Diagnostic Approach to Pulmonary Hypertension in Premature Neonates

Multidisciplinary bronchopulmonary dysplasia care

INTRODUCTION

Bronchopulmonary dysplasia (BPD) is a chronic respiratory disease in neonates and infants, which often presents with multisystem organ involvement, co-morbidities, and prolonged hospital stays. Therefore, a multidisciplinary chronic care approach is needed in the severest forms of BPD to optimize outcomes. However, this approach can be challenging to implement. The objective of this article is to review and synthesize the available literature regarding multidisciplinary care in infants and children with established BPD, and to provide a framework that can guide clinical practice and future research.

AREAS COVERED

A literature search was conducted using Ovid MEDLINE, CINAHL, and Embase and several components of multidisciplinary management of BPD were identified and reviewed, including chronic care, team development, team members, discharge planning, and outpatient care.

EXPERT OPINION

Establishing a core multidisciplinary group familiar with the chronicity of established BPD is recommended as best practice for this population. Acknowledging this is not feasible for all individual centers, it is important for clinical practice and future research to focus on the development and incorporation of national consulting services, telemedicine, and educational resources.

Impact of premature rupture of membranes on clinical outcomes of extremely premature infants: A propensity score matching study

Background

Premature rupture of membranes (PROM) is a common cause of extremely premature infants (EPIs) and also leads to adverse preterm complications. However, the effect of PROM on EPIs remains contradictory. This study used propensity score matching (PSM) to adjust the baseline characteristics to explore the impact of PROM on clinical outcomes of extremely premature infants (EPIs).

Methods

Medical data of 470 EPIs at gestational age < 28weeks who received prenatal examination in our hospital between January 1, 2015 and December 31, 2020 were analyzed retrospectively. According to the presence or absence of PROM, they were divided into a PROM group and a non-PROM group. Ten covariates including birth weight, male sex, artificial conception, cesarean delivery, 5-min Apgar score ≤ 7, oligohydramnios, gestational hypertension, preeclampsia, antenatal steroid use, and complete steroid treatment were matched 1:1 by PSM. The major complication occurrence and mortality during hospitalization were compared between the two groups by t-test, nonparametric test or x 2 test.

Results

Among the 470 infants enrolled, 157 (33.4%) were in the PROM group and 313 in the no-PROM group. After matching the ten confounding factors,276 cases were successfully enrolled. The incidence of early pulmonary hypertension (EPH) and severe retinopathy of prematurity (ROP) in the PROM group were higher than those in the no-PROM group [44.2% (61/138) vs. 29.0% (40/138); 34.8% (48/138) vs. 21.7% (30/138), x ² = 6.886 and 5.790, both P < 0.05]. However, there was no significant difference in the in-hospital mortality and the incidence of other major complications between the two groups (all P > 0.05).

Conclusions

PROM increased the incidence of EPH and severe ROP in EPI, but had no significant impact on in-hospital mortality, length of hospital stay, and the incidence of other complications.

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.

A prediction model of pulmonary hypertension in preterm infants with bronchopulmonary dysplasia

OBJECTIVE

Pulmonary hypertension (PH) is a severe cardiovascular complication of bronchopulmonary dysplasia (BPD) that contributes to the high mortality rates for preterm infants. The objective of this study is to establish a prediction model of BPD-associated PH (BPD-PH) by integrating multiple predictive factors for infants with BPD.

METHOD

A retrospective investigation of the perinatal clinical records and data of echocardiography in all the preterm infants with BPD was performed from January 2012 to December 2019. A prediction model of BPD-PH was established based on the univariate and multivariate logistic regression analysis of the clinical data and evaluated by using the area under the receiver operating characteristic (ROC) curve (AUC), combined with the Hosmer-Lemeshow (HL) test. Internal validation was performed with bootstrap resampling.

RESULT

A total of 268 infants with BPD were divided into the BPD-PH group and the no-PH group. Multivariate logistic regression analysis showed that the independent predictive factors of BPD-PH were moderate to severe BPD, small for gestational age, duration of hemodynamically significant patent ductus arteriosus ≥ 28 days, and early PH. A prediction model was established based on the β coefficients of the four predictors. The area under the ROC curve of the prediction model was 0.930. The Hosmer-Lemeshow test (p = 0.976) and the calibration curve showed good calibration.

