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Lung vascular permeability changes in lambs with hyaline membrane disease
H W Sundell1, J Grogaard, J Rojas
1Newborn Lung Center, Vanderbilt University School of Medicine, Nashville, Tennessee 37232.
Journal of Developmental Physiology
|December 1, 1989
Summary
Hyaline membrane disease (HMD) in premature lambs causes increased lung water due to delayed fetal lung liquid absorption and higher pulmonary vessel permeability. This study investigated the underlying mechanisms of pulmonary edema in HMD.
Area of Science:
- Neonatal Physiology
- Pulmonary Medicine
- Pathophysiology
Background:
- Hyaline membrane disease (HMD) is a significant cause of respiratory distress in premature infants.
- Pulmonary edema is a key feature of HMD, but its precise mechanisms remain incompletely understood.
Purpose of the Study:
- To elucidate the mechanisms contributing to pulmonary edema in premature lambs with HMD.
- To investigate the role of lymphatic fluid dynamics and pulmonary vascular permeability in HMD-associated edema.
Main Methods:
- Collection of mediastinal lymph in premature lambs before and after cesarean delivery.
- Measurement of lymph flow, lymph/plasma protein concentration ratios, and extravascular lung water.
- Histological verification of HMD in study subjects.
Main Results:
- Lambs with HMD exhibited significantly higher lung lymph flow and extravascular lung water post-delivery compared to controls.
- Elevated lymph/plasma concentration ratios for small proteins in HMD lambs indicated increased pulmonary vascular permeability.
- Lymph flow dynamics differed between HMD and control groups, suggesting impaired fluid absorption.
Conclusions:
- Pulmonary edema in HMD is multifactorial, involving both delayed fetal lung liquid absorption and increased pulmonary vascular permeability.
- Lymphatic dysfunction plays a critical role in the development of pulmonary edema in HMD.
- Findings provide insights into the pathophysiology of HMD, informing potential therapeutic strategies.