A systematic review of randomized controlled trials for the prevention of bronchopulmonary dysplasia in infants

Nutritional Needs of the Infant with Bronchopulmonary Dysplasia

Growth failure is a common problem in infants with established bronchopulmonary dysplasia (BPD). Suboptimal growth for infants with BPD is associated with unfavorable respiratory and neurodevelopmental outcomes; however, high-quality evidence to support best nutritional practices are limited for this vulnerable patient population. Consequently, there exists a wide variation in the provision of nutritional care and monitoring of growth for infants with BPD. Other neonatal populations at risk for growth failure, such as infants with congenital heart disease, have demonstrated improved growth outcomes with the creation and compliance of clinical protocols to guide nutritional management. Developing clinical protocols to guide nutritional management for infants with BPD may similarly improve long-term outcomes. Given the absence of high-quality trials to guide nutritional practice in infants with BPD, the best available evidence of systematic reviews and clinical recommendations can be applied to optimize growth and decrease variation in the care of these infants.

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.

Developing a Respiratory Quality Improvement Program to Prevent and Treat Bronchopulmonary Dysplasia in the Neonatal Intensive Care Unit

Improvements in respiratory care have resulted in improved outcomes for preterm infants over the past three decades. To target the multifactorial nature of neonatal lung diseases, neonatal intensive care units (NICUs) should consider developing comprehensive respiratory quality improvement programs that address all drivers of neonatal respiratory disease. This article presents a potential framework for developing a quality improvement program to prevent bronchopulmonary dysplasia in the NICU. Drawing on available research and quality improvement reports, the authors discuss key components, measures, drivers, and interventions that should be considered when building a respiratory quality improvement program devoted to preventing and treating bronchopulmonary dysplasia.

Low flow nasal cannula requirement among preterm infants: predictors and description of clinical course

OBJECTIVE

We aim to identify potential risk factors associated with longer duration of supplemental oxygen use in preterm infants at risk for bronchopulmonary dysplasia (BPD) to better inform families and weaning protocols.

STUDY DESIGN

This is a retrospective study of infants with a birth gestational age (GA) < 32 0/7 weeks admitted to the neonatal intensive care unit (NICU) between October 2017 and September 2019.

RESULTS

A total of 172 infants met criteria for inclusion and analysis, of which 69 (40.1%) infants required LFNC. Risk factors for longer duration included lower birth GA or birth weight, increased ventilator days, and diagnosis of a patent ductus arteriosus (PDA). BPD was diagnosed in 69.6% who required LFNC, of which 47.8% were discharged on home oxygen.

CONCLUSION

Younger birth GA, lower birth weight, increased ventilator days, and presence of a PDA were identified as risk factors for longer LFNC duration.

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.

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.

Parental voice - what outcomes of preterm birth matter most to families?

Neonatal follow-up studies traditionally report on long-term neurodevelopmental outcomes as a metric of success of neonatal intensive care. Research endpoints are also typically deficit-based, assessing whether disabilities, such as cerebral palsy, cognitive impairment, deafness or blindness, are present or not. These historical approaches have resulted in neonatal follow-up programs that narrowly focus on the early identification of neurodevelopmental problems, possibly to the detriment of other outcomes that matter to parents. This focus on neurodevelopmental disability may also contribute to the negative stereotypes associated with extreme preterm birth. In this article, we discuss parental perspectives regarding important long-term outcomes. We examine limitations with current definitions of outcomes and propose a strength-based approach to generate meaningful findings both for clinicians and families.

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.

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

OBJECTIVE

To characterize the safety of sildenafil in premature infants.

STUDY DESIGN

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

RESULTS

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

CONCLUSION

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

CLINICAL TRIAL

ClinicalTrials.gov Identifier: NCT01670136.

The Relationship Between Cord Blood Cytokine Levels and Perinatal Characteristics and Bronchopulmonary Dysplasia: A Case-Control Study

OBJECTIVE

To establish the association between serial levels of inflammatory cytokines in cord blood and perinatal characteristics and bronchopulmonary dysplasia (BPD) in preterm infants.

METHODS

147 premature infants with gestational age ≤32 weeks who were born and hospitalized in the First Affiliated Hospital of Zhengzhou University between July 2019 and August 2021 were enrolled in this retrospective case-control study. Multiple microsphere flow immunofluorescence was used to detect seven cytokines in cord blood collected within 24 h of birth. Demographics, delivery characteristics, maternal factors, neonatal characteristics, and clinical outcomes were collected for the two groups. An unconditional logistic regression model was used in this study to assess the clinical variables.

RESULTS

IL-6 cord blood levels at birth were significantly higher in the BPD group than in the non-BPD group, but the odds ratio (OR) was very small (OR = 1). No differences in other cytokine concentrations were observed between the two groups. Multivariable logistic regression analysis demonstrated that increased maternal white blood cell (WBC) count on admission and lower birth weight increased the risk of BPD progression.

CONCLUSIONS

Increased IL-6 cord blood levels at birth in preterm infants may have trivial significance for predicting BPD. Furthermore, higher maternal WBC count on admission and lower birth weight increased the risk of BPD.

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.

The challenge of accurately describing the epidemiology of bronchopulmonary dysplasia (BPD) based on the various current definitions of BPD

Despite marked improvements in the survival of extremely low birth weight preterm infants, bronchopulmonary dysplasia (BPD) remains a prevalent morbidity. BPD has evolved pathologically and epidemiologically but the definition has failed to keep up. The majority of the definitions of BPD still use the respiratory support provided to the infants at a single timepoint. The lack of a uniform definition of BPD presently reflects the changing BPD pathogenesis and phenotype and limits defining the epidemiology. To address the epidemiology of BPD, the definition should be clarified; even the newer definitions have not been validated entirely. The definition needs to be meaningful clinically and be predictive of long-term respiratory outcomes. We believe the definition should have a composite assessment like a score (quantitative measurement) and include the different phenotypes (qualitative measurements) so that optimally they can be applied to the different phases of BPD and at different timepoints. Furthermore, the definitions need to be easy to measure and assess so that generalizability is enhanced.

Should Vitamin A Injections to Prevent Bronchopulmonary Dysplasia or Death Be Reserved for High-Risk Infants? Reanalysis of the National Institute of Child Health and Human Development Neonatal Research Network Randomized Trial

OBJECTIVE

To determine whether infants at higher risk of bronchopulmonary dysplasia (BPD) or death benefit more from vitamin A therapy than those at lower risk.