CONCLUSION

The prediction model based on the four risk factors predicts the development of BPD-PH with high sensitivity and specificity and might help clinicians to make individualized interventions to minimize the disease risk.

Early pulmonary hypertension is a risk factor for bronchopulmonary dysplasia-associated late pulmonary hypertension in extremely preterm infants

This study evaluated whether early pulmonary hypertension (PH) in extremely preterm infants (EPIs) at 22–27 weeks of gestation detected clinically with echocardiography at 4–7 postnatal days (PND) is a risk factor for death before 36 weeks post-menstrual age (PMA) or late PH in moderate or severe (m/s) bronchopulmonary dysplasia (BPD) (BPD-PH). We analyzed risk factors for death before 36 weeks PMA or BPD-PH. Among 247 EPIs enrolled, 74 (30.0%) had early PH. Twenty-one (28.4%) infants with early PH and 18 (10.4%) without early PH died before 36 weeks PMA; 14 (18.9%) infants with early PH and 9 (5.2%) without early PH had BPD-PH at 36–38 weeks PMA. Multivariate analysis revealed that early PH (adjusted odds ratio, 6.55; 95% confidence interval, 3.10–13.82, P < 0.05), clinical chorioamnionitis (2.50; 1.18–5.31), intraventricular hemorrhage (grade 3–4) (3.43; 1.26–9.37), and late sepsis (6.76; 3.20–14.28) independently increased the risk of development of death before 36 weeks PMA or BPD-PH. Subgroup analysis among m/s BPD patients revealed that early PH (4.50; 1.61–12.58) and prolonged invasive ventilator care (> 28 days) (4.91; 1.02–23.68) increased the risk for late PH independently. In conclusion, EPIs with early PH at 4–7 PND should be monitored for BPD-associated late PH development.

Children with Bronchopulmonary Dysplasia-Associated Pulmonary Hypertension Treated with Pulmonary Vasodilators-The Pediatric Cardiologist Point of View

Pulmonary hypertension in children with bronchopulmonary dysplasia (BPD-PH) significantly worsens the prognosis. Pulmonary vasodilators are often used in BPD-PH but the short-term outcome of treatment is not well described. The aim of this study was to evaluate BPD-PH children diagnosed beyond 36 weeks postmenstrual age treated with pulmonary vasodilators (sildenafil, bosentan, or both) and to assess the short and long-term effect of oral pulmonary vasodilators treatment. Twenty patients were included in the study. Cardiology evaluation (WHO-FC, NTproBNP, oxygen saturation, pulmonary to systemic pressure ratio PAP/SAP) was performed at diagnosis and after treatment initiation. In the majority of patients improvement in all evaluated factors was observed. No side effects of vasodilators were observed. PH resolved in 10 patients after a mean of 21.4 months of treatment. Six patients died. The number of poor prognostic factors commonly used to assess patients with pulmonary arterial hypertension (PAH) decreased significantly during BPD-PH treatment. The influence of BPD-PH perinatal risk factors on prognosis was considered but was not confirmed. In conclusion, the treatment of BPD-PH with pulmonary vasodilators was well tolerated and led to a clinical improvement with the possibility of discontinuation without recurrence of PH. Prognostic factors used in pediatric PAH risk stratification also seem to be useful in assessing treatment efficacy and prognosis in patients with BPD-PH.

Evidence for the Management of Bronchopulmonary Dysplasia in Very Preterm Infants

BACKGROUND

Very preterm birth often results in the development of bronchopulmonary dysplasia (BPD) with an inverse correlation of gestational age and birthweight. This very preterm population is especially exposed to interventions, which affect the development of BPD.

OBJECTIVE

The goal of our review is to summarize the evidence on these daily procedures and provide evidence-based recommendations for the management of BPD.

METHODS

We conducted a systematic literature research using MEDLINE/PubMed on antenatal corticosteroids, surfactant-replacement therapy, caffeine, ventilation strategies, postnatal corticosteroids, inhaled nitric oxide, inhaled bronchodilators, macrolides, patent ductus arteriosus, fluid management, vitamin A, treatment of pulmonary hypertension and stem cell therapy.

RESULTS

Evidence provided by meta-analyses, systematic reviews, randomized controlled trials (RCTs) and large observational studies are summarized as a narrative review.

