Thus far, the closed-loop ventilation mode INTELLiVENT-ASV has been extensively tested in various groups of critically ill patients, and has been shown to be effective and safe in various groups of ventilated patients, including those at risk of acute respiratory distress syndrome (ARDS), patients with ARDS, and patients with chronic obstructive pulmonary disease (COPD). Some of these studies included acute brain injury (ABI) patients, but the effectiveness, efficacy and safety of INTELLiVENT-ASV has never been thoroughly tested in these patients. The current study will investigate the effectiveness in providing both brain- and lung protective ventilation, the safety and the efficacy of a closed-loop ventilation mode (INTELLiVENT-ASV) in acute brain injury patients, using breath-by-breath data.