Chest radiographic course after exogenous surfactant therapy in baboons with respiratory distress syndrome.

Exogenous surfactant materials have been used under a variety of treatment protocols in cases of neonatal respiratory distress syndrome (RDS). To evaluate the differences in radiologic changes that follow either an early or late therapy with exogenous bovine surfactant, we reviewed 189 serially obtained chest radiographs from 48 premature baboons with RDS studied under different treatment regimen. Twenty-six animals were controls (100 chest films), and 22 received 100 mg/kg bovine surfactant instilled via the trachea in three study protocols (89 chest films). Surfactant was given within 10 min of birth in one group and at 2 h of age in the other. In 25/26 controls, radiologic evidence of severe RDS was seen by 2 h of age; these changes persisted in 15 animals at 24 h. By contrast, a rapid clearing of radiologic features of RDS was seen following surfactant instillation in all 22 (100%) animals within 4 h, but one (4.5%) of these 22 deteriorated at 9 h of age. Pulmonary interstitial emphysema (PIE) was seen in 9/26 (34.6%) and pneumothorax in 5/26 (19.2%) control animals, while 1/22 (4.5%) surfactant-treated animals developed PIE, and none had pneumothorax. The presence of a shunt via the patent ductus arteriosus did not affect radiographic findings in 20 animals studied by contrast injection. Therapy for patent ductus arteriosus (PDA) also had no substantial influence on the radiographic findings, or with regard to the pulmonary course. Radiographic clearing of RDS occurred approximately 18 to 20 h prior to the improvement in pulmonary compliance.(ABSTRACT TRUNCATED AT 250 WORDS)