DISCUSSION

There is strong evidence for the use of antenatal corticosteroids, surfactant-replacement therapy, especially in combination with noninvasive ventilation strategies, caffeine and lung-protective ventilation strategies. A more differentiated approach has to be applied to corticosteroid treatment, the management of patent ductus arteriosus (PDA), fluid-intake and vitamin A supplementation, as well as the treatment of BPD-associated pulmonary hypertension. There is no evidence for the routine use of inhaled bronchodilators and prophylactic inhaled nitric oxide. Stem cell therapy is promising, but should be used in RCTs only.

Prenatal Maternal Lipopolysaccharide and Mild Newborn Hyperoxia Increase Intrapulmonary Airway but Not Vessel Reactivity in a Mouse Model

Maternal infection is a risk for preterm delivery. Preterm newborns often require supplemental oxygen to treat neonatal respiratory distress. Newborn hyperoxia exposure is associated with airway and vascular hyperreactivity, while the complications of maternal infection are variable. In a mouse model of prenatal maternal intraperitoneal lipopolysaccharide (LPS, embryonic day 18) with subsequent newborn hyperoxia (40% oxygen × 7 days) precision-cut living lung slices were used to measure intrapulmonary airway and vascular reactivity at 21 days of age. Hyperoxia increased airway reactivity to methacholine compared to room air controls. Prenatal maternal LPS did not alter airway reactivity in room air. Combined maternal LPS and hyperoxia exposures increased airway reactivity vs. controls, although maximal responses were diminished compared to hyperoxia alone. Vessel reactivity to serotonin did not significantly differ in hyperoxia or room air; however, prenatal maternal LPS appeared to attenuate vessel reactivity in room air. Following room air recovery, LPS with hyperoxia lungs displayed upregulated inflammatory and fibrosis genes compared to room air saline controls (TNFαR1, iNOS, and TGFβ). In this model, mild newborn hyperoxia increases airway but not vessel reactivity. Prenatal maternal LPS did not further increase hyperoxic airway reactivity. However, inflammatory genes remain upregulated weeks after recovery from maternal LPS and newborn hyperoxia exposures.

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.

Notch3 signaling activation in smooth muscle cells promotes extrauterine growth restriction-induced pulmonary hypertension

BACKGROUND AND AIMS

Early postnatal life is a critical developmental period that affects health of the whole life. Extrauterine growth restriction (EUGR) causes cardiovascular development problems and diseases, including pulmonary arterial hypertension (PAH). PAH is characterized by proliferation, migration, and anti-apoptosis of pulmonary artery smooth muscle cells (PASMCs). However, the role of PASMCs in EUGR has not been studied. Thus, we hypothesized that PASMCs dysfunction played a role in EUGR-induced pulmonary hypertension.

METHODS AND RESULTS

Here we identified that postnatal nutritional restriction-induced EUGR rats exhibited an elevated mean pulmonary arterial pressure and vascular remodeling at 12 weeks old. PASMCs of EUGR rats showed increased cell proliferation and migration features. In EUGR-induced PAH rats, Notch3 signaling was activated. Relative mRNA and protein expression levels of Notch3 intracellular domain (Notch3 ICD), and Notch target gene Hey1 in PASMCs were upregulated. We further demonstrated that pharmacological inhibition of Notch3 activity by using a γ-secretase inhibitor DAPT, which blocked the cleavage of Notch proteins to ICD peptides, could effectively inhibit PASMC proliferation. Specifically knocked down of Notch3 in rat PASMCs by shRNA restored the abnormal PASMC phenotype in vitro. We found that administration of Notch signaling inhibitor DAPT could successfully reduce mean pulmonary arterial pressure in EUGR rats.

CONCLUSIONS

The present study demonstrated that upregulation of Notch3 signaling in PASMCs was crucial for the development of EUGR-induced PAH. Blocking Notch3-Hey1 signaling pathway in PASMCs provides a potential therapeutic target for PAH.