STUDY DESIGN

We conducted a post hoc reanalysis of a landmark phase III randomized controlled trial conducted from January 1996 to July 1997 at 14 university-affiliated neonatal intensive care units in the US. Data analysis was performed from October 2019 to October 2020. Infants born weighing 401-1000 g and receiving respiratory support at 24 hours of age were assigned to intramuscular vitamin A 5000 IU or sham procedure 3 times weekly for 4 weeks. The primary outcome was BPD, defined as use of supplemental oxygen, or death at 36 weeks postmenstrual age. An externally validated model for predicting BPD or death was used to estimate the risk of these outcomes for each infant.

RESULTS

As previously reported, 222 of 405 infants (54.8%) assigned vitamin A therapy and 248 of 402 infants (61.7%) in the control group developed BPD or died (relative risk [RR], 0.89 [95% CI, 0.80-0.99]; risk difference [RD], -6.9% [95% CI, -13.0 to -0.7]). The predicted individual risks of BPD or death ranged from 7.1% to 98.6% (median, 61.5%; mean, 60.9%). The effect of vitamin A therapy on BPD or death depended on infants' risk of the primary outcome (P = .03 for interaction): for example, a RR of 0.73 (RD, -14.5%) for infants with a 25% predicted risk and a RR of 0.96 (RD, -1.0%) for infants with a 75% risk. There was no difference in the decrease in vitamin A deficiency across risk groups.

CONCLUSIONS

Contrary to expectations, the effect of vitamin A therapy on BPD or death was greater for lower risk than higher risk infants.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01203488.

Association between probiotics and bronchopulmonary dysplasia in preterm infants

Bronchopulmonary dysplasia is a chronic pulmonary disease with a high incidence in premature infants, and there is still no effective treatment. The purpose of our study was to analyze the association between the use of probiotics and BPD in premature infants. We retrospectively collected clinical data of infants with gestational age < 32 weeks admitted to the NICU of The First Hospital of Jilin University from January 1, 2019 to March 31, 2020. Demographic and clinicopathological data of the inclusion population were collected. The outcome was the incidence of BPD or death. The χ² tests was used to compare the categorical variables. The t test and non-parametric Wilcoxon rank-sum test were used to compare the continuous data. Univariate and multivariate logistic regression were used to analyze the association between probiotics and BPD. A total of 318 newborns met the inclusion criteria, of which 94 received probiotics and 224 received no probiotics. There were 16 deaths and 115 newborns with BPD in the included population. The results of univariate analysis showed differences in the maternal diabetes, the proportion of systemic antibiotics given to mother within 24 h before birth, the receiving rate of invasive mechanical ventilation, the prevalence of BPD/death, PDA, RDS and Ivh between newborns with and without probiotics (p < 0.05); The results of unadjusted univariate logistic regression model showed that probiotic (OR 0.034, 95% CI 0.012-0.096) was the factor affecting BPD in preterm infants (p < 0.05). Multivariate logistic regression result (OR 0.037, 95% CI 0.013-0.105) was consistent with univariate analysis (P < 0.001). Probiotics are associated with a reduced risk of BPD in preterm infants < 32 weeks of age. More prospective studies with large samples are still needed.

An Update on the Prevention and Management of Bronchopulmonary Dysplasia

Bronchopulmonary dysplasia (BPD) is a common morbidity affecting preterm infants and is associated with substantial long-term disabilities. There has been no change in the incidence of BPD over the past 20 years, despite improvements in survival and other outcomes. The preterm lung is vulnerable to injuries occurring as a result of invasive ventilation, hyperoxia, and infections that contribute to the development of BPD. Clinicians caring for infants in the neonatal intensive care unit use multiple therapies for the prevention and management of BPD. Non-invasive ventilation strategies and surfactant administration via thin catheters are treatment approaches that aim to avoid volutrauma and barotrauma to the preterm developing lung. Identifying high-risk infants to receive postnatal corticosteroids and undergo patent ductus arteriosus closure may help to individualize care and promote improved lung outcomes. In infants with established BPD, outpatient management is complex and requires coordination from several specialists and therapists. However, most current therapies used to prevent and manage BPD lack solid evidence to support their effectiveness. Further research is needed with appropriately defined outcomes to develop effective therapies and impact the incidence of BPD.

Morbidity and respiratory outcomes in infants requiring tracheostomy for severe bronchopulmonary dysplasia

OBJECTIVE

The decision for tracheostomy for bronchopulmonary dysplasia (BPD) is highly variable and often dictated by local practice. We aimed to characterize morbidity, mortality, and respiratory outcomes in preterm infants undergoing tracheostomy for severe BPD.

STUDY DESIGN

We retrospectively reviewed a single-center 4-year cohort of all infants born <33 weeks gestational age (GA) that required tracheostomy due to severe BPD. Indications for tracheostomy apart from BPD were excluded. Demographic information, comorbidities, respiratory management, age at tracheostomy, post-discharge respiratory outcomes, and survival were examined up to at least 5 years of age.

RESULTS

At a mean corrected GA of 43.3 weeks, 49 preterm infants with severe BPD required tracheostomy. Forty-six infants (94%) had long-term follow-up. Compared to survivors, the 12 (26.1%) infants that died were significantly more likely to be small for gestational age (SGA) or require treatment for pulmonary hypertension. GA, birth weight, sex, antenatal corticosteroid exposure, need for patent ductus arteriosus ligation, and magnitude of respiratory support at tracheostomy placement were not associated with mortality. At the latest follow-up, 97% were liberated from mechanical ventilation and 79% decannulated. Morbidities of the upper airway were common, and 13/27 (47%) decannulated infants had required airway reconstruction.

CONCLUSION

Preterm infants undergoing tracheostomy experienced significant mortality, particularly those who were SGA or had pulmonary hypertension. However, by 5 years of age, most infants liberalized from mechanical ventilation and decannulated. Magnitude of respiratory support at time of tracheostomy was not associated with mortality and should not deter intervention. Nearly half of patients required airway reconstruction before decannulation.

Specificity of International Classification of Diseases codes for bronchopulmonary dysplasia: an investigation using electronic health record data and a large insurance database

OBJECTIVE

International Classification of Diseases (ICD) codes in electronic health records (EHRs) are increasingly used for health services research, in spite of unknown diagnostic accuracy. The accuracy of ICD codes to identify bronchopulmonary dysplasia (BPD) is unknown.

STUDY DESIGN

Retrospective cohort study in a single-center NICU (n = 166) to evaluate sensitivity and specificity of ICD-10 codes for the diagnosis of BPD. Analysis of large insurance claims database (n = 7887) to determine date of assignment of the code.

