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Pulmonary vascular extraction of circulating norepinephrine in infants with bronchopulmonary dysplasia
S H Abman1, M S Schaffer, J Wiggins
1Department of Pediatrics, University of Colorado School of Medicine, Denver 80262.
Insights
Infants with severe bronchopulmonary dysplasia (BPD) show altered norepinephrine metabolism in the lungs, with reduced clearance or net production. This suggests potential links to pulmonary hypertension and cardiovascular issues in BPD.
Area of Science:
- Pediatric Pulmonology
- Neonatal Cardiology
- Respiratory Medicine
Background:
- Infants with advanced bronchopulmonary dysplasia (BPD) exhibit abnormal pulmonary vascular structure and vasoreactivity.
- Pulmonary metabolic lung functions in infants with severe BPD remain largely unstudied.
- Norepinephrine metabolism is a key indicator of lung vascular function.
Purpose of the Study:
- To investigate the hypothesis that severe BPD is associated with abnormal metabolic lung function.
- To assess the pulmonary vascular extraction of norepinephrine in infants with severe BPD.
Main Methods:
- Cardiac catheterization was performed in six children with BPD.
- Simultaneous blood samples were drawn from the main pulmonary artery and left atrium/femoral artery to measure plasma norepinephrine levels.
- Norepinephrine extraction percentage was calculated and compared to a control group of four infants with mild heart disease.
Main Results:
- Infants with BPD demonstrated significantly lower pulmonary vascular extraction of norepinephrine compared to controls (-7% vs. +27%).
- Three infants with BPD exhibited net production of norepinephrine across the lungs (arterial > venous).
- Altered catecholamine metabolism showed poor correlation with cardiac index and vascular resistance indices.
Conclusions:
- Severe BPD in infants is associated with decreased pulmonary vascular clearance or net production of norepinephrine.
- The findings suggest potential alterations in pulmonary catecholamine metabolism in severe BPD.
- Further research is needed to clarify the links between altered norepinephrine metabolism and cardiovascular abnormalities in BPD.
Abstract:
Although the pulmonary circulation in infants with advanced bronchopulmonary dysplasia (BPD) is characterized by abnormal structure and vasoreactivity, metabolic lung functions have not been studied in these infants. To test the hypothesis that patients with severe BPD may have abnormal metabolic lung function, we assessed the pulmonary vascular extraction of circulating norepinephrine in six children with BPD during cardiac catheterization. Plasma norepinephrine levels were measured from simultaneously drawn mixed venous (main pulmonary artery) and left atrium or femoral artery samples. In comparison with four infants with mild heart disease without pulmonary hypertension, we found that infants with BPD extract proportionately less norepinephrine than non-BPD infants [-7 +/- 50% (BPD) versus +27 +/- 6% (non-BPD); P less than 0.001, t test]. Three infants with BPD had higher arterial than mixed venous concentrations of plasma norepinephrine, suggesting net production across the lung. Plasma catecholamine levels and percent extraction correlated poorly with cardiac index and systemic and pulmonary vascular resistance indices. However, this study group was characterized by a high incidence of pulmonary (6/6) and systemic (4/6) hypertension, left ventricular hypertrophy (4/6), and subsequent death (3/6). We conclude that infants with severe BPD and pulmonary hypertension have decreased pulmonary vascular clearance or net production of circulating norepinephrine, but links between altered pulmonary catecholamine metabolism and pulmonary hypertension, or other cardiovascular abnormalities associated with BPD, remain speculative.