Special considerations in oxygen therapy of infants and children.

There are several unique aspects of O2 therapy in infants. Inhalation of O2 by preterm infants decreases the frequency of apnea and cyanosis, and increases the ventilatory response to CO2, but the reasons for this are unclear. Immature infants receiving O2 therapy are subject to retinopathy, but we do not know the magnitude or duration of hyperoxia necessary to damage the developing retina. Newborns with persistent pulmonary hypertension, without radiographic signs of pulmonary disease, frequently remain hypoxemic despite breathing 100% O2. In these infants, the unresponsiveness of teh postnatal pulmonary circulation to high concentrations of inspired O2 needs elucidation. Babies with respiratory failure who are treated with O2 and mechanical ventilation often acquire chronic pulmonary disease. The etiologic importance of O2 compared to postive airway pressure in the development of this condition remains controversial. Some laboratory studies suggest that newborn animals are resistant to pulmonary injury from O2; other studies indicate that youth offers no protection. The results of experiments carried out with newborn mice and lambs provide evidence that diet may be an important element in the susceptibility of newborn animals to pulmonary O2 toxicity.