Comparing High-flow Nasal Cannula Oxygen and Noninvasive Ventilation to Standard Oxygenation in Non-selected ICU Patients Admitted for Hypoxemic ARF

Inclusion Criteria: * Adult (age ≥ 18 years) * A diagnosis of hypoxemic ARF occurring defined as the presence and persistence for more than 30 minutes of hypoxemia (defined by a partial oxygen pressure \<60 mm Hg when breathing room air or \<80 mmHg when breathing 15 L/min of oxygen or a peripheral oxygen saturation \[SpO2\] ≤90% when breathing room air and/or a PaO2(partial pressure of oxygen)/FiO2 ratio \< 300 mmHg plus either \[1\] a respiratory rate higher than 30/min or \[2\] clinical signs suggestive of intense respiratory muscle work and/or labored breathing, such as use of accessory respiratory muscles, paradoxical motion of the abdomen, or intercostal retraction). Exclusion Criteria: * Contraindications to NIV and/or HFNO * Sleep apnea syndrome with home ventilator * Immediate tracheal intubation * Requirement for an emergent surgical procedure requiring intubation * Hypercapnia with a formal indication for NIV (formal indication for NIV with PaCO2 ≥ 50 mmHg or clinical signs of hypercapnia) * Isolated cardiogenic pulmonary edema (formal indication for NIV). Patients with pulmonary edema associated with another ARF etiology can be included. * Anatomical factors precluding the use of NIV and/or HFNO * Patients with limitation or withdrawal of life-sustaining therapies with a do-not-intubate order * Pregnancy in progress or planned during the study period or breastfeeding women * Patients protected by law (Art. L1121-6 and L1121-8 of the Code de la Santé Publique): Adult protected by law or patient under guardianship or curatorship * Subjects not covered by public health insurance * Absence of written informed consent from the patient or his or her proxy (if present) before inclusion or when possible when the patient has been included in an emergency setting