Association of BNP, NTproBNP, and early postnatal pulmonary hypertension in very preterm infants

Biomarker screening for pulmonary hypertension in VLBW infants at risk for bronchopulmonary dysplasia

BACKGROUND

Very low birth weight (VLBW) infants demonstrate altered alveolar and pulmonary vascular development and carry an increased risk of developing bronchopulmonary dysplasia (BPD) and pulmonary hypertension (PH). Risk stratification for BPD-associated PH (BPD-PH) in at-risk infants may help tailor management, improve outcomes, and optimize resource utilization.

METHODS

VLBW infants were screened for PH with blood gas measurements, serum NT-proBNP and bicarbonate (HCO3) levels, and echocardiograms if they remained on respiratory support at 34 weeks corrected gestational age. We then tested 11 models using different cutoffs for NT-proBNP and HCO3 to predict infants at low risk of BPD-PH.

RESULTS

We identified PH in 34 of 192 (17.6%) VLBW infants. The median NT-proBNP in VLBWs with PH was 2769 pg/mL versus 917 pg/mL in those without PH (p < 0.0001). A model with NT-proBNP < 950 pg/mL and HCO3 < 32 mmol/L had a sensitivity of 100%, specificity of 34.2%, and negative predictive value of 100%. Using this model, 54 of 192 (28%) of the patients in this study would have been categorized as low risk for PH and could have avoided a screening echocardiogram.

CONCLUSION

NT-proBNP and HCO3 together may serve as sensitive and cost-effective screening tools for BPD-PH in VLBW infants.

IMPACT

NT-proBNP and HCO3 concentrations obtained together may help identify very low birth weight infants at risk for bronchopulmonary dysplasia who should undergo screening for pulmonary hypertension with echocardiography. This large dataset demonstrates that NT-proBNP and HCO3 levels together are more sensitive than NT-proBNP alone in identifying VLBW infants to undergo echocardiography. The combination of NT-proBNP and HCO3 levels may identify VLBW infants at low risk for pulmonary hypertension and thus those who may be able to avoid screening echocardiography.

Early Pulmonary Hypertension in Preterm Infants

Pulmonary hypertension (PH) in preterm neonates has multifactorial pathogenesis with unique characteristics. Premature surfactant-deficient lungs are injured following exposure to positive pressure ventilation and high oxygen concentrations resulting in variable phenotypes of PH. The prevalence of early PH is variable and reported to be between 8% and 55% of extremely preterm infants. Disruption of the lung development and vascular signaling pathway could lead to abnormal pulmonary vascular transition. The management of early PH and the off-label use of selective pulmonary vasodilators continue to be controversial.

Early diagnosis and targeted approaches to pulmonary vascular disease in bronchopulmonary dysplasia

Pulmonary hypertension has emerged as a life-threatening disease in preterm infants suffering from bronchopulmonary dysplasia (BPD). Its development is closely linked to respiratory disease, as vasculogenesis and alveologenesis are closely interconnected. Once clinically significant, BPD-associated pulmonary hypertension (BPD-PH) can be challenging to manage, due to poor reversibility and multiple comorbidities frequently associated. The pulmonary vascular disease process underlying BPD-PH is the result of multiple innate and acquired factors, and emerging evidence suggests that it progressively develops since birth and, in certain instances, may begin as early as fetal life. Therefore, early recognition and intervention are of great importance in order to improve long-term outcomes. Based on the most recent knowledge of BPD-PH pathophysiology, we review state-of-the-art screening and diagnostic imaging techniques currently available, their utility for clinicians, and their applicability and limitations in this specific population. We also discuss some biochemical markers studied in humans as a possible complement to imaging for the detection of pulmonary vascular disease at its early stages and the monitoring of its progression. In the second part, we review pharmacological agents currently available for BPD-PH treatment or under preclinical investigation, and discuss their applicability, as well as possible approaches for early-stage interventions in fetuses and neonates. IMPACT: BPD-associated PH is a complex disease involving genetic and epigenetic factors, as well as environmental exposures starting from fetal life. The value of combining multiple imaging and biochemical biomarkers is emerging, but requires larger, multicenter studies for validation and diffusion. Since "single-bullet" approaches have proven elusive so far, combined pharmacological regimen and cell-based therapies may represent important avenues for research leading to future cure and prevention.

