Longitudinal changes of brain-type natriuretic peptide in preterm neonates.

Objective: To determine age-related concentrations of brain-type natriuretic peptide in preterm infants using bedside Triage brain-type natriuretic peptide test and correlate it to the presence or absence of the patent ductus arteriosus and ventilatory support.

Methods: Serum brain-type natriuretic peptide levels were measured in infants who were born at <32 weeks' gestation from birth to 2 months of age. Serial echocardiograms were performed, until closure of the patent ductus arteriosus, or until discharge. Brain-type natriuretic peptide levels were correlated to the day of life, gestational age, presence or absence of the patent ductus arteriosus, and the degree of ventilatory support. Nineteen preterm infants (gestational age: 24-31 weeks; birth weight: 645-1670 g) were enrolled prospectively during the first 2 weeks of life. Serum brain-type natriuretic peptide levels (pg/mL) were determined in 177 blood samples, and 87 paired echocardiograms were performed.

Results: Significant negative correlation was found between brain-type natriuretic peptide levels and the day of life and remained significant when the patients were stratified by gestational age (< or =28 weeks and >28 weeks). Higher brain-type natriuretic peptide levels correlated with increasing grade of the patent ductus arteriosus. Significant differences in brain-type natriuretic peptide levels were seen with increasing ventilatory support. Comparisons between the size of patent ductus arteriosus and the degree of ventilatory support to brain-type natriuretic peptide levels revealed that the size of the patent ductus arteriosus was the major determinant of both brain-type natriuretic peptide levels and the degree of ventilatory support.

Conclusions: Similar to term infants, brain-type natriuretic peptide levels of preterm infants are related to the chronological age and decline during the first month of life. Rapid bedside Triage brain-type natriuretic peptide is a potentially valuable and practical assay in determining the hemodynamic changes in preterm infants.