Interest of Tracheal Extubation in Positive Pressure on Postoperative Oxygenation in Adult Digestive Surgery

Inclusion Criteria: * Age\> 18 and \<80 * Patient going to benefit from general anesthesia with orotracheal intubation for surgery lasting more than 60 minutes at the visceral surgery unit of the Rouen University Hospital. * Person affiliated to a social security scheme * Person who has read and understood the newsletter and signed the consent form Exclusion Criteria: * Minor patients or age\> 80 years * History of Obstructive Sleep Apnea Syndrome * Chronic respiratory failure / History of chronic obstructive pulmonary disease * Surgery \< 60 minutes * Use of methylene blue intraoperatively * Extubation finally performed in the operating room * orotracheal intubation difficult to induce general anesthesia * Suspected inhalation during orotracheal intubation * Pneumothorax per operative * Heart failure authenticated by trans thoracic ultrasound \<50% * Neuromuscular pathologies (myasthenia gravis, myopathies) * Body mass index\> 35 * Emergency surgery * Patient with an ASA IV score (ie according to the definition of the American Society of Anesthesiology) * Major surgical complications (hemorrhagic shock) * Major anesthetic complications (anaphylactic shock, bronchospasm) * Pregnant or parturient or lactating woman or woman of childbearing age without proven contraception * Person deprived of their liberty by an administrative or judicial decision or person placed under the protection of justice / guardianship or curatorship