurological outcomes in survivors of cardiac arrest. Despite growing interest from healthcare workers and researchers, many questions remain unanswered regarding this treatment tool. Recent large multicentre trials raised as many questions as they provided answers. In this review, we will try to reconcile new and old data, explain discordant results, and discuss future trials of therapeutic hypothermia and other aspects of the management of cardiac arrest survivors. Indications of Therapeutic Hypothermia Cardiac Arrest in Shockable Rhythm For the past 12 years, treatment decisions for cardiac arrest survivors have relied largely on two trials reported in 2002 (Hypothermia after Cardiac Arrest Study Group 2002; Bernard et al. 2002). Both trials showed improved neurological outcomes with hypothermia between 32° and 34° compared to normothermia after cardiac arrest in shockable rhythm. The vast majority of observational, retrospective, and propensity-adjusted cohort studies support this finding. The landmark Targeted Temperature Management (TTM) trial reported in 2013 (Nielsen et al. 2013) failed to demonstrate any difference in neurological outcomes or survival between hypothermia at 33° and hypothermia at 36°C. The results of the TTM trial complicate the interpretation of another preliminary study showing better outcomes with hypothermia at 32°C compared to 34°C (Lopezde-Sa et al. 2012). These data have generated active controversy. The International Liaison Committee on Resuscitation (ILCOR) issued the following statement: