Risk Factors and Clinical Outcomes in Preterm Infants with Pulmonary Hypertension

A comprehensive study on machine learning models combining with oversampling for bronchopulmonary dysplasia-associated pulmonary hypertension in very preterm infants

BACKGROUND

Bronchopulmonary dysplasia-associated pulmonary hypertension (BPD-PH) remains a devastating clinical complication seriously affecting the therapeutic outcome of preterm infants. Hence, early prevention and timely diagnosis prior to pathological change is the key to reducing morbidity and improving prognosis. Our primary objective is to utilize machine learning techniques to build predictive models that could accurately identify BPD infants at risk of developing PH.

METHODS

The data utilized in this study were collected from neonatology departments of four tertiary-level hospitals in China. To address the issue of imbalanced data, oversampling algorithms synthetic minority over-sampling technique (SMOTE) was applied to improve the model.

RESULTS

Seven hundred sixty one clinical records were collected in our study. Following data pre-processing and feature selection, 5 of the 46 features were used to build models, including duration of invasive respiratory support (day), the severity of BPD, ventilator-associated pneumonia, pulmonary hemorrhage, and early-onset PH. Four machine learning models were applied to predictive learning, and after comprehensive selection a model was ultimately selected. The model achieved 93.8% sensitivity, 85.0% accuracy, and 0.933 AUC. A score of the logistic regression formula greater than 0 was identified as a warning sign of BPD-PH.

CONCLUSIONS

We comprehensively compared different machine learning models and ultimately obtained a good prognosis model which was sufficient to support pediatric clinicians to make early diagnosis and formulate a better treatment plan for pediatric patients with BPD-PH.

Factors in the Neonatal Period Associated With Pulmonary Hypertension at 28 Days of Life in Broncho-Pulmonary Dysplasia

Objectives. To identify factors associated with pulmonary hypertension (PH) at 28 days of life in preterm infants with bronchopulmonary dysplasia (BPD). Methods. This observational study included 128 premature infants with BPD between January 2022 and February 2023 from the neonatal intensive care unit of Vietnam National Children's Hospital. Results. PH was observed using echocardiography in 29 patients (22.66%). The prevalence of severe BPD in the PH group (62.07%) was significantly higher than that in the non-PH group (18.18%). The multivariate logistic regression showed 2 predictors of PH in BPD: invasive mechanical ventilation up to 28 days of life (odds ratio [OR]:9.440; 95% confidence interval [CI]: 3.090-28.833; P < .001) and history of shock (OR: 2.962; 95% CI: 1.067-8.225; P = .037). Conclusion. We found 2 predictors of PH at 28 days of life in BPD: invasive mechanical ventilation up to 28 days of life and history of shock.

Diameter of ductus arteriosus on postnatal Day 7 is associated with late pulmonary hypertension in extremely preterm infants

OBJECTIVES

A clinically feasible biomarker for pulmonary hypertension (PH) prediction is still lacking. Thus, we aim to assess the association between ductus arteriosus (DA) diameter and PH in extremely preterm infants.

STUDY DESIGN

A retrospective case-control study was performed to compare the diameter of DA in infants with and without late PH. Propensity scores were calculated to match the gestational age in two groups with a match ratio of 1:2. The diameter of DA was measured by echocardiography on postnatal Days 3 and 7.

RESULTS

A total of 91 infants were included in the study. The diagnosis of late PH was made in 32 infants between postnatal life of 28-159 days. Univariable analysis showed that late PH was associated with birth weight, invasive mechanical ventilation, hemodynamically significant PDA (hsPDA), duration of PDA exposure, the rate of surgical ligation, and diameter of DA on postnatal Days 3 and 7. After adjusting for these selected factors, the diameter of DA measured on postnatal Day 7 was independently associated with the risk of late PH (odds ratios: 5.511, 95% confidence interval: 1.552-19.562, p = .008). Receiver operator curve analysis indicated that 1.95 mm in DA diameter on postnatal Day 7 was the cutoff value for late PH with an area under the curve of 0.697.

