This study includes comatose survivors of out-of-hospital cardiac arrest treated with 24 hours or 48 hours of targeted temperature management.

The overall aim is to evaluate the importance of plasma complement protein concentrations in patients resuscitated after out-of-hospital cardiac arrest and treated with 24 hours or 48 hours of targeted temperature management.

The specific aim is to evaluate:

• the concentration of plasma lectin pathway proteins the first, second and third day after cardiac arrest
• the relation between concentration of plasma lectin pathway proteins and mortality
• if prolonged targeted temperature management influences the concentration of plasma lectin pathway proteins

This study is a sub-study to the trial entitled: "Time-differentiated targeted temperature management (TTH48) (ClinicalTrials.gov Identifier: NCT01689077)"

The following Complement Lectin Pathway proteins will be measured: Mannan-Binding-Lectin, M-ficolin, H-ficolin, CL-L1, MASP-1, MASP-2, MASP-3, MAp19 and MAp44.

Inclusion Criteria:

• Out-of-Hospital Cardiac Arrest of presumed cardiac cause
• Return of spontaneous circulation (ROSC)
• Glasgow Coma Score < 8
• Age > 18 years and < 80 years

Exclusion Criteria:

• > 60 minutes from the circulatory collapse to ROSC
• Time interval > 4 hours from cardiac arrest to initiation of targeted temperature management
• Terminal illness
• Coagulation disorder
• Unwitnessed asystolia
• Cerebral performance category 3-4 before the cardiac arrest
• Severe persistent cardiogenic shock
• Pregnancy
• Persistent cardiogenic shock (systolic bloodpressure < 80 despite inotropic treatment)
• New apoplexy or cerebral hemorrhage
• Lack of consent from the relatives
• Lack of consent from the general practitioner
• Lack of consent from the patient