The on-going randomized clinical trial TTM2 (Target Hypothermia Versus Targeted Normothermia After Out-of-hospital Cardiac Arrest, NCT02908308) investigates if there is a difference in mortality, neurological function or quality of life in comatose survivors after out-of-hospital cardiac arrest if treated (Group A) at target temperature of 33 oC or (Group B) by avoiding fever during the first 24 h. In this sub study, the effect of different target temperatures on cardiac and circulatory physiology is evaluated by echocardiography and pulmonary artery catheter. Tissue damage after cardiac arrest in part is caused by an activation of different parts of the inflammatory system (reperfusion injury). This study investigates the effect of temperature management on inflammation and the link to the circulatory effects.