RESULTS

The sensitivity of any BPD-related ICD codes ranged from 0.82 to 0.95, while the specificity ranged from 0.25 to 0.36. In a large national insurance database, the most common date of ICD-9 or ICD-10 code assignment was the day of birth, which is inconsistent with the clinical definition.

CONCLUSIONS

ICD codes registered for BPD are unlikely to accurately reflect the current clinical definition and should be interpreted with caution.

Mechanical Ventilation Duration, Brainstem Development, and Neurodevelopment in Children Born Preterm: A Prospective Cohort Study

OBJECTIVES

To determine, in children born preterm, the association of mechanical ventilation duration with brainstem development, white matter maturation, and neurodevelopmental outcomes at preschool age.

STUDY DESIGN

This prospective cohort study included 144 neonates born at <30 weeks of gestation (75 male, mean gestational age 27.1 weeks, SD 1.6) with regional brainstem volumes automatically segmented on magnetic resonance imaging at term-equivalent age (TEA). The white matter maturation was assessed by diffusion tensor imaging and tract-based spatial statistics. Neurodevelopmental outcomes were assessed at 4.5 years of age using the Movement Assessment Battery for Children, 2nd Edition, and the Wechsler Primary and Preschool Scale of Intelligence, 4th Edition, full-scale IQ. The association between the duration of mechanical ventilation and brainstem development was validated in an independent cohort of children born very preterm.

RESULTS

Each additional day of mechanical ventilation predicted lower motor scores (0.5-point decrease in the Movement Assessment Battery for Children, 2nd Edition, score by day of mechanical ventilation, 95% CI -0.6 to -0.3, P < .0001). Prolonged exposure to mechanical ventilation was associated with smaller pons and medulla volumes at TEA in 2 independent cohorts, along with widespread abnormalities in white matter maturation. Pons and medulla volumes at TEA predicted motor outcomes at 4.5 years of age.

CONCLUSIONS

In neonates born very preterm, prolonged mechanical ventilation is associated with impaired brainstem development, abnormal white matter maturation, and lower motor scores at preschool age. Further research is needed to better understand the neural pathological mechanisms involved.

Using Experimental Models to Identify Pathogenic Pathways and Putative Disease Management Targets in Bronchopulmonary Dysplasia

Bronchopulmonary dysplasia (BPD) is a common and serious complication of preterm birth. Limited pharmacological and other medical interventions are currently available for the management of severely affected, very preterm infants. BPD can be modelled in preclinical studies using experimental animals, and experimental animal models have been extremely valuable in the development of hallmark clinical management strategies for BPD, including pulmonary surfactant replacement and single-course antenatal corticosteroids. A gradual move away from large animal models of BPD in favor of term-born rodents has facilitated the identification of a multitude of new mechanisms of normal and stunted lung development, but this has also potentially limited the utility of experimental animal models for the identification of pathogenic pathways and putative disease management targets in BPD. Indeed, more recent pharmacological interventions for the management of BPD that have been validated in randomized controlled trials have relied very little on preclinical data generated in experimental animal models. While rodent-based models of BPD have tremendous advantages in terms of the availability of genetic tools, they also have considerable drawbacks, including limited utility for studying breathing mechanics, gas exchange, and pulmonary hemodynamics; and they have a less relevant clinical context where lung prematurity and a background of infection are now rarely present in the pathophysiology under study. There is a pressing need to refine existing models to better recapitulate pathological processes at play in affected infants, in order to better evaluate new candidate pharmacological and other interventions for the management of BPD.

Tobacco Smoking During Pregnancy Is Associated With Increased Risk of Moderate/Severe Bronchopulmonary Dysplasia: A Systematic Review and Meta-Analysis

Epidemiological evidence and animal studies support that intrauterine exposure to tobacco smoke disturbs lung development and has a negative effect in the pulmonary health of the offspring. Individual studies suggest an association between fetal exposure to maternal smoking and risk of developing bronchopulmonary dysplasia (BPD). However, this association has not yet been systematically investigated. We aimed to conduct a systematic review of studies reporting on tobacco smoking during pregnancy as potential risk factor for BPD. PubMed/MEDLINE and EMBASE databases were searched. BPD was defined as requirement of supplemental oxygen on postnatal day 28 (BPD28; all BPD), at the postmenstrual age (PMA) of 36 weeks (BPD36; moderate/severe BPD), or as requirement of more than 30% oxygen and/or positive pressure at 36 weeks PMA (severe BPD). Pooled risk ratios (RR) and 95% confidence intervals (CI) were calculated using a random-effects model. Of 2,894 potentially relevant studies, 33 met the inclusion criteria. The included studies evaluated 171,772 infants and included 30,445 cases of exposure to maternal smoking and 25,340 cases of BPD of any severity. Meta-analysis showed a significant association between tobacco smoking during pregnancy and BPD36 (17 studies, RR 1.126, 95% CI 1.008-1.259, p = 0.036), but could not demonstrate a significant association between tobacco smoking during pregnancy and BPD28 (16 studies, RR 1.021, 95% CI 0.924-1.129, p = 0.681), or severe BPD (3 studies, RR 1.143, 95% CI 0.528-2.478, p = 0.734). In conclusion, our data suggest that tobacco smoking during pregnancy increases the risk of moderate/severe BPD. Our results highlight the detrimental effects of tobacco smoking and reinforce the hypothesis of the involvement of prenatal insults in the etiopathogenesis of BPD.

Population pharmacokinetics of sildenafil in extremely premature infants

AIMS

To characterize the population pharmacokinetics (PK) of sildenafil and its active metabolite, N-desmethyl sildenafil (DMS), in premature infants.

METHODS

We performed a multicentre, open-label trial to characterize the PK of sildenafil in infants ≤28 weeks gestation and < 365 postnatal days (cohort 1) or < 32 weeks gestation and 3-42 postnatal days (cohort 2). In cohort 1, we obtained PK samples from infants receiving sildenafil as ordered per the local standard of care (intravenous [IV] or enteral). In cohort 2, we administered a single IV dose of sildenafil and performed PK sampling. We performed a population PK analysis and dose-exposure simulations using the software NONMEM®.

