The COMACARE trial is a pilot multicenter randomized trial to assess the feasibility and effect on brain injury markers of targeting low or high normal arterial oxygen tension (PaO2), arterial carbon dioxide tension (PaCO2) and mean arterial pressure (MAP) in comatose, mechanically ventilated patients after out-of-hospital cardiac arrest. Using factorial design, participants are randomized at admission to intensive care unit to one of eight groups targeting either low or high normal values of PaO2, PaCO2 and MAP for 36 h. In this way, investigators will be assessing the feasibility and effect of all three variables at the same time.