CORRECTION OF CONGENITAL DIAPHRAGMATIC-HERNIA IN-UTERO .8. RESPONSE OF THE HYPOPLASTIC LUNG TO TRACHEAL OCCLUSION

Most fetuses with congenital diaphragmatic hernia (CDH) diagnosed befo re 24 weeks' gestation die despite optimal postnatal care. In fetuses with liver herniation into the chest, prenatal repair has not been suc cessful. In the course of exploring the pathophysiology of CDH and its repair in fetal lambs, the authors found that obstructing the normal egress of fetal lung fluid enlarges developing fetal lungs, reduces th e herniated viscera, and accelerates lung growth, resulting in improve d pulmonary function after birth. They developed and tested experiment ally a variety of methods to temporarily occlude the fetal trachea, al low fetal lung growth, and reverse the obstruction at birth. The autho rs applied this strategy of temporary tracheal occlusion in eight huma n fetuses with CDH and liver herniation at 25 to 28 weeks' gestation. With ongoing experimental and clinical experience, the technique of tr acheal occlusion evolved from an internal plug (two patients) to an ex ternal clip (six patients), and a technique was developed for unpluggi ng the trachea at the time of birth (Ex Utero Intrapartum Tracheoplast y [EXIT]). Two fetuses had a foam plug placed inside the trachea. The first showed dramatic lung growth in utero and survived; the second (w ho had a smaller plug to avoid tracheomalacia) showed no demonstrable lung growth and died at birth. Two fetuses had external spring-loaded aneurysm clips placed on the trachea; one was aborted due to tocolytic failure, and the other showed no lung growth (presumed leak) and died 3 months after birth. Four fetuses had metal clips placed on the trac hea. All showed dramatic lung growth in utero, with reversal of pulmon ary hypoplasia documented after birth. However, all died of nonpulmona ry causes. Temporary occlusion of the fetal trachea accelerates fetal lung growth and ameliorates the often fatal pulmonary hypoplasia assoc iated with severe CDH. Although the strategy is physiologically sound and technically feasible, complications encountered during the evoluti on of these techniques have limited the survival rate. Further evoluti on of this technique is required before it can be recommended as thera py for fetal pulmonary hypoplasia. Copyright (C) 1996 by W.B. Saunders Company