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.

Role of sex as a biological variable in neonatal alveolar macrophages.

The lung macrophages play a crucial role in health and disease. Sexual dimorphism significantly impacts the phenotype and function of tissue-resident macrophages. The primary mechanisms responsible for sexually dimorphic outcomes in bronchopulmonary dysplasia (BPD) remain unidentified. We tested the hypothesis that biological sex plays a crucial role in the transcriptional state of alveolar macrophages, using neonatal murine hyperoxia-induced lung injury as a relevant model for human BPD. The effects of neonatal hyperoxia exposure (95 % FiO2, PND1-5: saccular stage) on the lung myeloid cells acutely after injury and during normoxic recovery were measured. Alveolar macrophages (AM) from room air- and hyperoxia exposed from male and female neonatal murine lungs were subjected to bulk-RNA Sequencing. AMs are significantly depleted in the hyperoxia-exposed lung acutely after injury, with subsequent recovery in both sexes. The transcriptome of the alveolar macrophages is impacted by neonatal hyperoxia exposure and by sex as a biological variable. Pathways related to DNA damage and interferon-signaling were positively enriched in female AMs. Metabolic pathways related to glucose and carbohydrate metabolism were positively enriched in the male AMs, while oxidative phosphorylation was negatively enriched. These pathways were shared with monocytes and airway macrophages from intubated male and female human premature neonates.

Interdisciplinary clinical bronchopulmonary dysplasia programs: development, evolution, and maturation.

Multidisciplinary bronchopulmonary dysplasia (BPD) programs provide improved and consistent medical management, care of the developing infant, family support, and smoother transitions in care resulting in improved survival, pulmonary, and extra-pulmonary outcomes. This review summarizes the benefits of interdisciplinary BPD management, as well as strategies for initial programmatic development, program growth, and maintenance at centers across the United States factoring in institutional, provider, and parent reported goals that were derived from a consensus conference on BPD management.

Long-term pulmonary outcomes in BPD throughout the life-course.

Respiratory disease is one of the most common complications of preterm birth. Survivors of prematurity have increased risks of morbidities and mortalities independent of prematurity, and frequently require multiple medications, home respiratory support, and subspecialty care to maintain health. Although advances in neonatal and pulmonary care have improved overall survival, earlier gestational age, lower birth weight, chorioamnionitis and late onset sepsis continue to be major factors in the development of bronchopulmonary dysplasia. These early life events associated with prematurity can have respiratory consequences that persist into adulthood. Furthermore, after initial hospital discharge, air pollution, respiratory tract infections and socioeconomic status may modify lung growth trajectories and influence respiratory outcomes in later life. Given that the incidence of respiratory disease associated with prematurity remains stable or increased, there is a need for pediatric and adult providers to be familiar with the natural history, manifestations, and common complications of disease.

Managing established bronchopulmonary dysplasia without using routine blood gas measurements.

OBJECTIVE: Routine blood gas measurements are common in infants with severe bronchopulmonary dysplasia (sBPD) and are a noxious stimulus. We developed a guideline-driven approach to evaluate the care of infants with sBPD without routine blood gas sampling in the chronic phase of NICU care (after diagnosis at 36 weeks PMA). STUDY DESIGN: We examined blood gas utilization and outcomes in our sBPD inpatient care unit using data collected between 2014 and 2020. RESULTS: 485 sBPD infants met inclusion criteria, and 303 (62%) never had a blood gas obtained after 36 weeks PMA. In infants who had blood gas measurements, the median number of total blood gases per patient was only 4 (IQR 1-10). We did not identify adverse effects on hospital outcomes in patients without routine blood gas measurements. CONCLUSIONS: We found that patients with established BPD could be managed without routine blood gas analyses after 36 weeks PMA.

Exploring the Association of Male Sex With Adverse Outcomes in Severe Bronchopulmonary Dysplasia: A Retrospective, Multicenter Cohort Study.

