Comparisons and Limitations of Current Definitions of Bronchopulmonary Dysplasia for the Prematurity and Respiratory Outcomes Program

Mitochondrial DNA mutations in extremely preterm infants with bronchopulmonary dysplasia

Bronchopulmonary dysplasia (BPD) is a serious chronic lung disease affecting extremely preterm infants. While mitochondrial dysfunction has been investigated in various medical conditions, limited research has explored mitochondrial DNA (mtDNA) gene mutations, specifically in BPD. This study aimed to evaluate mitochondrial mtDNA gene mutations in extremely preterm infants with BPD. In this prospective observational study, we enrolled a cohort of extremely preterm infants diagnosed with BPD. Clinical data were collected to provide comprehensive patient profiles. Peripheral blood mononuclear cells were isolated from whole-blood samples obtained within a defined timeframe. Subsequently, mtDNA extraction and sequencing using next-generation sequencing technology were performed to identify mtDNA gene mutations. Among the cohort of ten extremely preterm infants with BPD, mtDNA sequencing revealed the presence of mutations in seven patients, resulting in a total of twenty-one point mutations. Notably, many of these mutations were identified in loci associated with critical components of the respiratory chain complexes, vital for proper mitochondrial function and cellular energy production. This pilot study provides evidence of mtDNA point mutations in a subset of extremely preterm infants with BPD. These findings suggest a potential association between mitochondrial dysfunction and the pathogenesis of BPD. Further extensive investigations are warranted to unravel the mechanisms underlying mtDNA mutations in BPD.

The Role of the Airway and Gut Microbiome in the Development of Chronic Lung Disease of Prematurity

Chronic lung disease (CLD) of prematurity, a common cause of morbidity and mortality in preterm-born infants, has a multifactorial aetiology. This review summarizes the current evidence for the effect of the gut and airway microbiota on the development of CLD, highlighting the differences in the early colonisation patterns in preterm-born infants compared to term-born infants. Stool samples from preterm-born infants who develop CLD have less diversity than those who do not develop CLD. Pulmonary inflammation, which is a hallmark in the development of CLD, may potentially be influenced by gut bacteria. The respiratory microbiota is less abundant than the stool microbiota in preterm-born infants. There is a lack of clear evidence for the role of the respiratory microbiota in the development of CLD, with results from individual studies not replicated. A common finding is the presence of a single predominant bacterial genus in the lungs of preterm-born infants who develop CLD. Probiotic preparations have been proposed as a potential therapeutic strategy to modify the gut or lung microbiota with the aim of reducing rates of CLD but additional robust evidence is required before this treatment is introduced into routine clinical practice.

Impact of severity and age with variable definitions of bronchopulmonary dysplasia on neurodevelopmental outcomes

BACKGROUND

Bronchopulmonary dysplasia (BPD) is associated with neurodevelopmental impairment (NDI).

METHODS

To compare the ability of NICHD 2001 and Jensen 2019 definitions of BPD and respiratory support at 40 weeks postmenstrual age (PMA) to predict NDI, a retrospective study (1/2010-12/2020) was conducted in infants with gestational age <32 weeks and birth weight <1500 g. The primary outcome measure was NDI at 18-24 months corrected age.

RESULTS

Of 1119 infants, 227 (20.7%) met the inclusion criteria and had adequate follow-up data. Multivariate regression analysis showed that the NICHD 2001 definition was not predictive of NDI. Infants with Grade 2 or 3 BPD (Jensen 2019) had 4.75 (95% CI: 1.282-17.563) times greater odds of having NDI than infants without BPD. Infants requiring respiratory support at 40 weeks PMA had 4.95 (95% CI: 1.490-16.47) times greater odds of having NDI. Receiver operating characteristic curves demonstrated that the 2 definitions of BPD and the need for respiratory support at 40 weeks PMA were similar in their ability to predict NDI.

CONCLUSION

There is no significant difference in the ability of the NICHD 2001 and Jensen 2019 BPD definitions, as well as the need for respiratory support at 40 weeks, for predicting NDI.

IMPACT STATEMENT

Current bronchopulmonary dysplasia (BPD) definitions may not effectively predict neurodevelopmental impairment (NDI) in preterm infants. Grades 2/3 BPD (Jensen 2019 criteria) significantly associate with NDI. Infants requiring respiratory support at 40 weeks post-menstrual age (PMA) have 5 times higher odds of NDI than those on room air at 40 weeks PMA. The NICHD 2001, Jensen 2019 definitions, and the requirement for respiratory support at 40 weeks PMA, do not differ in their ability to predict NDI. Future studies should include multiple centers, with level III-IV NICUs, catering to socioeconomic, culturally, and racially diverse populations.

First-year outcomes of very low birth weight preterm singleton infants with hypoxemic respiratory failure treated with milrinone and inhaled nitric oxide (iNO) compared to iNO alone: A nationwide retrospective study

BACKGROUND

Inhaled nitric oxide (iNO) has a beneficial effect on hypoxemic respiratory failure. The increased use of concurrent iNO and milrinone was observed. We aimed to report the trends of iNO use in the past 15 years in Taiwan and compare the first-year outcomes of combining iNO and milrinone to the iNO alone in very low birth weight preterm (VLBWP) infants under mechanical ventilation.

METHODS

This nationwide cohort study enrolled preterm singleton infants with birth weight <1500g treated with iNO from 2004 to 2019. Infants were divided into two groups, with a combination of intravenous milrinone (Group 2, n = 166) and without milrinone (Group 1, n = 591). After propensity score matching (PSM), each group's sample size is 124. The primary outcomes were all-cause mortality and the respiratory condition, including ventilator use and duration. The secondary outcomes were preterm morbidities within one year after birth.

RESULTS

After PSM, more infants in Group 2 needed inotropes. The mortality rate was significantly higher in Group 2 than in Group 1 from one month after birth till 1 year of age (55.1% vs. 13.5%) with the adjusted hazard ratio of 4.25 (95%CI = 2.42-7.47, p <0.001). For infants who died before 36 weeks of postmenstrual age (PMA), Group 2 had longer hospital stays compared to Group 1. For infants who survived after 36 weeks PMA, the incidence of moderate and severe bronchopulmonary dysplasia (BPD) was significantly higher in Group 2 than in Group 1. For infants who survived until one year of age, the incidence of pneumonia was significantly higher in Group 2 (28.30%) compared to Group 1 (12.62%) (p = 0.0153).

CONCLUSION

Combined treatment of iNO and milrinone is increasingly applied in VLBWP infants in Taiwan. This retrospective study did not support the benefits of combining iNO and milrinone on one-year survival and BPD prevention. A future prospective study is warranted.

Prevalence, Severity Patterns and Risk Factors of Bronchopulmonary Dysplasia in Preterm Infants Younger than 32 Weeks of Gestation in a Tertiary Centre in Oman

Objectives

This study aimed to determine the rate and severity patterns of bronchopulmonary dysplasia (BPD) and identify antenatal and postnatal factors associated with BPD in preterm infants <32 weeks of gestational age (GA).

Methods

This retrospective observational study included preterm neonates <32 weeks of gestation admitted into the neonatal intensive care unit between January 2010 and December 2017 at Sultan Qaboos University Hospital, Muscat, Oman. A data set of antenatal and perinatal factors were collected. BPD was defined as the need for oxygen and/or respiratory support at 36 weeks post-menstrual age (PMA). Infants with and without BPD were compared in their antenatal and perinatal factors.

Results

A total of 589 preterm infants <32 weeks were admitted. Among them, 505 (85.7%) survived to 36 weeks' PMA and 90 (17.8%) had BPD. The combined BPD and mortality rate was 28.4%. Grades 1, 2 and 3 BPD constituted 77.8%, 7.8% and 14.4%, respectively. BPD was associated with lower GA, lower birth weight, need for intubation at resuscitation, lower Apgar scores, longer duration of ventilation, surfactant therapy and higher rates of neonatal morbidities. On binary logistic regression analysis, predictors of BPD were longer duration of ventilation, intraventricular haemorrhage (IVH) and necrotising enterocolitis (NEC).

Conclusion

In an Omani centre, 17.8% of preterm infants (<32 weeks GA) developed BPD. Various perinatal and neonatal factors were associated with BPD. However, longer duration of ventilation, IVH grades 1 and 2 and NEC stages II and III were significant predictors. Future multicentre research is necessary to provide the overall prevalence of BPD in Oman to help optimise the resources for BPD prevention and management in preterm infants.

Assessing the agreement of chronic lung disease of prematurity diagnosis between radiologists and clinical criteria

BACKGROUND

Chronic lung disease of prematurity (CLD) is the most prevalent complication of preterm birth and indicates an increased likelihood of long-term pulmonary complications. The accurate diagnosis of this condition is critical for long-term health management. Numerous definitions define CLD with different clinical parameters and radiology findings, making diagnosis of the disease ambiguous and potentially inaccurate.

METHODS

95 patients were identified for this study, as determined by the diagnosis or confirmation of CLD in the impression of the radiologist's report on chest x-ray. Pulmonary function and complications were recorded at multiple benchmark timeframes within each patient's first few months of life and used for determining eligibility under each definition.

RESULTS

Each clinical definition of CLD had a high sensitivity for patients identified to have CLD by radiologists, correctly fitting over 90% of patients. Most patients included required invasive mechanical ventilation or positive pressure ventilation at 36 weeks postmenstrual age, indicating patients with radiographically confirmed CLD tended to have more severe disease. Radiologists tended to diagnose CLD before 36 weeks postmenstrual age, a timepoint used by multiple standard clinical definitions, with cases called earlier fitting under a larger percentage of definitions than those called later.

