Postoperative respiratory failure, particularly after surgery under general anesthesia, adds to the morbidity and mortality of surgical patients. Anesthesiologists inconsistently use positive end–expiratory pressure (PEEP) and recruitment maneuvers in the hope that this may improve oxygenation and protect against postoperative pulmonary complications (PPCs), especially in obese patients. While it is uncertain whether a strategy that uses higher levels of PEEP with recruitment maneuvers truly prevents PPCs in these patients, use of higher levels of PEEP with recruitment maneuvers could compromise intra–operative hemodynamics. This study is a collaboration with The European Society of Anaesthesiology Clinical Trial Network.