Intrauterine tracheal obstruction, a new treatment for congenital diaphragmatic hernia, decreases amniotic fluid sodium and chloride concentrations in the fetal lamb.

Abstract

To evaluate the effect of fetal tracheal occlusion on sodium and chloride concentrations in amniotic and tracheal fluid. Intrauterine tracheal occlusion has been proposed to reverse pulmonary hypoplasia, an important prognostic factor in congenital diaphragmatic hernia. In early human trials, technical failure of the obstructive device has been reported. Eight fetal lambs (gestational age = 95 days) were subjected to fetal tracheoscopy, and amniotic and tracheal fluid samples were taken. In multiple pregnancies (n = 6), amniotic fluid was also sampled from the contralateral amniotic sac and used as a control. Subsequently, endotracheal obstruction, using a detachable balloon, was performed. After 14 days, all fetuses were delivered, and sodium and chloride concentrations in amniotic and tracheal fluid were measured again. Statistical analysis was done using a two-tailed Student's t test, paired or unpaired as appropriate. In controls, between 95 and 109 days gestational age, no significant changes occurred in sodium or chloride concentrations in amniotic or tracheal fluid. After 2 weeks of tracheal obstruction, however, chloride and sodium concentrations in amniotic fluid decreased (chloride = 76.7 mEq/L vs. 107.6 mEq/L, p = 0.0003; sodium = 109.6 mEq/L vs. 125.9 +/- 5.2 mEq/L, p = 0.019). A concomitant increase in chloride and sodium concentration was observed in tracheal fluid (chloride = 145.4 mEq/L vs. 130.0 mEq/L, p = 0.047; sodium = 153.1 mEq/L vs. 142.9 mEq/L, p = 0.051). When comparing groups at 109 days, chloride and sodium concentrations in amniotic fluid were markedly lower in the treated group versus controls (p = 0.0004 and p = 0.05 for chloride and sodium, respectively). Complete tracheal occlusion in ovine fetuses results in a significant decrease of amniotic fluid sodium and chloride concentrations.