CONCLUSIONS

Radiologists tend to diagnose CLD in young patients with severe respiratory compromise, and can accurately diagnose the condition before developmental milestones for clinical definitions are met.

Incidence and Predictors of Bronchopulmonary Dysplasia Development and Severity Among Preterm Infants Born at 32 Weeks of Gestation or Less

Background As the most common chronic lung disease (CLD) related to premature birth, bronchopulmonary dysplasia (BPD) is associated with long-term lung disease along with cardiovascular and neurodevelopmental disorders. However, data on the incidence and predictors of BPD in Qatar are lacking. Objectives In this study, we aimed to determine the incidence of BPD among infants born at ≤ 32 weeks gestational age (GA) at our neonatal unit, and identify risk factors for the development of BPD and moderate-severe BPD. Methods This was a retrospective observational cohort study conducted at a single site: a level-III neonatal intensive care unit (NICU) in Qatar. We included 1539 neonates born at ≤ 32 weeks of gestation with birth weights of ≤ 1500 grams who were admitted to the NICU between 2017 and 2020. Univariate and multivariate logistic regression analyses were performed to identify potential factors and predictors and their possible associations with the development of BPD and moderate-severe BPD. We also applied BPD classifications to determine the variability in the incidence of BPD in our cohort according to various definitions (2001 National Institute of Child Health and Human Development (NICHD) Diagnostic Criteria, 2016 Revisions of NICHD Criteria, and 2019 Neonatal Research Network Jensen Grading). Results A total of 451 infants (29.3%) had BPD (BPD group) while 1088 (70.7%) did not (non-BPD group), and the overall incidence of BPD was 29.3%. The most relevant risk factors associated with a higher risk of developing BPD identified in the multivariate logistic regression analysis were appropriate weight for gestational age (adjusted OR (aOR) 3.67, 95%CI 2.02-6.67, P < 0.001), presence of patent ductus arteriosus (PDA) (aOR 2.61, 95%CI 1.86-3.66, P < 0.001), late-onset sepsis (aOR 2.16; 95%CI 1.29-3.62; P = 0.003), and use of invasive ventilation (aOR 1.90; 95%CI 1.35-2.69; P < 0.001). The most relevant independent risk factors associated with a higher risk for developing moderate-severe BDP were postnatal steroids (aOR 7.12, 95%CI 3.77-13.44, P < 0.001), use of inhaled nitric oxide (aOR 3.65, 95%CI 1.48-9.01, P = 0.005), use of invasive ventilation (aOR 2.13, 95%CI 1.13-4.00, P = 0.019), late-onset sepsis (aOR 2.07, 95%CI 1.10-3.91, P = 0.025), and male sex (aOR 2.04, 95%CI 1.24-3.36, P = 0.005). The difference in the distribution of BPD severity across the three different definitions of NICHD was significant (P < 0.001). Conclusion The results of this study showed that the incidence of BPD remained high in infants born at ≤ 32 weeks of gestational age and birth weight <1500 g with appropriate weight for gestational age. The presence of PDA at birth or first echocardiography, late-onset sepsis, and use of invasive ventilation were significant risk factors for the incidence of BPD. The identification of risk factors will contribute to the implementation of lung-protective strategies for at-risk infants who may benefit from potential preventive therapy.

Machine learning predictive models for grading bronchopulmonary dysplasia: umbilical cord blood IL-6 as a biomarker

Objectives

This study aimed to analyze the predictive value of umbilical cord blood Interleukin-6 (UCB IL-6) for the severity-graded BPD and to establish machine learning (ML) predictive models in a Chinese population based on the 2019 NRN evidence-based guidelines.

Methods

In this retrospective analysis, we included infants born with gestational age <32 weeks, who underwent UCB IL-6 testing within 24 h of admission to our NICU between 2020 and 2022. We collected their medical information encompassing the maternal, perinatal, and early neonatal phases. Furthermore, we classified the grade of BPD according to the 2019 NRN evidence-based guidelines. The correlation between UCB IL-6 and the grades of BPD was analyzed. Univariate analysis and ordinal logistic regression were employed to identify risk factors, followed by the development of ML predictive models based on XGBoost, CatBoost, LightGBM, and Random Forest. The AUROC was used to evaluate the diagnostic value of each model. Besides, we generated feature importance distribution plots based on SHAP values to emphasize the significance of UCB IL-6 in the models.

Results

The study ultimately enrolled 414 preterm infants, with No BPD group (n = 309), Grade 1 BPD group (n = 73), and Grade 2-3 BPD group (n = 32). The levels of UCB IL-6 increased with the grades of BPD. UCB IL-6 demonstrated clinical significance in predicting various grades of BPD, particularly in distinguishing Grade 2-3 BPD patients, with an AUROC of 0.815 (95% CI: 0.753-0.877). All four ML models, XGBoost, CatBoost, LightGBM, and Random Forest, exhibited Micro-average AUROC values of 0.841, 0.870, 0.851, and 0.878, respectively. Notably, UCB IL-6 consistently appeared as the most prominent feature across the feature importance distribution plots in all four models.

Conclusion

UCB IL-6 significantly contributes to predicting severity-graded BPD, especially in grade 2-3 BPD. Through the development of four ML predictive models, we highlighted UCB IL-6's importance.

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.

The Optimal State Scoring Tool: guidance for interdisciplinary care of infants with severe bronchopulmonary dysplasia and its relation to linear growth

OBJECTIVE

Infants with severe bronchopulmonary dysplasia (sBPD) have complex medical courses. We developed the clinician-rated Optimal State Scoring Tool (OSST) that measures factors relevant to clinical improvement of sBPD and investigated preliminary validity using linear growth outcome and OSST scores in sBPD patients.

METHODS

Tool development process and pilot findings are provided for 13 patients evaluated longitudinally. OSST scores, length measurements, and steroid dependency values were obtained. Changes in OSST scores and lengths were examined using linear mixed-effect models.

RESULTS

OSST scores were significantly correlated with linear growth (95% CI 0.36, 0.57). The steroid-dependent group showed significantly slower rate of linear growth (95% CI 0.74, 1.05) and slower rate of increase in OSST scores (95% CI 0.99, 2.13) compared to the non-steroid-dependent group, with the OSST showing the largest effect size.

CONCLUSION

Pilot data reflect promising evidence for OSST construct validity in monitoring clinical outcomes in sBPD patients.

The hydrocortisone-responsive urinary metabolome of premature infants

BACKGROUND

Extremely premature infants are at risk for circulatory collapse or respiratory failure that are often treated with hydrocortisone (HC); however, there is no information on the metabolic consequences of this therapy.

METHODS

Longitudinal urine samples from infants <28 weeks gestation in the Trial of Late Surfactant were analyzed by untargeted UHPLC:MS/MS. Fourteen infants who received a tapering course of HC beginning at 3 mg/kg/day for ≥9 days were compared to 14 matched control infants. A secondary cross-sectional analysis by logistic regression used urines from 314 infants.

RESULTS

Of 1145 urinary metabolites detected, abundance of 219, representing all the major biochemical pathways, changed at p < 0.05 in the HC-treated group with 90% decreasing; 3 cortisol derivatives increased ~2-fold with HC therapy. Only 11% of regulated metabolites remained responsive at the lowest HC dose. Regulated metabolites included two steroids and thiamin that are associated with lung inflammation in infants. HC responsiveness was confirmed in 57% of metabolites by cross-sectional analysis.

CONCLUSIONS

HC treatment of premature infants influenced in a dose-dependent manner abundance of 19% of identified urinary metabolites of diverse biochemical systems, primarily reducing concentrations. These findings indicate that exposure to HC reversibly impacts the nutritional status of premature infants.

IMPACT

Hydrocortisone treatment of premature infants with respiratory failure or circulatory collapse alters levels of a subset of urinary metabolites representing all major biochemical pathways. This is the first description of the scope, magnitude, timing and reversibility of metabolomic changes in infants in response to hydrocortisone, and it confirms corticosteroid regulation of three biochemicals that are associated with lung inflammatory status. The findings indicate a dose-dependency of hydrocortisone for metabolomic and anti-inflammatory effects, that prolonged therapy may lower the supply of many nutrients, and that monitoring concentrations of cortisol and inflammation markers may be a useful clinical approach during corticosteroid therapy.

Two-Year Outcomes After Minimally Invasive Surfactant Therapy in Preterm Infants: Follow-Up of the OPTIMIST-A Randomized Clinical Trial

Importance

The long-term effects of surfactant administration via a thin catheter (minimally invasive surfactant therapy [MIST]) in preterm infants with respiratory distress syndrome remain to be definitively clarified.

Objective

To examine the effect of MIST on death or neurodevelopmental disability (NDD) at 2 years' corrected age.

Design, Setting, and Participants

Follow-up study of a randomized clinical trial with blinding of clinicians and outcome assessors conducted in 33 tertiary-level neonatal intensive care units in 11 countries. The trial included 486 infants with a gestational age of 25 to 28 weeks supported with continuous positive airway pressure (CPAP). Collection of follow-up data at 2 years' corrected age was completed on December 9, 2022.

Interventions

Infants assigned to MIST (n = 242) received exogenous surfactant (200 mg/kg poractant alfa) via a thin catheter; those assigned to the control group (n = 244) received sham treatment.

