Lung function in lambs with diaphragmatic hernia after reversible fetal tracheal occlusion

BACKGROUND/PURPOSE: Short-duration resuscitation (< or =4 hours) of lambs with diaphragmatic hernia treated in utero with tracheal occlusion have shown improved lung function compared with untreated diaphragmatic hernia. This may be a transient phenomenon in the treated diaphragmatic hernia lambs because of surfactant deficiency. Our objective was to analyze the effect of fetal tracheal occlusion with or without release of the occlusion 1 week before delivery on pulmonary function during a longer period of resuscitation (8 hours) in the diaphragmatic hernia lamb model. METHODS: Four groups were compared: diaphragmatic hernia (n = 5), diaphragmatic hernia and tracheal occlusion until delivery (n = 5), diaphragmatic hernia and tracheal occlusion with release of the occlusion 1 week before delivery (n = 5), and normal controls (n = 4). RESULTS: Despite persistently decreased surfactant levels, diaphragmatic hernia lambs treated with tracheal occlusion had normal-sized lungs with marked improvement in lung function and gas exchange over 8 hours when compared with untreated lambs with diaphragmatic hernia. Release of the tracheal occlusion 1 week before delivery added no benefit. CONCLUSIONS: It appears that surfactant-independent mechanisms such as pulmonary growth and structural changes are of foremost importance in relating to improved compliance, oxygenation, and ventilation of diaphragmatic hernia lambs treated with tracheal occlusion.