Is oxygen toxic?

Hyperoxia involves the administration of high concentrations of inspired oxygen to the lung. Hyperoxemia reflects high levels of oxygen in the blood. In general, a PaO₂ >100 mm Hg/13.3 kPa reflects hyperoxia. Hyperoxia leads to development of reactive oxygen species (ROS). These ROS cause oxidative damage to the lung, nucleic acids, and proteins, leading to cellular injury and inflammation. Hyperoxic-induced lung injury probably contributes to the morbidity and mortality of ventilator-induced lung injury. Hyperoxia has been associated with infantile respiratory distress syndrome and ocular damage. In adults, hyperoxemia has been associated with worse outcomes in chronic obstructive pulmonary disease (COPD), flares, acute myocardial infarction, cardiac arrest, traumatic brain injury, and stroke. Therapeutic hyperoxemia to prevent surgical site infections remains controversial and may worsen long-term outcomes. Hyperbaric oxygen therapy has a limited number of indications and care must be taken to avoid seizures and other side effects of hyperoxemia.