Main Outcomes and Measures

The key secondary outcome of death or moderate to severe NDD was assessed at 2 years' corrected age. Other secondary outcomes included components of this composite outcome, as well as hospitalizations for respiratory illness and parent-reported wheezing or breathing difficulty in the first 2 years.

Results

Among the 486 infants randomized, 453 had follow-up data available (median gestation, 27.3 weeks; 228 females [50.3%]); data on the key secondary outcome were available in 434 infants. Death or NDD occurred in 78 infants (36.3%) in the MIST group and 79 (36.1%) in the control group (risk difference, 0% [95% CI, -7.6% to 7.7%]; relative risk [RR], 1.0 [95% CI, 0.81-1.24]); components of this outcome did not differ significantly between groups. Secondary respiratory outcomes favored the MIST group. Hospitalization with respiratory illness occurred in 49 infants (25.1%) in the MIST group vs 78 (38.2%) in the control group (RR, 0.66 [95% CI, 0.54-0.81]) and parent-reported wheezing or breathing difficulty in 73 (40.6%) vs 104 (53.6%), respectively (RR, 0.76 [95% CI, 0.63-0.90]).

Conclusions and Relevance

In this follow-up study of a randomized clinical trial of preterm infants with respiratory distress syndrome supported with CPAP, MIST compared with sham treatment did not reduce the incidence of death or NDD by 2 years of age. However, infants who received MIST had lower rates of adverse respiratory outcomes during their first 2 years of life.

Trial Registration

anzctr.org.au Identifier: ACTRN12611000916943.

Modified lung ultrasound score for bronchopulmonary dysplasia predicts late respiratory outcomes in preterm infants

OBJECTIVE

Lung ultrasound (LUS) is a useful and radiation-free diagnostic tool for predicting bronchopulmonary dysplasia, which is a risk factor for late respiratory disease. However, data on the relationship of LUS with late respiratory disease was scarce. This study aims to determine whether LUS is associated with late respiratory disease during early childhood.

METHODS

This prospective cohort study enrolled preterm infants born before 32 weeks of gestation. LUS was performed at 36 weeks' postmenstrual age. The predictive values of a modified lung ultrasound (mLUS) score based on eight standard sections were assessed to predict late respiratory disease, defined as a physician diagnosis of bronchopulmonary dysplasia deterioration, asthma, reactive airway disease, bronchiolitis, pneumonia, or respiratory-related hospitalization during the first 2 years of life.

RESULTS

A total of 94 infants completed follow-up, of whom 74.5% met the late respiratory disease criteria. The mLUS scores were significantly associated with late respiratory disease (adjusted odds ratio: 1.23, CI: 1.10-1.38, p < 0.001). The mLUS scores also well predicted late respiratory disease (AUC = 0.820, 95% CI: 0.733-0.907). These scores were superior to the classic lung ultrasound score (p = 0.02) and as accurate as the modified NICHD-defined bronchopulmonary dysplasia classification (p = 0.91). A mLUS score ≥14 was the optimal cutoff point for predicting late respiratory disease.

CONCLUSION

The modified lung ultrasound score correlates significantly with late respiratory disease and well predicts it in preterm infants during the first 2 years of life.

The Urinary Metabolomic Fingerprint in Extremely Preterm Infants on Total Parenteral Nutrition vs. Enteral Feeds

Total Parenteral Nutrition (TPN), which uses intravenous administration of nutrients, minerals and vitamins, is essential for sustaining premature infants until they transition to enteral feeds, but there is limited information on metabolomic differences between infants on TPN and enteral feeds. We performed untargeted global metabolomics on urine samples collected between 23-30 days of life from 314 infants born <29 weeks gestational age from the TOLSURF and PROP cohorts. Principal component analysis across all metabolites showed a separation of infants solely on TPN compared to infants who had transitioned to enteral feeds, indicating global metabolomic differences between infants based on feeding status. Among 913 metabolites that passed quality control filters, 609 varied in abundance between infants on TPN vs. enteral feeds at p < 0.05. Of these, 88% were in the direction of higher abundance in the urine of infants on enteral feeds. In a subset of infants in a longitudinal analysis, both concurrent and delayed changes in metabolite levels were observed with the initiation of enteral feeds. These infants had higher concentrations of essential amino acids, lipids, and vitamins, which are necessary for growth and development, suggesting the nutritional benefit of an enteral feeding regimen.

Comparison of two novel diagnostic criteria for bronchopulmonary dysplasia in predicting adverse outcomes of preterm infants: a retrospective cohort study

BACKGROUND

This study aimed to compare the predictive value of two diagnostic criteria for bronchopulmonary dysplasia (BPD) in preterm infants with gestational age (GA) < 32 weeks for death or severe respiratory morbidity at corrected age of 18-24 months.

METHODS

In this retrospective cohort study, clinical data from July 2019 to September 2021 were classified by 2018 National Institute of Child Health and Human Development (NICHD) and 2019 Jensen definitions of BPD. Based on the follow-up results, the enrolled population was divided into adverse outcome group and normal outcome group. Logistic regression and receiver operating characteristic (ROC) curve analyses were conducted to explore the risk factors of adverse outcomes and evaluate the predictive value of both diagnostic criteria.

RESULTS

Of 451 infants, 141 (31.3%) had adverse outcomes, which increased with increasing severity of BPD. Logistic regression analysis showed only BPD was an independent risk factor for adverse outcomes in preterm infants. ROC analysis revealed that both diagnostic criteria showed similar predictive values (2018 NICHD definition AUC = 0.771 vs. 2019 Jensen definition AUC = 0.770), with specificities of 93.5% and 96.8%, respectively; however, combining them separately with GA or birth weight did not improve their predictive values.

CONCLUSIONS

The two novel definitions of BPD demonstrate similar predictive values in predicting death or severe respiratory morbidity at corrected age of 18-24 months, with higher specificity observed in both.

Phthalate exposure in the neonatal intensive care unit is associated with development of bronchopulmonary dysplasia

OBJECTIVE

Bronchopulmonary dysplasia (BPD) is a serious yet common morbidity of preterm birth. Although prior work suggests a possible role for phthalate exposure in the development of BPD, no study has rigorously evaluated this. Our objective was to determine whether hospital-based phthalate exposure is associated with the development of BPD and to identify developmental windows sensitive to exposure.

STUDY DESIGN

This is a prospective multicenter cohort study of 360 preterm infants born at 23-33 weeks gestation participating in the Developmental Impact of NICU Exposures (DINE) cohort. 939 urine specimens collected during the NICU stay were analyzed for biomarkers of phthalate exposure by liquid chromatography with tandem mass spectrometry. The modified Shennan definition was used to diagnose bronchopulmonary dysplasia. Reverse distributed-lag modeling identified developmental windows sensitive to specific phthalate exposure, controlling for relevant covariates including sex and respiratory support.

RESULTS

Thirty-five percent of participants were diagnosed with BPD. Exposure to specific phthalate mixtures at susceptible points in preterm infant development are associated with later diagnosis of BPD in models adjusted for use of respiratory support. The weighted influence of specific phthalate metabolites in the mixtures varied by sex. Metabolites of di(2-ethylhexyl) phthalate, a phthalate previously linked to neonatal respiratory support equipment, drove this association, particularly among female infants, at 26- to 30-weeks post-menstrual age.

CONCLUSIONS

This is the largest and only multi-site study of NICU-based phthalate exposure and clinical impact yet reported. In well-constructed models accounting for infant sex and respiratory support, we found a significant positive association between ultimate diagnosis of BPD and prior exposure to phthalate mixtures with DEHP predominance at 26- to 30-weeks PMA or 34-36-weeks PMA. This information is critically important as it identifies a previously unrecognized and modifiable contributing factor to BPD.

Genetic analysis of potential biomarkers and therapeutic targets associated with ferroptosis from bronchopulmonary dysplasia

Ferroptosis is a recently identified form of cell death that is distinct from the conventional modes such as necrosis, apoptosis, and autophagy. Its role in bronchopulmonary dysplasia (BPD) remains inadequately understood. To address this gap, we obtained BPD-related RNA-seq data and ferroptosis-related genes (FRGs) from the GEO database and FerrDb, respectively. A total of 171 BPD-related differentially expressed ferroptosis-related genes (DE-FRGs) linked to the regulation of autophagy and immune response were identified. Least absolute shrinkage and selection operator and SVM-RFE algorithms identified 23 and 14 genes, respectively, as marker genes. The intersection of these 2 sets yielded 9 genes (ALOX12B, NR1D1, LGMN, IFNA21, MEG3, AKR1C1, CA9, ABCC5, and GALNT14) with acceptable diagnostic capacity. The results of the functional enrichment analysis indicated that these identified marker genes may be involved in the pathogenesis of BPD through the regulation of immune response, cell cycle, and BPD-related pathways. Additionally, we identified 29 drugs that target 5 of the marker genes, which could have potential therapeutic implications. The ceRNA network we constructed revealed a complex regulatory network based on the marker genes, further highlighting their potential roles in BPD. Our findings offer diagnostic potential and insight into the mechanism underlying BPD. Further research is needed to assess its clinical utility.

Lung Transplantation for Bronchopulmonary Dysplasia

BACKGROUND

Patients with bronchopulmonary dysplasia (BPD) have poor respiratory trajectories and are at increased risk of lung function decline with age. Lung transplant (LTx) is a possible treatment option for this growing patient population, but little has been published on LTx in this patient group.

RESEARCH QUESTION

What are the characteristics of patients with BPD who are listed for LTx? How do waitlist and post-LTx outcomes for BPD compare with LTx for other diagnoses?

