[Mechanisms of oxygen-induced lung injury]

Normobaric oxygen is responsible for pulmonary lesions which probably result from excessive production of free radicals derived from oxygen. The lung contains a number of enzymatic systems (superoxide dismutase, catalase, glutathione peroxidase) or non enzymatic systems (vitamins C and E, glutathione) capable of preventing lesions induced by these radicals. However the respective role of the various antioxidants in this tolerance to oxygen remains uncertain. The intra- or extracellular sites of overproduction of free radicals appear to involve different toxic mechanisms. Numerous aspects of pulmonary oxygen toxicity are still poorly understood, but studies in vitro show promises of forthcoming progress in this field of pathophysiology.