Abstract
PARTICIPANTS in this workshop have so far discussed the clinical, radiologic, pathologic, and epidemiologic features of bronchopulmonary dysplasia and the factors related to its develoPment. It is apparent from these presentations that oxygen, endotracheal intubation, and positive pressure mechanical ventilation are major factors implicated in the pathogenesis of BPD. However, since positive pressure ventilation via endotracheal intubation delivers 'elevated oxygen concentrations under pressure directiy to the Pulmonary lining cells, the etiolog3/of BPD has remained controversial and is probably multifactorial. The toxic effects of oxygen on the lungs and on other tissues have been known for many years. 1-'~ Furthermore. it is not surprising that the lungs appear particularly sensitive to the toxic effects of oxygen ~n view of the high concentrations of oxygen to which its lining cells, both epithelial and endothelial, are directly exposed. Factors contributing to the occurrence of oxygen-induced lung injury include the concentration (or the partial pressure) of the inspired oxygen, the duration of exposure to oxygen, and the individual's susceptibility to oxygen damage, which is related to such factors as the metabolic rate and the level of endogenous antioxidant protection . . . . . The pathologic findings of pulmonary oxygen toxicity in the mammalian lung have been reasonably well established and have been the subject of a number of reviews. . . . . . Similar changes have been found in the human.7, s including the neonate. This pathology includes interstitial fibrosis: airway obstruction by eosinophilic debris which contains necrotic epithelial cells. mucus, and inflammatory cells; squamous metaplasia of
Published Version
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