Introduction: Despite many relevant advances in neonatal intensive care, the mortality rate of newborns with CDH is still high, due to pulmonary alterations. In a previous report, we described an experimental model of CDH in rabbits and demonstrated that pulmonary hipoplasia was obtained (J Ped Surg 29:882, 1994). In the present study, we investigated if the intraamniotic administration of surfactant could reverse the functional and structural changes of the lungs in the animals with CDH. Matherial and Methods: Pregnant New Zealand rabbits were operated on gestational day 24 or 25. A midline laparotomy was performed to expose the bicornuate uterus and the most distal fetus of the each horn was chosen to be operated. The left foreleg was exteriorized through a linear histerotomy, to permit the exposition of the corresponding chest wall. A low lateral thoracotomy was performed and the diaphragm was partially excised. Thoracotomy, histerotomy and the maternal laparotomy were then closed. In a group of six fetus, 0.5ml(40mg) of Curosurf was injected in the amniotic cavity just after performing the closure of histerostomy. On gestational day 30, the fetus were delivered by cesarean section and the lungs, bronchi and trachea were removed. The lungs were submitted to study of compliance and the left lung was submitted to morphological (weight and volume) and morphometric analysis (alveolar septs and the number of alveoli/mm2). The lungs were divided in three groups, acording to the previous procedure. Results: Are expressed as mean±SD Conclusion: The administration of surfactant could not reverse the changes in weight and volume of the lungs associated with CDH, but improved morphometric parameters and partially corrected the decrease in the compliance. Table

Table 1