STUDY DESIGN AND METHODS

The United Network for Organ Sharing (UNOS) registry was queried for patients of all ages listed for or who underwent LTx (2000-2020). Descriptive analysis, waitlist outcomes, and post-LTx survival at 1, 5, and 10 years were assessed comparing patients with BPD vs LTx patients with other diagnoses. Post-LTx survival for patients with BPD born in the pre-surfactant era (pre-SE, before 1990) and those born in the post-surfactant era (post-SE) was compared. Propensity score matching was performed to control for the risk factors and match patients with BPD with other LTx patients on a 1:1 ratio.

RESULTS

BPD was reported in 65 patients, of whom 32 (49.2%) underwent LTx. Patients with BPD at listing were younger than those with other diagnoses (median age, 21 [interquartile range, 5-31] years vs 57 [45-63] years; P < .001), and more were likely to receive mechanical ventilation at listing (23% vs 3.7%; P < .001). Patients with BPD had an FEV1 of 17% compared with 34% predicted in other patients (P = .002). Patients with BPD had an overall similar post-LTx survival compared with patients with other diagnoses (P = .106), even following propensity score matching (P = .41).

INTERPRETATION

LTx for BPD has increased over the last 20 years. Patients with BPD have similar post-LTx outcomes compared with those of other patient populations in the modern era. Thus, LTx could be considered for patients with BPD experiencing progressive respiratory deterioration.

Environmental influences on child health outcomes: cohorts of individuals born very preterm

The National Institutes of Health's Environmental influences on Child Health Outcomes (ECHO) Program was designed to address solution-oriented research questions about the links between children's early life environment and their risks of pre-, peri-, and post-natal complications, asthma, obesity, neurodevelopmental disorders, and positive health. Children born very preterm are at increased risk for many of the outcomes on which ECHO focuses, but the contributions of environmental factors to this risk are not well characterized. Three ECHO cohorts consist almost exclusively of individuals born very preterm. Data provided to ECHO from cohorts can be used to address hypotheses about (1) differential risks of chronic health and developmental conditions between individuals born very preterm and those born at term; (2) health disparities across social determinants of health; and (3) mechanisms linking early-life exposures and later-life outcomes among individuals born very preterm. IMPACT: The National Institutes of Health's Environmental Influences on Child Health Outcomes Program is conducting solution-oriented research on the links between children's environment and health. Three ECHO cohorts comprise study participants born very preterm; these cohorts have enrolled, to date, 1751 individuals born in 14 states in the U.S. in between April 2002 and March 2020. Extensive data are available on early-life environmental exposures and child outcomes related to neurodevelopment, asthma, obesity, and positive health. Data from ECHO preterm cohorts can be used to address questions about the combined effects of preterm birth and environmental exposures on child health outcomes.

Machine learning to predict late respiratory support in preterm infants: a retrospective cohort study

Bronchopulmonary dysplasia (BPD) has been a critical morbidity in preterm infants. To improve our definition and prediction of BPD is challenging yet indispensable. We aimed to apply machine learning (ML) to investigate effective models by using the recently-proposed and data-driven definition to predict late respiratory support modalities at 36 weeks' post menstrual age (PMA). We collected data on very-low-birth-weight infants born between 2016 and 2019 from the Taiwan Neonatal Network database. Twenty-four attributes associated with their early life and seven ML algorithms were used in our analysis. The target outcomes were overall mortality, death before 36 weeks' PMA, and severity of BPD under the new definition, which served as a proxy for respiratory support modalities. Of the 4103 infants initially considered, 3200 were deemed eligible. The logistic regression algorithm yielded the highest area under the receiver operating characteristic curve (AUROC). After attribute selection, the AUROC of the simplified models remain favorable (e.g., 0.801 when predicting no BPD, 0.850 when predicting grade 3 BPD or death before 36 weeks' PMA, and 0.881 when predicting overall mortality). By using ML, we developed models to predict late respiratory support. Estimators were developed for clinical application after being simplified through attribute selection.

Comparison of New Bronchopulmonary Dysplasia Definitions on Long-Term Outcomes in Preterm Infants

OBJECTIVE

To compare the discriminative performances of the 2018 National Institutes of Health (NIH) and the 2019 Jensen definitions of bronchopulmonary dysplasia (BPD) with the 2001 NIH definition on adverse neurodevelopmental and respiratory outcomes at 2 years and 5 years corrected age.

STUDY DESIGN

In this single-center retrospective cohort study, outcomes of infants born at <30 weeks of gestational age were collected. The 3 definitions of BPD were compared by adding the different definitions to the National Institute of Child Health and Human Development's outcome prediction model for neurodevelopmental impairment (NDI) or death. Discriminative performance was compared for both outcomes at 2 years and 5 years corrected age by calculating the areas under the receiver operating characteristic curve and z-statistics.

RESULTS

The presence of BPD and its severity were determined in 584 infants. There were considerable shifts in BPD grading among the different definitions. At both time points, all BPD definition models had comparable discriminating power for NDI and respiratory morbidity, with one exception. Compared with the 2001 NIH definition, the 2018 NIH definition had less predictive power for the neurologic outcome at 2 years corrected age.

CONCLUSIONS

Our comparison of the 3 BPD definitions shows similar discriminative performance on long term neurodevelopmental and respiratory outcomes at 2 years and 5 years corrected age.

Validation of disease-specific biomarkers for the early detection of bronchopulmonary dysplasia

OBJECTIVE

To demonstrate and validate the improvement of current risk stratification for bronchopulmonary dysplasia (BPD) early after birth by plasma protein markers (sialic acid-binding Ig-like lectin 14 (SIGLEC-14), basal cell adhesion molecule (BCAM), angiopoietin-like 3 protein (ANGPTL-3)) in extremely premature infants.

METHODS AND RESULTS

Proteome screening in first-week-of-life plasma samples of n = 52 preterm infants <32 weeks gestational age (GA) on two proteomic platforms (SomaLogic^®, Olink-Proteomics^®) confirmed three biomarkers with significant predictive power: BCAM, SIGLEC-14, and ANGPTL-3. We demonstrate high sensitivity (0.92) and specificity (0.86) under consideration of GA, show the proteins' critical contribution to the predictive power of known clinical risk factors, e.g., birth weight and GA, and predicted the duration of mechanical ventilation, oxygen supplementation, as well as neonatal intensive care stay. We confirmed significant predictive power for BPD cases when switching to a clinically applicable method (enzyme-linked immunosorbent assay) in an independent sample set (n = 25, p < 0.001) and demonstrated disease specificity in different cohorts of neonatal and adult lung disease.

CONCLUSION

While successfully addressing typical challenges of clinical biomarker studies, we demonstrated the potential of BCAM, SIGLEC-14, and ANGPTL-3 to inform future clinical decision making in the preterm infant at risk for BPD.

TRIAL REGISTRATION

Deutsches Register Klinische Studien (DRKS) No. 00004600; https://www.drks.de .

IMPACT

The urgent need for biomarkers that enable early decision making and personalized monitoring strategies in preterm infants with BPD is challenged by targeted marker analyses, cohort size, and disease heterogeneity. We demonstrate the potential of the plasma proteins BCAM, SIGLEC-14, and ANGPTL-3 to identify infants with BPD early after birth while improving the predictive power of clinical variables, confirming the robustness toward proteome assays and proving disease specificity. Our comprehensive analysis enables a phase-III clinical trial that allows full implementation of the biomarkers into clinical routine to enable early risk stratification in preterms with BPD.

Echocardiography parameters used in identifying right ventricle dysfunction in preterm infants with early bronchopulmonary dysplasia: A scoping review

Background

Bronchopulmonary Dysplasia (BPD) is a chronic condition that affects preterm infants and is associated with long-term complications. Haemodynamic effects of BPD can lead to right ventricular (RV) dysfunction.

Objective

To synthesise and map the evidence of echo parameters used in identifying RV dysfunction in the first two weeks-after-birth (WAB) of preterm infants with early BPD.

Information Sources

This scoping review included the databases: Medline, CINAHL, PubMed, EMBASE, Scopus, ProQuest, Web of Science, Cochrane Library, JBI Evidence-Based Practise and Gray Literature.

Search Strategy

The search utilised Boolean operators and descriptors registered in Medical Subject Headings.

Inclusion and exclusion criteria

Included were studies utilising echo parameters to examine RV function in preterm infants with early BPD in the first two WAB.

Synthesis of results

The results are presented as a map of the extracted findings in a tabular format with a narrative summary.

Results

Eight studies were included. Differences were observed in the number and timing of echo scans performed in the first two WAB and the variations in the echo parameters used to compare preterm infants with and without early BPD. Only echo scans performed at the end of the first WAB, demonstrated significant differences in the echo parameters measurements between preterm infants with and without BPD. Studies using RV Myocardial Performance Index (MPI) to identify RV-dysfunction associated with early BPD demonstrated similar findings. The Pulsed-Wave Doppler technique identified differences in RV-MPI between preterm infants with and without BPD, while Tissue-Doppler-Imaging did not demonstrate similar results. Speckle tracking can measure strain (S) and strain rate (SR) and diagnose RV-dysfunction. However, the findings of studies that utilised speckle tracking varied. Finally, two of the included studies added blood tests to their diagnostic model of early BPD, which was able to demonstrate significant differences in blood test results between BPD-affected and control preterm infants.

Conclusion

BPD could adversely affect the myocardium function of the RV; these negative influences can be captured in the first two WAB. However, there are still knowledge gaps regarding the appropriate number, timing and the most suitable echo parameters to assess RV function.

