Standard Oxygen Versus High Flow Nasal Cannula Oxygen Therapy in Patients With Acute Hypoxemic Respiratory Failure

Inclusion Criteria: All consecutive patients older than 18 years with an acute hypoxemic respiratory failure will be enrolled if they meet all the following criteria: * Respiratory rate \>25 breaths/min whatever the oxygen support * Pulmonary infiltrate, * PaO2/FiO2 ≤200 mmHg * Informed consent from the patient or relatives. Exclusion Criteria: * PaCO2 \> 45 mm Hg * Need for emergent intubation: pulse oximetry \< 90% with maximum oxygen support, respiratory arrest, cardiac arrest, or Glasgow coma scale below 8 points * Hemodynamic instability defined by signs of hypoperfusion or use of vasopressors \> 0.3 µg/kg/min * Glasgow coma scale equal to or below 12 points * Exacerbation of chronic lung disease including chronic obstructive pulmonary disease (grade 3 or 4 of Gold classification), or another chronic lung disease with long term oxygen or ventilatory support * Cardiogenic pulmonary edema as main reason for acute respiratory failure * Coronavirus SARS-2 infection as reason for acute respiratory failure (the SOHO-COVID study has been completed) * Post-extubation respiratory failure within 7 days after extubation, * Post-operative patients within 7 days after abdominal or cardiothoracic surgery, * Do not intubate order; * Already included in the study, refusal to participate or participation in another interventional study with the same primary outcome. * Patients without any healthcare insurance scheme or not benefiting from it through a third party, * Persons under law…