Effects of Non-invasive Ventilation Therapies on the Lung in Hypoxemic Chest Trauma Patients

Inclusion Criteria: * Age \> 18 years old * Chest trauma \< 5 days * At least 3 ribs fracture on initial CT-scan * Need of oxygen moderated to maintain monitoring oxygen saturation Sp02 \> 92% or partial pressure of arterial oxygen Pa02/ Fraction of inspired oxygen FiO2 \> 200 * Intensive Care Unit admission * Need a chest CT control during the five first days after the trauma Exclusion Criteria: * Patient intubated or with respiratory failure : measured or estimated Pa02/FiO2 \< 200 or indication for intubation (several with respiratory rate \> 35/min, abundant tracheal secretions, significant increase in work of accessory respiratory muscles on inspiration, signs of respiratory exhaustion on arterial blood gas with The potential of Hydrogen pH \< 7,3 or PaCO2 \> 50 mmHg, severe hypoxemia with PaO2/FiO2 ratio \< 100 or desaturation \< 88% for more than 5 minutes) * Inability to maintain 10 seconds of apnoea required for scan acquisition * Patient treated with ventilatory support by NIV or HFO in the 12 hours prior the investigation * Uncontrolled circulatory failure with need for introduction of Noradrenaline \> 0,15 ug/kg/min * Uncontrolled neurological failure with Glasgow Coma Scale (CGS \< 15 * Unstable facial trauma or with pneumocephalus or basilar skull trauma * Large, undrained pneumothorax with lateral separation at the level of the hilum \> 2 cm and extensive throughout the axillary line * Patients with identified cognitive impairment * Persons deprived of liberty, persons under protective measures * Persons not affiliated to a social security insurance * Current pregnancy or breastfeeding * Refusal to participate in the study