Dangers of hyperoxia

Oxygen (O(2)) toxicity remains a concern, particularly to the lung. This is mainly related to excessive production of reactive oxygen species (ROS). Supplemental O(2), i.e. inspiratory O(2) concentrations (F(I)O(2)) > 0.21 may cause hyperoxaemia (i.e. arterial (a) PO(2) > 100 mmHg) and, subsequently, hyperoxia (increased tissue O(2) concentration), thereby enhancing ROS formation. Here, we review the pathophysiology of O(2) toxicity and the potential harms of supplemental O(2) in various ICU conditions. The current evidence base suggests that PaO(2) > 300 mmHg (40 kPa) should be avoided, but it remains uncertain whether there is an “optimal level” which may vary for given clinical conditions. Since even moderately supra-physiological PaO(2) may be associated with deleterious side effects, it seems advisable at present to titrate O(2) to maintain PaO(2) within the normal range, avoiding both hypoxaemia and excess hyperoxaemia. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s13054-021-03815-y.