Therapeutic Hypothermia After Cardiac Arrest in Adults: Mechanism of Neuroprotection, Phases of Hypothermia, and Methods of Cooling

Mild therapeutic hypothermia (32 degrees C-34 degrees C) has been shown to improve survival and neurologic outcomes after sudden cardiac arrest in clinical studies. Its use is recommended by the American Heart Association for unconscious adult patients with spontaneous circulation after out-of-hospital ventricular fibrillation. It decreases cerebral metabolism and protects the brain after ischemia by reduction of brain metabolism, attenuation of neuroexcitotoxic cascade, abolition of reactive oxygen species, and inhibition of apoptosis. This article addresses the mechanism of neuroprotection, phases of hypothermia, and noninvasive and invasive cooling methods.