Nasal high flow cannula (NHFC) has been described as an attractive and well-tolerated method of non-invasive oxygen delivery. Previous studies have shown that NHFC generates a low level of positive airway pressure, increases end-expiratory lung volume and reduces airway resistance, thus contributing to a reduction in work of breathing. To date, however, no clinical trials have compared NHFC to standard oxygen therapy in the prevention of postoperative hypoxemia after abdominal surgery in patients with intermediate to high risk of postoperative pulmonary complications.