CONCLUSIONS

Our findings suggest that DA diameter (larger than or equal to 1.95 mm) on postnatal Day 7 might serve as a predictor for late PH in extremely preterm infants.

Treatment of Patent Ductus Arteriosus in Premature Infants: Intravenous Paracetamol or Oral Ibuprofen?

BACKGROUND

The similarity in the mechanism of action between paracetamol and ibuprofen can cause similar side effects. However, in preterm neonates with feeding intolerance, intravenous (IV) paracetamol has replaced oral ibuprofen. Therefore, a comparison of the effectiveness and side effects is essential.

METHODS

In this retrospective cohort study, the data of 118 preterm infants with a definite diagnosis of patent ductus arteriosus (PDA), including 59 patients who received oral ibuprofen and 59 patients who received IV paracetamol were analyzed. Laboratory evaluations of serum total and direct bilirubin, hemoglobin, and creatinine levels before and seven days after treatment were made. Using analysis of covariance (ANCOVA) and multiple multinomial logistic regression models, the effect of two treatment groups on the post-treatment variables as well as their efficacy comparison were evaluated.

RESULTS

In both pre- and post-treatment periods, there was no significant association between echocardiography variables with treatment groups. The results from the ANCOVA model showed that the paracetamol and ibuprofen were followed by a significant decrease in the mean total bilirubin and Hct variables after treatment by 1.38 and 1.65 units, respectively. In addition, results from the Mann-Whitney U test revealed that the median Hb and K differences after and before treatment had a significant difference between the two treatment groups. Furthermore, based on the multiple multinomial logistic model results, the odds of complete arterial duct closure with IV paracetamol was 1.27 times higher than with oral ibuprofen, while in the oral ibuprofen group, the odds of closing was 1.44 times higher than the IV paracetamol group, but there was no statistically significant difference between the two groups.

CONCLUSION

Intravenous paracetamol has equal efficacy compared to oral ibuprofen in the treatment of PDA. Also, it seems to be associated with a lower risk of hyperbilirubinemia following the treatment.

Outcomes of and factors associated with the development of bronchopulmonary dysplasia with pulmonary hypertension in very low birth weight infants: A retrospective study in a medical center

Introduction

Bronchopulmonary dysplasia (BPD) with pulmonary hypertension (PH) leads to increased morbidity and mortality in extremely preterm infants. Recent studies have analyzed factors associated with development of PH in BPD; however, this research remains inconclusive, and controversy exists regarding the correlation between BPD and PH. This study aimed to investigate potential associated factors, clinical characteristics, and outcomes of BPD with pulmonary hypertension in very low birth weight (VLBW) preterm infants.

Methods

We conducted a retrospective study, reviewing the records of infants with gestational age (GA) <32 weeks and birth weight <1,500 g admitted to a tertiary neonatal intensive care unit between January 2020 and October 2021 who were diagnosed with moderate to severe BPD. Echocardiogram was performed at the postmenstrual age of 36 weeks or before discharge. The diagnosis of PH was based on the findings of echocardiogram. Prenatal and postnatal characteristics, demographic data, treatment details, and outcomes were collected and analyzed.

Results

A total of 139 VLBW infants with BPD were enrolled and divided into a PH group (n = 25) and a non-PH group (n = 114). The mean GA was 27.3 ± 2.3 weeks and the mean birth weight of infants with BPD was 927.3 ± 293.3 g. A multivariate logistic regression model revealed that a high positive end-expiratory pressure (PEEP) setting (OR: 2.105; 95% CI: 1.472-3.011; p < 0.001) in established BPD and surgical closure of patent ductus arteriosus (PDA; OR: 6.273; 95% CI: 1.574-24.977; p = 0.009) were associated with BPD-PH. Neonates with BPD who developed pulmonary hypertension remained hospitalized for longer (p < 0.001), received invasive mechanical ventilation support for longer (p < 0.001), had a higher incidence of retinopathy of prematurity (ROP; OR: 4.201; 95% CI: 1.561-11.304; p = 0.003), were more likely to require oxygen support at discharge (OR: 5.600; 95% CI: 2.175-14.416; p < 0.001), and were more likely to undergo tracheostomy (OR: 35.368; 95% CI: 4.03-310.43; p < 0.001).

