Obese adult patients with body mass index (BMI) ≥ 35 kg/m² scheduled for open or laparoscopic surgery under general anesthesia (Screening).

• Patient scheduled for open or laparoscopic surgery under general anesthesia
• Intermediate-to-high risk for PPCs following surgery, according to the ARISCAT risk score (≥ 26)
• BMI ≥ 35 kg/m²
• Expected duration of surgery ≥ 2 h

A patient meeting any of the exclusion criteria listed below must be excluded from participating in the trial.

• Age < 18 years
• Previous lung surgery (any)
• Persistent hemodynamic instability, intractable shock (considered hemodynamically unsuitable for the study by the patient’s managing physician)
• History of previous severe chronic obstructive pulmonary disease (COPD) (non–invasive ventilation and/or oxygen therapy at home, repeated systemic corticosteroid therapy for acute exacerbations of COPD)
• Recent immunosuppressive medication (patients receiving chemotherapy or radiation therapy up to two months prior to surgery)
• Severe cardiac disease (New York Heart Association class III or IV, acute coronary syndrome or persistent ventricular tachyarrhythmias)
• Invasive mechanical ventilation longer than 30 minutes (e.g., general anesthesia for surgery) within last 30 days
• Pregnancy (excluded by anamneses and/or laboratory analysis)
• Prevalent acute respiratory distress syndrome expected to require prolonged postoperative mechanical ventilation
• Severe pulmonary arterial hypertension, defined as systolic pulmonary artery pressure > 40 mmHg
• Intracranial injury or tumor
• Need for intraoperative prone or lateral decubitus position
• Need for one-lung ventilation
• Cardiac surgery
• Neurosurgery
• Planned reintubation following surgery
• Enrolled in other interventional study or refusal of informed consent