Oxygen is a commonly used therapy for a wide variety of cardiopulmonary disorders. It is effective in reversing arterial hypoxemia from all causes except pure venoarterial shunting. In the vast majority of patients, oxygen therapy is safe. Oxygen toxicity has been well studied in animal models, which have led to a detailed understanding of morphology, pathogenesis, and treatment of this form of acute lung injury. In contrast, there remain significant gaps in the understanding of oxygen toxicity in humans. Pulmonary oxygen toxicity in humans is most likely to occur in the intensive care unit setting when patients are exposed to high concentrations of oxygen for prolonged time intervals. These patients usually have acute lung injury and other concurrent illnesses making it difficult to extrapolate information from animal studies and normal humans. There are no currently available techniques to diagnose oxygen toxicity in these patients, and there are no definitive guidelines for what constitutes a 'safe' amount of oxygen exposure. The best treatment is prevention, which consists of limiting oxygen exposure to the lowest F102 that supports a Pao2 of 55 to 60 torr. Clinical experience suggests that this strategy is usually effective and raises questions about the importance of oxygen toxicity in critically ill patients. It is possible that the lungs of critically ill patients are better able to withstand the injurious effects of oxygen than normal lungs. This article stun information about nonnobaric oxygen toxicity obtained from animal models and humans and addresses controversies that relate to oxygen therapy in critically ill patients.
- Free radicals
- Mechanical ventilation
- Oxygen toxicity
ASJC Scopus subject areas
- Pulmonary and Respiratory Medicine
- Critical Care and Intensive Care Medicine