Intensive Care for Brain Injury After Cardiac Arrest: Therapeutic Hypothermia and Related Neuroprotective Strategies

Brain injury continues to be the leading cause of disability after cardiac arrest, despite seminal advances in intensive care and cardiovascular therapy over the last several decades. Care of these patients can be challenging, and it requires a great deal of medical resources and expense. In addition, dozens of clinical trials of neuroprotective strategies that showed promise in preclinical studies have yielded disappointing results in clinical trials. The emergence of therapeutic hypothermia as a successful neuroprotective measure in comatose survivors of ventricular fibrillation arrest-demonstrating benefit in survival and functional outcome measures-has created renewed enthusiasm for the amelioration of brain injury in these patients. Several challenges and uncertainties persist about therapeutic hypothermia, including basic understanding mechanisms of benefit, the optimal depth of hypothermia, timing of initiation of therapy, treatment duration, the best mechanism for achieving hypothermia (internal or external cooling), and the availability of a bedside indicator of brain response to hypothermia. These questions need to be answered by larger series of clinical trials and registry-reported data. Implementation of the American Heart Association and ILCOR recommendations to initiate hypothermia as soon as possible after resuscitation from out-of-hospital ventricular fibrillation arrest has been slow, even in academic medical centers. With a number needed to treat of around six to achieve survival and functional benefits, hypothermia is proving to be an extremely robust and important therapy for cardiac arrest survivors. Hospitals must prioritize establishing hypothermia protocols and systems to improve compliance with treatment recommendations.