FETAL LUNG COMPLIANCE IN PREMATURE AND TERM LAMBS AFTER 2 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 th e ''silo'' repair method were assessed in 55 lambs by measuring the st atic respiratory system compliance (CST,RS) at birth in term (approxim ately 145 day) and in premature (128 day) animals. Results - Both meth ods resulted in similar improvements in CST,RS in term lambs, but in p remature 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 we ight or a measure of lung volume showed there was no difference betwee n any experimental groups in either term or premature lambs. Conclusio ns - These findings suggest that there was no difference in the intrin sic compliance of the lung tissue between normal, unrepaired and repai red animals, and that the differences in respiratory system compliance measured at birth may be due primarily to differences in lung size. T he silo repair method appears to provide an earlier improvement in CST ,RS than the patch repair method.