Genetic Strain and Sex Differences in a Hyperoxia-Induced Mouse Model of Varying Severity of Bronchopulmonary Dysplasia

Bronchopulmonary dysplasia (BPD) is a disease prevalent in preterm babies with a need for supplemental oxygen, resulting in impaired lung development and dysregulated vascularization. Epidemiologic studies have shown that males are more prone to BPD and have a delayed recovery compared with females, for reasons unknown. Herein, we tried to recapitulate mild, moderate, and severe BPD, using two different strains of mice, in males and females: CD1 (outbred) and C57BL/6 (inbred). Aside from higher body weight in the CD1 strain, there were no other gross morphologic differences with respect to alveolar development between the two strains. With respect to lung morphology after oxygen exposure, females had less injury with better preservation of alveolar chord length and decreased alveolar protein leak and inflammatory cells in the bronchoalveolar lavage fluid. In addition, housekeeping genes, which are routinely used as loading controls, were expressed differently in males and females. In the BPD mouse model, gonadotropin-releasing hormone was increased in females compared with males. Specific miRNAs (miR-146 and miR-34a) were expressed differently in the sexes. In the severe BPD mouse model, administering miR-146 mimic to males attenuated lung damage, whereas administering miR-146 inhibitor to females increased pulmonary injury.

Target oxygen saturation and development of pulmonary hypertension and increased pulmonary vascular resistance in preterm infants

OBJECTIVE

Determine whether higher targeted oxygen levels are associated with reduced incidence of pulmonary hypertension (PH) and elevated pulmonary vascular resistance (PVR) in extremely premature infants.

STUDY DESIGN

Retrospective chart review of 252 extremely preterm infants (<29 weeks), who underwent echocardiogram prior to discharge. PH rates were compared during periods (June 2012-May 2015 and June 2015-April 2016) when lower (88-92%) or higher (90-95%) oxygen saturation targets were used. PH was determined on echocardiography. The ratio of pulmonary artery acceleration time to right ventricular ejection time was computed, with values <0.31 indicative of elevated PVR. Survival analysis compared the effects of oxygen saturation group on development/resolution of PH and elevated PVR.

RESULTS

The higher saturation group had significantly lower risk of developing PH (hazard ratio (HR) = 0.50, 95%CI 0.26-0.95; P = 0.03) or elevated PVR (HR = 0.55, 95%CI 0.38-0.81; P = 0.002), compared to the lower oxygen saturation group. Median time to PH development was significantly shorter in the lower saturation group than in the higher saturation group (5 days vs 12 days; P = 0.02), as was time to development of elevated PVR (4 days vs 6 days; P < 0.001). Duration of PH (P = 0.12) and elevated PVR (P = 0.86) did not differ significantly between groups. Cumulative incidence of PH (P = 0.04) and elevated PVR (P = 0.01) at 36 weeks post-menstrual age was significantly lower in the high saturation group compared to the lower saturation group.

CONCLUSION

Higher targeted oxygen saturation was associated with reduced risk of PH or elevated PVR in extremely preterm infants compared to lower oxygen saturation target.

Bronchopulmonary dysplasia: clinical aspects and preventive and therapeutic strategies

BACKGROUND

Bronchopulmonary dysplasia (BPD) is the result of a complex process in which several prenatal and/or postnatal factors interfere with lower respiratory tract development, leading to a severe, lifelong disease. In this review, what is presently known regarding BPD pathogenesis, its impact on long-term pulmonary morbidity and mortality and the available preventive and therapeutic strategies are discussed.

MAIN BODY

Bronchopulmonary dysplasia is associated with persistent lung impairment later in life, significantly impacting health services because subjects with BPD have, in most cases, frequent respiratory diseases and reductions in quality of life and life expectancy. Prematurity per se is associated with an increased risk of long-term lung problems. However, in children with BPD, impairment of pulmonary structures and function is even greater, although the characterization of long-term outcomes of BPD is difficult because the adults presently available to study have received outdated treatment. Prenatal and postnatal preventive measures are extremely important to reduce the risk of BPD.

CONCLUSION

Bronchopulmonary dysplasia is a respiratory condition that presently occurs in preterm neonates and can lead to chronic respiratory problems. Although knowledge about BPD pathogenesis has significantly increased in recent years, not all of the mechanisms that lead to lung damage are completely understood, which explains why therapeutic approaches that are theoretically effective have been only partly satisfactory or useless and, in some cases, potentially negative. However, prevention of prematurity, systematic use of nonaggressive ventilator measures, avoiding supraphysiologic oxygen exposure and administration of surfactant, caffeine and vitamin A can significantly reduce the risk of BPD development. Cell therapy is the most fascinating new measure to address the lung damage due to BPD. It is desirable that ongoing studies yield positive results to definitively solve a major clinical, social and economic problem.