Non-invasive Early Oxygen- Reserve-index (ORI) Determination to Prevent Hypoxaemia During Endotracheal Intubation

Inclusion Criteria: * ICU admission and need for ETI to allow mechanical ventilation * Need for supplemental oxygen (via any device and at any flow rate) to obtain SpO2\>97% * Patient or next of kin informed about the study and having consented to participation of the patient in the study (patients with coma are unable to consent). If patient is no competent and no next of kin can be contacted during screening for the study, trial inclusion will be completed as an emergency procedure by the ICU physician, in compliance with French law * Patients affiliated to a social security system Exclusion Criteria: * Patients participating in intubation research with an oxygenation endpoint will not be eligible for inclusion * Fiberoptic intubation required according to physician in charge * Contra-indications to laryngoscopy (e.g., unstable spinal lesion) * Insufficient time to include and randomise the patient (e.g., because of cardiac arrest) * Age \<18 years * Currently pregnant or breastfeeding * Correctional facility inmate * Under guardianship, curatorship or under protection of justice