RESULTS

We enrolled 34 infants (cohort 1 n = 25; cohort 2 n = 9) and collected 109 plasma PK samples. Sildenafil was given enterally (0.42-2.09 mg/kg) in 24 infants in cohort 1 and via IV (0.125 or 0.25 mg/kg) in all infants in cohort 2. A 2-compartment PK model for sildenafil and 1-compartment model for DMS, with presystemic conversion of sildenafil to DMS, characterized the data well. Coadministration of fluconazole (n = 4), a CYP3A inhibitor, resulted in an estimated 59% decrease in sildenafil clearance. IV doses of 0.125, 0.5 and 1 mg/kg every 8 hours (in the absence of fluconazole) resulted in steady-state maximum sildenafil concentrations that were generally within the range of those reported to inhibit phosphodiesterase type 5 activity in vitro.

CONCLUSIONS

We successfully characterized the PK of sildenafil and DMS in premature infants and applied the model to inform dosing for a follow-up, phase II study.

Lack of whey acidic protein (WAP) four-disulfide core domain protease inhibitor 2 (WFDC2) causes neonatal death from respiratory failure in mice

Respiratory failure is a life-threatening problem for pre-term and term infants, yet many causes remain unknown. Here, we present evidence that whey acidic protein (WAP) four-disulfide core domain protease inhibitor 2 (Wfdc2), a protease inhibitor previously unrecognized in respiratory disease, may be a causal factor in infant respiratory failure. Wfdc2 transcripts are detected in the embryonic lung and analysis of a Wfdc2-GFP knock-in mouse line shows that both basal and club cells, and type II alveolar epithelial cells (AECIIs), express Wfdc2 neonatally. Wfdc2-null-mutant mice display progressive atelectasis after birth with a lethal phenotype. Mutant lungs have multiple defects, including impaired cilia and the absence of mature club cells from the tracheo-bronchial airways, and malformed lamellar bodies in AECIIs. RNA sequencing shows significant activation of a pro-inflammatory pathway, but with low-quantity infiltration of mononuclear cells in the lung. These data demonstrate that Wfdc2 function is vitally important for lung aeration at birth and that gene deficiency likely causes failure of the lung mucosal barrier.

Association of Chorioamnionitis With Bronchopulmonary Dysplasia Among Preterm Infants: A Systematic Review, Meta-analysis, and Metaregression

Importance

Bronchopulmonary dysplasia (BPD), a chronic lung disease of prematurity, remains one of the major and most common complications of very preterm birth. Insight into factors associated with the pathogenesis of BPD is key to improving its prevention and treatment.

Objective

To perform a systematic review, meta-analysis, and metaregression of clinical studies exploring the association between chorioamnionitis (CA) and BPD in preterm infants.

Data Sources

PubMed and Embase were searched without language restriction (last search, October 1, 2018). Key search terms included bronchopulmonary dysplasia, chorioamnionitis, and risk factors.

Study Selection

Included studies were peer-reviewed studies examining preterm (<37 weeks' gestation) or very low-birth-weight (<1500 g) infants and reporting primary data that could be used to measure the association between exposure to CA and the development of BPD.

Data Extraction and Synthesis

The Meta-analysis of Observational Studies in Epidemiology (MOOSE) guideline was followed. Data were independently extracted by 2 researchers. A random-effects model was used to calculate odds ratios (ORs) and 95% CIs. Heterogeneity in effect size across studies was studied using multivariate, random-effects metaregression analysis.

Main Outcomes and Measures

The primary outcome was BPD, defined as supplemental oxygen requirement on postnatal day 28 (BPD28) or at the postmenstrual age of 36 weeks (BPD36). Covariates considered as potential confounders included differences between CA-exposed and CA-unexposed infants in gestational age, rates of respiratory distress syndrome (RDS), exposure to antenatal corticosteroids, and rates of early- and late-onset sepsis.

Results

A total of 3170 potentially relevant studies were found, of which 158 met the inclusion criteria (244 096 preterm infants, 20 971 CA cases, and 24 335 BPD cases). Meta-analysis showed that CA exposure was significantly associated with BPD28 (65 studies; OR, 2.32; 95% CI, 1.88-2.86; P < .001; heterogeneity: I2 = 84%; P < .001) and BPD36 (108 studies; OR, 1.29; 95% CI, 1.17-1.42; P < .001; heterogeneity: I2 = 63%; P < .001). The association between CA and BPD remained significant for both clinical and histologic CA. In addition, significant differences were found between CA-exposed and CA-unexposed infants in gestational age, birth weight, odds of being small for gestational age, exposure to antenatal corticosteroids, and early- and late-onset sepsis. Chorioamnionitis was not significantly associated with RDS (48 studies; OR, 1.10; 95% CI, 0.92-1.34; P = .24; heterogeneity: I2 = 90%; P < .001), but multivariate metaregression analysis with backward elimination revealed that a model combining the difference in gestational age and the odds of RDS was associated with 64% of the variance in the association between CA and BPD36 across studies.

Conclusions and Relevance

The results of this study confirm that among preterm infants, exposure to CA is associated with a higher risk of developing BPD, but this association may be modulated by gestational age and risk of RDS.

Global incidence of bronchopulmonary dysplasia among extremely preterm infants: a systematic literature review

BACKGROUND

Infants born extremely preterm (<28 weeks gestational age (GA)) face a high risk of neonatal mortality. Bronchopulmonary dysplasia (BPD) is the most common morbidity of prematurity.

OBJECTIVE

To evaluate the global incidence of BPD among infants born extremely preterm.

DESIGN

A systematic review of the literature was conducted in Embase and MEDLINE (via PubMed) using a prespecified search strategy for BPD and prematurity. Observational studies published in English between 16 May 2006 and 16 October 2017 reporting on the occurrence of BPD in infants born <28 weeks GA were included.

RESULTS

Literature searches yielded 103 eligible studies encompassing 37 publications from Europe, 38 publications from North America, two publications from Europe and North America, 19 publications from Asia, one publication from Asia and North America, six publications from Oceania, and zero publications from Africa or South America. The reported global incidence range of BPD was 10-89% (10-73% in Europe, 18-89% in North America, 18-82% in Asia, and 30-62% in Oceania). When only population-based observational studies that defined BPD as requiring supplemental oxygen at 36 weeks postmenstrual age were included, the global incidence range of BPD was 17-75%. The wide range of incidences reflected interstudy differences in GA (which was inversely related to BPD incidence), birthweight, and survival rates across populations and institutions.

CONCLUSIONS

BPD is a common health morbidity occurring with extremely preterm birth. Further study of factors that impact incidence, aside from low GA, may help to elucidate modifiable risks.