Conclusion

PDA ligation and a higher PEEP setting were associated with BPD-PH in our cohort study. Compared with VLBW infants with BPD but without PH, infants with BPD and PH were hospitalized for longer, and also had a higher incidence of oxygen support after discharge, ROP, and tracheostomy.

Prognostic Role of Biomarkers for Pulmonary Arterial Hypertension Associated with Bronchopulmonary Dysplasia in Extremely Premature Infants

To explore the association of the biochemical markers after birth with BPD-PAH, factors independently predicting BPD-PAH risk were identified by multivariate logistic regression. Cut off values were determined by plotting receiver-operator curve (ROC), for the sake of dichotomizing continuous variables that showed independent relation with BPD-PAH risk. The results show that uric acid (UC) and blood urea nitrogen (BUN) contents markedly increased among infants experiencing BPD-PAH in comparison with those without BPD-PAH (11.6 vs. 9.7 mmol/L, P = 0.006 and 482.0 vs. 249.0 μmol/L, P < 0.001, separately). As shown by multivariate logistic regression, serum BUN levels (OR = 1.143) and uric acid levels (OR = 1.034) were important risk factors for BPD-PAH. Through a lot of experiments, the effectiveness and the advanced nature of the framework proposed in this paper are proved effectively. The framework proposed in this paper can provide some reference and thinking for follow-up research.

Safety of sildenafil in extremely premature infants: a phase I trial

OBJECTIVE

To characterize the safety of sildenafil in premature infants.

STUDY DESIGN

A phase I, open-label trial of sildenafil in premature infants receiving sildenafil per usual clinical care (cohort 1) or receiving a single IV dose of sildenafil (cohort 2). Safety was evaluated based on adverse events (AEs), transaminase levels, and mean arterial pressure monitoring.

RESULTS

Twenty-four infants in cohort 1 (n = 25) received enteral sildenafil. In cohort 2, infants received a single IV sildenafil dose of 0.25 mg/kg (n = 7) or 0.125 mg/kg (n = 2). In cohort 2, there was one serious AE related to study drug involving hypotension associated with a faster infusion rate than specified by the protocol. There were no AEs related to elevated transaminases.

CONCLUSION

Sildenafil was well tolerated by the study population. Drug administration times and flush rates require careful attention to prevent infusion-related hypotension associated with faster infusions of IV sildenafil in premature infants.

CLINICAL TRIAL

ClinicalTrials.gov Identifier: NCT01670136.

Risk factors and clinical characteristics for bronchopulmonary dysplasia associated pulmonary hypertension in very-low-birth-weight infants

BACKGROUND

Pulmonary hypertension (PH) is a common complication of bronchopulmonary dysplasia (BPD) in very-low-birth-weight infants (VLBWIs). Although recent studies have increased awareness that PH contributes significantly to the high morbidity and mortality of BPD, the risk factors and clinical characteristics for PH in VLBWIs are little known.

OBJECTIVES

To investigate the risk factors and clinical characteristics for BPD-associated pulmonary hypertension (BPD-PH) in VLBWIs.

METHODS

A retrospective case-control observational study of VLBWIs with BPD admitted to a neonatal intensive care unit (NICU) over 4 years. According to echocardiograms confirming elevated pulmonary artery pressure after 28 days after birth, we divided BPD infants into PH group (n = 18) and non-PH group (n = 65). We compared pre- and postnatal characteristics between VLBWIs with or without PH. Multivariable logistic regression analysis was conducted with backward selection.

RESULTS

A total of 83 infants with BPD were divided into PH group (n = 18) or non-PH group (n = 65). The average birth weight of the infants with BPD was 1078.1 g. Compared with those infants of the non-PH group, the birth weight of BPD-PH infants was significantly lower (968.1 ± 187.7 vs. 1108.5 ± 185.8, P = 0.006). Infants in the PH group had a higher incidence of patent ductus arteriosus (PDA) and underwent longer durations of oxygen therapy and mechanical ventilation compared to those in the non-PH group. In all subjects, birth weight (OR 0.995; 95% CI 0.991-0.999; P = 0.025) and PDA (OR 13.355; 95% CI 2.950-60.469; P = 0.001) were found to be specific risk factors for BPD-PH in this cohort.

