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Therapeutic Hypothermia for Comatose Survivors of Cardiac Arrest

Comatose cardiac arrest patients benefit from controlled mild hypothermia.

Severe neurologic impairment is perhaps the most feared outcome after resuscitation from cardiac arrest. Recent animal research has shown that induction of hypothermia improves neurologic outcomes after cardiac arrest. Now, 2 human studies corroborate the animal results.

A European trial included 275 patients who suffered witnessed out-of-hospital cardiac arrests secondary to ventricular arrhythmia; other enrollment criteria were a 5- to 15-minute interval between arrest and attempted resuscitation, 60 minutes or less between arrest and restoration of spontaneous circulation, and unresponsiveness to verbal commands after resuscitation. In addition to standard intensive care, patients were randomized to receive either 24 hours of hypothermia, induced by a device that circulated cool air over patients (target temperature, 32°C to 34°C), or normothermia. At 6 months, patients in the hypothermia group were significantly more likely than were those in the normothermia group to have favorable neurologic outcomes (55% vs. 39%) and to survive (59% vs. 45%).

In a similar study from Australia that involved 77 comatose survivors of cardiac arrest, good outcomes (discharge from hospital to home or to rehabilitation facilities) were significantly more likely with hypothermia than with normothermia (49% vs. 26% of patients). In this study, hypothermia was induced with ice packs.

Comment: Based on these findings, editorialists recommend the use of hypothermia in comatose survivors of cardiac arrest. However, keep in mind that both studies had numerous exclusion criteria, thus limiting the generalizability of their results.

— Allan S. Brett, MD

Published in Journal Watch General Medicine February 26, 2002

Citation(s):

The Hypothermia after Cardiac Arrest Study Group. Mild therapeutic hypothermia to improve the neurologic outcome after cardiac arrest. N Engl J Med 2002 Feb 21; 346:549-56.

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Bernard SA et al. Treatment of comatose survivors of out-of-hospital cardiac arrest with induced hypothermia. N Engl J Med 2002 Feb 21; 346:557-63.

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• Medline abstract (Free)

Safar PJ and Kochanek PM. Therapeutic hypothermia after cardiac arrest. N Engl J Med 2002 Feb 21; 346:612-3.

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• Medline abstract (Free)