Acute respiratory distress syndrome (ARDS) is a severe form of acute respiratory failure with mortality rates reaching as high as 35%. Management of ARDS is based on the treatment (if possible) of the underlying cause of ARDS and on invasive mechanical ventilation with positive expiratory pressure (PEEP). Another strategy of invasive ventilation, Time-Controlled Adaptative Ventilation (TCAV), is the application of specific settings to the airway pressure release ventilation (APRV) mode.

TCAV is based on a prolonged time at plateau pressure, creating a phase of continuous positive pressure, associated with brief release phases allowing the elimination of carbon dioxide. In prospective and retrospective clinical reviews, as well as in experimental animal studies, TCAV has demonstrated improvements in oxygenation and lung function, with the ability to prevent ARDS.

The thoracic computed tomography (CT) scan evaluates lung recruitment (re-aeration by positive pressure of non-ventilated lung territories) and the adverse effects of positive pressure on the parenchyma (hyperinflation).

The objective of this study is to evaluate, with CT scans performed to assess lungs of patients with ARDS, the effects of TCAV compared to a standard volumetric controlled ventilation, by measuring alveolar recruitment and over-distension.

Inclusion Criteria:

• ARDS according to the Berlin definition
• invasive ventilation for no longer than 72 hours
• patient requiring a diagnostic thoracic CT scan
• consent of a family member or the person of trust
• social security affiliation

Exclusion Criteria:

• Use of iodinated contrast media injection before CT acquisitions
• ARDS criteria present during 72 hours or more
• Severe COPD
• Pneumothorax or other barotrauma-related complication
• Right ventricular failure other than acute cor pulmonale
• Absence of sedative agents and neuromuscular blockade
• Severe hemodynamic instability (norepinephrine > 0.5 µg/kg/min)
• VA-ECMO assistance
• Pregnancy
• Absence of the capacity to give consent before admission to the ICU