Descriptive Observational Study of Patient-performed Pre-oxygenation

Inclusion Criteria: * Patient undergoing scheduled surgery with general anesthesia * Patient classified ASA I or II * Patient understanding and speaking French * Patient informed of the study and not opposed to it * Decision to have preoxygenation carried out by the patient. Exclusion Criteria: * Patients with grade II or III obesity (BMI\>35) * Patient with at least one respiratory comorbidity * Smoking patient * Pregnant patients * Patient with an allergy to one of the mask's components * Patient with cognitive impairment or known comprehension difficulties * Patient under guardianship or curatorship * Patient not affiliated to health care system