Respiratory morbidity in preterm infants predicted by natriuretic peptide (MR-proANP) and endothelin-1 (CT-proET-1)

BACKGROUND

Bronchopulmonary dysplasia (BPD) is a major complication in preterm infants <32 weeks. We aimed to assess whether plasma levels of mid-regional pro-atrial natriuretic peptide (MR-proANP) and C-terminal pro-endothelin-1 (CT-proET-1) predict respiratory morbidity.

METHODS

This was a prospective, two-center, observational cohort study. MR-proANP and CT-proET-1 were measured at day 7 (±2) of life. Associations with duration of supplemental oxygen and the composite outcome of moderate or severe BPD or death (BPD/death) were investigated.

RESULTS

Two hundred and twenty-nine infants <32 weeks were included (median gestational age [GA] 29.6 weeks [interquartile range 29.0-30.7], median birth weight 1150 g [IQR 840-1410]). MR-proANP and CT-proET-1 were associated with the duration of supplemental oxygen in univariable analysis (both p < 0.001) but not after adjusting for co-factors. Infants with BPD/death showed higher plasma levels of MR-proANP (623.50 pmol/L [IQR 458.50-881.38] vs. 308.35 pmol/L [IQR 216.72-538.10]; p < 0.001) and CT-proET-1 (255.40 pmol/L [IQR 202.60-311.15] vs. 198.30 pmol/L [IQR 154.70-297.95]; p = 0.015) compared to infants without BPD/death. Levels of both biomarkers were significantly associated with BPD/death in univariable models but not after adjusting for co-factors.

CONCLUSIONS

MR-proANP and CT-proET-1 are associated with the duration of supplemental oxygen and the composite outcome BPD/death, but their prognostic value does not complement that of clinical risk factors.

IMPACT

Plasma levels of MR-proANP and CT-proET-1, measured on day 7 of life (±2 days) are associated in univariable analyses with duration of supplemental oxygen and the combined outcome of BPD or death in VLGA infants. Associations between both biomarkers and respiratory morbidity do not persist in multivariable models, in particular when gestational age is included. MR-proANP and CT-proET-1 have limited additional value to predict respiratory morbidity in VLGA infants compared to clinical parameters.

Development of a Nomogram for Moderate-to-Severe Bronchopulmonary Dysplasia or Death: Role of N-Terminal Pro-brain Natriuretic Peptide as a Biomarker

Objectives: This study aimed to explore the clinical value of N-terminal pro-brain natriuretic peptide (NT-proBNP) in predicting moderate-to-severe bronchopulmonary dysplasia (BPD)/death, and to establish an effective clinical predictive nomogram. Methods: We retrospectively analyzed very low birth weight infants (VLBWs) with gestational age ≤ 32 weeks. The NT-proBNP values were determined on the 1st, 3rd, 7th, 14th, 21st, and 28th days after birth. The correlation between NT-proBNP level and moderate-to-severe BPD/death was evaluated. Receiver operating characteristic (ROC) curve analysis was used to evaluate the prediction ability. Then, we used multivariable logistic regression to build the prediction model and nomogram, and calibration of the model was assessed by calibration curve. Results: In total, 556 VLBWs were involved, among whom 229 developed BPD (mild: n = 109; moderate: n = 68; severe: n = 52) and 18 died. The NT-proBNP level in the moderate-to-severe BPD/death group was significantly higher than that in the no-to-mild BPD group from the 3rd to 28th day (P < 0.001). When the natural logarithm of the serum NT-ProBNP level increased by 1 unit at day 7 (±2 days) of life, the risk of moderate and severe BPD/death was the highest (OR = 3.753; 95% CI: 2.984~4.720), and ROC analysis identified an optimal cutoff point of 3360 ng/L (sensitivity: 80.0%; specificity: 86.2%; AUC: 0.861). After adjusting for confounding factors, the level of NT-proBNP at day 7 (±2 days) of life still had important predictive value for the development of moderate-to-severe BPD/death, significantly improving the predictive ability of the model. Conclusion: The level of NT-proBNP at day 7 (±2 days) of life can be used as an early promising biomarker for VLBWs to develop moderate-to-severe BPD/death. We constructed an early predictive nomogram to help clinicians identify high-risk populations.