Oral vitamin A supplementation in very low birth weight neonates: a randomized controlled trial

This randomized double-blind placebo-controlled trial evaluated the effects of early postnatal oral vitamin A supplementation (VAS) in 196 inborn very-low birth weight (VLBW) infants requiring respiratory support at 24 h of age. Eligible infants were randomized to receive aqueous syrup of vitamin A (10,000 IU of retinol/dose; n = 98) or placebo (n = 98) on alternate days for 28 days. Primary outcome variable was composite incidence of all-cause mortality and/or oxygen requirement for 28 days. Secondary outcome variables were safety/tolerability of VAS, serum retinol concentration at recruitment and day 28, duration of oxygen requirement and respiratory support and incidences of complications. On intention-to-treat analysis, composite incidence of all-cause mortality and oxygen requirement for 28 days was significantly lower in vitamin A group (relative risk (95% confidence interval), 0.440 (0.229-0.844); p < 0.05, number needed to benefit, 7). Requirement and duration of oxygen supplementation and non-invasive respiratory support, incidences of late-onset sepsis, patent ductus arteriosus, and duration of hospital stay were also significantly lower in vitamin A group. Serum retinol concentration improved significantly after VAS. No major adverse effect was observed.Conclusions: Early postnatal oral VAS was associated with better composite outcome of all-cause mortality and oxygen requirement without any major adverse effects.Clinical Trial Registration: Clinical Trials Registry of India (CTRI/2017/03/008131). What is Known: • Postnatal intramuscular vitamin A supplementation improves the survival, respiratory outcome and other morbidities in very low birth weight neonates without major adverse effects. • Limited studies on oral vitamin A supplementation did not document substantial benefits. What is New: • Early postnatal alternate-day oral vitamin A supplementation at the dose of 10,000 IU/dose for 28 days improves the composite outcome of death and oxygen requirement in very low birth weight neonates with respiratory distress • No major adverse effects were documented.

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.

Pulmonary vascular disease is evident in gene regulation of experimental bronchopulmonary dysplasia

Objective: To examine the gene expression regarding pulmonary vascular disease in experimental bronchopulmonary dysplasia in young mice. Premature delivery puts babies at risk of severe complications. Bronchopulmonary dysplasia (BPD) is a common complication of premature birth leading to lifelong affection of pulmonary function. BPD is recognized as a disease of arrested alveolar development. The disease process is not fully described and no complete cure or prevention is known. The focus of interest in the search for treatment and prevention of BPD has traditionally been at airspace level; however, the pulmonary vasculature is increasingly acknowledged in the pathology of BPD. The aim of the investigation was to study the gene expression in lungs with BPD with regards to pulmonary vascular disease (PVD).Methods: We employed a murine model of hyperoxia-induced BPD and gene expression microarray technique to determine the mRNA expression in lung tissue from young mice. We combined gene expression pathway analysis and analyzed the biological function of multiple single gene transcripts from lung homogenate to study the PVD relevant gene expression.Results: There were n = 117 significantly differentially regulated genes related to PVD through down-regulation of contractile elements, up- and down-regulation of factors involved in vascular tone and tissue-specific genes. Several genes also allowed for pinpointing gene expression differences to the pulmonary vasculature. The gene Nppa coding for a natriuretic peptide, a potent vasodilator, was significantly down-regulated and there was a significant up-regulation of Pde1a (phosphodiesterase 1A), Ptger3 (prostaglandin e receptor 3), and Ptgs1 (prostaglandin-endoperoxide synthase one).Conclusion: The pulmonary vasculature is affected by the arrest of secondary alveolarization as seen by differentially regulated genes involved in vascular tone and pulmonary vasculature suggesting BPD is not purely an airspace disease. Clues to prevention and treatment may lie in the pulmonary vascular system.

Bronchopulmonary Dysplasia: 50 Years after the Original Description

Bronchopulmonary dysplasia (BPD) is one of the few diseases in neonatal medicine that has continued to evolve since its first description about 50 years ago. Over these years, advancements in neonatal medicine such as antenatal steroids and exogenous surfactant therapy have significantly reduced neonatal mortality and lowered the limits of viability for preterm infants. Although the incidence of BPD continues to be high, especially in extremely low birth weight infants, the clinical picture has evolved into a milder disease with low mortality or significant morbidities. This new BPD is the result of complex interactions between altered alveolar and vascular development, injury by ante- and postnatal pathogenic factors, and reparative processes in the lung. There has been significant progress in our understanding of risk factors for BPD, but challenges persist in its definition, and in finding effective preventive strategies. There are promising developments with newer preventive interventions such as mesenchymal stem cells, exosomes, immunomodulators, and growth factors, but they are still in preclinical stage. The future challenges include finding ways to define BPD based on the severity of lung pathology, which can better predict long-term outcomes, development of early predictors of lung disease, and finding innovative and evidence-based preventive and management strategies.

Temperature and Humidity Associated With Artificial Ventilation in the Premature Infant: An Integrative Review of the Literature

BACKGROUND

Approximately half of the 55,000 very low birth-weight infants (<1500 g) born in the United States each year develop bronchopulmonary dysplasia (BPD). Many etiologies have been associated with the development of BPD, including aberrant temperature/humidity levels of artificial ventilation.

PURPOSE

The purpose of this literature review is to explore what is known regarding inspired air temperature/humidity levels from artificial ventilation in very premature infants, focusing on what levels these infants actually receive, and what factors impact these levels.

METHODS/SEARCH STRATEGY

PubMed, CINAHL, Scopus, and Web of Science were searched. Of the 830 articles retrieved, 23 were synthesized for study purpose, sample/study design, and temperature/humidity findings.

FINDINGS/RESULTS

Heating and humidification practices studied in neonatal ventilation did not maintain recommended levels. In addition, human neonatal studies and noninvasive neonatal ventilation research were limited. Furthermore, ventilation settings, environmental temperatures, and mouth position (in noninvasive ventilation) were found to impact temperature/humidity levels.

IMPLICATIONS FOR PRACTICE

Environmental temperatures and ventilatory settings merit consideration during artificial ventilation. In addition, aberrant temperature/humidity levels may impact infant body temperature stability; thus, employing measures to ensure adequate thermoregulation while receiving artificial ventilation must be a priority.

IMPLICATIONS FOR RESEARCH

This review underscores the need for further research into current warming and humidification techniques for invasive and noninvasive neonatal ventilation. A focus on human studies and the impact of aberrant levels on infant body temperature are needed. Future research may provide management options for achieving and maintaining target temperature/humidity parameters, thus preventing the aberrant levels associated with BPD.

