THE PLUG ODSSSEY - ADVENTURES IN EXPERIMENTAL FETAL TRACHEAL OCCLUSION

In animal experiments, it has been Shown that tracheal occlusion count eracts the pulmonary hypoplasia associated with congenital diaphragmat ic hernia (CDH). Successful clinical implementation requires a reliabl e, reversible, and atraumatic technique of occluding the fetal trachea . With this clinical goal in mind, the authors evaluated the following three methods of tracheal occlusion in a fetal lamb CDH model: (1) an occluded foam-cuffed endotracheal tube, (2) a foam-cuffed endotrachea l tube with a magnetically controlled-flow valve, and (3) a tracheal i nsert constructed of a water impermeable, expandable, polymeric foam, which is placed by a translaryngeal approach. The foam-cuffed endotrac heal tube did not provide consistently reliable fetal tracheal occlusi on. Although the magnetically triggered flow valve functioned well, it was not necessary to open the valve in utero (to prevent overdistensi on of the lungs), and the presence of the valve contributed to several occlusive failures. In contrast, the foam insert was easy to position and to remove from the trachea, while providing reliable tracheal occ lusion for several weeks with consequent enlarged fetal lungs, increas ed lung fluid volumes, complete reduction of abdominal viscera, and im proved pulmonary gas exchange after birth. Bronchoscopic evaluation of the foam-occluded neonatal tracheas showed little or no tracheal dama ge, which was confirmed during necropsy by gross and histological exam ination. Translaryngeal placement of a compressible, water-impermeable polymeric foam appears to be a simple and safe technique to achieve f etal tracheal occlusion. Copyright (C) 1995 by W.B. Saunders Company