The purpose of this study is to determine if 48 hours of mild therapeutic hypothermia following out of hospital cardiac arrest gives a better cerebral outcome compared to 24 hours therapeutic hypothermia.

Sudden out-of-hospital cardiac arrest (OOH-CA) remains a significant cause of death. However, in 2002 it was in two clinical trials demonstrated that mild therapeutic hypothermia in comatose OOH-CA victims yields a better cerebral outcome measured by Cerebral Performance Category Score (CPC) after 6 month. The optimal mild hypothermia treatment time is however not known. The two trials from 2002 apply the treatment for 12 and 24 hours respectively. In newborns with cerebral hypoxic damage the standard treatment time is 72 hours. It is therefore relevant to investigate the influence of the treatment time on the cerebral outcome in OOH-CA victims. In the present study cerebral outcome after mild therapeutic hypothermia (target temperature 33 degrees centigrade) in OOH-CA patients for 24 is compared to outcome after 48 hours of mild hypothermia. The main outcome parameter is mortality and CPC score measured 6 month after the treatment.

Inclusion Criteria:

1. Out of hospital cardiac arrest of suspected cardiac origin
2. Return of spontaneous circulation (ROSC)
3. Glasgow Coma Score < 8
4. Estimated time interval from cardiac arrest to ROSC ≤ 60 min

Exclusion Criteria:

1. OOH-CA of suspected origin other than cardiac
2. In hospital Cardiac arrest
3. Terminal disease
4. Coagulation disorders
5. Unwitnessed asystolia
6. Time from cardiac arrest to start of hypothermia treatment > 240 min
7. GCS ≥ 8
8. Pregnancy
9. Persistent cardiogenic shock (Systolic blood pressure < 80 mmHg despite inotropic treatment and aortic balloon pump).
10. CPC 3-4 before cardiac arrest
11. Acute intra cerebral bleeding
12. Acute stroke
13. Acute coronary artery bypass grafting