Effect of dexamethasone exposure on the neonatal unit on the school age lung function of children born very prematurely

Optimal respiratory support for extremely low birth weight infants - do we have the answers?

Survival rates for extremely low birth weight (ELBW) infants have improved over the recent years, yet morbidity remains high. This review explores respiratory management strategies for this unique cohort and how it may impact their long-term outcomes. Although there is a preference towards non-invasive respiratory support in less immature infants, ELBW infants often require invasive ventilation. This comes with an increased risk of bronchopulmonary dysplasia, adverse neurodevelopmental outcomes and lifelong respiratory impairment. There are a range of options available to reduce volutrauma and minimise lung injury, including volume targeted ventilation and high-frequency ventilation. In the absence of high-quality evidence focussing on ELBW infants, much of current practice is inferred from studies involving infants with a broader range of gestational ages and experiences at high-volume centres. This highlights the need for further research targeted to this specific population with a focus on long-term respiratory health.

Investigating the effects of dexamethasone on pulmonary surfactant lipids based on lipidomics studies

Dexamethasone, a glucocorticoid commonly used in pediatric patients, has potent anti-inflammatory and immunosuppressive properties. However, it is associated with side effects such as reduced lung function and decreased immunity. Pulmonary surfactant lipids are closely linked to lung disease and play a role in reducing surface tension, immune response and antiviral activity. The dysregulation of lipid metabolism is closely associated with lung disease. Hence, untargeted lipidomics may be instrumental in elucidating the effects of dexamethasone on pulmonary surfactant lipids. We obtained surfactant lipid samples from the bronchoalveolar lavage fluid of young mice injected subcutaneously with dexamethasone and conducted a comprehensive lipidomic analysis, comparing them with a control group. We observed a decrease in lipids, such as phosphatidylcholine, phosphatidylglycerol and phosphatidylethanolamine, and an increase in ceramide, fatty acid, diacylglycerol and monoglyceride, which may impact lung health. This study revealed the influence of dexamethasone on pulmonary surfactant lipids, offering new insights into adverse reactions in clinical settings.

Postnatal corticosteroid usage in United Kingdom and Ireland neonatal units

AIM

To perform a survey on postnatal corticosteroids usage in neonatal units in the United Kingdom and Ireland.

METHODS

An 18-item structured questionnaire was created asking for the level of neonatal care and corticosteroid prescribing practices. A consultant neonatologist or senor specialty training registrar/advanced neonatal nurse practitioner was contacted in every neonatal unit in the UK and Ireland between September and December 2022.

RESULTS

The response rate to the survey was 96% (203 of 211 units). Postnatal corticosteroids were prescribed in 48% of units: 5% of special care units, 43% of local neonatal units and 100% of neonatal intensive care units. Most units (90%) prescribed dexamethasone, which was prescribed to infants born at gestational ages less than 30 weeks in all those units prescribing postnatal corticosteroids, however, eight units also reported use in infants greater than 30 weeks of gestation. Dexamethasone regimens varied with starting doses from 50 to 500 μg/kg/day. Most tertiary units (97%) prescribed repeated courses of dexamethasone. In all levels of neonatal care, postnatal corticosteroids were prescribed to ventilated infants as well as those receiving non-invasive respiratory support.

CONCLUSION

There is use of postnatal corticosteroids in all levels of neonatal care and much of the practice is not evidence based.

Prenatal exposure to metal mixtures and lung function in children from the New Hampshire birth cohort study

Prenatal exposure to metals/metalloids, even at common US population levels, may pose risks to fetal health, and affect children's lung function. Yet, the combined effects of simultaneous prenatal exposures on children's lung function remain largely unexplored. This study analyzed 11 metals (As speciation, Cd, Co, Cu, Mo, Ni, Pb, Sb, Se, Sn, Zn) in maternal urine during weeks 24-28 of gestation and evaluated lung function, including forced vital capacity (FVC) and forced expiratory volume in the first second of expiration (FEV1), in 316 US mother-child pairs at around age 7. We used Bayesian Kernel Machine Regression (BKMR), weighted quantile sum regression (WQSR), and multiple linear regression to examine the association between metal mixture exposure and children's lung function, adjusting for maternal smoking, child age, sex, and height. In BKMR models assessing combined exposure effects, limited evidence of metal non-linearity or interactions was found. Nevertheless, Co, As species, and Pb showed a negative association, while Mo exhibited a positive association with children's FVC and FEV1, with other metals held constant at their medians. The weighted index, from WQSR analysis assessing the cumulative impact of all metals, highlighted prenatal Mo with the highest positive weight, and Co, As, and Sb with the most substantial negative weights on children's FVC and FEV1. Urinary Co and Pb were negatively associated with FVC (β = -0.09, 95% confidence interval (CI) (-0.18; -0.01) and β = -0.07, 95% CI (-0.13; 0.00), respectively). Co was also negatively associated with FEV1 (β = -0.09, 95% CI (-0.18; 0.00). There was a negative association between As and FVC, and a positive association between Mo and both FVC and FEV1, though with wide confidence intervals. Our findings suggest that prenatal trace element exposures may impact children's lung function, emphasizing the importance of reducing toxic exposures and maintaining adequate nutrient levels.

