Pulmonary epithelial permeability in hyaline-membrane disease.

Neonatal hyaline-membrane disease is complicated by pulmonary edema, yet left atrial pressures are normal. Alveolar-capillary-membrane permeability may therefore be increased. To assess pulmonary epithelial permeability, we measured the pulmonary clearance and half-life of aerosolized 99mTc-diethylenetriamine pentacetate (99mTc-DTPA) on 31 occasions in 15 intubated premature infants with hyaline-membrane disease. Three infants with respiratory failure due to other diseases were studied on four occasions. All studies of infants with hyaline-membrane disease that were performed in the first 72 hours of life demonstrated a biphasic clearance curve with a rapid-phase half-life of 1.6 +/- 0.6 minutes (mean +/- S.D.). As these infants recovered, the curve became monophasic with a half-life of 56.0 +/- 32.1 minutes. Two infants remained dependent on oxygen and ventilator support and had persistent biphasic curves with a rapid-phase half-life of 1.5 +/- 0.7 minutes. All infants without hyaline-membrane disease had monophasic curves with a half-life of 65.4 +/- 33.6 minutes. Using a similar technique, we observed that newborn lambs and piglets have a monophasic pulmonary clearance of 99mTc-DTPA (114 +/- 59 minutes in lambs and 52.5 +/- 16.3 minutes in piglets). We conclude that the lungs of neonates with hyaline-membrane disease are abnormally permeable to small solutes and that this abnormality persists in infants with subsequent chronic lung disease.