Blood glutathione redox ratio as a parameter of oxidative stress in premature infants with IRDS.

Oxygen toxicity is thought to play an important pathogenic role in several neonatal diseases, including idiopathic respiratory distress syndrome (IRDS). Therefore, the development of a reliable measure of the actual oxidative stress status of patients would be of great clinical significance. In order to obtain information about the oxidative stress during the first week of life in premature infants with IRDS, the blood concentrations of oxidized and reduced glutathione, as well as their molar ratios, were determined by a highly sensitive, specific enzymic assay. The fractional inspired oxygen concentrations needed to maintain adequate arterial oxygen tension and the arterio-alveolar oxygen ratios were chosen as parameters indicating the severity of illness in premature infants at a given time. There was a highly significant positive correlation between the glutathione redox ratios and the fractional inspired oxygen concentrations. A maturity-related difference was also found; the oxidized glutathione concentrations were the highest in the least mature infants, accompanied by a pronounced compensatory rise in the reduced glutathione concentrations as well. A significant negative correlation was found between the arterio-alveolar oxygen ratio and the glutathione redox ratio: i.e., an improvement in oxygenation was accompanied by a decrease in the glutathione redox ratio. The efficient recycling of reduced glutathione in erythrocytes providing antioxidant protection for premature infants, permits the use of the blood glutathione redox ratio as a noninvasive measure of in vivo oxidative stress.