Clinical Significance of Early Pulmonary Hypertension in Preterm Infants

Treatment With Inhaled Nitric Oxide and General Intelligence in Preterm Children in Two European Cohorts

AIM

To investigate whether treatment with inhaled nitric oxide is associated with cognitive performance at age 5-6 years in preterm-born children.

METHODS

We analysed preterm children from two large European cohort studies, the German Neonatal Network (GNN) (N = 3606) and the French EPIPAGE-2 cohort (N = 2579) admitted to neonatal care and followed up at age 5-6 years. Both cohorts had recorded data on iNO treatment. General cognitive ability was tested with IQ tests. Classification and Regression trees analysis was used to identify prenatal, perinatal and neonatal, clinical and social-environmental predictors of IQ.

RESULTS

In both cohorts, treatment with inhaled nitric oxide was not associated with IQ at age 5-6 years. Analysis identified maternal educational level, gestational age at discharge from hospital, intraventricular haemorrhage and maternal country of birth as important factors associated with IQ scores.

CONCLUSION

Treatment with inhaled nitric oxide was neither negatively nor positively associated with IQ at age 5-6 years. Neonatal and brain health, as well as socioeconomic factors are important for cognitive performance in early childhood.

Pulmonary vasodilator use in very preterm infants in United States children's hospitals

OBJECTIVES

To describe common pulmonary vasodilators (PV), exposure timing, and characteristics associated with their use in very preterm (VP) infants.

STUDY DESIGN

Observational study of VP infants discharged from U.S. children's hospitals (2011-2021). PV exposures during hospitalization were identified, and multivariable modeling determined characteristics associated with exposure.

RESULTS

Among 37,428 infants, 6.3% received PV. Early inhaled nitric oxide (iNO) and late sildenafil were most common. Early exposure was associated with lower gestational age, aOR: 9.2 (7.3-11.7), 22-25 vs. 29-31 weeks) and small for gestational age (SGA), 2.3 (2.0-2.7). Late exposure was associated with bronchopulmonary dysplasia (BPD) grade, 26.2 (16.8-40.9), grade 3 vs. no BPD) and early PV exposure, 3.7 (2.9-4.8).

CONCLUSIONS

Early iNO and late sildenafil are used in VP infants despite limited evidence. Prospective early studies enrolling extremely preterm and SGA infants and late studies enrolling infants with early PV exposure and high-grade BPD would target current evidence gaps.

Association between early pulmonary arterial pressure measurements and bronchopulmonary dysplasia or mortality in very preterm infants: a prospective cohort study

BACKGROUND

Prematurity is a significant risk for bronchopulmonary dysplasia related pulmonary artery pressure.

OBJECTIVE

To determine the association between pulmonary artery pressure in the early days of life and the development of bronchopulmonary dysplasia or mortality.

METHODS

This prospective observational cohort study included infants born at <32 weeks and weighing <1500 g. Pulmonary artery pressure was measured between postnatal days 3 and 7. Pulmonary hypertension was defined as systolic pulmonary artery pressure ≥40 mm Hg or systolic pulmonary artery pressure/systolic blood pressure >0.5 (pulmonary hypertension criterion-1). Infants were categorised into pulmonary hypertension and non-pulmonary hypertension groups. The primary endpoint was bronchopulmonary dysplasia or mortality. Receiver operating characteristic analysis established a new threshold value for predicting bronchopulmonary dysplasia or mortality (pulmonary hypertension criterion-2). Infants were reanalysed according to new criteria.

RESULTS

A total of 329 infants were included in this study. Moderate-to-severe pulmonary hypertension was identified in 24% (n=79) of the infants. The pulmonary hypertension group exhibited a significantly lower gestational age, lower birth weight and a higher incidence of small for gestational age. Systolic pulmonary artery pressure >25 mm Hg or systolic pulmonary artery pressure/systolic blood pressure >0.35 was defined as the pulmonary hypertension criterion-2. Logistic regression analysis identified pulmonary hypertension criterion-2 as an independent risk factor for moderate-to-severe bronchopulmonary dysplasia or mortality (OR 2.67, 95% CI 1.3 to 5.51, p<0.01).