BACKGROUND: Bronchopulmonary dysplasia (BPD) is a significant contributor to morbidity and death in infants who are born premature. Male sex is an independent risk factor for the development of BPD. However, whether male sex is associated with adverse outcomes that occur after formal diagnosis of severe BPD prior to hospital discharge remains unclear. RESEARCH QUESTION: Is male sex associated with a higher risk of adverse outcomes in infants with established severe BPD? STUDY DESIGN AND METHODS: A retrospective, multicenter cohort study of infants enrolled in the BPD Collaborative Registry from January 1, 2015, to June 29, 2022, was performed. Demographics, clinical characteristics, and outcomes were stratified by sex (ie, male vs female). Regression modeling was used to estimate the association of sex with the primary composite outcome of death or tracheostomy at hospital discharge. RESULTS: We identified 1,156 infants with severe BPD, defined at 36 weeks postmenstrual age by the National Institutes of Health 2001 consensus definition. The cohort was predominantly male (59% male infants, 41% female infants). However, rates of mechanical ventilation at 36 weeks postmenstrual age (ie, type 2 severe BPD) did not differ by sex. Overall mortality rates within the cohort were low (male infants, 5.3%; female infants, 3.6%). The OR of death or tracheostomy for male-to-female infants was 1.0 (95% CI, 0.7-1.5). INTERPRETATION: Our results lead us to speculate that, although sex is an important variable that contributes to the development and pathogenesis of severe BPD, it does not appear to be associated with adverse outcomes in this cohort of infants with established disease. The surprising results raise important questions surrounding the temporal role of biological sex in the development of severe BPD and its progression during the neonatal ICU stay. As we explore the phenotypes and endotypes of BPD, it is imperative to consider how sex modulates the disease from birth through hospital discharge.

Classifying multicenter approaches to invasive mechanical ventilation for infants with bronchopulmonary dysplasia using hierarchical clustering analysis.

INTRODUCTION: Evidence-based ventilation strategies for infants with severe bronchopulmonary dysplasia (BPD) remain unknown. Determining whether contemporary ventilation approaches cluster as specific BPD strategies may better characterize care and enhance the design of clinical trials. The objective of this study was to test the hypothesis that unsupervised, multifactorial clustering analysis of point prevalence ventilator setting data would classify a discrete number of physiology-based approaches to mechanical ventilation in a multicenter cohort of infants with severe BPD. METHODS: We performed a secondary analysis of a multicenter point prevalence study of infants with severe BPD treated with invasive mechanical ventilation. We clustered the cohort by mean airway pressure (MAP), positive end expiratory pressure (PEEP), set respiratory rate, and inspiratory time (Ti) using Ward's hierarchical clustering analysis (HCA). RESULTS: Seventy-eight patients with severe BPD were included from 14 centers. HCA classified three discrete clusters as determined by an agglomerative coefficient of 0.97. Cluster stability was relatively strong as determined by Jaccard coefficient means of 0.79, 0.85, and 0.77 for clusters 1, 2, and 3, respectively. The median PEEP, MAP, rate, Ti, and PIP differed significantly between clusters for each comparison by Kruskall-Wallis testing (p < 0.0001). CONCLUSIONS: In this study, unsupervised clustering analysis of ventilator setting data identified three discrete approaches to mechanical ventilation in a multicenter cohort of infants with severe BPD. Prospective trials are needed to determine whether these approaches to mechanical ventilation are associated with specific severe BPD clinical phenotypes and differentially modify respiratory outcomes.

Respiratory Outcomes for Ventilator-Dependent Children With Bronchopulmonary Dysplasia.

OBJECTIVES: To describe outpatient respiratory outcomes and center-level variability among children with severe bronchopulmonary dysplasia (BPD) who require tracheostomy and long-term mechanical ventilation. METHODS: Retrospective cohort of subjects with severe BPD, born between 2016 and 2021, who received tracheostomy and were discharged on home ventilator support from 12 tertiary care centers participating in the BPD Collaborative Outpatient Registry. Timing of key respiratory events including time to tracheostomy placement, initial hospital discharge, first outpatient clinic visit, liberation from the ventilator, and decannulation were assessed using Kaplan-Meier analysis. Differences between centers for the timing of events were assessed via log-rank tests. RESULTS: There were 155 patients who met inclusion criteria. Median age at the time of the study was 32 months. The median age of tracheostomy placement was 5 months (48 weeks' postmenstrual age). The median ages of hospital discharge and first respiratory clinic visit were 10 months and 11 months of age, respectively. During the study period, 64% of the subjects were liberated from the ventilator at a median age of 27 months and 32% were decannulated at a median age of 49 months. The median ages for all key events differed significantly by center (P ≤ .001 for all events). CONCLUSIONS: There is wide variability in the outpatient respiratory outcomes of ventilator-dependent infants and children with severe BPD. Further studies are needed to identify the factors that contribute to variability in practice among the different BPD outpatient centers, which may include inpatient practices.