The Potentials and Caveats of Mesenchymal Stromal Cell-Based Therapies in the Preterm Infant

Preponderance of proinflammatory signals is a characteristic feature of all acute and resulting long-term morbidities of the preterm infant. The proinflammatory actions are best characterized for bronchopulmonary dysplasia (BPD) which is the chronic lung disease of the preterm infant with lifelong restrictions of pulmonary function and severe consequences for psychomotor development and quality of life. Besides BPD, the immature brain, eye, and gut are also exposed to inflammatory injuries provoked by infection, mechanical ventilation, and oxygen toxicity. Despite the tremendous progress in the understanding of disease pathologies, therapeutic interventions with proven efficiency remain restricted to a few drug therapies with restricted therapeutic benefit, partially considerable side effects, and missing option of applicability to the inflamed brain. The therapeutic potential of mesenchymal stromal cells (MSCs)—also known as mesenchymal stem cells—has attracted much attention during the recent years due to their anti-inflammatory activities and their secretion of growth and development-promoting factors. Based on a molecular understanding, this review summarizes the positive actions of exogenous umbilical cord-derived MSCs on the immature lung and brain and the therapeutic potential of reprogramming resident MSCs. The pathomechanistic understanding of MSC actions from the animal model is complemented by the promising results from the first phase I clinical trials testing allogenic MSC transplantation from umbilical cord blood. Despite all the enthusiasm towards this new therapeutic option, the caveats and outstanding issues have to be critically evaluated before a broad introduction of MSC-based therapies.

Donor Human Milk Protects against Bronchopulmonary Dysplasia: A Systematic Review and Meta-Analysis

Bronchopulmonary dysplasia (BPD) is the most common complication after preterm birth. Pasteurized donor human milk (DHM) has increasingly become the standard of care for very preterm infants over the use of preterm formula (PF) if the mother's own milk (MOM) is unavailable. Studies have reported beneficial effects of DHM on BPD. We conducted a systematic review and meta-analysis of randomized controlled trials (RCTs) and observational studies on the effects of DHM on BPD and other respiratory outcomes. Eighteen studies met the inclusion criteria. Meta-analysis of RCTs could not demonstrate that supplementation of MOM with DHM reduced BPD when compared to PF (three studies, risk ratio (RR) 0.89, 95% confidence interval (CI) 0.60-1.32). However, meta-analysis of observational studies showed that DHM supplementation reduced BPD (8 studies, RR 0.78, 95% CI 0.67-0.90). An exclusive human milk diet reduced the risk of BPD, compared to a diet with PF and/or bovine milk-based fortifier (three studies, RR 0.80, 95% CI 0.68-0.95). Feeding raw MOM, compared to feeding pasteurized MOM, protected against BPD (two studies, RR 0.77, 95% CI 0.62-0.96). In conclusion, our data suggest that DHM protects against BPD in very preterm infants.

Bronchopulmonary Dysplasia: Comparison Between the Two Most Used Diagnostic Criteria

Objectives: To compare the Shennan's and the consensus definition of Bronchopulmonary Dysplasia (BPD) from the National Institutes of Health (NIH) workshop and analyze specific risk factors associated with each definition. Study design: Retrospective analysis of records of 274 infants admitted to a level IV intensive care unit. Infants were classified as having BPD or no BPD by both definitions. Differences in incidence and risk factors were analyzed. Statistical methods included descriptive statistics, comparative tests, and marginal logistic regression modeling. Results: The estimated difference in prevalence was 32% [95% CI: (26%, 37%), (p < 0.0001)] between both criteria. The prevalence of BPD was 80% higher based on the NIH criteria [RR = 1.80; 95% CI: (1.58, 2.06)]. Infants with no BPD by the Shennan definition were breathing room air with or without positive or continuous pressure support and were most likely to be discharged home on oxygen [OR = 4.47, 95% CI: (1.20, 16.61), p = 0.03]. Gestational age, birth weight, and 1-min Apgar score predicted BPD by both definitions. Chorioamnionitis increased the risk of BPD by the Shennan definition but was associated with lower risk by the NIH criteria. IUGR was associated with BPD by the Shennan definition and with severe BPD by the NIH criteria. Conclusion: Compared to the Shennan's definition, the NIH consensus identified 80% more infants with BPD and is a better predictor of oxygen requirement at discharge. Until a new better criteria is develop, the NIH consensus definition should be used across centers.

Mesenchymal stem cells for the prevention and treatment of bronchopulmonary dysplasia in preterm infants

BACKGROUND

Bronchopulmonary dysplasia (BPD) remains a major complication of prematurity and currently lacks efficient treatments. Mesenchymal stem/stromal cells (MSCs) have been extensively explored as a potential therapy in several preclinical and clinical settings. Human and animal MSCs have been shown to prevent and treat lung injury in various preclinical models of lung diseases, including experimental BPD.

OBJECTIVES

To determine if MSCs, administered intravenously or endotracheally, are safe and effective in preventing or treating BPD, or both, in preterm infants.

SEARCH METHODS

We used the standard search strategy of the Cochrane Neonatal Review Group to search the Cochrane Central Register of Controlled Trials (CENTRAL 2016, Issue 10), MEDLINE via PubMed (1966 to 6 November 2016), Embase (1980 to 6 November 2016), and CINAHL (1982 to 6 November 2016). We also searched clinical trials databases, conference proceedings, and the reference lists of retrieved articles for randomized controlled trials (RCTs) and quasi-RCTs.

SELECTION CRITERIA

We considered RCTs and quasi-RCTs investigating prevention or treatment of BPD, or both, in preterm infants.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trial quality according to prespecified criteria.

MAIN RESULTS

We found no RCTs or quasi-RCTs addressing the use of MSCs for prevention or treatment of BPD in premature infants. Two RCTs are currently registered and ongoing.

AUTHORS' CONCLUSIONS

There is insufficient evidence to determine the safety and efficacy of MSCs in the treatment or prevention of BPD in premature infants. The results of the ongoing trials addressing this issue are expected in the near future.

