Atrial natriuretic factor and pulmonary status in premature infants with respiratory distress syndrome: preliminary investigation

Role of digoxin-like immunoreactive substance in the pathogenesis of transient tachypnea of newborn

Background. Transient tachypnea of newborn (TTN) is usually observed in term or near-term infants. It constitutes an important part of the respiratory distress cases observed in the neonatal intensive care unit (NICU). Aim. This paper examines the effects of digoxin-like immunoreactive substance (DLIS) on fluid and ion balance, hemodynamic and echocardiographic parameters of neonates with TTN. Methods. Plasma DLIS, Na⁺, K⁺, urea, creatinine, serum and urine osmolarity, urine FeNa⁺, 24-hour urine output, echocardiographic investigation and mean blood pressure, and clinical parameters of disease severity were recorded in TTN group and compared with control on the 1st and 7th days of their lives. Results. Plasma DLIS levels were statistically higher in TTN group (0.66 ± 0.37 ng/mL) compared to control group (0.24 ± 0.20 ng/mL) both on the 1st day (P < 0.01) and the 7th day (P < 0.05). For TTN group, significant correlation was found between plasma DLIS levels and maximum respiratory rate, duration of tachypnea, and length of hospitalization on the 1st day. Plasma DLIS levels were correlated negatively with serum osmolarity levels. Plasma DLIS levels were positively correlated with urine output, urinary FeNa⁺ levels, cardiac output, left ventricles end diastolic diameters, and right ventricles end diastolic diameters. Conclusions. Increased DLIS levels were correlated with disease severity in cases with TTN. This increase may be a primary or secondary event in the disease progress. It may help reduce the fluid overload due to already disturbed cardiac functions in patients by increasing urine output and natriuresis; however it may also contribute to disease pathogenesis, by inhibiting alveolar Na⁺-K⁺-ATPase which further decreases fetal alveolar fluid resorption.

The role of plasma N-terminal pro-B-type natriuretic peptide in predicting the severity of transient tachypnea of the newborn

BACKGROUND/AIM

Transient tachypnea of the newborn (TTN) is a consequence of inadequate neonatal lung fluid clearance. Natriuretic peptides play an important role in the regulation of extracellular fluid volume. The aim of the study was to investigate the relation between plasma N-terminal pro-B-type natriuretic peptide (NT-proBNP) levels and TTN, and to find out its role in predicting disease severity.

METHODS

A prospective controlled study involving 67 infants with TTN and 33 controls ≥34 weeks gestational age was conducted. Study and control groups were compared for plasma NT-proBNP levels measured on the 6th, 24th, 72nd and 120th hours of life. Cardiac systolic functions were evaluated by echocardiography.

RESULTS

NT-proBNP levels were significantly higher in neonates with TTN compared to controls at 6th, 24th, 72nd and 120th hours (p<0.001). NT-proBNP levels at 24th and 72nd hours were significantly higher in infants with prolonged tachypnea (p=0.007 and p=0.03) and in those who required respiratory support (p=0.006 and p<0.001). Tachypnea duration was correlated with NT-proBNP levels at 24h (r=0.41, p=0.001). At a cut-off value of 6575 pg/ml, NT-proBNP had a sensitivity of 85% and specificity of 64% to predict mechanical ventilation requirement. Cardiac systolic functions were normal in all TTN patients.

CONCLUSION

Plasma NT-proBNP levels are increased in neonates with TTN. Measurement of plasma NT-proBNP can be useful for predicting infants who will have prolonged tachypnea and mechanical ventilation requirement.

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.