A multidisciplinary approach to severe bronchopulmonary dysplasia is associated with resolution of pulmonary hypertension.

Objective: To describe our multidisciplinary bronchopulmonary dysplasia (BPD) consult team's systematic approach to BPD associated pulmonary hypertension (PH), to report our center outcomes, and to evaluate clinical associations with outcomes. Study design: Retrospective cohort of 60 patients with BPD-PH who were referred to the Seattle Children's Hospital BPD team from 2018 to 2020. Patients with critical congenital heart disease were excluded. Demographics, comorbidities, treatments, closure of hemodynamically relevant intracardiac shunts, and clinical outcomes including time to BPD-PH resolution were reviewed. Results: Median gestational age of the 60 patients was 25 weeks (IQR: 24-26). 20% were small for gestational age (SGA), 65% were male, and 25% received a tracheostomy. With aggressive cardiopulmonary management including respiratory support optimization, patent ductus arteriosus (PDA) and atrial septal defect (ASD) closure (40% PDA, 5% ASD, 3% both), and limited use of pulmonary vasodilators (8%), all infants demonstrated resolution of PH during the follow-up period, including three (5%) who later died from non-BPD-PH morbidities. Neither SGA status nor the timing of PH diagnosis (<36 vs. ≥36 weeks PMA) impacted the time to BPD-PH resolution in our cohort [median 72 days (IQR 30.5-166.5)]. Conclusion: Our multidisciplinary, systematic approach to BPD-PH management was associated with complete resolution of PH with lower mortality despite less sildenafil use than reported in comparable cohorts. Unique features of our approach included aggressive PDA and ASD device closure and rare initiation of sildenafil only after lack of BPD-PH improvement with respiratory support optimization and diagnostic confirmation by cardiac catheterization.

Approaches to Interdisciplinary Care for Infants with Severe Bronchopulmonary Dysplasia: A Survey of the Bronchopulmonary Dysplasia Collaborative.

OBJECTIVE: Bronchopulmonary dysplasia (BPD) remains the most common late morbidity for extremely premature infants. Care of infants with BPD requires a longitudinal approach from the neonatal intensive care unit to ambulatory care though interdisciplinary programs. Current approaches for the development of optimal programs vary among centers. STUDY DESIGN: We conducted a survey of 18 academic centers that are members of the BPD Collaborative, a consortium of institutions with an established interdisciplinary BPD program. We aimed to characterize the approach, composition, and current practices of the interdisciplinary teams in inpatient and outpatient domains. RESULTS: Variations exist among centers, including composition of the interdisciplinary team, whether the team is the primary or consult service, timing of the first team assessment of the patient, frequency and nature of rounds during the hospitalization, and the timing of ambulatory visits postdischarge. CONCLUSION: Further studies to assess long-term outcomes are needed to optimize interdisciplinary care of infants with severe BPD. KEY POINTS: · Care of infants with BPD requires a longitudinal approach from the NICU to ambulatory care.. · Benefits of interdisciplinary care for children have been observed in other chronic conditions.. · Current approaches for the development of optimal interdisciplinary BPD programs vary among centers..

Ventilatory Strategies in Infants with Established Severe Bronchopulmonary Dysplasia: A Multicenter Point Prevalence Study.

We performed a point prevalence study on infants with severe bronchopulmonary dysplasia (BPD), collecting data on type and settings of ventilatory support; 187 infants, 51% of whom were on invasive positive-pressure ventilation (IPPV), from 15 centers were included. We found a significant center-specific variation in ventilator modes.

Outpatient Respiratory Management of Infants, Children, and Adolescents with Post-Prematurity Respiratory Disease: An Official American Thoracic Society Clinical Practice Guideline.

