TRACHEAL LIGATION DOES NOT CORRECT THE SURFACTANT DEFICIENCY ASSOCIATED WITH CONGENITAL DIAPHRAGMATIC-HERNIA

Introduction: Experimental tracheal ligation (CDH + TL) has been shown to reverse the profound lung hypoplasia associated with congenital di aphragmatic hernia (CDH) and to normalize gas exchange. The aim of thi s study was to determine whether this experimental therapy would corre ct the surfactant deficiency present in the fetal lamb model of CDH. M ethods: The CDH lamb model was created at 80 days' gestation, and trac heal ligation was performed at 110 days. At term, the lambs were deliv ered and were ventilated for 30 minutes. The lambs were killed, a pres sure volume curve performed, and the lungs lavaged to measure total li pid content. Finally, type II pneumocytes were isolated, and surfactan t synthesis was assessed by the incorporation of tritiated choline int o phosphatidylcholine. Results: CDH + TL resulted in a lung significan tly larger than that of CDH alone, The lungs of the former also had be tter oxygenation and ventilation. However, lung compliance was reduced compared with controls. Total alveolar phospholipid was dramatically lower, with a decrease in the proportion of phosphatidylcholine presen t. Surfactant synthesis by the isolated type II pneumocyte was signifi cantly impaired. Conclusion: Occlusion of the fetal trachea produces a lung comparable in size to a normal control lung. However, broncheoal veolar ravage analysis shows a marked reduction in total phospholipid, with a decrease in surfactant synthesis by the type II pneumocyte. Th e normalization of gas exchange reported for this animal model may be only a transient phenomenon. Further studies are required to assess th e impact of this surfactant deficiency on long-term lung function. (C) 1996 by W.B. Saunders Company