Impact of oxygen therapy on antioxidant status in newborns. Relationship with infection risk.

Newborns requiring intensive clinical care are susceptible to a wide range of excessive oxygen free radical production-related problems. In utero, fetal organs, particularly lungs, are exposed to relatively hypoxic tensions which rise abruptly after birth and this transition may cause oxidative injury in the neonate. The aims of this study were to determine oxygen free radical activity in neonates at the first 24 h, examine the role of immaturity and infection risk and compare the degree of oxidant stress in newborns treated with different oxygen concentrations. Plasma selenium levels in neonates with high infection risk (IR) were significantly lower than in healthy neonates. Comparative study of selenium in preterm, term and young infants showed age-related increases and differences were significant. Plasma selenium values were lower when oxygen therapy was administered. Vitamin E levels were significantly decreased in IR compared with healthy newborns. The results suggest that selenium and vitamin E deficiencies predispose to neonatal infection and that supplementary oxygen contributes significantly to decreasing the antioxidant defence system.