CONCLUSIONS

The study shows PDA and birth weight are specific risk factors for BPD-PH in VLBWIs.

Understanding hydrogen sulfide signaling in neonatal airway disease

INTRODUCTION

Airway dysfunction leading to chronic lung disease is a common consequence of premature birth and mechanisms responsible for early and progressive airway remodeling are not completely understood. Current therapeutic options are only partially effective in reducing the burden of neonatal airway disease and premature decline of lung function. Gasotransmitter hydrogen sulfide (H2S) has been recently recognized for its therapeutic potential in lung diseases.

AREAS COVERED

Contradictory to its well-known toxicity at high concentrations, H2S has been characterized to have anti-inflammatory, antioxidant, and antiapoptotic properties at physiological concentrations. In the respiratory system, endogenous H2S production participates in late lung development and exogenous H2S administration has a protective role in a variety of diseases such as acute lung injury and chronic pulmonary hypertension and fibrosis. Literature searches performed using NCBI PubMed without publication date limitations were used to construct this review, which highlights the dichotomous role of H2S in the lung, and explores its promising beneficial effects in lung diseases.

EXPERT OPINION

The emerging role of H2S in pathways involved in chronic lung disease of prematurity along with its recent use in animal models of BPD highlight H2S as a potential novel candidate in protecting lung function following preterm birth.

Safety of sildenafil in premature infants with severe bronchopulmonary dysplasia (SILDI-SAFE): a multicenter, randomized, placebo-controlled, sequential dose-escalating, double-masked, safety study

Background

Pulmonary hypertension is a deadly complication of bronchopulmonary dysplasia, the most common pulmonary morbidity of prematurity. Despite these catastrophic consequences, no evidence-based therapies are available for the prevention of pulmonary hypertension in this population. Sildenafil is a potent pulmonary vasodilator approved by the US Food and Drug Administration for the treatment of pulmonary hypertension in adults. Preclinical models suggest a beneficial effect of sildenafil on premature lungs through improved alveolarization and preserved vascular development. Sildenafil may therefore prevent the development of pulmonary hypertension associated with lung disease of prematurity by reducing pulmonary vascular remodeling and lowering pulmonary vascular resistance; however, clinical trial evidence is needed. The present study, supported by the National Institutes of Health’s National Heart Lung and Blood Institute, will generate safety, pharmacokinetics, and preliminary effectiveness data on sildenafil in a population of premature infants with severe bronchopulmonary dysplasia at risk for pulmonary hypertension.

Methods

We have designed a multicenter, randomized, placebo-controlled, sequential dose-escalating, double-masked, safety trial of sildenafil in premature infants with severe bronchopulmonary dysplasia. We will randomize 120 premature infants < 29 weeks gestational age with severe bronchopulmonary dysplasia at 32–40 weeks postmenstrual age in a dose-escalating approach 3:1 (sildenafil: placebo) sequentially into each of 3 cohorts at ~ 30 clinical sites. Participants will receive up to 34 days of study drug, followed by 28 days of safety monitoring. The primary outcome will be safety as determined by incidence of hypotension. Secondary outcomes will include pharmacokinetics and preliminary effectiveness of sildenafil based on presence or absence of pulmonary hypertension diagnosed by echocardiography at the end of treatment period.

Discussion

Sildenafil is a promising intervention to prevent the development of pulmonary hypertension in premature infants with bronchopulmonary dysplasia. Clinical trials of sildenafil specifically designed for premature infants are urgently needed. The current study will make substantial contributions to scientific knowledge of the safety of sildenafil in premature infants at risk for pulmonary hypertension. Results from the study will be used by investigators to inform the design of a pivotal efficacy trial.