Association of newer definitions of bronchopulmonary dysplasia with pulmonary hypertension and long-term outcomes

BACKGROUND

The definition of bronchopulmonary dysplasia (BPD) has been evolved recently from definition by the National Institute of Child Health and Human Development in 2001 (NICHD 2001) to the definition reported in 2018 (NICHD 2018) and that proposed by Jensen et al. in 2019 (NICHD 2019). The definition was developed based on the evolution of non-invasive respiratory support and to achieve better prediction of later outcomes. Our objective was to evaluate the association between different definitions of BPD and occurrence of pulmonary hypertension (PHN) and long term outcomes.

METHODS

This retrospective study enrolled preterm infants born at < 32 weeks of gestation between 2014 and 2018. The association between re-hospitalization owing to a respiratory illness until a corrected age (CA) of 24 months, neurodevelopmental impairment (NDI) at a CA of 18-24 months, and PHN at a postmenstrual age (PMA) of 36 weeks was evaluated, with the severity of BPD defined based on these three definitions.

RESULTS

Among 354 infants, the gestational age and birth weight were the lowest in severe BPD based on the NICHD 2019 definition. In total, 14.1% of the study population experienced NDI and 19.0% were re-hospitalized owing to a respiratory illness. At a PMA of 36 weeks, PHN was identified in 9.2% of infants with any BPD. Multiple logistic regression analysis showed that the adjusted odds ratio (OR) for re-hospitalization was the highest for Grade 3 BPD of the NICHD 2019 criteria (5.72, 95% confidence interval [CI]: 1.37-23.92), while the adjusted OR of Grade 3 BPD was 4.96 (95% CI: 1.73-14.23) in the NICHD 2018 definition. Moreover, no association of the severity of BPD was found in the NICHD 2001 definition. The adjusted ORs for NDI (12.09, 95% CI: 2.52-58.05) and PHN (40.37, 95% CI: 5.15-316.34) were also the highest for Grade 3 of the NICHD 2019 criteria.

CONCLUSION

Based on recently suggested criteria by the NICHD in 2019, BPD severity is associated with long-term outcomes and PHN at a PMA of 36 weeks in preterm infants.

Safety of sildenafil in premature infants at risk of bronchopulmonary dysplasia: Rationale and methods of a phase II randomized trial

Bronchopulmonary dysplasia (BPD) is a disease of chronic respiratory insufficiency stemming from premature birth and iatrogenic lung injury leading to alveolar simplification, impaired alveolar-capillary development, interstitial fibrosis, and often pulmonary hypertension. BPD is the most common pulmonary sequela of prematurity and is often fatal; however, there remains no FDA-approved therapies to treat or prevent BPD. Sildenafil is increasingly used off-label in premature infants despite scant safety and efficacy data. Sildenafil reduces lung injury and preserves normal vasculature in preclinical models, and improves outcomes in children with pulmonary hypertension, and thus is a promising candidate for BPD. Following phase I studies, we developed the phase II SIL02 trial to describe the safety, pharmacokinetics and preliminary effectiveness of intravenous and enteral sildenafil in premature infants at risk for BPD. SIL02 is a randomized, double-blind, placebo-controlled, 3-cohort, sequential dose-escalating trial of enteral or intravenous (IV) sildenafil dosed every 8 h for up to 34 days. The target IV doses were 0.125, 0.5 and 1 mg/kg/dose in cohorts 1, 2 and 3, respectively; while the enteral doses will be double the IV doses. Eligible infants must be < 29 weeks' gestation at birth and requiring respiratory support at 7–28 days' postnatal age. Adverse events and preliminary effectiveness will be compared by treatment group. Using the final population PK model, empirical Bayesian estimates will be generated for each patient. Preliminary effectiveness will be measured by the incidence of moderate to severe BPD or death at 36 weeks and change in the BPD risk estimation.

Comparison of definitions of bronchopulmonary dysplasia to reflect the long-term outcomes of extremely preterm infants

Survivors of neonatal bronchopulmonary dysplasia (BPD) have persistent respiratory, neurodevelopmental, and growth impairment over the first few years of life and later childhood, which represents an emerging burden for health systems. Therefore, there is an increasing need for a new definition and grading system of BPD that predicts long-term outcomes of high-risk infants who need timely and proper intervention to improve outcomes. We compared new definitions of BPD (National Institute of Child Health and Human Development [NICHD] 2018 and Neonatal Research Network [NRN] 2019) to the original NICHD 2001 definition at 3 years of age using a nationwide cohort of extreme preterm infants. New definitions and severity grading were clearly related to respiratory, neurodevelopmental, and growth impairments at 3 years of age and at 18-24 months corrected age (CA), whereas the original NICHD 2001 definition was not. Furthermore, the negative effect of BPD on growth was ameliorated at 3 years of age compared to 18-24 months CA. However, the negative effect of BPD in neonates on the respiratory system and neurodevelopment persisted at 3 years of age. These new definitions should be adopted to identify high-risk infants and improve long-term outcomes by exact diagnosis and BPD severity classification.

Dose-Response Effects of Glutathione Supplement in Parenteral Nutrition on Pulmonary Oxidative Stress and Alveolarization in Newborn Guinea Pig

In premature infants, glutathione deficiency impairs the capacity to detoxify the peroxides resulting from O₂ metabolism and those contaminating the parenteral nutrition (PN) leading to increased oxidative stress, which is a major contributor to bronchopulmonary dysplasia (BPD) development. In animals, the supplementation of PN with glutathione prevented the induction of pulmonary oxidative stress and hypoalveolarization (characteristic of BPD). Hypothesis: the dose of glutathione that corrects the plasma glutathione deficiency is sufficient to prevent oxidative stress and preserve pulmonary integrity. Three-day-old guinea pigs received a PN, supplemented or not with GSSG (up to 1300 µg/kg/d), the stable form of glutathione in PN. Animals with no handling other than being orally fed constituted the control group. After 4 days, lungs were removed to determine the GSH, GSSG, redox potential and the alveolarization index. Total plasma glutathione was quantified. The effective dose to improve pulmonary GSH and prevent the loss of alveoli was 330 µg/kg/d. A 750 µg/kg/d dose corrected the low-plasma glutathione, high-pulmonary GSSG and oxidized redox potential. Therefore, the results suggest that, in a clinical setting, the dose that improves low-plasma glutathione could be effective in preventing BPD development.

Extreme prematurity-associated alterations of pulmonary inflammatory mediators before and after surfactant administration

BACKGROUND

The role of prematurity and pulmonary inflammation in the pathogenesis of bronchopulmonary dysplasia (BPD) is very well-defined. However, there is limited knowledge about whether the level of prematurity and surfactant therapy alter the pulmonary cytokines and endothelial growth factor (VEGF).

METHODS

This study analyzed the VEGF and cytokines, including interleukin (IL)-1β, IL-6, IL-8, and IL-10, and tumor necrosis factor α (TNF-α) in the tracheal aspirate (TA) of preterm infants obtained before (within 2 h after birth) and 10-12 h after the administration of the first dose of surfactant. TA was collected from 40 infants of 35 or fewer weeks of gestation, including extremely (Group 1, n = 19), very (Group 2, n = 13), and moderate/late (Group 2, n = 8) preterm neonates. In addition to univariate analysis, controlled regression models estimated the association of perinatal factors with the tested parameters and their role in the development of BPD.

RESULT

We recorded significantly lower post-partum levels of VEGF and higher IL-8, IL-1β, and TNF-α in the TA of Group 1 infants than in Group 2 and 3. Compared to the infants in Group 2 and 3, the post-surfactant increases of pulmonary VEGF, IL-8, IL-10, and TNF-α were more significant in Group 1. All tested parameters in Group 1 and 2 infants, before and after surfactant administration, were comparable. BPD was recorded in nearly 60% of the extremely preterm survivors and was significantly predicted by increased IL-8 before, and elevated TNF-α level after surfactant administration.

CONCLUSION

This study indicates the association of birth at extremely preterm gestation with reduction in pulmonary VEGF and exacerbation of pro-inflammatory cytokines followed by greater elevation post-surfactant administration levels of VEGF, IL-8, TNF-α, and IL-10 than in neonates born with gestational age of 28-35 weeks.

Lung ultrasound completely replaced chest X-ray for diagnosing neonatal lung diseases: a 3-year clinical practice report from a neonatal intensive care unit in China

BACKGROUND AND OBJECTIVE

Lung ultrasound (LUS) has been widely used in the diagnosis and differential diagnosis of neonatal lung diseases (NLDs), but whether it can replace the routine use of chest X-ray (CXR) in neonatal intensive care units (NICUs) remains controversial. This paper summarizes the clinical practice of our neonatal intensive care unit (NICU) during the past three years to explore the feasibility and necessity of using LUS instead of CXR to diagnose NLDs in the NICU setting.

METHODS

The clinical data and LUS examination results from 1,381 newborn infants with respiratory difficulty who were hospitalized in our NICU from March 2017 to February 2020 were retrospectively collected to analyze the types of lung diseases diagnosed and the reliability of LUS for diagnosing NLDs.

