AbstractObjective:To compare endotracheal fluid (EF) and amniotic fluid (AF) phospholipidic profile changes following tracheal occlusion (TO) in the congenital diaphragmatic hernia (CDH) fetal lamb model, in order to support the efficacy of TO on lung maturity.Methods:A diaphragmatic defect was induced at 70 days’ gestation, TO was carried out at day 102 and cesarean section at 136 days’ gestation. EF and AF samples, collected at delivery, were evaluated using mass spectrometry (the analysis focused on palmitoyloleoyl-phosphatidylcholine [POPC, PC(18:1/16:0)], dipalmitoyl-phosphatidylcholine [DPPC, PC(16:0/16:0)] and sphingomyelins [SMs]).Results:The effects of CDH and TO were different on AF and EF. POPC levels were higher than DPPC levels in AF of healthy lambs. Following induction of the diaphragmatic malformation, an evident decrease in POPC was noted, while a substantial return to normal POPC levels and an increased DPPC peak were prompted by the TO. After CDH induction, a decrease in N-palmitoyl-D-sphingomyelin [SM(d18:1/16:0)] was revealed (P<0.01) and an increased peak in SMs in AF was prompted by the TO (P=0.05). While the most represented phosphatidylcholine (PC) species in EF of healthy lambs was DPPC, CDH induced a decrease in the DPPC peak and treatment with TO induced its partial recovery. SMs were detectable only in healthy EF samples.Conclusion:The phospholipid recovery profile following TO suggests the potential role of this therapy in restoring processes involved in surfactant-mediated lung maturation, even though other interactions involved in AF turnover should be considered. Moreover, these metabolites could be used as biomarkers of fetal pulmonary development.