Reference values for N-terminal Pro-brain natriuretic peptide in premature infants during their first weeks of life

The aim of our study was to observe the temporal distribution of serum N-terminal pro-brain natriuretic peptide (NT-proBNP) in premature infants of ≤ 31 weeks of gestational age (GA) during the first weeks of life. NT-proBNP values of 118 preterm infants born ≤ 31 weeks GA were determined during the first week of life, after 4 ± 1 weeks of life, and at a corrected GA of 36 ± 2 weeks. Infants were divided into two groups: those without relevant complications and those with complications related to prematurity. NT-proBNP values of infants without complications define our exploratory reference values. The Median NT-proBNP level of these infants was 1896 ng/l (n = 27, interquartile range (IQR): 1277-5200) during the first week of life, 463 ng/l (n = 26, IQR: 364-704) at 4 ± 1 weeks of life, and 824 ng/l (n = 33, IQR: 714-1233) at a corrected GA of 36 ± 2 weeks. Infants born < 28 + 0 weeks GA had significantly higher NT-proBNP values (n = 9, median: 5200, IQR: 1750-8972) than infants born ≥ 28 + 0-31 weeks GA (n = 18, median: 1528, IQR: 838-3052; p = 0.017). Growth restriction or PDA status could not account for the difference in NT-proBNP values between GA groups.Conclusions: The results of our observational and cross-sectional study describe exploratory reference values for NT-proBNP levels in preterm infants of ≤ 31 weeks GA according to postnatal age. NT-proBNP levels during the first week of life are high and widely distributed in preterm infants and decrease subsequently to reach a distinctly lower and stable plateau at around 1 month of life. Our results suggest an influence of GA on NT-proBNP values in the first week of life. What is Known: • Several complications related to prematurity, e.g., hemodynamically significant PDA, pulmonary hypertension, bronchopulmonary dysplasia, and retinopathy of prematurity, have been associated with a temporary rise in NT-proBNP values in preterm infants during their first weeks of life. What is New: • This observational study provides reference values for NT-proBNP levels of very and extremely preterm infants during their first weeks of life. • In premature infants without complications, NT-proBNP values during their first week of life depend on gestational age at birth.

Updates on Management for Acute and Chronic Phenotypes of Neonatal Pulmonary Hypertension

Neonatal pulmonary hypertension is a heterogeneous disease in term and preterm neonates. It is characterized by persistent increase of pulmonary artery pressures after birth (acute) or an increase in pulmonary artery pressures after approximately 4 weeks of age (chronic); both phenotypes result in exposure of the right ventricle to sustained high afterload. In-depth clinical assessment plus echocardiographic measures evaluating pulmonary blood flow, pulmonary vascular resistance, pulmonary capillary wedge pressure, and myocardial contractility are needed to determine the cause and provide individualized targeted therapies. This article summarizes the causes, risk factors, hemodynamic assessment, and management of neonatal pulmonary hypertension.

Urinary NT-proBNP as a potential noninvasive biomarker for screening of pulmonary hypertension in preterm infants: a pilot study

OBJECTIVE

This pilot study aimed to determine the feasibility of urinary NT-proBNP (NT-proBNP) as a potential noninvasive screening marker for pulmonary hypertension (PH).

STUDY DESIGN

A prospective cross-sectional study was conducted. Preterm infants (PI) (birthweight <1500 gm and <30 weeks gestational age (GA)) were enrolled. Serial urinary NT-proBNP measurements and echocardiograms (ECHO) were performed at 28, 32, and 36 weeks.

RESULTS

Thirty-six patients were included in the final analysis (BPD-PH group = 6, BPD group = 20, control = 10). Urinary NT-proBNP levels were higher in the BPD-PH group compared with BPD and control groups at all study intervals. A urine NT-proBNP cutoff level of 2345 pg/ml at 28 weeks of GA had a sensitivity and specificity of 83.3% and 84.2%, respectively, for detection of BPD-PH (AUC 0.816, p = 0.022).