RESULTS

(1) During this period, 1381 newborn infants with dyspnea were admitted to our NICU, accounting for 41.2% of all hospitalized children. (2) Among the 1381 infants, 17 patients with respiratory distress were confirmed as having severe heart disease by echocardiography, while the remaining 1364 patients had different kinds of lung diseases: pneumonia (697 patients, 51.1%), respiratory distress syndrome (251 patients, 17.4%), transient tachypnea of the newborn (197 patients, 13.3%), atelectasis (89 patients, 5.6%), pneumothorax (46 patients, 3.2%), pulmonary hemorrhage (69 patients, 4.5%), severe pleural effusion (18 patients, 1.32%), congenital pulmonary sequestration (3 patients, 0.22%), bullae of the lung (2 patients, 0.15%), and congenital cystic adenomatoid malformation (2 patients). (5) Among the 1381 infants, 217 received CXR examination before admission, which resulted in misdiagnosis in 45 patients (20.7%) and missed diagnosis in 12 patients (5.5%); the missed diagnosis and misdiagnosis rate was 26.3%.

CONCLUSION

Our 3-year clinical practice experience indicated that LUS could completely replace chest X-ray for the diagnosis and differential diagnosis of NLDs in the NICU. Compared with X-ray, LUS had higher accuracy and reliability in diagnosing NLDs.

Early histological changes of bronchopulmonary dysplasia and pulmonary hypertension may precede clinical diagnosis in preterm infants

Bronchopulmonary Dysplasia (BPD), the commonest complication of prematurity, is defined by treatment with oxygen for ≥28 days. Pulmonary hypertension (PH) often coexists with BPD and is associated with increased mortality. In 42 autopsies, histological changes of BPD and PH were demonstrated in 25 % and 65 % respectively of preterm infants <28 days of age, highlighting the need for early diagnosis and treatment.

Premature Infants Have Normal Maturation of the T Cell Receptor Repertoire at Term

Premature infants are known to have immature immune systems compared to term infants; however, the impacts of ex utero immune development are not well characterized. Our previous retrospective clinical review showed prolonged T cell lymphopenia in a subset of extremely premature infants, suggesting that they may have lasting abnormalities in their T cell compartments. We used T cell receptor (TCR) repertoire sequencing to analyze the composition of the T cell compartment in premature and term infants in our NICU. We collected twenty-eight samples from individual subjects and analyzed the number of clonotypes, repertoire diversity, CDR3 length, and V gene usage between groups based on gestational age at birth and postmenstrual age at the time of sample collection. Further, we examined the TCR repertoire in infants with severe bronchopulmonary dysplasia (BPD) and those with abnormal T cell receptor excision circle (TREC) assays. Former extremely premature infants who were corrected to term postmenstrual age had TCR repertoire diversity that was more similar to term born infants than extremely premature infants, supporting normal maturation of the repertoire. Infants with severe BPD did not appear to have increased abnormalities in repertoire diversity. Decreased TCR repertoire diversity was associated with repeatedly abnormal TREC screening, although the diversity was within the normal range for subjects without low TRECs. This study suggests that extremely premature infants demonstrate normal maturation of the T cell repertoire ex utero. Further work is needed to better characterize postnatal T cell development and function in this population.

Pulmonary hypertension in infants with bronchopulmonary dysplasia: risk factors, mortality and duration of hospitalisation

OBJECTIVES

Pulmonary hypertension (PH) is a complication of bronchopulmonary dysplasia (BPD) and associated with increased mortality and morbidity. Our aim was to identify, in infants with BPD, the effect of PH on health-care utilisation and health related cost of care.

METHODS

An electronic data recording system was used to identify infants ≤32 weeks of gestation who developed BPD. PH was classified as early (≤28 days after birth) or late (>28 days after birth).

RESULTS

In the study period, 182 infants developed BPD; 22 (12.1%) developed late PH. Development of late PH was associated with a lower gestational age [24.6 (23.9-26.9) weeks, p=0.001] and a greater need for positive pressure ventilation on day 28 after birth (100%) compared to infants without late PH (51.9%) (odds ratio (OR) 19.5, 95% CI: 2.6-148), p<0.001. Late PH was associated with increased mortality (36.4%) compared those who did not develop late PH (1.9%) after adjusting for gestational age and ventilation duration (OR: 26.9, 95% CI: 3.8-189.4), p<0.001. In infants who survived to discharge, late PH development was associated with a prolonged duration of stay [147 (118-189) days] compared to the infants that did not develop late PH [109 (85-149) days] (p=0.03 after adjusting for gestational age). Infants who had late PH had a higher cost of stay compared to infants with BPD who did not develop late PH (median £113,494 vs. £78,677, p=0.016 after adjusting for gestational age).

CONCLUSIONS

Development of late PH was associated with increased mortality, a prolonged duration of stay and higher healthcare cost.

The Next Frontier of Prematurity: Predicting Respiratory Morbidity During the First Two Years of Life in Extremely Premature Babies

Background

Advances in perinatal and neonatal medicine have led to an increasing number of infants surviving extreme prematurity (≤27 weeks gestational age, GA). The goal of this study was to examine the respiratory outcomes after neonatal intensive care unit (NICU) discharge of this vulnerable population. We hypothesized that the rates of respiratory hospitalizations are disproportionally higher in the subset of infants born ≤27 weeks GA relative to premature infants born 28-32 weeks GA.

Methodology

A retrospective longitudinal study of severe premature children (≤32 weeks GA, n = 183) was conducted. We subdivided our sample into extremely preterm infants (≤27 weeks GA; n = 101) and those born very preterm (28-32 weeks GA; n = 82). Our main outcome was the presence of respiratory hospitalizations within 24 months of NICU discharge.

Results

Extremely premature infants had more than three times higher odds of respiratory hospitalization at 24 months relative to infants born 28-32 weeks GA (adjusted odds ratio = 3.4; 95% confidence interval = 1.8, 6.4; p < 0.01). The increased risk of respiratory hospitalization in extremely premature infants was independent of GA. Regression models identified that the duration of supplemental oxygen and Black/African American ethnicity were significant predictors of respiratory hospitalizations in both prematurity groups independent of gender and birth weight.

Conclusions

The results support that babies born ≤27 weeks GA represent a distinct high-risk group of severely premature infants that needs novel preventive strategies and targeted interventions to improve their respiratory outcomes after NICU discharge.

A modified lung ultrasound score to evaluate short-term clinical outcomes of bronchopulmonary dysplasia

Background

Lung ultrasound (LUS) is a useful tool for assessing the severity of lung disease, without radiation exposure. However, there is little data on the practicality of LUS in assessing the severity of bronchopulmonary dysplasia (BPD) and evaluating short-term clinical outcomes. We adapted a LUS score to evaluate BPD severity and assess the reliability of mLUS score correlated with short-term clinical outcomes.

Methods

Prospective diagnostic accuracy study was designed to enroll preterm infants with gestational age < 34 weeks. Lung ultrasonography was performed at 36 weeks postmenstrual age. The diagnostic and predictive values of new modified lung ultrasound (mLUS) scores based on eight standard sections were compared with classic lung ultrasound (cLUS) scores.

Results

A total of 128 infants were enrolled in this cohort, including 30 without BPD; 31 with mild BPD; 23 with moderate BPD and 44 with severe BPD. The mLUS score was significantly correlated with the short-term clinical outcomes, superior to cLUS score. The mLUS score well correlated with moderate and severe BPD (AUC = 0.813, 95% CI 0.739–0.888) and severe BPD (AUC = 0.801, 95% CI 0.728–0.875), which were superior to cLUS score. The ROC analysis of mLUS score to evaluate the other short-term outcomes also showed significant superiority to cLUS score. The optimal cutoff points for mLUS score were 14 for moderate and severe BPD and 16 for severe BPD.

Conclusions

The mLUS score correlates significantly with short-term clinical outcomes and well evaluates these outcomes in preterm infants.

High-Resolution Computed Tomography Scores in Cases of Bronchopulmonary Dysplasia

Background

Bronchopulmonary dysplasia (BPD) carries a risk of long-term pulmonary sequelae. High-resolution computed tomography (HRCT) is a method of detecting such structural changes. This study is aimed at characterizing structural abnormalities associated with BPD and at evaluating the clinical findings in the newborn period associated with HRCT scores.

Methods

28 patients born with a mean gestation age of 30 ± 2.9 weeks and diagnosed as BPD in their neonatal period were reevaluated when they were between the postnatal ages of 6 and 12 months. HRCT was performed in 20 patients with a history of moderate and severe BPD. Scans were interpreted by one radiologist using a scoring system.

Results

Patients were 9.8 ± 2.3 months at the time of reevaluation. The average HRCT score of patients was, respectively, 7.20 ± 4.05 with moderate and 7.40 ± 2.84 with severe BPD. The difference between them was not significant (p = 0.620). When moderate and severe groups were collected as a whole on the basis of physical findings and drug treatment, 6 had normal physical examination findings, no oxygen and no drug requirement; 14 had at least one finding at the time of reevaluation. No significant difference was detected in terms of HRCT score between the two groups (6.50 ± 3.83 versus 7.64 ± 3.30).

Conclusions

More studies are needed in terms of the role of HRCT in the assessment of BPD prognosis. A contemporary definition of BPD that correlates with respiratory morbidity in childhood is needed. Also, a new lung ultrasound technique for predicting the respiratory outcome in patients with BPD can be used instead of HRCT.

Macitentan attenuates cardiovascular remodelling in infant rats with chronic lung disease

Background

Cardiovascular impairment contributes to increased mortality in preterm infants with chronic lung disease. Macitentan, an endothelin-1 receptor antagonist, has the potential to attenuate pulmonary and cardiovascular remodelling.

