Inclusion Criteria:  Patients over 18 years of age requiring elective surgery under general anesthesia and hospitalization. Patients with a moderate or high risk of postoperative pulmonary complication according to the ARISCAT score (score of 26 or more)  Exclusion Criteria:  Expected or known difficult intubation according to the treating anesthesiologist Postoperative mechanical ventilation (planned or unplanned) Neuromuscular disease Intrathoracic surgery Respiratory failure, sepsis or mechanical ventilation in the month preceding anesthesia Pregnancy Patient refusal  Ultrasound sub-study:  Body mass index greater than 40 kg.m-2 Extensive postoperative chest dressings Clinician's refusal to participate