Probiotic Supplementation in Preterm Infants Does Not Affect the Risk of Bronchopulmonary Dysplasia: A Meta-Analysis of Randomized Controlled Trials

Probiotic supplementation reduces the risk of necrotizing enterocolitis (NEC) and late-onset sepsis (LOS) in preterm infants, but it remains to be determined whether this reduction translates into a reduction of other complications. We conducted a systematic review and meta-analysis to evaluate the possible role of probiotics in altering the risk of bronchopulmonary dysplasia (BPD). Fifteen randomized controlled trials (4782 infants; probiotics: 2406) were included. None of the included studies assessed BPD as the primary outcome. Meta-analysis confirmed a significant reduction of NEC (risk ratio (RR) 0.52, 95% confidence interval (CI) 0.33 to 0.81, p = 0.004; random effects model), and an almost significant reduction of LOS (RR 0.82, 95% CI 0.65 to 1.03, p = 0.084). In contrast, meta-analysis could not demonstrate a significant effect of probiotics on BPD, defined either as oxygen dependency at 28 days of life (RR 1.01, 95% CI 0.91 to 1.11, p = 0.900, 6 studies) or at 36 weeks of postmenstrual age (RR 1.07, 95% CI 0.96 to 1.20, p = 0.203, 12 studies). Meta-regression did not show any significant association between the RR for NEC or LOS and the RR for BPD. In conclusion, our results suggest that NEC and LOS prevention by probiotics does not affect the risk of developing BPD in preterm infants.

Lung development, regeneration and plasticity: From disease physiopathology to drug design using induced pluripotent stem cells

Lungs have a complex structure composed of different cell types that form approximately 17 million airway branches of gas-delivering bronchioles connected to 500 million gas-exchanging alveoli. Airways and alveoli are lined by epithelial cells that display a low rate of turnover at steady-state, but can regenerate the epithelium in response to injuries. Here, we review the key points of lung development, homeostasis and epithelial cell plasticity in response to injury and disease, because this knowledge is required to develop new lung disease treatments. Of note, canonical signaling pathways that are essential for proper lung development during embryogenesis are also involved in the pathophysiology of most chronic airway diseases. Moreover, the perfect control of these interconnected pathways is needed for the successful differentiation of induced pluripotent stem cells (iPSC) into lung cells. Indeed, differentiation of iPSC into airway epithelium and alveoli is based on the use of biomimetics of normal embryonic and fetal lung development. In vitro iPSC-based models of lung diseases can help us to better understand the impaired lung repair capacity and to identify new therapeutic targets and new approaches, such as lung cell therapy.

Chorioamnionitis: Is a major player in the development of bronchopulmonary dysplasia?

Chorioamnionitis is an inflammation in the fetal membranes or placenta. When chorioamnionitis develops, fetal lungs are exposed to inflammatory cytokines and mediators via amniotic fluid. Because inflammation plays a pivotal role in the development of bronchopulmonary dysplasia (BPD), a chronic lung disease of prematurity, fetal lung inflammation induced by chorioamnionitis has been considered to be one of the major pathogenetic factors for BPD. Although there have been a number of studies that demonstrated the relationship between chorioamnionitis and BPD, there are still controversies on this issue. The controversies on the relationship between chorioamnionitis and BPD arise from not-unified definitions of chorioamnionitis and BPD, different study populations, and the proportion of contribution between inflammation and infectious microorganisms. The publication bias also contributes to the controversies. Clinical trials targeting chorioamnionitis or microorganisms that cause chorioamnionitis will answer on the actual relationship between chorioamnionitis and BPD and provide a novel prophylactic strategy against BPD based on that relationship.

The Randomized, Controlled Trial of Late Surfactant: Effects on Respiratory Outcomes at 1-Year Corrected Age

OBJECTIVE

To determine the effects of late surfactant on respiratory outcomes determined at 1-year corrected age in the Trial of Late Surfactant (TOLSURF), which randomized newborns of extremely low gestational age (≤28 weeks' gestational age) ventilated at 7-14 days to late surfactant and inhaled nitric oxide vs inhaled nitric oxide-alone (control).

STUDY DESIGN

Caregivers were surveyed in a double-blinded manner at 3, 6, 9, and 12 months' corrected age to collect information on respiratory resource use (infant medication use, home support, and hospitalization). Infants were classified for composite outcomes of pulmonary morbidity (no PM, determined in infants with no reported respiratory resource use) and persistent PM (determined in infants with any resource use in ≥3 surveys).

RESULTS

Infants (n = 450, late surfactant n = 217, control n = 233) were 25.3 ± 1.2 weeks' gestation and 713 ± 164 g at birth. In the late surfactant group, fewer infants received home respiratory support than in the control group (35.8% vs 52.9%, relative benefit [RB] 1.28 [95% CI 1.07-1.55]). There was no benefit of late surfactant for No PM vs PM (RB 1.27; 95% CI 0.89-1.81) or no persistent PM vs persistent PM (RB 1.01; 95% CI 0.87-1.17). After adjustment for imbalances in baseline characteristics, relative benefit of late surfactant treatment increased: RB 1.40 (95% CI 0.89-1.80) for no PM and RB 1.24 (95% CI 1.08-1.42) for no persistent PM.

CONCLUSION

Treatment of newborns of extremely low gestational age with late surfactant in combination with inhaled nitric oxide decreased use of home respiratory support and may decrease persistent pulmonary morbidity.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT01022580.

Scoping review shows wide variation in the definitions of bronchopulmonary dysplasia in preterm infants and calls for a consensus

The use of different definitions for bronchopulmonary dysplasia (BPD) has been an ongoing challenge. We searched papers published in English from 2010 and 2015 reporting BPD as an outcome, together with studies that compared BPD definitions between 1978 and 2015. We found that the incidence of BPD ranged from 6% to 57%, depending on the definition chosen, and that studies that investigated correlations with long-term pulmonary and/or neurosensory outcomes reported moderate-to-low predictive values regardless of the BPD criteria.

CONCLUSION

A comprehensive and evidence-based definition for BPD needs to be developed for benchmarking and prognostic use.

Correlates of Elevated Interleukin-6 and 8-Hydroxy-2'-Deoxyguanosine Levels in Tracheal Aspirates from Very Low Birth Weight Infants Who Develop Bronchopulmonary Dysplasia

BACKGROUND

Bronchopulmonary dysplasia (BPD) remains the most common complication of very low birth weight (VLBW) preterm infants, and inflammatory regulation plays a role in the development of the BPD. Interleukin-6 (IL-6) has an important role in airway inflammation and therefore can be used as a marker of airway injury. The study aimed to compare the changes between IL-6 and oxidative stress marker with 8-hydroxy-2'-deoxyguanosine (8-OHdG) from serum and tracheal aspiration (TA) in VLBW preterm infants following development of BPD.

METHODS

This birth cohort study enrolled 80 VLBW preterm infants, including 26 who developed BPD. All infants completed the study and survived at 36 weeks postmenstrual age. IL-6 and 8-OHdG concentrations from serum and TA on Day 1 and Day 28 after birth were measured using immunoassay.