Methods

In a prospective randomized placebo-controlled intervention trial, Sprague–Dawley rats were exposed to 0.21 or 1.0 fraction of inspired oxygen (FiO2) for 19 postnatal days. Rats were treated via gavage with placebo or macitentan from days of life 5 to 19. Alveoli, pulmonary vessels, α-smooth muscle actin content in pulmonary arterioles, size of cardiomyocytes, right to left ventricular wall diameter ratio, and endothelin-1 plasma concentrations were assessed.

Results

FiO2 1.0 induced typical features of chronic lung disease with significant alveolar enlargement (p = 0.012), alveolar (p = 0.048) and pulmonary vessel rarefaction (p = 0.024), higher α-smooth muscle actin content in pulmonary arterioles (p = 0.009), higher right to left ventricular wall diameter ratio (p = 0.02), and larger cardiomyocyte cross-sectional area (p < 0.001). Macitentan treatment significantly increased pulmonary vessel count (p = 0.004) and decreased right to left ventricular wall diameter ratios (p = 0.002). Endothelin-1 plasma concentrations were higher compared to placebo (p = 0.015). Alveolar number and size, α-smooth muscle actin, and the cardiomyocyte cross-sectional area remained unchanged (all p > 0.05).

Conclusion

The endothelin-1 receptor antagonist macitentan attenuated cardiovascular remodelling in an infant rat model for preterm chronic lung disease. This study underscores the potential of macitentan to reduce cardiovascular morbidity in preterm infants with chronic lung disease.

Risk factors and bronchopulmonary dysplasia severity: data from the Spanish Bronchopulmonary Dysplasia Research Network

GEIDIS is a national-based research-net registry of patients with bronchopulmonary dysplasia (BPD) from public and private Spanish hospitals. It was created to provide data on the clinical characterization and follow-up of infants with BPD until adulthood. The purpose of this observational study was to analyze the characteristics and the impact of perinatal risk factors on BPD severity. The study included 1755 preterm patients diagnosed with BPD. Of the total sample, 90.6% (n = 1591) were less than 30 weeks of gestation. The median gestational age was 27.1 weeks (25.8-28.5) and median birth weight 885 g (740-1,070 g). A total of 52.5% (n = 922) were classified as mild (type 1), 25.3% (n = 444) were moderate (type 2), and 22.2% (n = 389) were severe BPD (type 3). In patients born at under 30 weeks' gestation, most pre-and postnatal risk factors for type 2/3 BPD were associated with the length of exposure to mechanical ventilation (MV). Independent prenatal risk factors were male gender, oligohydramnios, and intrauterine growth restriction. Postnatal risk factors included the need for FiO2 of > 0.30 in the delivery room, nosocomial pneumonia, and the length of exposure to MV. Conclusion: In this national-based research-net registry of BPD patients, the length of MV is the most important risk factor associated with type 2/3 BPD. Among type 3 BPD patients, those who required an FiO2 > .30 at 36 weeks' postmenstrual age had a higher morbidity, during hospitalization and at discharge, compared to those with nasal positive pressure but FiO2 < .30. What is Known: • BPD is a highly complex multifactorial disease associated with preterm birth. What is New: • The length of exposure to mechanical ventilation is the most important postnatal risk factor associated to bronchopulmonary severity which modulate the effect of most pre and postnatal risk factors. • Among patients with BPD, the requirement for FiO2 >.30% at 36 weeks of postmenstrual age is associated with greater morbidity during hospitalization and at discharge.

Pulmonary function tests in extremely low gestational age infants at one year of age

RATIONALE

Identifying neonatal and post-discharge exposures among extremely low gestational age newborns (ELGANs) that drive increased pulmonary morbidity and abnormal lung function at 1 year of age proves challenging.

OBJECTIVE

The NIH-sponsored Prematurity and Respiratory Outcomes Program (PROP), evaluated infant pulmonary function tests (iPFTs) at 1 year corrected age to determine which demographic and clinical factors are associated with abnormal lung function.

METHODS

iPFTs were performed on a PROP subcohort of 135 participants following Institutional Review Board (IRB)-approved written consent. Demographic data, Neonatal Intensive Care Unit (NICU) clinical care, and post-NICU exposures were analyzed for association with iPFTs.

MAIN RESULTS

A significant decrease in forced expiratory volume at 0.5 s (FEV_0.5 ) and/or forced expiratory flows at 75% of forced vital capacity (FEF₇₅ ), were associated with male sex and African American race. Clinical factors including longer duration of ventilatory support, exposure to systemic steroids, and weight less than the 10th percentile at 36 weeks postmenstrual age were also associated with airflow obstruction, whereas supplemental oxygen requirement and bronchopulmonary dysplasia were not. Additionally, the need for respiratory medications, technology, or hospitalizations during the first year, ascertained by a quarterly survey, were the only post-NICU factors associated with decreased FEV_0.5 and FEF₇₅ . Only 7% of infants had reversible airflow obstruction.

CONCLUSIONS

Neonatal demographic factors, respiratory support in the NICU, and a history of greater post-NICU medical utilization for respiratory disease had the strongest association with lower lung function at 1 year in ELGANs.

Volume-guarantee vs. pressure-limited ventilation in evolving bronchopulmonary dysplasia

INTRODUCTION

Extremely premature infants are at high risk for developing bronchopulmonary dysplasia (BPD). While noninvasive support is preferred, they may require ventilator support. Although volume-targeted ventilation (VTV) has been shown to be beneficial in preventing BPD, no data exists to guide ventilator management of infants with evolving BPD. Thus, clinicians employ a host of ventilator strategies, traditionally time-cycled pressure-limited ventilation (PLV) and more recently volume-guarantee ventilation (VGV) (a form of VTV). In this study, we sought to test the hypothesis that use of VGV in evolving BPD is associated with improved clinical and pulmonary outcomes when compared with PLV.

DESIGN

Single-center, retrospective cohort review of premature infants born less than 28 weeks inborn to a Level 4 NICU from January 2015 to December 2020. Data abstracted included demographics, maternal and birth data, and ventilator data until death or discharge. Exposure to either VGV or PLV was also examined, including ventilator "dose" (number of time points from DOL 14, 21 and 28 the patient was on that particular ventilator) during the period of evolving BPD.

RESULTS

Of a total of 471 patients with ventilation data available on DOL 14, 268 were not ventilated and 203 were ventilated. PLV at DOL 21 and 28 was associated with significantly higher risk of BPD and the composite outcome of BPD or death before 36 weeks compared to VGV. Both increasing VGV and PLV doses were significantly associated with higher odds of BPD and the composite outcome. For each additional time point of VGV and PLV exposure, the predicted length of stay (LOS) increased by 15.3 days (p < 0.001) and 28.8 days (p < 0.001), respectively.

DISCUSSION

Our study demonstrates the association of use of VGV at DOL 21 and 28 with decreased risk of BPD compared to use of PLV. Prospective trials are needed to further delineate the most effective ventilatory modality for this population with "evolving" BPD.

Bronchopulmonary dysplasia from chest radiographs to magnetic resonance imaging and computed tomography: adding value

Bronchopulmonary dysplasia (BPD) is a common long-term complication of preterm birth. The chest radiograph appearance and survivability have evolved since the first description of BPD in 1967 because of improved ventilation and clinical strategies and the introduction of surfactant in the early 1990s. Contemporary imaging care is evolving with the recognition that comorbidities of tracheobronchomalacia and pulmonary hypertension have a great influence on outcomes and can be noninvasively evaluated with CT and MRI techniques, which provide a detailed evaluation of the lungs, trachea and to a lesser degree the heart. However, echocardiography remains the primary modality to evaluate and screen for pulmonary hypertension. This review is intended to highlight the important findings that chest radiograph, CT and MRI can contribute to precision diagnosis, phenotyping and prognosis resulting in optimal management and therapeutics.

Pulmonary hypertension with bronchopulmonary dysplasia: Aichi cohort study

BACKGROUND

The incidence of pulmonary hypertension (PH) associated with bronchopulmonary dysplasia (BPD) has not been investigated in regional cohorts. The aim of this study was to clarify the incidence of PH associated with BPD in all very low birthweight infants (VLBWIs) born during the study period in Aichi Prefecture, Japan.

METHODS

We conducted a retrospective observational cohort study of all VLBWIs born in Aichi Prefecture. The inclusion criteria were VLB, birth between 1 January 2015 and 31 December 2015, and admission to any neonatal intensive care unit in Aichi Prefecture. BPD28d and BPD36w were defined as the need for supplemental oxygen or any respiratory support at 28 days of age or 36 weeks of postmenstrual age (PMA). The primary outcome was the incidence of PH after 36 weeks' PMA (PH36w) in VLBWIs with BPD28d and BPD36w. The secondary outcomes were the clinical factors related to PH36w in BPD36w patients. Mann-Whitney U-test and Fisher's exact test were used for univariate analysis. Differences were considered statistically significant at P < 0.05. Risk ratio (RR) and 95% confidence interval (CI) were also evaluated.

RESULTS

A total of 441 patients were analyzed. A total of 217 and 131 patients met the definition of BPD28d and BPD36w, respectively. Nine patients were diagnosed with PH36w (4.2% and 6.9% of the BPD28d and BPD36w patients, respectively). The presence of oligohydramnios (RR, 2.71; 95% CI: 1.55-4.73, P = 0.014) and sepsis (RR, 3.62; 95% CI: 1.51-8.63, P = 0.025) was significant in the PH36w patients.

CONCLUSIONS

The incidence of PH36w was 4.2% and 6.9% in the BPD28d and BPD36w patients, respectively. Oligohydramnios and sepsis were significantly associated with PH36w in VLBWIs.

