High-flow nasal oxygen therapy (HFNO) is an oxygenation technique frequently used in intensive care.

The main objective of our study is to show that the use of a protocol for weaning patients off high-flow nasal oxygen therapy (HFNO) in the intensive care unit increases the probability that patients will be weaned from HFNO at Day 7 post-randomisation.

This is a open-label multicentre randomised controlled trial conducted in two parallel groups.

The primary endpoint is the success rate at Day 7, with success defined as "definitive" weaning from HFNO, i.e. patients weaned from HFNO for more than 48 hours without recourse to non-invasive ventilation (NIV) or intubation and still alive at Day 7.

The weaning protocol will be started as soon as the patient meets all the inclusion criteria, considered to be the prerequisites for initiating weaning from HFNO. Patients will be monitored until Day 28 maximum.

Inclusion Criteria:

• Major patient admitted to the intensive care unit or continuous care unit for de novo hypoxaemic acute respiratory failure (with a PaO2/FiO2 ratio <300 mmHg)
• Treated with HDNO for at least 24 hours in an intensive care unit or continuous care unit
• Treated with HFNO with a flow rate ≥ 50L/min and inspired oxygen fraction (FiO2) ≥ 0.5, at inclusion
• With a ROX index (SpO2/FiO2/Respiratory Rate) stable or improving in the 6 hours prior to inclusion and greater than 4.88 (the patient must not be in a worsening phase).
• Had a blood gas test under HFNO within 24 hours of inclusion
• Participant covered by or entitled to social security
• Informed consent signed by the patient or its relatives if the patient is incapable; this consent must then be confirmed by the patient as soon as possible

Exclusion Criteria:

• Presence of a patient included in the study and not weaned off HFNO in the sector managed by the nurse of the patient assessed for eligibility
• Concomitant non-invasive ventilation treatment
• Use of HFNO within 7 days of extubation
• Chronic obstructive pulmonary disease (Gold grade 3 or 4)
• Cardiogenic acute pulmonary oedema as the main cause of acute respiratory failure
• Diffuse interstitial lung disease as a medical history
• Patient with long-term non-invasive ventilation with external positive pressure
• Patient on long-term oxygen therapy at home
• Pregnant women, women in labour and breastfeeding mothers
• Persons deprived of their liberty by a judicial or administrative decision, persons hospitalised without consent and persons admitted to a health or social establishment for purposes other than research.
• Minor
• Adult subject to a legal protection measure (guardianship, curators, person under court protection)
• Patient with a medical decision not to intubate
• Patients already included in the study, neither for the same stay if they were to present the inclusion criteria again, nor for subsequent stays