Intraoperative Protective Mechanical Ventilation in Patients Requiring Emergency Abdominal Surgery

Inclusion Criteria: * Adult (≥18 years) * Patients requiring emergency (defined by the need to proceed to surgery within a few hours after diagnosis) * Laparoscopic or non-laparoscopic abdominal surgery under general anesthesia and with an expected duration of at least two hours Exclusion Criteria: * Patients already receiving mechanical ventilation for more than 12 hours before enrollment * Intracranial hypertension * Chronic respiratory disease requiring oxygen therapy or mechanical ventilation at home * Undrained pneumothorax or subcutaneous emphysema * Patients for which death is deemed imminent and inevitable or patients with an underlying disease process with a life expectancy of less than 3 month * Body mass index (BMI) \>40 kg/m2 * Pregnant or breastfeeding women * Patients already enrolled in the IMPROVE-2 trial * Participation in a confounding trial with mortality or PRF as the main endpoint * Patient's or relative's refusal to participate * Guardianship or trusteeship patient * No affiliation to the Social Security system