Background: Premature birth affects millions of neonates each year, placing them at risk for respiratory disease due to prematurity. Bronchopulmonary dysplasia is the most common chronic lung disease of infancy, but recent data suggest that even premature infants who do not meet the strict definition of bronchopulmonary dysplasia can develop adverse pulmonary outcomes later in life. This post-prematurity respiratory disease (PPRD) manifests as chronic respiratory symptoms, including cough, recurrent wheezing, exercise limitation, and reduced pulmonary function. This document provides an evidence-based clinical practice guideline on the outpatient management of infants, children, and adolescents with PPRD. Methods: A multidisciplinary panel of experts posed questions regarding the outpatient management of PPRD. We conducted a systematic review of the relevant literature. The Grading of Recommendations, Assessment, Development, and Evaluation approach was used to rate the quality of evidence and the strength of the clinical recommendations. Results: The panel members considered the strength of each recommendation and evaluated the benefits and risks of applying the intervention. In formulating the recommendations, the panel considered patient and caregiver values, the cost of care, and feasibility. Recommendations were developed for or against three common medical therapies and four diagnostic evaluations in the context of the outpatient management of PPRD. Conclusions: The panel developed recommendations for the outpatient management of patients with PPRD on the basis of limited evidence and expert opinion. Important areas for future research were identified.

Acute Kidney Injury and Bronchopulmonary Dysplasia in Premature Neonates Born Less than 32 Weeks' Gestation.

OBJECTIVE: This study aimed to evaluate the association between acute kidney injury (AKI) and bronchopulmonary dysplasia (BPD) in infants born <32 weeks of gestational age (GA). STUDY DESIGN: Present study is a secondary analysis of premature infants born at <32 weeks of GA in the Assessment of Worldwide Acute Kidney Injury Epidemiology in Neonates (AWAKEN) retrospective cohort (n = 546). We stratified by gestational age and used logistic regression to determine association between AKI and moderate or severe BPD/mortality. RESULTS: Moderate or severe BPD occurred in 214 of 546 (39%) infants, while death occurred in 32 of 546 (6%); the composite of moderate or severe BPD/death occurred in 246 of 546 (45%). For infants born ≤29 weeks of gestation, the adjusted odds ratio (OR) of AKI and the primary outcome was 1.15 (95% confidence interval [CI] = 0.47-2.86; p = 0.76). Infants born between 29 and 32 weeks of gestation with AKI had four-fold higher odds of moderate or severe BPD/death that remained after controlling for multiple factors (adjusted OR = 4.21, 95% CI: 2.07-8.61; p < 0.001). CONCLUSION: Neonates born between 29 and 32 weeks who develop AKI had a higher likelihood of moderate or severe BPD/death than those without AKI. Further studies are needed to validate our findings and evaluate mechanisms of multiorgan injury.

Acute Kidney Injury is Associated with Poor Lung Outcomes in Infants Born ≥32 Weeks of Gestational Age.

OBJECTIVE: This study aimed to evaluate the association between acute kidney injury (AKI) and lung outcomes in infants born ≥32 weeks of gestational age (GA). STUDY DESIGN: Secondary analysis of infants ≥32 weeks of GA in the assessment of worldwide acute kidney injury epidemiology in neonates (AWAKEN) retrospective cohort (n = 1,348). We used logistic regression to assess association between AKI and a composite outcome of chronic lung disease (CLD) or death at 28 days of age and linear regression to evaluate association between AKI and duration of respiratory support. RESULTS: CLD occurred in 82/1,348 (6.1%) infants, while death occurred in 22/1,348 (1.6%); the composite of CLD/death occurred in 104/1,348 (7.7%). Infants with AKI had an almost five-fold increased odds of CLD/death, which remained after controlling for GA, maternal polyhydramnios, multiple gestations, 5-minute Apgar's score, intubation, and hypoxic-ischemic encephalopathy (adjusted odds ratio [OR] = 4.9, 95% confidence interval [CI]: 3.2-7.4; p < 0.0001). Infants with AKI required longer duration of respiratory support (count ratio = 1.59, 95% CI: 1.14-2.23, p = 0.003) and oxygen (count ratio = 1.43, 95% CI: 1.22-1.68, p < 0.0001) compared with those without AKI. CONCLUSION: AKI is associated with CLD/death and longer duration of respiratory support in infants born at ≥32 weeks of GA. Further prospective studies are needed to elucidate the pathophysiologic relationship.