CONCLUSION

Urinary NT-proBNP measurement is feasible in preterm infants and appears to be a good noninvasive screening tool for PH.

Follow-up of isolated congenital complete atrioventricular block with longitudinal measurements of serum NT-proBNP and cardiothoracic ratio

There are a few children with isolated congenital complete atrioventricular block (ICCAVB) who do not require a pacemaker. We report a female infant born at 36 weeks by emergency cesarean section because of fetal heart rate abnormalities who was diagnosed as having ICCAVB. In accordance with the echocardiographic findings, we simultaneously measured the cardiothoracic ratio (CTR) by chest radiography and serum N-terminal pro-BNP (NT-proBNP) and have continued to follow her as an outpatient for about 8 years. CTR and NT-proBNP showed strong positive correlation (r=0.894, p<0.05). In such few children with ICCAVB as this patient, CTR measurement during their follow-up would be very useful to easily understand their cardiac load status.

Serum and Urinary N-Terminal Pro-brain Natriuretic Peptides as Biomarkers for Bronchopulmonary Dysplasia of Preterm Neonates

Bronchopulmonary dysplasia (BPD) is a common cause of respiratory illness in preterm newborns with high morbidity and mortality rates. At present, there are no early prognostic biomarkers that can be used in clinical practice to predict the development of BPD. In this review, we critically appraise evidence regarding the use of serum N-terminal pro-brain natriuretic peptide (NTproBNP) levels as a biomarker for BPD in neonates. Furthermore, we summarize studies assessing the feasibility of urinary NTproBNP levels as a non-invasive method to predict BPD in preterm infants. Multiple studies reported a strong association between NTproBNP serum levels and the onset of BPD. For urinary NTproBNP there is scarce evidence showing an association with BPD. Given the promising data obtained by preliminary studies, further assessment of this biomarker in both serum and urine is needed. Standardized reference values should be defined before conducting any further clinical studies.

NTproBNP is a useful early biomarker of bronchopulmonary dysplasia in very low birth weight infants

Bronchopulmonary dysplasia (BPD) is a severe complication of prematurity that impacts survival and neurodevelopment. Currently, no early marker exists which could help clinicians identify which preterm infants will develop BPD. Given the evidence that NTproBNP is elevated in children with BPD, we hypothesized that it could be used as an early marker of BPD development. We conducted a prospective cohort study including very low birth weight infants (VLBWI) admitted to our NICU between January 2015 and January 2017 in which we determined serial NTproBNP levels on days 1 and 3 and then weekly, until 49 days of life. A total of 101 patients were recruited (mean birth weight 1152 g (SD 247.5), mean gestational age 28.9 weeks (SD 1.9)). NTproBNP levels differed among infants who did and did not develop BPD from 14 to 35 days of life with the greatest difference on day 14 of life (non-BPD group (n = 86): 1155 (IQR 852-1908) pg/mL, BPD (n = 15): 9707 (IQR 3212-29,560) pg/mL; p = 0.0003). The presence of HsPDA did not account for higher levels of NTproBNP at day 14 (p = 0.165). We calculated an optimal cutoff point of 2264 pg/mL at 14 days of life (sensitivity 100%, specificity 86% and AUC 0.93).Conclusions: NTproBNP at 14 days of life could be used as an early marker of later BPD development in VLBWI. What is Known: • Children with BPD have elevated NTproBNP levels, which are related to the severity of BPD and the development of pulmonary hypertension. What is New: • NTproBNP at 14 days of life is higher in those who later develop BPD, regardless of the presence of hemodynamically significant patent ductus arteriosus. • A calculated cutoff point of 2264 pg/mL of NTproBNP at 14 days has a sensitivity of 100% and specificity of 86% in the prediction of BPD.

