Perioperative Prophylactic Positive Pressure Ventilation Reduces Postoperative Pulmonary Complications.

Inclusion Criteria: * Patients who have signed the informed consent form and are willing to comply with the study protocol; * Age ≥ 18 years and ≤ 90 years; * ASA physical status classification I to III; * Scheduled for major elective abdominal surgery; * Undergoing general anesthesia with endotracheal intubation; * ARISCAT (Assessement of Respiratory Risk in Surgical Patients in Catalonia) score ≥ 45; * Anticipated surgery duration ≥ 2 hours. Exclusion Criteria: * Untreated ischemic heart disease; severe cardiovascular or cerebrovascular disease; * Severe asthma, pulmonary bullae/bullous lung disease, pneumothorax, bronchopleural fistula, etc.; * Severe underlying hepatic or renal disease; * Age \< 18 years or \> 90 years; * Refusal to participate in the clinical study.