Mechanical Ventilation in Obese Surgical Patients

Inclusion criteria

• Age ≥ 18 years;
• Body Mass Index (BMI) ≥ 35 kg/m2;
• 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

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