Obesity is a risk factor for difficult intubation, with an incidence of up to 15.5%, and difficult mask ventilation. Obesity also reduces the functional residual capacity (FRC) of the lungs, the main reservoir of oxygen during apnoea. Complications associated with induction and intubation in the operating room are more frequent in obese patients. Preoxygenation is a cornerstone in the management of patients at risk of desaturation during induction. The study aims to compare two oxygenation strategies , in obese patients. Oxygenation using a combination of NIV (Non Invasive Ventilation) and HFNO (High Flow Nasal Oxygen) compared with NIV alone in the operating room for induction of general anaesthesia with orotracheal intubation.

Inclusion Criteria:

• Patient requiring general anaesthesia with orotracheal intubation in the operating room
• Obese patient (Body Mass Index , BMI ≥ 30kg/m2)
• Patient affiliated to or benefiting from a social security scheme
• Patient having signed the free and informed consent form.

Exclusion Criteria:

• Haemodynamic instability
• Intubation without laryngoscopy (fibroscope intubation) or nasotracheal intubation
• Emergency surgery not allowing patient consent.
• Patient with a contraindication to NIV or OHD
• Protected patients: Adults under guardianship, curatorship or other legal protection; deprived of liberty by judicial or administrative decision; pregnant, breast-feeding or parturient women; hospitalised without consent.