Serum BNP levels in patent ductus arteriosus cases

AIM: Prognosis of preterms will be improved with a biochemical parameter that will allow early diagnosis of hemodynamically significant patent ductus arteriosus (hsPDA) and aid in prediction of medical treatment failure. Owing to its acceptable correlation with echocardiography, brain natriuretic peptide (BNP) is a promising tool in premature babies.Our primary aim is to evaluate the echocardiographic parameters and investigate their relationship between BNP and their diagnostic relevance in predicting the need for PDA treatment in the early postnatal period. Our secondary aim is to evaluate the roles of endotelin-1 (ET1) and platelet derived growth factor (PDGF) in ductal closure.MATERIAL AND METHOD: Fifty-three preterm babies with gestational age of 32 weeks or below, followed between December 1; 2011 - November 1; 2012 were included into the study. Infants underwent echocardiographic evaluation by a pediatric cardiologist on 48-72 hours after birth. Infants with ductal diameter >1.4 mm, LA/AO >1,4:1, retrograde diastolic flow in aorta, diastolic flow in pulmonary artery >0.20 m/sc were diagnosed as hsPDA. Increase in respiratory distress, need for increment in mechanical ventilation parameters, metabolic acidosis, apnea, hyperdynamic precordium, bounding pulses, typical systolic ejection or continious murmur, hypotension, pulmonary edema on chest X-ray or pink secretions from endotrocheal tube were the clinical signs taken into account for treatment decision. Ibuprofen was the drug of choice for medical treatment. One ml of blood was withdrawn from the infants on 48-72 hours and 5-7th days for BNP, ET1 and PDGF analysis.RESULTS: Mean birth weight and gestational age of the infants were 1368,8±351,1 (700-2070) g, and 29,6±1,6 (26-32) weeks. Thirty-one (58,5%) babies were male. Thirty-two infants (60.4%) had closed ductus on 48-72 hours of life, nine infants (17%) achieved closure spontaneously later on, and twelve infants (22%) required treatment. Mean birth weight was significantly lower in infants who required treatment for PDA than the infants without PDA, whereas mean gestational age did not differ among groups. Any antenatal factor affecting PDA incidence was not identified. Need for respiratory support on 48-72. hours were higher in the infants who required treatment than the other groups (p<0,01). The incidence of RDS and the ratio of the cases that required at least two doses of surfactant were higher in the treatment group than the cases without PDA (p<0,01). Among echocardiographic parameters, ductal diameter, pulsatility index, antegrad diastolic flow in pulmonary artery (APA diastolic), LV/Ao ratio, displayed high sensitivity and specificity. Diagnostic sensitivity and specificity of SVC, LVO/SVC, mitral E/A were low. Clinical signs, when considered alone were not sufficient to predict treatment need in the early postnatal period. Plazma BNP >149,7 pg/ml can predict treatment need with a sensitivity of 91,7% and with a specificity of 73,2%. Mean plazma ET1 concentrations did not differ between groups on 48-72. hours whereas it was significantly higher in spontaneous closure group on 5-7th days than the cases without PDA. PDGF, MPV, PDW, platelet count and mass were not statistically correlated with PDA incidence.CONCLUSION: Echocardiography revealed high specificity and sensitivity for diagnosis of PDA in the postnatal period. BNP measured on 48-72. hours of life, owing to its good correlation with echocardiography and high specificity and sensitivity,can be used to predict treatment need when echocardiography is not feasible or for preterms with less prominent echocardiographic findings. Prospective human studies are required in order to investigate the roles of ET1, platelets and PDGF in the ductal closure.