Apneic Oxygenation With High-flow Nasal Oxygenation After Preoxygenation With Noninvasive Ventilation Before Intubation in Hypoxemic Patients in Intensive Care Unit.

The aim of this clinical study is to assess whether apneic oxygenation with High-Flow Nasal Oxygen (HFNO) would decrease the incidence of severe hypoxemia compared to no apneic oxygenation during the intubation procedure (from the start of laryngoscopy to 5 minutes after successful intubation) in patients with hypoxemic acute respiratory failure. The sponsor expects that apneic oxygenation (between the laryngoscopy and the success of intubation) with HFNO compared to no apneic oxygenation could decrease the risk of severe hypoxemia after intubation in hypoxemic critical ill patients. Participants will be enrolled according to eligibility criteria and randomized into one of the following groups: Experimental group : Apneic oxygenation will be used with HFNO between the laryngoscopy and the successful intubation (study intervention). non-invasive ventilation (NIV) alone will be used for the preoxygenation and hypoventilation phase until the laryngoscopy. The nasal cannulas of HFNO will be placed on hold beneath the patient's chin (with HFNO on and set with a flow at 60-70L.min-1, FiO2 1.0) pending laryngoscopy began. At the time of laryngoscopy: after removing the facemask of NIV, the nasal cannulas for HFNO will be placed in the patient's nares then the laryngoscopy will be performed. Control group: The control group will receive usual care, i.e., no oxygen during the apneic phase (between the laryngoscopy and the success of the intubation procedure) During the preoxygenation and hypoventilation phase until laryngoscopy, NIV alone will be used as in the experimental group.