Pulmonary epithelial permeability in hyaline-membrane disease

Area of Science:

• Neonatal Medicine
• Pulmonary Physiology
• Radiopharmaceutical Imaging

Background:

• Neonatal hyaline-membrane disease (HMD) is often associated with pulmonary edema despite normal left atrial pressures.
• This suggests increased permeability of the alveolar-capillary membrane in affected neonates.

Purpose of the Study:

• To assess pulmonary epithelial permeability in premature infants with HMD.
• To investigate the persistence of abnormal permeability and its potential link to chronic lung disease.

Main Methods:

• Measured pulmonary clearance and half-life of aerosolized 99mTc-diethylenetriamine pentacetate (99mTc-DTPA).
• Studied 15 intubated premature infants with HMD and 3 infants with other respiratory failure.
• Compared findings in HMD infants with healthy controls and animal models (lambs, piglets).

Main Results:

• Infants with HMD showed biphasic 99mTc-DTPA clearance (rapid-phase half-life: 1.6 ± 0.6 min) in the first 72 hours.
• Recovering HMD infants and healthy infants exhibited monophasic clearance (half-life: 56.0 ± 32.1 min and 65.4 ± 33.6 min, respectively).
• Persistent biphasic curves were observed in infants with ongoing respiratory support.

Conclusions:

• Neonates with HMD have abnormally increased pulmonary epithelial permeability to small solutes.
• This increased permeability is a characteristic finding in HMD and may persist, contributing to chronic lung disease in infants.