Clinical Advisory:
Hypothermia After VF Cardiac Arrest

The International Liaison Committee on Resuscitation (ILCOR) has issued 2 recommendations for use of hypothermia in selected cardiac-arrest patients:

• Unconscious adults with spontaneous out-of-hospital cardiac arrest and an initial rhythm of ventricular fibrillation (VF) should be cooled to 32°-34°C for 12 to 24 hours.
• Such cooling also may be beneficial for other rhythms or for in-hospital cardiac arrest.

The recommendations derive from 2 randomized trials: one European, the other Australian.

In the European trial, 275 patients with cardiac arrest due to VF or nonperfusing ventricular tachycardia were randomized either to standard normothermic care or to mild hypothermia (treatment with an external cooling device for 24 hours; target temperature, 32°-34°C). All had been resuscitated within 5 to 15 minutes and had restoration of spontaneous circulation (ROSC) within 60 minutes. Compared with the normothermia group, the hypothermia group had a significantly higher 6-month rate of favorable neurologic outcomes (55% vs. 39%) and a significantly lower 6-month mortality rate (41% vs. 55%).

The Australian trial (77 patients) had similar entry criteria and a similar randomization protocol. Compared with the normothermia group, the hypothermia group had a significantly higher rate of good neurologic function at hospital discharge (49% vs. 26%) and a significantly lower in-hospital mortality rate (51% vs. 68%).

Comment: The ILCOR recommendations, which can be implemented easily, are specific in identifying which patients benefit from cooling, according to the evidence. Other cardiac-arrest patients (e.g., children, patients without documented VF, and patients with in-hospital arrest of cardiac etiology) may also benefit from therapeutic hypothermia, although benefit for these groups has not been established. As the authors note, thrombolytic therapy does not preclude use of hypothermia; patients who received thrombolytic therapy were included in both of the cited trials. Note, however, that hypothermia is not appropriate in some cardiac-arrest patients (e.g., those with severe cardiogenic shock, pregnant women). In general, therapeutic hypothermia should be used after cardiac arrest more frequently, and certainly in the groups specified by this advisory.

— Hugh Calkins, MD

Published in Journal Watch Cardiology October 3, 2003

Source

Nolan JP et al. Therapeutic hypothermia after cardiac arrest: An advisory statement by the Advanced Life Support Task Force of the International Liaison Committee on Resuscitation. Circulation 2003 Jul 8; 108:118-21.