Fetal lung growth after short-term tracheal occlusion is linearly related to intratracheal pressure

Prenatal tracheal occlusion (TO) has been shown to accelerate fetal lung growth, yet the mechanism is poorly understood. The goal of this study was to determine the relationship between fetal intratracheal pressure (Pitr) and fetal lung growth after TO. Fetal lambs underwent placement of an intratracheal catheter and a reference catheter at 115–120 days gestation (term, 145 days). Fetal Pitr was continuously controlled at three levels (high, 8 mmHg; moderate, 4 mmHg; low, 1 mmHg) by a servo-regulated pump. The animals were killed after 4 days, and the parameters of lung growth were compared. Lung volume (136.0 ± 16.7, 94.9 ± 9.7, 55.5 ± 12.4 ml/kg), lung-to-body weight ratio (6.31 ± 0.70, 4.89 ± 0.38, 3.39 ± 0.22%), whole right lung dry weight (3.01 ± 0.29, 2.53 ± 0.15, 2.07 ± 0.24 g/kg), right lung DNA (130.0 ± 11.3, 116.7 ± 8.6, 97.5 ± 10.9 mg/kg), and protein contents (1,865.5 ± 92.5, 1,657.6 ± 106.8, 1,312.0 ± 142.5 mg/kg) in high, moderate, and low groups, respectively, all increased in the moderate ...