Tracheal occlusion: A review of obstructing fetal lungs to make them grow and mature

Abstract

Fetal lung growth and functional differentiation are affected strongly by the extent that pulmonary tissue is distended (expanded) by liquid that naturally fills developing future airspaces. Methods that prevent normal egress of this lung fluid through the trachea magnify mechanical stretching of lung parenchymal cells, thereby promoting lung development. Indeed, experimental observations demonstrate that in utero tracheal occlusion (TO) performed on fetuses during the late canalicular-early saccular stage potently stimulates pulmonary growth and maturation. In this review, we present the four principle non-human animal models of TO/obstruction and discuss them in relation to their utility in elucidating lung development, in remedying congenital diaphragmatic hernia (CDH) as well as in investigating the stretching effects on growth and remodeling of the fine vasculature.

Predictors of neonatal morbidity in fetuses with severe isolated congenital diaphragmatic hernia undergoing fetoscopic tracheal occlusion

“…However, even after correction for gestational age at birth, early prenatal balloon removal improved the chances of survival. In animal experiments, cyclical or temporary occlusion has been shown to improve lung maturation 26,27,31 . This might also be the case clinically, although early morbidity parameters were unaffected by prenatal balloon removal.…”

“…The FETO procedure has been described in detail 22,23,28 . Briefly it consists of the percutaneous fetoscopic insertion of a balloon into the fetal trachea, which in general is performed at approximately 26-28 (range, [23][24][25][26][27][28][29][30][31][32][33] weeks' gestation. The balloon is preferentially removed in utero at approximately 34 weeks by tracheoscopy or ultrasound-guided puncture.…”

The making of fetal surgery

“…Nearly normal lung growth and maturation was achieved in sheep by a cyclical occlusion protocol, that is, a 47 h occlusion period altered by 1 h release, and this between 110 and 138 days (Nelson et al, 2005). For further details on these and other studies related to experimental tracheal occlusion, we refer to some comprehensive reviews (Nelson et al, 2006;Khan et al, 2007).…”

Clinical Syndromes and Associations with Persistent Pulmonary Hypertension of the Newborn

“…A number of animal studies have demonstrated that surgical tracheal occlusion applied during the canalicular and saccular stages of lung development not only improves dry lung weight but also increases airway branching, alveolarization, alveolar surface area, type II pneumocytes and pulmonary vascular growth (Khan, Cloutier, & Piedboeuf, 2007).…”