CONCLUSION

Pulmonary artery pressure exceeding 25 mm Hg in the early days of life may be considered a potential risk factor for bronchopulmonary dysplasia or mortality.

Inhaled Nitric Oxide Treatment of Early Pulmonary Hypertension to Reduce the Risk of Death or Bronchopulmonary Dysplasia in Infants Born Extremely Preterm: A Masked Randomized Controlled Trial

OBJECTIVE

To determine whether inhaled nitric oxide (iNO) treatment of early pulmonary hypertension (PH) would decrease the risk of death or bronchopulmonary dysplasia (BPD) among infants born extremely preterm.

STUDY DESIGN

This was a single-center, masked, randomized controlled trial involving infants born at ≤29 weeks' gestation and requiring positive pressure ventilation. Exclusion criteria included infants of COVID-19 positive mothers, large patent ductus arteriosus with left to right shunting, left ventricle dysfunction (ejection fraction <40%), significant congenital anomalies/genetic disorders, or iNO treatment by clinicians prior to the study echocardiogram. Initial echocardiogram was performed at 72 ± 24 hours of life to randomize infants with early PH into 2 study arms (iNO vs placebo). Serial echocardiograms were performed every 24-48 hours, up to 14 days of life. Treatment was weaned until PH resolved (responders) or if no improvement was documented ≥72-hours (nonresponders). Primary outcome was death or BPD at 36-weeks postmenstrual age.

RESULTS

From July 2019 to October 2023, 683 eligible infants were admitted. We excluded 88 infants; 413 mothers declined consent or were not approached. iNO treatment was clinically started for 51 infants due to hypoxic respiratory failure. Screening echocardiograms were completed for 180 infants; of these, 32 infants with early PH were randomized to iNO or placebo groups. After a planned interim analysis, termination of the trial was recommended by the Data Safety Monitoring Committee because of futility.

CONCLUSION

iNO treatment does not reduce the risk of BPD or death among extremely preterm infants with echocardiographic evidence of early pulmonary hypertension without hypoxic respiratory failure.

Outcomes of infants and children with bronchopulmonary dysplasia-associated pulmonary hypertension who required home ventilation

BACKGROUND

To characterize a cohort of ventilator-dependent infants and children with bronchopulmonary dysplasia-associated pulmonary hypertension (BPD-PH) and to describe their cardiorespiratory outcomes.

METHODS

Subjects with BPD on chronic home ventilation were recruited from outpatient clinics. PH was defined by its presence on ≥1 cardiac catheterization or echocardiogram on or after 36 weeks post-menstrual age. Kaplan-Meier analysis was used to compare the timing of key events.

RESULTS

Of the 154 subjects, 93 (60.4%) had PH and of those, 52 (55.9%) required PH-specific medications. The ages at tracheostomy, transition to home ventilator, and hospital discharge were older in those with PH. Most subjects were weaned off oxygen and liberated from the ventilator by 5 years of age, which did not occur later in subjects with PH. The mortality rate after initial discharge was 2.6%.

CONCLUSIONS

The majority of infants with BPD-PH receiving chronic invasive ventilation at home survived after initial discharge. Subjects with BPD-PH improved over time as evidenced by weaning off oxygen and PH medications, ventilator liberation, and tracheostomy decannulation. While the presence of PH was not associated with later ventilator liberation or decannulation, the use of PH medications may be a marker of a more protracted disease trajectory.

IMPACT STATEMENT

There is limited data on long-term outcomes of children with bronchopulmonary dysplasia (BPD) who receive chronic invasive ventilation at home, and no data on those with the comorbidity of pulmonary hypertension (PH). Almost all subjects with BPD-PH who were on chronic invasive ventilation at home survived after their initial hospital discharge. Subjects with BPD-PH improved over time as evidenced by weaning off oxygen, PH medications, liberation from the ventilator, and tracheostomy decannulation. The presence of PH did not result in later ventilator liberation or decannulation; however, the use of outpatient PH medications was associated with later ventilation liberation and decannulation.

