Impact on Mortality of a Strategy Including Continuous Positive Airway Pressure Plus High Flow Nasal Cannula Oxygen Therapy Versus High Flow Nasal Cannula Oxygen Therapy Alone in Patients With de Novo Acute Hypoxemic Respiratory Failure: a Prospective, Randomized Controlled Trial.

Exclusion Criteria

• •1. Refusal of study participation by the patient or the proxy
• •2. Anatomical factors precluding the use of a nasal cannula or CPAP
• •3. Long term oxygen
• •4. Home CPAP or NIV or CPAP or NIV initiated prior to ICU admission
• •5. Hypercapnia indicating NIV (PaCO2 \> 45 mmHg)
• •6. Isolated cardiogenic pulmonary oedema indicating NIV
• •7. Known pregnancy or breastfeeding
• •8. Absence of coverage by the French statutory health care insurance system (including AME)
• •9. Abdominal, thoracic or cardiac surgery within the last 6 days
• •10. Use of vasopressors (norepinephrine\>0.3 mcg/kg/min)
• •11. Glasgow coma scale \< 13
• •12. Urgent need for endotracheal intubation
• •13. Patients at an end-of-life stage receiving compational oxygenation
• •14. Exacerbation of a chronic respiratory disease
• •15. Legal protection (curatorship or tutorship)
• •16. Undrained pneumothorax