A comparison of newer classifications of bronchopulmonary dysplasia: findings from the Children's Hospitals Neonatal Consortium Severe BPD Group

OBJECTIVE

To compare three bronchopulmonary dysplasia (BPD) definitions against hospital outcomes in a referral-based population.

STUDY DESIGN

Data from the Children's Hospitals Neonatal Consortium were classified by 2018 NICHD, 2019 NRN, and Canadian Neonatal Network (CNN) BPD definitions. Multivariable models evaluated the associations between BPD severity and death, tracheostomy, or length of stay, relative to No BPD references.

RESULTS

Mortality was highest in 2019 NRN Grade 3 infants (aOR 225), followed by 2018 NICHD Grade 3 (aOR 145). Infants with lower BPD grades rarely died (<1%), but Grade 2 infants had aOR 7-21-fold higher for death and 23-56-fold higher for tracheostomy.

CONCLUSIONS

Definitions with 3 BPD grades had better discrimination and Grade 3 2019 NRN had the strongest association with outcomes. No/Grade 1 infants rarely had severe outcomes, but Grade 2 infants were at risk. These data may be useful for counseling families and determining therapies for infants with BPD.

Comparisons of two definitions of bronchopulmonary dysplasia for the premature infants

OBJECTIVE

Bronchopulmonary dysplasia (BPD) is a very common respiratory disease in premature infants, but there is still a different understanding of the definition of BPD. Therefore, this study is intended to compare are main clinical results and health economic expenditures under different BPD definitions.

METHODS

This study included premature infants who came into the neonatal intensive care unit (NICU) from January 2018 to January 2020, who were not more than 32 weeks of premenstrual age. The main clinical consequences and health economic expenditures were analyzed by the National Institute of Health and Human Development definition (Workshop) and Jensen definition.

RESULTS

Total 303 survivors were evaluated at 36 weeks. BPD was performed in 47.5% and 37.6% of infants, respectively, with Workshop's and Jensen's definitions. The percentage of unclassified BPD infants was 0.9% in Workshop's and 3.3% in Jensen's definitions. Further discussing the health economic burden and found that Jensen's definitions had a significantly correlated with NICU charges than the Workshop's definitions.

CONCLUSION

Comparing the Workshop definition of BPD, the Jensens definition was better correlated to health expenditure.

Risk factors and prediction score model for unplanned readmission among neonates with NRDS under one year of age: A retrospective cohort study

OBJECTIVE

This study aimed to analyze the risk factors and establish a prediction score model for unplanned readmission among neonates with neonatal respiratory distress syndrome (NRDS) for respiratory problems under one year of age.

METHODS

This retrospective cohort study enrolled 230 neonates with NRDS who were admitted between January 2020 and December 2020. The infants were classified into two subgroups based on whether they were readmitted for respiratory problems under one year of age: readmit group and non-readmit group. Readmission risk factors for NRDS were analyzed by logistic regression and a prediction score model was generated.

RESULTS

Among the 230 enrolled infants, 51 (22%) were readmitted, and 179 (78%) were not readmitted. In univariate analysis, compared with non-readmit group infants, readmit group infants had a significantly younger birth gestational age (31.9 ± 2.3 vs. 32.8 ± 2.5 weeks, p = 0.012), lower birth weight (1,713.7 ± 501.3 g vs. 1,946.8 ± 634.4 g, p = 0.007), older age at discharge (41.7 vs. 31.7 days, p = 0.012), higher proportion of necrotizing enterocolitis (NEC) (31% vs. 16%, p = 0.016), higher rate of blood transfusion (39% vs. 25%, p = 0.049), higher rate of postnatal dexamethasone (DEX) administration (28% vs. 9.5%, p = 0.001), and higher rate of home oxygen therapy (HOT) (57% vs. 34%, p = 0.003). Moreover, readmit group infants had significantly longer antibiotic days usage (12.0 vs. 10.0 days, p = 0.026) and a longer duration of hospital stay (41.0 vs. 31.0 days, p = 0.012) than non-readmit group infants. The multivariate logistic regression analysis showed that taking readmission as a target variable, postnatal DEX administration (OR: 2.689, 95% CI: 1.168-6.189, p = 0.020), HOT (OR: 2.071, 95% CI: 1.060-4.046, p = 0.033), and NEC (OR: 2.088, 95% CI: 0.995-4.380, p = 0.051) could be regarded as risk factors for readmission. A scoring model predicting readmission was administered with a positive predictive value of 0.651 (95% CI: 0.557-0.745, p = 0.002), with a sensitivity of 0.412 and a specificity of 0.888 at a cut-off of 3.5 points, which were evaluated on the receiver operating characteristic curve.

CONCLUSIONS

Postnatal DEX administration, HOT, and NEC were risk factors for readmission of NRDS. NRDS infants with a predictive score of 3.5 points or more were at high risk for unplanned readmission.

Randomized trial of azithromycin to eradicate Ureaplasma respiratory colonization in preterm infants: 2-year outcomes

BACKGROUND

To assess the potential impact of azithromycin treatment in the first week following birth on 2-year outcomes in preterm infants with and without Ureaplasma respiratory colonization who participated in a double-blind, placebo-controlled randomized controlled trial.

METHODS

Respiratory morbidity was assessed at NICU discharge and at 6, 12, and 22-26 months corrected age using pulmonary questionnaires. Comprehensive neurodevelopmental assessments were completed between 22 and 26 months corrected age. The primary and secondary composite outcomes were death or severe respiratory morbidity and death or moderate-severe neurodevelopmental impairment, respectively, at 22-26 months corrected age.

RESULTS

One hundred and twenty-one randomized participants (azithromycin, N = 60; placebo, N = 61) were included in the intent-to-treat analysis. There were no significant differences in death or serious respiratory morbidity (34.8 vs 30.4%, p = 0.67) or death or moderate-severe neurodevelopmental impairment (47 vs 33%, p = 0.11) between the azithromycin and placebo groups. Among all trial participants, tracheal aspirate Ureaplasma-positive infants experienced a higher frequency of death or serious respiratory morbidity at 22-26 months corrected age (58%) than tracheal aspirate Ureaplasma-negative infants (34%) or non-intubated infants (21%) (p = 0.028).

CONCLUSIONS

We did not observe strong evidence of a difference in long-term pulmonary and neurodevelopment outcomes in preterm infants treated with azithromycin in the first week of life compared to placebo.

IMPACT

No strong evidence of a difference in long-term pulmonary and neurodevelopment outcomes was identified at 22-26 months corrected age in infants treated with azithromycin in the first week of life compared to placebo. The RCT is the first study of 2-year pulmonary and neurodevelopmental outcomes of azithromycin treatment in ELGANs. Provides evidence that ELGANs with lower respiratory tract Ureaplasma have the most frequent serious respiratory morbidity in the first 2 years of life, suggesting that a Phase III trial of azithromycin to prevent BPD targeting this population is warranted.

Definitions of bronchopulmonary dysplasia and long-term outcomes of extremely preterm infants in Korean Neonatal Network

New definitions for bronchopulmonary dysplasia (BPD) have recently been suggested, and an accurate diagnosis, including severity classification with proper definition, is crucial to identify high-risk infants for appropriate interventions. To determine whether recently suggested BPD definitions can better predict long-term outcomes of BPD in extremely preterm infants (EPIs) than the original BPD definition, BPD was classified with severity 1, 2, and 3 using three different definitions: definition A (original), National Institute of Child Health and Human Development (NICHD) definition in 2001; definition B, the modified NICHD 2016 definition (graded by the oxygen concentration and the respiratory support at 36 weeks’ postmenstrual age [PMA]); and definition C, the modified Jensen 2019 definition (graded by the respiratory support at 36 weeks’ PMA). We evaluated 1050 EPIs using a national cohort. Whereas EPIs with grade 2 or 3 BPD as per definition A did not show any increase in the risk, EPIs with BPD diagnosed by definition B and C showed significantly increased risk for poor outcomes, such as respiratory mortality and morbidities, neurodevelopmental delay, and growth restriction at 18–24 months of corrected age. The recently suggested definition and severity grading better reflects long-term childhood morbidities than the original definition in EPIs.

Global incidence of intraventricular hemorrhage among extremely preterm infants: a systematic literature review

OBJECTIVES

To conduct a systematic literature review to evaluate the global incidence of intraventricular hemorrhage grade 2-4 among extremely preterm infants.

METHODS

We performed searches in MEDLINE and Embase for intraventricular hemorrhage and prematurity cited in English language observational studies published from May 2006 to October 2017. Included studies analyzed data from infants born at ≤28 weeks' gestational age and reported on intraventricular hemorrhage epidemiology.

RESULTS

Ninety-eight eligible studies encompassed 39 articles from Europe, 31 from North America, 25 from Asia, five from Oceania, and none from Africa or South America; both Europe and North America were included in two publications. The reported global incidence range of intraventricular hemorrhage grade 3-4 was 5-52% (Europe: 5-52%; North America: 8-22%; Asia: 5-36%; Oceania: 8-13%). When only population-based studies were included, the incidence range of intraventricular hemorrhage grade 3-4 was 6-22%. The incidence range of intraventricular hemorrhage grade 2 was infrequently documented and ranged from 5-19% (including population-based studies). The incidence of intraventricular hemorrhage was generally inversely related to gestational age.

CONCLUSIONS

Intraventricular hemorrhage is a frequent complication of extremely preterm birth. Intraventricular hemorrhage incidence range varies by region, and the global incidence of intraventricular hemorrhage grade 2 is not well documented.