Infants with evolving bronchopulmonary dysplasia demonstrate monocyte-specific expression of IL-1 in tracheal aspirates.

Bronchopulmonary dysplasia (BPD) remains a devastating consequence of prematurity. Repeated inflammatory insults worsen lung injury, but there are no predictors for BPD-related respiratory outcomes or targeted therapies. We sought to understand inflammatory mechanisms in evolving BPD through molecular characterization of monocytes in tracheal aspirates from infants at risk for developing BPD. We performed flow cytometry targeting myeloid cell populations on prospectively collected tracheal aspirates from intubated patients born before 29 wk of gestation and <30 days old. We identified CD14+CD16+ (double-positive) and CD14+CD16- (single-positive) monocytes and characterized their gene expression profiles by RNA sequencing and quantitative PCR. We further analyzed differential gene expression between time points to evaluate changes in monocyte function over the first weeks of life. Expression of IL-1A, IL-1B, and IL-1 receptor antagonist mRNA was increased in monocytes collected at day of life (DOL) 7, DOL 14, and DOL 28 compared with those collected at DOL 3. This study suggests that early changes in monocyte-specific IL-1 cytokine pathways may be associated with evolving BPD.

Imbalance of Ly-6Chi and Ly-6Clo Monocytes/Macrophages Worsens Hyperoxia-Induced Lung Injury and Is Rescued by IFN-γ.

Inflammation in response to oxygen exposure is a major contributing factor in neonatal lung injury leading to bronchopulmonary dysplasia. Although increased levels of proinflammatory cytokines are seen in airway samples and blood from bronchopulmonary dysplasia patients, the innate immune responses in this common neonatal lung condition have not been well characterized. We previously reported that depletion of murine CD11b-expressing mononuclear phagocytes at birth led to severe acute hyperoxia-induced lung injury (HILI) and significant mortality. In this study, we further define the mononuclear phagocyte populations that are present in the neonatal lung and characterize their responses to hyperoxia exposure. We used myeloid depleter mice (CD11b-DTR and CCR2-DTR) to contrast the effects of depleting different monocyte/macrophage subpopulations on the innate immune response to hyperoxia. Using RNA sequencing and subsequent data analysis, we identified an IFN-γ-mediated role for interstitial monocytes/macrophages in acute HILI, in which decreased IFN-γ expression led to increased disease severity and increased Mmp9 mRNA expression. Importantly, intranasal administration of rIFN-γ largely rescued CD11b-DTR+ mice from severe HILI and decreased Mmp9 mRNA expression in Ly-6Clo and Ly-6Chi interstitial monocyte/macrophages. We conclude that the proinflammatory effects of hyperoxia exposure are, at least in part, because of the modulation of effectors downstream of IFN-γ by pulmonary monocytes/macrophages.

CD11b(+) Mononuclear Cells Mitigate Hyperoxia-Induced Lung Injury in Neonatal Mice.

Bronchopulmonary dysplasia (BPD) is a common consequence of life-saving interventions for infants born with immature lungs. Resident tissue myeloid cells regulate lung pathology, but their role in BPD is poorly understood. To determine the role of lung interstitial myeloid cells in neonatal responses to lung injury, we exposed newborn mice to hyperoxia, a neonatal mouse lung injury model with features of human BPD. In newborn mice raised in normoxia, we identified a CD45(+) F4/80(+) CD11b(+), Ly6G(lo-int) CD71(+) population of cells in lungs of neonatal mice present in significantly greater percentages than in adult mice. In response to hyperoxia, surface marker and gene expression in whole lung macrophages/monocytes was biased to an alternatively activated phenotype. Partial depletion of these CD11b(+) mononuclear cells using CD11b-diphtheria toxin (DT) receptor transgenic mice resulted in 60% mortality by 40 hours of hyperoxia exposure with more severe lung injury, perivascular edema, and alveolar hemorrhage compared with DT-treated CD11b-DT receptor-negative controls, which displayed no mortality. These results identify an antiinflammatory population of CD11b(+) mononuclear cells that are protective in hyperoxia-induced neonatal lung injury in mice, and suggest that enhancing their beneficial functions may be a treatment strategy in infants at risk for BPD.