The Danish Out-of-Hospital Cardiac Arrest Study

Inclusion Criteria: 1. Age ≥18 years 2. OHCA of presumed cardiac cause 3. Sustained ROSC, defined as persistent signs of circulation and no need for chest compressions or mechanical circulatory support for 20 minutes 4. Unconsciousness (GCS \<9) (patients not able to obey verbal commands) after sustained ROSC at the time of randomization Exclusion Criteria: 1. Females of childbearing potential if pregnancy is suspected (unless a negative HCG test can rule out pregnancy within the inclusion window) 2. Known bleeding diathesis (medically induced coagulopathy (e.g. warfarin, NOAC, clopidogrel) does not exclude the patient) 3. Suspected or confirmed acute intracranial bleeding 4. Suspected or confirmed acute stroke 5. Unwitnessed asystole 6. Known limitations in therapy and Do Not Resuscitate-order 7. Known disease making 180 days survival unlikely 8. Known pre-arrest CPC 3 or 4 functional status 9. \>3 hours (180 minutes) from ROSC to screening 10. Systolic blood pressure \<80 mm Hg despite fluid loading/vasopressor and/or inotropic medication (If the systolic blood pressure is recovering during the inclusion window of 180 minutes the patient may be included) 11. Use of intra-aortic balloon pump/axial flow device/ECMO (If the patient is weaned and the device is removed during the inclusion window of 180 minutes the patient may be included) 12. Temperature on admission \<30°C 13. Known allergy for dexamethasone or olanzapine 14. Ongoing (within 48 h) treatment with olanzapine or dexamethasone 15. Known back or hip condition that precluded the patients from being positioned with backrest from 0 to 45-degree angle 16. Known or suspected Long QT Syndrome (LQTS) 17. Known active fungal disease. Localized skin lesions do not exclude patients from inclusion 18. Estimated body weight \<45kg