Pulmonary vasodilator use in very preterm infants in United States children's hospitals

Objectives

To describe common pulmonary vasodilators (PV), exposure timing, and characteristics associated to their use in very preterm (VP) infants.

Study Design

Observational study of VP infants discharged from U.S. children's hospitals (2011-2021). PV exposures during hospitalization were identified, and multivariable modeling determined characteristics associated with exposure.

Results

Among 37,428 infants, 6.3% received PV. Early inhaled nitric oxide (iNO) and late sildenafil were most common. Early exposure was associated with lower gestational age, aOR: 9.2 (7.3-11.7), 22-25 vs. 29-31 weeks) and small for gestational age (SGA), 2.3 (2.0-2.7). Late exposure was associated with bronchopulmonary dysplasia (BPD) grade, 26.2 (16.8-40.9), grade 3 vs. no BPD) and early PV exposure, 3.7 (2.9-4.8).

Conclusions

Early iNO and late sildenafil are used in VP infants despite limited evidence. Prospective early studies enrolling extremely preterm or SGA infants and late studies enrolling infants with early PV exposure or high-grade BPD would target current evidence gaps.

Aberrant PGC-1α signaling in a lamb model of persistent pulmonary hypertension of the newborn

BACKGROUND

Persistent Pulmonary Hypertension of the Newborn (PPHN) is characterized by elevated pulmonary vascular resistance (PVR), resulting in hypoxemia. Impaired angiogenesis contributes to high PVR. Pulmonary artery endothelial cells (PAECs) in PPHN exhibit decreased mitochondrial respiration and angiogenesis. We hypothesize that Peroxisome Proliferator-Activated Receptor Gamma Co-Activator-1α (PGC-1α) downregulation leads to reduced mitochondrial function and angiogenesis in PPHN.

METHODS

Studies were performed in PAECs isolated from fetal lambs with PPHN induced by ductus arteriosus constriction, with gestation-matched controls and in normal human umbilical vein endothelial cells (HUVECs). PGC-1α was knocked downed in control lamb PAECs and HUVECs and overexpressed in PPHN PAECs to investigate the effects on mitochondrial function and angiogenesis.

RESULTS

PPHN PAECs had decreased PGC-1α expression compared to controls. PGC-1α knockdown in HUVECs led to reduced Nuclear Respiratory Factor-1 (NRF-1), Transcription Factor-A of Mitochondria (TFAM), and mitochondrial electron transport chain (ETC) complexes expression. PGC-1α knockdown in control PAECs led to decreased in vitro capillary tube formation, cell migration, and proliferation. PGC-1α upregulation in PPHN PAECs led to increased ETC complexes expression and improved tube formation, cell migration, and proliferation.

CONCLUSION

PGC-1α downregulation contributes to reduced mitochondrial oxidative phosphorylation through control of the ETC complexes, thereby affecting angiogenesis in PPHN.

IMPACT

Reveals a novel mechanism for angiogenesis dysfunction in persistent pulmonary hypertension of the newborn (PPHN). Identifies a key mitochondrial transcription factor, Peroxisome Proliferator-Activated Receptor Gamma Co-Activator-1α (PGC-1α), as contributing to the altered adaptation and impaired angiogenesis function that characterizes PPHN through its regulation of mitochondrial function and oxidative phosphorylation. May provide translational significance as this mechanism offers a new therapeutic target in PPHN, and efforts to restore PGC-1α expression may improve postnatal transition in PPHN.

Neonatal outcomes of preterm infants with pulmonary hypertension: clustering based on prenatal risk factors

BACKGROUND

To investigate association of prenatal risk factors and neonatal outcomes of preterm infants with pulmonary hypertension (PH).

