Alterations in pulmonary mechanics in an animal model with nitrofen induced congenital diagraphmatic hernia (CDH) 1496

This study was designed to compare pulmonary mechanic changes in a nitrofen induced CDH animal model with controls. Methods: Dated pregant rats received nitrofen at 9 days of gestation and the fetuses were delivered at gestation day 21. Fetuses with the trachea cannulated were fully immersed in normal saline and placed on a precision balance and the lungs were inflated at stepwise pressure increments of 5 cm H₂O as previously described (1). A total of 31 studies were carried out. Nineteen controls, and 12 nitrofen treated. Of those 12 studies, 5 fetuses had CDH and 7 did not. Inflation and deflation curves were plotted for each study. The differences between the inflation and deflation lung volumes at same pressures were then calculated. Results: At pressures of 0, 20 and 25 cms of H₂0, lung volumes were significantly different among the three groups(Nitrofen with and without CDH and controls) by ANOVA. At pressure of 0 cms of H₂O animals with CDH retained greater lung volumes than animals of the other two groups (p < 0.008). At greater pressures, 20 and 25 cms of H₂O, the control animals retained greater lung volumes when compared with animals of both nitrofen groups (p < 0.02 for both). In conclusion, nitrofen influences lung mechanics, more so in the presence of CDH. We speculate that CDH by itself alters elasticity or surfactant production.Figure