Mechanical Ventilation in Obese Surgical Patients

Inclusion Criteria:

1. Age ≥ 18 years;
2. Body Mass Index (BMI) ≥ 35 kg/m2;
3. Scheduled for laparoscopic surgery expected to exceed 2h (from incision to closure) under general anesthesia, as determined pre-operatively by the attending surgeon and surgical team based on typical scheduling estimates, prior experience, procedure type, planned surgical approach, and patient-specific factors.

Exclusion Criteria:

1. Previous lung surgery;
2. Invasive mechanical ventilation for \>30 minutes within the last 30 days prior to surgery;
3. Receipt of immunosuppressive medication (chemotherapy or radiotherapy) up to two months prior to surgery;
4. Neurological procedures or cardiac surgery;
5. Need for one-lung ventilation or planned re-intubation following surgery;
6. Requirement for intraoperative prone or lateral decubitus positioning;
7. Enrollment in another interventional study or refusal to give written informed consent;
8. Pregnancy, determined by anamnesis and/or laboratory testing;
9. Persistent hemodynamic instability or intractable shock, considered hemodynamically unsuitable for the study by the patient's managing physician;
10. Severe chronic obstructive pulmonary disease (COPD, defined as non-invasive ventilation and/or oxygen therapy at home or repeated systemic corticosteroid therapy for acute exacerbations of COPD);
11. Severe cardiac disease (defined as New York Heart Association class III or IV, acute coronary syndrome or persistent ventricular tachyarrhythmia);
12. Acute respiratory distress syndrome (according to the Berlin definition 2) expected to require prolonged postoperative mechanical ventilation;
13. Severe pulmonary arterial hypertension (defined as systolic pulmonary artery pressure \> 40 mmHg)
14. Intracranial injury, intracranial tumor, or neuromuscular disease;
15. Known esophageal disease or anatomy that would preclude the safe placement of a standard orogastric tube