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 (FIO2) > 0.21 may cause hyperoxaemia (i.e. arterial (a) PO2 > 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 PaO2 > 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 PaO2 may be associated with deleterious side effects, it seems advisable at present to titrate O-2 to maintain PaO2 within the normal range, avoiding both hypoxaemia and excess hyperoxaemia.

Automated summary

Oxygen toxicity is mainly related to the excessive production of reactive oxygen species, supplemental oxygen may cause hyperoxemia and hyperoxia which should be avoided, titrating oxygen to maintain PaO2 within the normal range is advisable to prevent deleterious side effects.