Fetal lung compliance in premature and term lambs after two methods of in utero repair of diaphragmatic hernia.

BACKGROUND

In utero surgery was used to correct a surgically induced model of congenital diaphragmatic hernia (CDH) in premature and term lambs, resulting in an improvement in lung mechanics at birth.

METHODS

The differences between the in utero "patch" repair method and the "silo" repair method were assessed in 55 lambs by measuring the static respiratory system compliance (CST,RS) at birth in term (approximately 145 day) and in premature (128 day) animals.

RESULTS

Both methods resulted in similar improvements in CST,RS in term lambs, but in premature lambs only the silo method produced an increase in compliance. Comparisons of specific compliance related to length or birth weight did not alter these findings; however, corrections related to lung weight or a measure of lung volume showed there was no difference between any experimental groups in either term or premature lambs.

CONCLUSIONS

These findings suggest that there was no difference in the intrinsic compliance of the lung tissue between normal, unrepaired and repaired animals, and that the differences in respiratory system compliance measured at birth may be due primarily to differences in lung size. The silo repair method appears to provide an earlier improvement in CST,RS than the patch repair method.