[The importance of oxygen free radicals in the neonatal period].

OBJECTIVE: Oxygen free radicals are extremely reactive species and they can lead to injury and cell death. The aim of this review is to study the main biochemical aspects of free radical formation and their role as an intermediate mechanism of injury in several neonatal diseases.METHODS: A brief history of oxygen therapy in neonatology and its relationship with complications associated with the production of free radicals. Definition, mechanism of action and antioxidant systems were described. Next, the neonatal factors of increased risk of free radical oxidative injury and the diseases associated with oxygen free radical toxicity were reviewed.RESULTS: Oxygen free radicals are reactive species that although crucial to normal biological processes, can lead to injury and cell death. They are implicated in the pathogenesis of many neonatal diseases such as perinatal asphyxia, bronchopulmonary dysplasia, retinopathy of prematurity, necrotizing enterocolitis, intracranial hemorrhage, pulmonary hypertension and persistence of ductus arteriosus. Birth is associated with transition to a hyperoxic environment in comparison with uterine environment, which leads to increased generation free radicals. The newborn has undeveloped antioxidant systems and, therefore, may be at increased risk of free radical oxidative injury.CONCLUSIONS: The understanding of neonatal factors involved in the pathogenesis of "oxygen free radical diseases" will lead to the development of new therapies for prevention and treatment of these neonatal diseases.