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.

Rationale: Closed-loop ventilation has been proven effective in lung-protective ventilation but its effectiveness, safety and efficacy in providing both lung- and brain-protective ventilation in patients with acute brain injury has not been investigated.

Objective: To evaluate the effectiveness, efficacy and safety of INTELLiVENT-ASV with respect to brain- and lung-protective ventilation in ABI patients

Hypothesis: We hypothesize that INTELLiVENT-ASV is effective with regard to brain- and lung-protective ventilation (that is achieving brain- and lung- protective targets), efficacious (that is improving outcomes), and that INTELLiVENT-ASV is safe in invasively ventilated ABI patients.

Study design: Single-center, crossover trial.

Methods: In this prospective observational study, breath-by-breath ventilation data will be available from before and after the switch to closed-loop ventilation with INTELLiVENT-ASV, wherein the decision to switch is determined by the attending healthcare worker, i.e., not protocolized and only for clinical/organizational reasons. High granular data are collected both before and after this switch, limited to three hours for conventional and three hours for closed-loop ventilation. Neuromonitoring is part of current clinical practice and data will be collected only when available.

Study population: Invasively ventilated patients diagnosed with acute brain injury Methods: When the ventilator is switched upon the caregivers decision, data will be collected from three hours before the switch and three hours after the switch.

Study endpoints: The primary composite endpoint is the proportion of breaths and proportion of time within predefined zones of ventilation (based on VT and airway pressures, saturation of peripheral O2 (SpO2) and end-tidal CO2 (EtCO2).

Inclusion Criteria:

• aged ≥ 18 years;
• intubated and receiving invasive ventilation for ABI;
• admitted to the Intensive Care Unit

Exclusion Criteria:

- receiving ventilation with a ventilator that does not allow INTELLiVENT-ASV

Invasively ventilated acute brain injury (ABI) patients admitted to the ICU of the Policlinico San Martino Hospital, Genova, Italy