Trial registration

ClinicalTrials.govNCT04447989. Registered 25 June 2020.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12887-020-02453-7.

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.

Meanings assigned by families about children's chronic disease diagnosis

OBJECTIVES

to understand the meanings assigned by family caregivers about children's chronic disease diagnosis.

METHODS

qualitative study, which used as theoretical framework the Symbolic Interactionism, and methodological, the Grounded Theory. It was held in a pediatric unit in Southern Brazil, in 2016, through interviews submitted to open and axial analysis, with the participation of 20 family caregivers of hospitalized children.

RESULTS

relatives, interacting with the nursing/health staff, perceive children's disease at birth. They are diagnosed with chronic disease by the physician and deny it. Subsequently, they accept and seek information on care.

CONCLUSIONS

the results pointed out the stages that relatives experience by assigning meanings to about children's chronic disease diagnosis. These meanings provide subsidies for nurses' actions, which need to be aware of children's and family's needs in order to offer comprehensive and humanized care.

Respiratory Phenotypes for Preterm Infants, Children, and Adults: Bronchopulmonary Dysplasia and More

Ongoing advancements in neonatal care since the late 1980s have led to increased numbers of premature infants surviving well beyond the neonatal period. As a result of increased survival, many individuals born preterm manifest chronic respiratory symptoms throughout infancy, childhood, and adult life. The archetypical respiratory disease of prematurity, bronchopulmonary dysplasia, is the second most common chronic pediatric respiratory disease after asthma. However, there are several commonly held misconceptions. These misconceptions include that bronchopulmonary dysplasia is rare, that bronchopulmonary dysplasia resolves within the first few years of life, and that bronchopulmonary dysplasia does not impact respiratory health in adult life. This focused review describes a spectrum of respiratory conditions that individuals born prematurely may experience throughout their lifespan. Specifically, this review provides quantitative estimates of the number of individuals with alveolar, airway, and vascular phenotypes associated with bronchopulmonary dysplasia, as well as non-bronchopulmonary dysplasia respiratory phenotypes such as airway malacia, obstructive sleep apnea, and control of breathing issues. Furthermore, this review illustrates what is known about the potential for progression and/or lack of resolution of these respiratory phenotypes in childhood and adult life. Recognizing the spectrum of respiratory phenotypes associated with individuals born preterm and providing comprehensive and personalized care to these individuals may help to modulate adverse respiratory outcomes in later life.

Mortality in infants with bronchopulmonary dysplasia: Data from cardiac catheterization

RATIONALE

Pulmonary hypertension (PH) is relatively common in infants with severe bronchopulmonary dysplasia (BPD), however, hemodynamic data and factors associated with mortality in this patient group are sparsely described in the literature.

OBJECTIVES

To characterize the hemodynamics of former preterm infants with BPD and PH, as measured at cardiac catheterization, and to identify respiratory and cardiovascular predictors of mortality.

METHODS

Single-center, retrospective cohort study, including, 30 patients born at less than 32-week gestational age (GA), who had an oxygen requirement at 36 weeks postmenstrual age and underwent cardiac catheterization between July 2014 and December 2017.

RESULTS

Median GA at birth was 25 5/7 weeks (interquartile range [IQR], 24 4/7-26 6/7 weeks). Median birth weight was 620 g (IQR, 530-700 g). With a median of 23 months of follow up (IQR, 11-39 months), mortality as of July 2018 was 27% (8 of 30). The alveolar-arterial oxygen gradient as a measure of lung disease did not correlate with mortality (log-rank test P = 0.28). However, indexed pulmonary vascular resistance (PVR) of greater than 3 Woods units × m ² showed a trend toward increased mortality (log-rank test P =  0.12). Pulmonary vein stenosis was the only predictor significantly associated with mortality (log-rank test P =  0.005).

CONCLUSIONS

In this cohort, the severity of lung disease as assessed by impaired oxygenation at cardiac catheterization did not correlate with mortality. The only factor significantly associated with mortality was the presence of pulmonary vein stenosis on cardiac catheterization, although PVR may also be an important factor.