METHODS

A prospective cohort study of very-low-birth-weight infants born at 22-29 weeks' gestation who received PH-specific treatment during hospitalization. Infants were classified using a two-step cluster analysis based on gestational age (GA), small-for-gestational-age (SGA), exposure to antenatal corticosteroids (ACS), histologic chorioamnionitis (HCA), and oligohydramnios.

RESULTS

Among 910 infants, six clusters were identified: cluster A (HCA, n = 240), cluster B (oligohydramnios, n = 79), cluster C (SGA, n = 74), cluster D (no-ACS, n = 109), cluster E (no dominant parameter, n = 287), and cluster F (HCA and oligohydroamnios, n = 121). Cluster A was used as a reference group for comparisons among clusters. Compared to cluster A, cluster C (aHR: 1.63 [95% CI: 1.17-2.26]) had higher risk of overall in-hospital mortality. Clusters B (aHR: 1.52 [95% CI: 1.09-2.11]), D (aHR: 1.71 [95% CI: 1.28-2.30]), and F (aHR: 1.51 [95% CI: 1.12-2.03]) had higher risks of receiving PH-specific treatment within the first week of birth compared to cluster A.

CONCLUSION

These findings may provide a better understanding of prenatal risk factors contributing to the development of PH.

IMPACT

Pulmonary hypertension (PH), presenting as hypoxic respiratory failure, has complex etiologies in preterm infants. Although multifactorial risks for the development of PH in preterm infants are known, few studies have classified infants with similar etiologies for PH. Each cluster has distinct patterns of prenatal condition and neonatal outcome.

Embracing the challenges of neonatal and paediatric pulmonary hypertension

Paediatric pulmonary arterial hypertension (PAH) shares common features with adult disease, but is associated with several additional disorders and challenges that require unique approaches. This article discusses recent advances, ongoing challenges and distinct approaches for caring for infants and children with PAH, as presented by the paediatric task force of the 7th World Symposium on Pulmonary Hypertension. We provide updates on diagnosing, classifying, risk-stratifying and treating paediatric pulmonary hypertension (PH) and identify critical knowledge gaps. An updated risk stratification tool and treatment algorithm is provided, now also including strategies for patients with associated cardiopulmonary conditions. Treatment of paediatric PH continues to be hindered by the lack of randomised controlled clinical trials. The challenging management of children failing targeted PAH therapy is discussed, including balloon atrial septostomy, lung transplantation and pulmonary-to-systemic shunt (Potts). A novel strategy using a multimodal approach for the management of PAH associated with congenital heart diseases with borderline pulmonary vascular resistance is included. Advances in diagnosing neonatal PH, especially signs and interpretation of PH by echocardiography, are highlighted. A team approach to the rapidly changing physiology of neonatal PH is emphasised. Challenges in drug approval are discussed, particularly the challenges of designing accurate paediatric clinical trials with age-appropriate end-points and adequate enrolment.

Improvement in Echocardiographic and Diagnostic Biomarkers after Systemic Glucocorticoid Therapy in Infants with Pulmonary Hypertension

OBJECTIVE

To assess the effect of treating pulmonary hypertension (PH) in infants younger than 1 year of age with systemic glucocorticoids while using echocardiographic and diagnostic biomarkers as measures of efficacy.

STUDY DESIGN

A retrospective chart review was performed on 17 hospitalized infants younger than 1 year of age at St Louis Children's Hospital who received a 5- to 7-day course of systemic glucocorticoid treatment followed by a 3-week taper with no significant intracardiac shunts from January 1, 2017, to December 31, 2021. Quantitative echocardiographic indices for PH, N-terminal pro b-type natriuretic peptide, and/or b-type natriuretic peptide levels were collected before glucocorticoid treatment, after the glucocorticoid burst, and after the 21-day taper.

