Oxygen administration during general anaesthesia for surgery

Oxygen is routinely administered to almost all patients undergoing general anaesthesia,1 to ensure adequate oxygenation from intubation until awakening—the period when complications due to hypoxaemia are most likely to occur.2 Currently, the optimal target for oxygen administration is not yet clear and varies from normal arterial oxygen saturation to hyperoxaemia (usually defined as >97-98% arterial oxygen saturation). The hyperoxaemia strategy has been widely used since a seminal study highlighted the benefits of liberal (80%) compared with restrictive (30-35%) inspired oxygen to reduce the risk of postoperative infection.3 Accordingly, the 2016 World Health Organization guidelines recommend that patients receive a liberal fraction of inspired oxygen during general anaesthesia and in the immediate postoperative period.45

Basic research, however, shows that oxygen can be a double edged sword.6 It is a fundamental substrate for the oxidative phosphorylation that feeds biological energy to every aerobic cell. But in certain circumstances, oxygen may give rise to highly reactive …