Correlation between changes in brain natriuretic peptide and echocardiographic features in persistent pulmonary hypertension of newborn

Objective: To investigate the correlation between changes in brain natriuretic peptide (BNP) and echocardiographic features in persistent pulmonary hypertension of newborn (PPHN).Patients and methods: A total of 76 patients with PPHN treated in our hospital from March 2017 to February 2018 were divided into mild group (n = 33), moderate group (n = 22) and severe group (n = 21) according to the pulmonary arterial systolic pressure, and they were compared with 30 normal newborns (control group) during the same period. All newborns underwent echocardiography, the BNP level was detected, and the correlation between echocardiographic features and BNP changes was analyzed.Results: The BNP level in control group was significantly lower than those in PPHN groups, and it was constantly increased from mild group to severe group (p<.05). There were no significant differences in left atrial diameter (LA) and left ventricular diameter (LV) among groups (p>.05), while there were significant differences in the right atrial diameter (RA), right ventricular diameter (RV) and peak velocity of tricuspid regurgitation (VTR) (p<.05). BNP had no correlations with LA and LV (p>.05), but had positive correlations with RA, RV and VTR (r = 0.527, 0.503 and 0.524, p<.05).Conclusion: The BNP level of patients with PPHN increases with the increasing severity of disease. BNP has close correlations with echocardiographic features of neonatal patients. Predicting the BNP changes via echocardiography is of certain value in guiding the clinical treatment.

[Clinical features and prognosis of bronchopulmonary dysplasia complicated by pulmonary hypertension in preterm infants]

OBJECTIVE

To study the clinical features and prognosis of bronchopulmonary dysplasia (BPD) complicated by pulmonary hypertension (PH) in preterm infants.

METHODS

A retrospective analysis was performed on the clinical data of 191 preterm infants with BPD.

RESULTS

In the 191 preterm infants with BPD, 37 (19.4%), all with moderate or severe BPD, developed PH beyond 36 weeks' corrected age. The incidence rates of PH in infants with moderate and severe BPD were 5.7% (5/87) and 47.8% (32/67) respectively. Gestational age and birth weight were lower in infants with PH than in those without PH (P<0.01). Infants with PH had higher incidence rates of small for gestational age (SGA), severe BPD, surgical ligation of patent ductus arteriosus (PDA), neonatal respiratory distress syndrome, hemodynamically significant PDA, and pneumonia than those without PH (P<0.01). Durations of oxygen therapy, intubation, and positive pressure ventilation were longer in infants with PH than in those without PH (P<0.01). Infants with PH had higher incidence rates of retinopathy of prematurity and extrauterine growth retardation, a higher mortality, and a longer length of hospital stay compared with those without PH (P<0.01). In the 37 infants with PH (6 with mild PH, 14 with moderate PH, and 17 with severe PH), those with mild or moderate PH all survived; 15(88%) out of 17 infants with severe PH died.

CONCLUSIONS

The incidence of PH is high in preterm infants with moderate or severe BPD. Regular screening of pulmonary artery pressure is recommended for infants with BPD. Infants with low gestational age and birth weight, SGA, and severe BPD are more likely to develop PH. Infants with BPD complicated by PH have relatively high incidence rates of complications, high mortality, and poor prognosis.

Predictors of length of stay for initial hospitalization in infants with bronchopulmonary dysplasia

OBJECTIVE

Longer initial hospitalizations for preterm infants with bronchopulmonary dysplasia (BPD) can delay family bonding and attainment of developmental milestones, increase the risk for hospital acquired complications, and increase healthcare costs. The goal of the study was to identify the characteristics associated with longer lengths of hospitalization in this high-risk population.

STUDY DESIGN

A retrospective analysis was performed on 660 children (born ≤32 weeks gestation) discharged from 13 Maryland NICUs recruited into an outpatient BPD registry.

RESULT

The mean age of discharge was 4.3 ± 2.9 months (median: 3.7 months). Subjects born with lower birthweights and covered by public insurance had longer lengths of hospitalization. Clinical characteristics at discharge associated with longer initial hospitalizations included gastrostomy tube, mechanical ventilation, tracheostomy, pulmonary hypertension, and supplemental oxygen.