RESULTS

Mean (±SD) gestational age was 32.1 (±5.8) weeks, 5 infants were (29%) concomitantly treated with sildenafil, and 8 were male. Twelve were classified as World Health Organization group 3 PH (71%) and 5 as World Health Organization group 1 PH. There were significant improvements 30 days after glucocorticoid initiation in b-type natriuretic peptide levels (P = .008), PCO2 (P = .03), eccentricity index (P = .005), right ventricular ejection time (P = .04), pulmonary artery acceleration time (P = .002), and pulmonary artery acceleration time-to-right ventricular ejection time ratio (P = .02). Tricuspid regurgitation velocity was not able to be assessed. There were no mortalities during the study timeline.

CONCLUSIONS

In our retrospective study, systemic glucocorticoid therapy was well tolerated and appeared to be associated with significant improvement in cardiopulmonary function in infants with PH. Further prospective study in a larger sample is warranted.

Cardiovascular Sequelae of Bronchopulmonary Dysplasia in Preterm Neonates Born before 32 Weeks of Gestational Age: Impact of Associated Pulmonary and Systemic Hypertension

Bronchopulmonary dysplasia (BPD) remains the most common respiratory disorder of prematurity for infants born before 32 weeks of gestational age (GA). Early and prolonged exposure to chronic hypoxia and inflammation induces pulmonary hypertension (PH) with the characteristic features of a reduced number and increased muscularisation of the pulmonary arteries resulting in an increase in the pulmonary vascular resistance (PVR) and a fall in their compliance. BPD and BPD-associated pulmonary hypertension (BPD-PH) together with systemic hypertension (sHTN) are chronic cardiopulmonary disorders which result in an increased mortality and long-term problems for these infants. Previous studies have predominantly focused on the pulmonary circulation (right ventricle and its function) and developing management strategies accordingly for BPD-PH. However, recent work has drawn attention to the importance of the left-sided cardiac function and its impact on BPD in a subset of infants arising from a unique pathophysiology termed postcapillary PH. BPD infants may have a mechanistic link arising from chronic inflammation, cytokines, oxidative stress, catecholamines, and renin-angiotensin system activation along with systemic arterial stiffness, all of which contribute to the development of BPD-sHTN. The focus for the treatment of BPD-PH has been improvement of the right heart function through pulmonary vasodilators. BPD-sHTN and a subset of postcapillary PH may benefit from afterload reducing agents such as angiotensin converting enzyme inhibitors. Preterm infants with BPD-PH are at risk of later cardiac and respiratory morbidities as young adults. This paper reviews the current knowledge of the pathophysiology, diagnosis, and treatment of BPD-PH and BPD-sHTN. Current knowledge gaps and emerging new therapies will also be discussed.

Clinical phenotype of pulmonary vascular disease requiring treatment in extremely preterm infants

BACKGROUND

Pulmonary vascular disease (PVD) and pulmonary hypertension (PH) is a significant disorder affecting prognosis of extremely preterm infants. However, there is still a lack of a consensus on the definition and optimal treatments of PH, and there is also a lack of research comparing these conditions with persistent pulmonary hypertension of newborn (PPHN), early PH, and late PH. To investigate PH in extremely preterm infants, this study compared the baseline characteristics, short-term outcomes, and treatment duration, categorized by the timing of requiring PH treatment.

METHODS

This study retrospectively analyzed extremely preterm infants admitted to a single tertiary center. Between 2018 and 2022, infants with clinical or echocardiographic diagnosis of PH who required treatment were divided into three groups based on the timing of treatment initiation: initial 3 days (extremely early-period), from day 4 to day 27 (early-period), and after day 28 (late-period). The study compared the outcomes, including mortality rates, bronchopulmonary dysplasia (BPD) severity, PH treatment duration, and oxygen therapy duration, among the three groups.

RESULTS

Among the 157 infants, 67 (42.7%) were treated for PH during their stay. Of these, 39 (57.3%) were treatment in extremely early, 21 (31.3%) in early, and seven (11.4%) in late periods. No significant differences were observed in maternal factors, neonatal factors, or morbidity between the three groups. However, infants who received extremely early-period treatment had a higher mortality rate, but shorter duration of noninvasive respiratory support, oxygen therapy, and PH medication use. On the other hand, the late-period treatment group received longer durations of respiratory support and treatment.