RESULTS

IL-6 and 8-OHdG in serum and TA were higher in the BPD group than in the non-BPD group on the 1^st day after birth (p < 0.05). The IL-6 and 8-OHdG levels in TA fluid were persistently increased on the 28^th day of life in the BPD group (p < 0.05). The TA IL-6 was positively correlated with 8-OHdG levels on the 1^st day (r = 0.64, p < 0.05) and 28^th day of life (r = 0.76, p < 0.05). Based on receiver operating characteristic curves as a predictor of BPD development, TA IL-6 (cutoff, 456.8 pg/mg) had 81.5% sensitivity and 77.8% specificity, whereas TA 8-OHdG (cutoff, 4.4 ng/mg) had a sensitivity of 81.5% and a specificity of 64.4%.

CONCLUSION

Persistent inflammation with oxidative DNA damage in the respiratory tract may be a crucial mechanism in BPD.

Early administration of inhaled corticosteroids for preventing chronic lung disease in very low birth weight preterm neonates

BACKGROUND

Chronic lung disease (CLD) remains a common complication among preterm infants. There is increasing evidence that inflammation plays an important role in the pathogenesis of CLD. Due to their strong anti-inflammatory properties, corticosteroids are an attractive intervention strategy. However, there are growing concerns regarding short- and long-term effects of systemic corticosteroids. Theoretically, administration of inhaled corticosteroids may allow for beneficial effects on the pulmonary system with a lower risk of undesirable systemic side effects.

OBJECTIVES

To determine the impact of inhaled corticosteroids administered to preterm infants with birth weight up to 1500 grams (VLBW) beginning in the first two weeks after birth for the prevention of CLD as reflected by the requirement for supplemental oxygen at 36 weeks' postmenstrual age (PMA).

SEARCH METHODS

Randomised and quasi-randomised trials were identified by searching the Cochrane Central Register of Controlled Trials (CENTRAL; 2015, Issue 12) in the Cochrane Library (searched 5 January 2016), MEDLINE (1966 to 5 January 2016), Embase (1980 to 5 January 2016), CINAHL (1982 to 5 January 2016), reference lists of published trials and abstracts published in Pediatric Research or electronically on the Pediatric Academic Societies web-site (1990 to May 2016).

SELECTION CRITERIA

We included in this review randomised controlled trials of inhaled corticosteroid therapy initiated within the first two weeks of life in VLBW preterm infants.

DATA COLLECTION AND ANALYSIS

We evaluated data regarding clinical outcomes, including: CLD at 28 days or 36 weeks' PMA; mortality; combined outcome of death or CLD at 28 days of age and at 36 weeks' PMA; the need for systemic corticosteroids; failure to extubate within 14 days; and adverse effects of corticosteroids. All data were analysed using Review Manager (RevMan) 5. Meta-analyses were performed using relative risk (RR) and risk difference (RD), along with their 95% confidence intervals (CI). If RD was significant, the number needed to treat for an additional beneficial outcome (NNTB) was calculated. We used the GRADE approach to assess the quality of evidence.

MAIN RESULTS

According to GRADE the quality of the studies was moderate. Three additional trials are included in this update. The present review includes data analyses based on 10 qualifying trials that enrolled 1644 neonates. There was no significant difference in the incidence of CLD at 36 weeks' PMA in the inhaled steroid versus the placebo group (5 trials, 429 neonates) among all randomised (typical RR 0.97, 95% CI 0.62 to 1.52; typical RD -0.00, 95% CI -0.07 to 0.06). There was no heterogeneity for this outcome (typical RR I² = 11%; typical RD I² = 0%). There was a significant reduction in the incidence of CLD at 36 weeks' PMA among survivors (6 trials, 1088 neonates) (typical RR 0.76, 95% CI 0.63 to 0.93; typical RD -0.07, 95% CI -0.13 to -0.02; NNTB 14, 95% CI 8 to 50). There was a significant reduction in the combined outcome of death or CLD at 36 weeks' PMA among all randomised neonates (6 trials, 1285 neonates) (typical RR 0.86, 95% CI 0.75 to 0.99; typical RD -0.06, 95% CI -0.11 to -0.00) (P = 0.04); NNTB 17, 95% CI 9 to infinity). There was no significant heterogeneity for any of these analyses (I² = 0%). A lower rate of reintubation was noted in the inhaled steroid group compared with the control group in one study. There were no statistically significant differences in short-term complications between groups and no differences in adverse events at long-term follow-up reported. Long-term follow-up of infants enrolled in the study by Bassler 2015 is ongoing.

AUTHORS' CONCLUSIONS

Based on this updated review, there is increasing evidence from the trials reviewed that early administration of inhaled steroids to VLBW neonates is effective in reducing the incidence of death or CLD at 36 weeks' PMA among either all randomised infants or among survivors. Even though there is statistical significance, the clinical relevance is of question as the upper CI limit for the outcome of death or CLD at 36 weeks' PMA is infinity. The long-term follow-up results of the Bassler 2015 study may affect the conclusions of this review. Further studies are needed to identify the risk/benefit ratio of different delivery techniques and dosing schedules for the administration of these medications. Studies need to address both the short- and long-term benefits and adverse effects of inhaled steroids with particular attention to neurodevelopmental outcome.

Systematic review and meta-analysis of clinical outcomes of early caffeine therapy in preterm neonates

AIMS

This study evaluated the therapeutic outcomes of early versus late caffeine therapy in preterm neonates.

METHODS

We performed a systematic literature search in PubMed, Embase, CINAHL and CENTRAL from inception to 30 June 2016 to identify studies investigating the use of early caffeine therapy (initiated at less than 3 days of life) in preterm infants. Effect estimates were combined using random-effects meta-analysis. The primary outcomes for this study were bronchopulmonary dysplasia and mortality.

RESULTS

The initial search found 4066 citations, of which 14 studies enrolling a total of 64 438 participants were included. The time of initiation of early caffeine therapy varied from the first 2 h to 3 days postnatal. Early caffeine therapy reduced the risk of bronchopulmonary dysplasia in both cohort studies (RR: 0.80, 95% CI: 0.66 to 0.96) and randomized controlled trials (RR: 0.67, 95% CI: 0.56 to 0.81). In cohort studies, neonates treated early with caffeine also showed decreased risks of patent ductus arteriosus, brain injury, retinopathy of prematurity and postnatal steroid use. However, the mortality rate was increased.

CONCLUSIONS

The findings suggest that early caffeine therapy is associated with reduced incidence of bronchopulmonary dysplasia and may help decrease the burden of morbidities in preterm infants.