Comparison of Intubating Conditions in 25° Head-up Position and Strict Supine

Inclusion Criteria: * \- patients scheduled for various surgeries requiring general anesthesia with curare, with intubation of the trachea, eligible for intubation by direct laryngoscopy. * \> 18 years * patients with social security Exclusion Criteria: * Emergency surgery. * Patient who requiring rapid sequence induction. * Intubation without curare. * Expected difficult intubation with planned modification of the intubation protocol (i. e. intubation under fibroscopy, airtrach or videolaryngoscopy) * Patient with a history of epilepsy, pulmonary or cardiovascular disease (including ischemic heart disease, symptomatic asthma or obstructive pulmonary disease). * Patient with mask phobia. * BMI\> 30kg / m2 * Patient who are refusing to take part. * Patient protected major, minor, pregnant women, patients deemed incapable of giving informed consent.