The use of IH for 24 hours in patients who remain comatose following resuscitation from out-of-hospital cardiac arrest improves outcomes. How-ever, the induction of hypothermia has several physiologic effects that need to be considered. A protocol for the rapid induction of hypothermia is described. At present, the rapid infusion of a large volume (40 mL/kg) of ice-cold crystalloid (ie, lactated Ringer's solution) would appear to be an inexpensive, safe strategy for the induction of hypothermia after cardiac arrest. Hypothermia (33 degrees C) should be maintained for 24 hours, followed by rewarming over 12 hours. Particular attention must be paid to potassium and glucose levels during hypothermia.