CONCLUSIONS

This study revealed differences in mortality rates, respiratory outcomes, and treatment duration between the three groups, suggesting varying pathophysiologies over time in extremely preterm infants.

Risk Factors for Mortality or Major Morbidities of Very Preterm Infants: A Study from Thailand

OBJECTIVE

Very preterm neonates have high rates of composite outcomes featuring mortality and major morbidities. If the modifiable risk factors could be identified, perhaps the rates could be decreased especially in resource-limited settings.

STUDY DESIGN

We performed a prospective study in a Thai neonatal intensive care unit to identify the risk factors of composite outcomes between 2014 and 2021. The inclusion criterion was neonates who were born in our hospital at a gestational age (GA) of less than 32 weeks. The exclusion criteria were neonates who died in the delivery room or had major congenital anomalies. The composite outcomes were analyzed by multivariable logistic regression with adjusted odds ratios (aORs) and a 95% confidence interval (CI).

RESULTS

Over the 8-year study period, 555 very preterm inborn neonates without major birth defects were delivered. The composite outcomes were 29.4% (163/555). The medians (interquartile ranges) of GA and birth weights of the neonates were 29 (27-31) weeks and 1,180 (860-1,475) grams, respectively. By multivariable analysis, GA (aOR: 0.65; 95% CI: 0.55-0.77), small for GA (aOR: 4.93; 95% CI: 1.79-13.58), multifetal gestation (aOR: 2.23; 95% CI: 1.12-4.46), intubation within 24 hours (aOR: 5.39; 95% CI: 1.35-21.64), and severe respiratory distress syndrome (aOR: 5.00; 95% CI: 1.05-23.89) were significantly associated with composite outcomes.

CONCLUSION

Very preterm infants who had a lower GA were small for GA, twins or more, respiratory failure on the first day of life, and severe respiratory distress syndrome were associated with mortality and/or major morbidities.

KEY POINTS

· In very preterm neonates, the composite outcomes and mortality rate were 29.4 and 12.3%.. · Composite outcomes were associated with lower GA, SGA, multifetal gestation, intubation, and severe RDS.. · Mortality was associated with lower GA or Apgar score at 5 minutes, SGA, and PPHN..

Seeing pulmonary hypertension through a paediatric lens: a viewpoint

Pulmonary hypertension (PH) is a life-threating condition associated with abnormally elevated pulmonary pressures and right heart failure. Current epidemiological data indicate that PH aetiologies are different between the adult and paediatric population. The most common forms of PH in adults are PH from left heart disease or chronic lung disease, followed by pulmonary arterial hypertension (PAH) [1]; in paediatric patients, PH is most often associated with developmental lung disorders and congenital heart disease (CHD) [2, 3]. In contrast to adults with PH, wherein patients worsen over time despite therapy, PH in children can improve with growth. For example, in infants with bronchopulmonary dysplasia (BPD) and PH morbidity and mortality are high, but with lung growth and ensuring no ongoing lung injury pulmonary vascular disease can improve as evidenced by discontinuation of vasodilator therapy in almost two-thirds of BPD-PH survivors by age 5 years [3, 4].

Paediatric pulmonary hypertension (PH) offers unique genetic and developmental insights that can help in the discovery of novel mechanisms and targets to treat adult PH https://bit.ly/3TMm6bi

Challenges in clinical identification of right ventricular dysfunction in preterm infants with persistent pulmonary hypertension of the newborn

BACKGROUND

Right ventricular dysfunction, typically qualitatively diagnosed (Q-RVd) in preterm infants, requires echocardiography which is not always acutely available. We aimed to identify clinical indices of Q-RVd in very preterm infants (gestational age, GA <32 weeks) with persistent pulmonary hypertension of newborn (PPHN) and examine the reliability and validity of Q-RVd.

