Endogenous antioxidant defenses in neonates.

Deficiencies of antioxidant defenses have been postulated as possible mechanisms in the development of bronchopulmonary dysplasia (BPD). Neonates, especially prematures with respiratory distress syndrome (RDS), are exposed to high oxygen tensions for prolonged periods. To evaluate the neonates' ability to respond to an oxygen challenge with increased superoxide dismutase (SOD), 9 prematures were studied immediately at birth and on days 1, 3, 5, and 7. An increase in plasma levels was noted during the first week of life in the patients who were exposed to oxygen. The mean endogenous SOD level at birth was 1.28 microgram/ml. On day 1, plasma SOD rose to 1.53 microgram/ml and to 2.25 micrograms/ml on day 3 (P = .003). This trend continued into the fifth and seventh days. Whether this increase in SOD has clinical significance in the prevention of BPD requires further investigation.