Myocardial Function Maturation in Very-Low-Birth-Weight Infants and Development of Bronchopulmonary Dysplasia

Background: Myocardial function in very-low-birth-weight infants (VLBWIs) develops during early postnatal life, but different patterns of temporal evolution that might be related to the development of bronchopulmonary dysplasia (BPD) are not completely understood. Methods: A prospective cohort study including VLBWIs admitted to our NICU from January 2015 to 2017 was conducted. Plasma N-terminal pro B type natriuretic peptide (NTproBNP) levels were measured, and echocardiograms were performed at 24 and 72 h of life and weekly thereafter until 36 weeks of postmenstrual age (PMA). We measured the tricuspid annular plane systolic excursion (TAPSE) by M-mode; the lateral tricuspid E', A', and S' waves; and the myocardial performance index (MPI) by tissue doppler imaging (TDI). The subjects were divided into non-BPD and BPD groups. Results: We included 101 VLBWIs. The TAPSE and E', A', and S' waves increased while MPI-TDI decreased over time. Birth gestational age (GA) and postnatal PMA impacted these parameters, which evolved differently in those who developed BPD compared to those in the non-BPD group. The NTproBNP levels at 14 days of life and different echocardiographic parameters were associated with the development of BPD in different multivariate models. Conclusion: TAPSE and TDI values depend on GA and PMA and follow a different temporal evolution that is related to the later development of BPD. Combined biochemical and echocardiographic biomarkers can help identify which VLBWIs are at higher risk of developing BDP.

NTproBNP as a surrogate biomarker for early screening of pulmonary hypertension in preterm infants with bronchopulmonary dysplasia

OBJECTIVE

Pulmonary hypertension (PH) is a known complication of bronchopulmonary dysplasia (BPD). This study aimed to determine the utility of serial N-Terminal pro-Brain Natriuretic Peptide (NTproBNP) levels in the screening of BPD associated PH (BPD-PH) in preterm infants.

STUDY DESIGN

Infants with birth weight <1500 g and <30 week corrected gestational age (CGA) were followed with serial NTproBNP levels and echocardiograms (ECHO). They were divided into control, BPD and BPD-PH groups. Statistical analyses included repeated measures analysis of variance and receiver operator curve (ROC) generation.

RESULTS

Infants in the BPD-PH and BPD group had significantly elevated NTproBNP levels as compared to the control group. ROC curves for NTproBNP at 28 weeks CGA provided a cut-point of 2329 pg/ml and 578.1 pg/ml for detection of BPD-PH and BPD, respectively.

CONCLUSIONS

NTproBNP appears to be a good screening tool to determine the onset of BPD-PH as early as 28 weeks CGA.

Recent advances in our understanding of the mechanisms of late lung development and bronchopulmonary dysplasia

The objective of lung development is to generate an organ of gas exchange that provides both a thin gas diffusion barrier and a large gas diffusion surface area, which concomitantly generates a steep gas diffusion concentration gradient. As such, the lung is perfectly structured to undertake the function of gas exchange: a large number of small alveoli provide extensive surface area within the limited volume of the lung, and a delicate alveolo-capillary barrier brings circulating blood into close proximity to the inspired air. Efficient movement of inspired air and circulating blood through the conducting airways and conducting vessels, respectively, generates steep oxygen and carbon dioxide concentration gradients across the alveolo-capillary barrier, providing ideal conditions for effective diffusion of both gases during breathing. The development of the gas exchange apparatus of the lung occurs during the second phase of lung development-namely, late lung development-which includes the canalicular, saccular, and alveolar stages of lung development. It is during these stages of lung development that preterm-born infants are delivered, when the lung is not yet competent for effective gas exchange. These infants may develop bronchopulmonary dysplasia (BPD), a syndrome complicated by disturbances to the development of the alveoli and the pulmonary vasculature. It is the objective of this review to update the reader about recent developments that further our understanding of the mechanisms of lung alveolarization and vascularization and the pathogenesis of BPD and other neonatal lung diseases that feature lung hypoplasia.

Pediatric pulmonology year in review 2016: Part 2

Pediatric Pulmonology continues to publish research and clinical topics related to the entire range of children's respiratory disorders. As we have done annually in recent years, we here summarize some of the past year's publications in our major topic areas, as well as selected literature in these areas from other core journals relevant to our discipline. This review (Part 2) covers selected articles on neonatology, asthma, physiology and lung function testing, and infectious diseases.