Radiographic Features of Pulmonary Oxygen Toxicity in the Newborn: Bronchopulmonary Dysplasia

Abstract

A new syndrome of pulmonary disease following prolonged oxygen and respirator therapy of the respiratory distress syndrome of the newborn has recently been reported (13). This disease entity has been called bronchopulmonary dysplasia to emphasize the involvement of all the tissues of the developing lung in the pathologic process. It is believed to represent the toxic manifestations of 80–100 per cent oxygen (high O2) on the developing lung superimposed upon the healing phase of respiratory distress syndrome. Based on clinical, radiologic, and pathologic findings, bronchopulmonary dysplasia has been divided into four stages: Stage I: Clinically and radiographically resembles ordinary respiratory distress syndrome except for excessive mucosal necrosis (one to three days of age). Stage II: Characterized by marked radiopacity of the lungs, inability to be weaned from high O2, and cycles of alveolar injury and repair (four to ten days of age). Stage III: Radiographic cystic appearance of the lungs with respiratory mucosal lesions, focal emphysema and persistence of hyaline membranes, and gradual weaning from high O2 (ten to twenty days of age). Stage IV: Symptomatic chronic lung disease predominant, with strands of pulmonary parenchymal density, increased thoracic volume, and cardiomegaly which may gradually clear or progress to cor pulmonale and death (beyond one month of age). This communication documents in greater detail the characteristic radiographic evolution of the pulmonary changes seen in this syndrome. Clinical Findings The 32 patients presented in the original report represented all the infants with severe respiratory distress syndrome, but without serious congenital abnormalities, who required twenty-four hours or more of continuous intermittent positive pressure respiration with high O2 as a lifesaving measure at the Stanford Premature Infant Research Center from September 1962 to November 1965. The patients selected for respirator therapy had failed to respond to more conservative therapy (antibiotics, control of body temperature, intravenous glucose and sodium bicarbonate to combat acidosis) and were cyanotic in 100 per cent oxygen, appeared moribund, and had undergone one or more prolonged apneic spells. The appearance of chronic lung disease—the late stage of bronchopulmonary dysplasia—was seen in only those infants who received more than six days (one hundred and fifty hours) of continuous high O2 therapy and lived longer than four weeks. Of the 13 infants treated with high O2 in excess of six days, 9 lived beyond four weeks of age. All 9 demonstrated prolonged pulmonary disease with cyanosis when crying or out of supplemental O2, and fine, diffuse râles were heard throughout the lungs or at the lung bases. Five of these infants died with cardiac enlargement and cor pulmonale between one and eleven months of age.