Effect of Exogenous Surfactant on the Development of Bronchopulmonary Dysplasia in a Baboon Hyaline Membrane Disease Model

To test the effect of exogenous surfactant on the evolution of histopathologic changes of bronchopulmonary dysplasia (BPD), we conducted a study in a premature baboon hyaline membrane disease model. One hundred mg/kg bovine surfactant sonicated in saline or 3 ml/kg saline placebo was instilled via the trachea at about 10 min of age. The clinical status and physiologic changes were monitored for 9 days, and pulmonary histopathology was evaluated after death. Compared to the control, the surfactant-treated animals showed a significant improvement in arterial/alveolar oxygen ratio and pulmonary compliance, facilitating rapid weaning from assisted ventilation. Lung histology revealed that pulmonary parenchyma expanded 70% to 95% without features of early BPD. Dysplastic maturation, air trapping, or cellular atypia was not seen. In contrast, lung histology in the control group revealed alveolar expansion less than or equal to 50%, basal cell hyperplasia in the bronchial and bronchiolar epithelium, dysplastic maturation with cellular atypia, extensive epithelial erosion, and type II cell hyperplasia, all features of early BPD. The results of this study suggest that in the premature baboon model, exogenous surfactant therapy improves pulmonary functional abnormalities and lessens the histologic features of BPD, perhaps because of rapid weaning and reduced barotrauma.