METHODS

Forty-seven infants with mean ± SD GA of 26.8 ± 2.7 weeks who had targeted neonatal echocardiography (TNE) ≤72 h old, during PPHN, were retrospectively studied. Three standard TNE clips were reviewed by two blinded assessors, and infants categorized as Q-RVd if moderate-severe RVd was diagnosed on ≥2 clips. Cardiopulmonary clinical indices at TNE and quantitative RV functional markers were compared between Q-RVd vs. no-RVd groups. Potential quantitative RVd definitions examined by classifying each measurement as "low" or "normal" using published data. Inter-rater agreement for Q-RVd assessed using Kappa statistics.

RESULTS

Mean age at TNE was 25.3 ± 20.4 h with Q-RVd diagnosed in 19(40 %) infants. Q-RVd group demonstrated higher peak oxygen requirements (96 ± 9 % vs. 84 ± 16 %, p < 0.01); however, no clinical parameters at TNE differentiated the groups. Quantitative measures were lower in Q-RVd patients, confirming classification validity. Among tested quantitative definitions, low RV stroke volume was associated with lower systolic blood pressure (41±7 vs. 47±9 mmHg, p = 0.02) and higher shock index (4.02±0.80 vs. 3.44±0.72, p = 0.02). Kappa for Q-RVd was 0.55 (95%CI 0.32-0.77).

CONCLUSIONS

The non-specific nature of clinical markers of RVd in preterm infants with PPHN necessitates echocardiographic diagnosis of RVd. Studies should examine prognostic relevance of RVd and establish outcome-based quantitative definitions in preterm infants.

Pulmonary Hypertension in Established Bronchopulmonary Dysplasia: Physiologic Approaches to Clinical Care

Preterm infants with bronchopulmonary dysplasia (BPD) are prone to develop pulmonary hypertension (PH). Strong laboratory and clinical data suggest that antenatal factors, such as preeclampsia, chorioamnionitis, oligohydramnios, and placental dysfunction leading to fetal growth restriction, increase susceptibility for BPD-PH after premature birth. Echocardiogram metrics and serial assessments of NT-proBNP provide useful tools to diagnose and monitor clinical course during the management of BPD-PH, as well as monitoring for such complicating conditions as left ventricular diastolic dysfunction, shunt lesions, and pulmonary vein stenosis. Therapeutic strategies should include careful assessment and management of underlying airways and lung disease, cardiac performance, and systemic hemodynamics, prior to initiation of PH-targeted drug therapies.

Comorbidities and Late Outcomes in Neonatal Pulmonary Hypertension

Long-term outcomes of persistent pulmonary hypertension of newborn (PPHN) depend on disease severity, duration of ventilation, and associated anomalies. Congenital diaphragmatic hernia survivors may have respiratory morbidities and developmental delay. The presence of PPHN is associated with increased mortality in hypoxic-ischemic encephalopathy, though the effects on neurodevelopment are less clear. Preterm infants can develop pulmonary hypertension (PH) early in the postnatal course or later in the setting of bronchopulmonary dysplasia (BPD). BPD-PH is associated with higher mortality, particularly within the first year. Evidence suggests that both early and late PH in preterm infants are associated with neurodevelopmental impairment.

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.

Practices and Outcomes from a Prospective, Multicenter Registry for Preterm Newborns with Pulmonary Hypertension

OBJECTIVE

To describe current treatment practices of preterm infants with early hypoxemic respiratory failure (HRF) and pulmonary hypertension (PH) and their association with patient outcomes.

STUDY DESIGN

We developed a prospective, observational, multicenter clinical registry of preterm newborns <34 weeks' gestation with HRF and PH, based on either clinical or echocardiographic evidence during the first 72 hours of life, from 28 neonatal intensive care units in the US from 2017 through 2022. The primary end point was mortality among those who did or did not receive PH-targeted treatment, and the secondary end points included comparisons of major morbidities. Variables were compared using t tests, Wilcoxon rank-sum tests, Fisher exact tests, and χ² tests.

