The PROBESE trial aims at comparing the effects of higher levels of PEEP with recruitment maneuvers versus lower levels of PEEP without recruitment maneuvers on pulmonary outcome measures during general anesthesia for surgery for obese patients at intermediate–to–high risk for PPCs and undergoing mechanical ventilation with lower tidal volumes.

The secondary objectives are to test whether higher PEEP levels combined with recruitment maneuvers as compared to lower PEEP levels without recruitment maneuvers during intraoperative mechanical ventilation:

• effects on intraoperative complications
• decreases the need for postoperative ventilatory support
• decreases the need for unexpected admission to intensive care unit (ICU)
• reduces the overall hospital-free days at postoperative day 90
• reduces mortality at day 90
• causes a reduction in postoperative extra-pulmonary complications
• influences wound healing

Proportion of patients with postoperative pulmonary complications (aspiration pneumonitis, bronchospasm, mild/moderate/severe respiratory failure, acute respiratory distress syndrome (ARDS), pulmonary infection, atelectasis, cardiopulmonary edema, pleural effusion, penumothorax, new pulmonary inflitrates on chest X-ray)

• Intra–operative complications, i.e., complications related to the ventilation strategy
• Need for postoperative ventilatory support (invasive or non–invasive ventilation)
• Unexpected need for ICU admission (i.e., before surgery the patient is not scheduled for ICU admission, but is admitted eventually)
• ICU readmission within 30 days
• Need for hospital readmission within 30 days
• Hospital–free days at day 90
• Mortality at day 90
• Postoperative extra–pulmonary complications
• Postoperative wound healing
• Systemic levels of markers of (pulmonary) inflammation
• Systemic levels of markers of lung injury
• Systemic levels of markers of distal organ injury