Oxidative Stress in Asphyxiated Term Infants Resuscitated With 100% Oxygen

Abstract

Although room air is adequate for resuscitating asphyxiated newborn infants, guidelines recommend using 100% oxygen. Hyperoxemia, as has been noted in animal studies, could cause delayed breathing, increased oxygen consumption, and disordered cerebral circulation. In addition, 100% oxygen has caused prolonged oxidation of blood glutathione in neonates. In this study, 51 asphyxiated neonates born at term were randomly assigned to resuscitation with room air (RAR) and 55 to resuscitation with 100% oxygen (OxR). The goal was to learn whether using oxygen for resuscitation triggers oxidative stress. Critical criteria were the Apgar score, the time of the first cry, and sustained respiration. Signs of asphyxia included hypotonia, apnea, a lack of response to external stimuli, pallor, bradycardia, and acidosis. Cesarean delivery was more than twice as frequent in asphyxiated infants than in control subjects, and 1- and 5-minute Apgar scores were reduced. Infants in both experimental groups took significantly longer to the first cry, but the RAR group needed less time of ventilation for resuscitation time than the OxR group (5.3 vs. 6.8 minutes). Hyperoxemia was associated with oxygen resuscitation but not with the use of room air (PO 2 of 126 and 72 mm Hg, respectively). Whole blood levels of reduced glutathione were decreased in both asphyxiated groups; and oxidized glutathione, glutathione cycle enzymes, and superoxide dismutase activity were increased. These changes were, however, significantly greater in the OxR group than in RAR infants. Follow up after the first week of lite and at age 4 weeks showed no differences between the experimental groups. These findings show that asphyxia of newborn infants causes oxidative stress, and that resuscitating them with 100% oxygen causes hyperoxemia and increases oxidative stress. The investigators conclude that room air might be preferable for resuscitating these infants.