RESULTS

We analyzed the results of 224 preterm infants enrolled in the registry. Of which, 84% (188/224) received PH-targeted treatment, most commonly inhaled nitric oxide (iNO). Early mortality in this cohort was high, as 33% (71/224) of this sample died in the first month of life, and 77% of survivors (105/137) developed bronchopulmonary dysplasia. Infants who received PH-targeted treatment had higher oxygenation indices at the time of enrollment (28.16 [IQR: 13.94, 42.5] vs 15.46 [IQR: 11.94, 26.15]; P = .0064). Patient outcomes did not differ between those who did or did not receive PH-targeted therapy.

CONCLUSIONS

Early-onset HRF with PH in preterm infants is associated with a high early mortality and a high risk of developing bronchopulmonary dysplasia. iNO is commonly used to treat early-onset PH in preterm infants with HRF. In comparison with untreated infants with lower oxygenation indices, iNO treatment in severe PH may prevent poorer outcomes.

Pulmonary phenotypes of bronchopulmonary dysplasia in the preterm infant

Bronchopulmonary dysplasia (BPD) remains the most common complication of premature birth, imposing a significant and potentially life-long burden on patients and their families. Despite advances in our understanding of the mechanisms that contribute to patterns of lung injury and dysfunctional repair, current therapeutic strategies remain non-specific with limited success. Contemporary definitions of BPD continue to rely on clinician prescribed respiratory support requirements at specific time points. While these criteria may be helpful in broadly identifying infants at higher risk of adverse outcomes, they do not offer any precise information regarding the degree to which each compartment of the lung is affected. In this review we will outline the different pulmonary phenotypes of BPD and discuss important features in the pathogenesis, clinical presentation, and management of these frequently overlapping scenarios.

Cardiopulmonary physiological effects of diuretic therapy in preterm infants with chronic pulmonary hypertension

OBJECTIVE

Using targeted neonatal echocardiography (TNE) to examine cardiopulmonary physiological impact of diuretics in preterm infants with chronic pulmonary hypertension (cPH).

STUDY DESIGN

Retrospective study comparing TNE indices pre- and ≤2 weeks (post) of initiating diuretic therapy in infants born <32 weeks gestational age with cPH.

RESULTS

Twenty-seven neonates with mean gestational age, birthweight and interval between pre-post diuretic TNE of 27.0 ± 2.8 weeks, 859 ± 294 grams, and 7.8 ± 3.0 days respectively were studied. Diuretics was associated with improvement in pulmonary vascular resistance [pulmonary artery acceleration time (PAAT); 34.27(9.76) vs. 40.24(11.10)ms, p = 0.01), right ventricular (RV) ejection time:PAAT ratio [5.92(1.66) vs. 4.83(1.14), p < 0.01)], RV fractional area change [41.6(9.8) vs. 46.4(6.5%), p = 0.03)] and left ventricular myocardial performance index [0.55(0.09) vs. 0.41(0.23), p < 0.01)]. Post-treatment, frequency of bidirectional/right-to-left inter-atrial shunts decreased significantly (24% vs. 4%, p = 0.05).

CONCLUSION

Primary diuretic treatment in neonates with cPH may result in improvement in PVR, RV and LV function and compliance.

An Extremely Preterm Infant Born at 23 Weeks' Gestation With an Interrupted Aortic Arch Complex: A Case Report

We present a case of an infant male born at 23 weeks' gestation with an interrupted aortic arch (IAA) complex. We treated the patient with hypoxic gas ventilation to address developing systemic undercirculation in the acute postnatal phase. As the symptoms of bronchopulmonary dysplasia evolved, hypoxic gas ventilation was no longer required to stabilize the hemodynamics. The patient was discharged home after undergoing the palliative surgical procedure of bilateral pulmonary artery banding and ductus arteriosus stent implantation. Although he suffered from pulmonary hypertension, it was controllable with oxygen supplementation and pulmonary vasodilators. There are limited therapeutic options available for extremely preterm infants with critical congenital heart defects (CHDs). Hypoxic gas ventilation might be considered as one of the options, with its risks taken into account, to manage extremely preterm infants with CHDs with pulmonary overcirculation before performing surgical interventions.