CONCLUSION

Identifying the risk factors associated with longer lengths of stay could prompt the implementation of personalized in-hospital interventions to improve outcomes and minimize length of stay in infants with BPD.

Atrial Septal Defects Accelerate Pulmonary Hypertension Diagnoses in Premature Infants

Between 4 and 16% of extremely premature infants have late pulmonary hypertension (PH) (onset >30 days of life), and infants with PH have a higher risk of tracheostomy and death. Atrial septal defects (ASD) increase pulmonary blood flow and may promote PH in at-risk infants. The objective of this study was to determine if infants with ASD develop PH sooner than those without ASD. Infants who were born at < 32 weeks' gestation, with an echocardiogram on day of life > 30, and without congenital anomalies were included. Infants with and without ASD were evaluated for the time to PH diagnosis, defined as the day of the first echocardiogram that showed PH. A multivariable model with ASD and significant variables on PH and a Cox proportional hazard model evaluating time to PH was determined. Of the 334 infants with echocardiograms, 57 had an ASD and 26% of these developed PH vs. 12% without ASD (p = 0.006). Infants with PH had lower gestational age (25.2 vs. 26.2 weeks, p = 0.005), smaller birthweight (699 vs. 816 gm, p = 0.001), and more prematurity complications than infants without PH. More PH infants had maternal African-American race (63.9 vs. 36.1%), right ventricular dysfunction (23.9 vs. 3.2%, p < 0.001), right ventricular dilation (52.1 vs. 8.6%, p < 0.001), or right ventricular hypertrophy (51.2 vs. 10.1%, p < 0.001), than infants without PH. At 150 days of life, 78.1% (95% CI 64.6-86.9%) of infants with ASD survived without PH, compared with 90.9% (95% CI 86.7-93.8%) of infants without ASD, and the unadjusted hazard for development of PH for infants with ASD was 2.37 (95% CI 1.29-4.36). When significant clinical variables were controlled, infants with ASD had a 2.44-fold (95% CI 1.27-4.68) increase in PH, compared with infants without ASD. Most PH in infants with or without ASD was diagnosed by day of life 150, but infants with ASD had an over 2-fold increased hazard for PH during their neonatal hospitalization. Premature infants with ASD should be followed closely for PH development and further studies to investigate the optimal timing of closure are needed.

Diagnostic Approach to Pulmonary Hypertension in Premature Neonates

Bronchopulmonary dysplasia (BPD) is a form of chronic lung disease in premature infants following respiratory distress at birth. With increasing survival of extremely low birth weight infants, alveolar simplification is the defining lung characteristic of infants with BPD, and along with pulmonary hypertension, increasingly contributes to both respiratory morbidity and mortality in these infants. Growth restricted infants, infants born to mothers with oligohydramnios or following prolonged preterm rupture of membranes are at particular risk for early onset pulmonary hypertension. Altered vascular and alveolar growth particularly in canalicular and early saccular stages of lung development following mechanical ventilation and oxygen therapy, results in developmental lung arrest leading to BPD with pulmonary hypertension (PH). Early recognition of PH in infants with risk factors is important for optimal management of these infants. Screening tools for early diagnosis of PH are evolving; however, echocardiography is the mainstay for non-invasive diagnosis of PH in infants. Cardiac computed tomography (CT) and magnetic resonance are being used as imaging modalities, however their role in improving outcomes in these patients is uncertain. Follow-up of infants at risk for PH will help not only in early diagnosis, but also in appropriate management of these infants. Aggressive management of lung disease, avoidance of hypoxemic episodes, and optimal nutrition determine the progression of PH, as epigenetic factors may have significant effects, particularly in growth-restricted infants. Infants with diagnosis of PH are managed with pulmonary vasodilators and those resistant to therapy need to be worked up for the presence of cardio-vascular anomalies. The management of infants and toddlers with PH, especially following premature birth is an emerging field. Nonetheless, combination therapies in a multi-disciplinary setting improves outcomes for these infants.