Arterio-venous extracorporeal membrane oxygenation of fetal goat incubated in artificial amniotic fluid (Artificial placenta): Influence on lung growth and maturation

Abstract

Purpose: The authors attempted to achieve extrauterine support of goat fetuses using arteriovenous extracorporeal membrane oxygenation (A-V ECMO) via umbilical vessels, incubated in a warm bath. They hypothesized that this extrauterine support system affected both the lung growth and maturation of goat fetuses. Methods: Four goat fetuses at about 125 days' gestation (term, 150 days) were placed in this fetal ECMO system. Their four twin fetuses with similar body weights were harvested and examined for baseline data before ECMO (pre-ECMO data). The mean duration of A-V ECMO was 138.8 ± 66.9 hours (range, 87 to 237 hours). Tracheal ligation was performed on all four fetuses to prevent the efflux of fetal tracheal fluid and to collect a sample of tracheal fluid daily. The surfactant and electrolytes of the tracheal fluid were analyzed in pre-ECMO (twin fetuses) and during ECMO. The surfactant of lung tissue, and lung weight were analyzed in pre-ECMO (twin fetuses) and after ECMO. Plasma cortisol and T3 levels were also assayed as hormonal factors that affected lung maturation in pre-ECMO and during ECMO. Results: The phospholipid, phosphatidylcholine, and lecithin-sphingomyelin ratio of the tracheal fluid on day 5 during ECMO (15.0 ± 7.1 mg/dL, 53.4 ± 26.5%, and 6.2 ± 7.1) were elevated above pre-ECMO (10.0 ± 4.6 mg/dL, 43.0 ± 0.6%, and 4.0 ± 2.9), but there were no significant differences. The phosphatidylcholine and disaturated phosphatidylcholine of the lung tissue after ECMO were 72.3 ± 15.4 mg/g and 19.2 ± 8.2 mg/g, which were significantly higher than pre-ECMO (53.7 ± 13.9 mg/g and 11.6 ± 4.1 mg/g). The Cl − and K + of the tracheal fluid were 123.5 ± 6.2 mEq/L and 3.7 ± 0.7 mEq/L on day 1 during ECMO, which were significantly lower than pre-ECMO (141.8 ± 2.9 mEq/L and 6.8 ± 1.1 mEq/L), but they then recovered to pre-ECMO levels. The wet and dry lung weights after ECMO were 87.8 ± 18.0 g and 6.3 ± 1.9 g, which were significantly higher than pre-ECMO (49.3 ± 5.9 g and 4.2 ± 1.3 g). Plasma cortisol levels and T3 levels during ECMO were significantly higher than pre-ECMO. Electron microscopy demonstrated a higher increase of mature type II cells in the lungs after ECMO than pre-ECMO. Conclusion: This fetal A-V ECMO system in the bath showed a production of surfactant, the maintenance of ion transport by the pulmonary epithelium, an increase in lung weight, and an increase in mature type II cells, resulting in lung growth and maturation.