TRACHEOSCOPIC ENDOTRACHEAL OCCLUSION IN THE OVINE MODEL - TECHNIQUE AND PULMONARY EFFECTS

Background/Purpose: The purpose of this study was to assess the trache oscopic placement of a detachable balloon to obstruct the trachea in t he fetal lamb model and to study the pulmonary effects 2 weeks later. Methods: Thirteen pregnant ewes carrying 27 fetuses were used in this trial. Thirteen fetuses underwent endotracheal plugging at a mean gest ational age of 95 (90 to 100) days (term, 145). Fourteen nonoperated f etuses served as controls. The intended duration of obstruction was 15 days. Study para meters consisted of operating time, fetal survival, performance of the balloon, and pulmonary changes. Results: Hysterotom y time was 41 +/- 25 minutes and tracheoscopy time was 7.2 +/- 3.4 min utes. There were no intraoperative deaths in this series. Postoperativ e fatalities occurred in 2 of 13 plugged fetuses and 1 of 14 controls. At completion of the experiment, the balloon was recovered intact in the trachea of 12 of 13 (92.3%) fetuses. The lung weight/body weight r atio was 76 +/- 16 mg/kg for plugged animals, while in controls it was 34 +/- 8 mg/kg (P = .0001). The lung volume/ body weight ratio was 10 1 +/- 17 mL/kg in plugged fetuses, compared with 47 +/- 4 mL/kg for co ntrols (P = .0002). Mean-terminal-bronchial-density was 0.937 +/- 0.30 3 for plugged animals, compared with 1.911 +/- 0.441 for controls (P = .0002). Mean linear intercept was 60.9 +/- 5.2 mu m in treated fetuse s, and 46.3 +/- 5.8 mu m for controls (P = .0004). Conclusions: Fetal endotracheal occlusion, using a tracheoscopically placed detachable ba lloon, is reliable, and results in pulmonary hyperplasia after 2 weeks of obstruction, This technique may be beneficial in treating the pulm onary hypoplasia seen in congenital diaphragmatic hernia, Further stud ies using this balloon device are now required to corroborate these fi ndings. Copyright(C) 1997 by W.B. Saunders Company.