INTRAUTERINE TRACHEAL OBSTRUCTION, A NEW TREATMENT FOR CONGENITAL DIAPHRAGMATIC-HERNIA, DECREASES AMNIOTIC-FLUID SODIUM AND CHLORIDE CONCENTRATIONS IN THE FETAL LAMB

Objective To evaluate the effect of fetal tracheal occlusion on sodium and chloride concentrations in amniotic and tracheal fluid. Summary B ackground Data Intrauterine tracheal occlusion has been proposed to re verse pulmonary hypoplasia, an important prognostic factor in congenit al diaphragmatic hernia. In early human trials, technical failure of t he obstructive device has been reported. Methods Eight fetal lambs (ge stational age = 95 days) were subjected to fetal tracheoscopy, and amn iotic and tracheal fluid samples were taken. in multiple pregnancies ( n = 6), amniotic fluid was also sampled from the contralateral amnioti c sac and used as a control. Subsequently, endotracheal obstruction, u sing a detachable balloon, was performed. After 14 days, all fetuses w ere delivered, and sodium and chloride concentrations in amniotic and tracheal fluid were measured again. Statistical analysis was done usin g a two-tailed Student's t test, paired or unpaired as appropriate. Re sults In controls, between 95 and 109 days gestational age, no signifi cant changes occurred in sodium or chloride concentrations in amniotic or tracheal fluid. After 2 weeks of tracheal obstruction, however, ch loride 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. 12 5.9 +/- 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 c oncentrations in amniotic fluid were markedly lower in the treated gro up versus controls (p = 0.0004 and p = 0.05 for chloride and sodium, r espectively). Conclusion Complete tracheal occlusion in ovine fetuses results in a significant decrease of amniotic fluid sodium and chlorid e concentrations.