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 (<= 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.