Systematic review of the long-term effects of postnatal corticosteroids

BACKGROUND

Dexamethasone administration can reduce bronchopulmonary dysplasia, our objective was to identify long term adverse effects.

CONTENT

A systematic review was performed to determine the childhood and adolescent cardiopulmonary and cognitive effects of dexamethasone systemically administered to preterm infants during neonatal intensive care. Relevant studies were identified by searching two electronic health databases and the grey literature. Spirometry assessments were used as respiratory outcomes, blood pressure and echocardiography assessments as cardiovascular outcomes and cognitive and motor function as cognitive outcomes. From 1,479 articles initially identified, 18 studies (overall 1,609 patients) were included (respiratory n=8, cardiovascular n=2, cognitive n=10); all were observational cohort studies. Dexamethasone exposure was associated with worse pulmonary outcomes in children and adolescents (more abnormal FVC and FEV1:FVC z scores). Dexamethasone exposure was associated in one study with lower IQ scores compared to preterm controls (mean 78.2 [SD 15.0] vs. 84.4 [12.6], [p=0.008]) and in two others was associated with lower total and performance IQ when compared to term controls (p<0.001).

SUMMARY AND OUTLOOK

Postnatal dexamethasone exposure has a negative influence on pulmonary and cognitive outcomes in childhood and adolescence. Medications with a better benefit to risk profile need to be identified.

Influence of sex on the requirement for and outcomes following late postnatal corticosteroid treatment

There remains a disparity between the outcomes of male and female prematurely born infants. Our aim was to assess the influence of sex on the requirement for late (> 7 days) postnatal corticosteroid (PNS) treatment and the outcomes following treatment. A retrospective whole population study of infants born at less than 28 weeks of gestation in all neonatal units in England between 2014 and 2018. The impact of exposure to at least five consecutive days of dexamethasone or hydrocortisone on bronchopulmonary dysplasia (BPD) at 36 weeks corrected gestation and survival to discharge from neonatal care was determined. Ten thousand, six hundred and fifty-five infants survived to seven days. Male sex was associated with an increased incidence of BPD (OR 1.41, 95%CI 1.287-1.552, p < 0.001) and death (OR 1.227, 95%CI 1.123-1.452, p < 0.001). Two thousand, three hundred and forty-four infants (22%) received at least one course of PNS at a median of 23 (IQR 15-40) days after birth. Males (23.6%) were more likely to receive PNS than females (20.1%), p < 0.001 and receive repeated courses (mean 1.67 compared to a mean of 1.59 in the females), p = 0.027. Multivariate regression analysis identified no significant differences in the incidence of BPD or death between male and females who received PNS.  Conclusions: Males and females had similar outcomes after receiving PNS, but a significantly greater proportion of males met the clinical threshold to receive PNS and were more likely to receive repeated courses which may expose them to a greater risk of adverse long-term outcomes. What is Known: • There remains a difference in outcomes of male and female infants born prematurely. • Prematurely born male infants were more likely to receive postnatal corticosteroids and a greater number of courses but had similar outcomes compared to female infants. What is New: • Postnatal corticosteroids have long-term adverse effects. Such outcomes should be considered when weighing up the risk-benefit ratio of prescribing postnatal corticosteroids, particularly in very prematurely born male infants.

The prevention and management strategies for neonatal chronic lung disease

INTRODUCTION

Survival from even very premature birth is improving, but long-term respiratory morbidity following neonatal chronic lung disease (bronchopulmonary dysplasia (BPD)) has not reduced. Affected infants may require supplementary oxygen at home, because they have more hospital admissions particularly due to viral infections and frequent, troublesome respiratory symptoms requiring treatment. Furthermore, adolescents and adults who had BPD have poorer lung function and exercise capacity.

AREAS COVERED

Antenatal and postnatal preventative strategies and management of infants with BPD. A literature review was undertaken using PubMed and Web of Science.

EXPERT OPINION

There are effective preventative strategies which include caffeine, postnatal corticosteroids, vitamin A, and volume guarantee ventilation. Side-effects, however, have appropriately caused clinicians to reduce use of systemically administered corticosteroids to infants only at risk of severe BPD. Promising preventative strategies which need further research are surfactant with budesonide, less invasive surfactant administration (LISA), neurally adjusted ventilatory assist (NAVA) and stem cells. The management of infants with established BPD is under-researched and should include identifying the optimum form of respiratory support on the neonatal unit and at home and which infants will most benefit in the long term from pulmonary vasodilators, diuretics, and bronchodilators.

Early origins of respiratory disease

Chronic respiratory morbidity is unfortunately common in childhood, particularly in those born very prematurely or with congenital anomalies affecting pulmonary development and those with sickle cell disease. Our research group, therefore, has focused on the early origins of chronic respiratory disease. This has included assessing antenatal diagnostic techniques and potentially therapeutic interventions in infants with congenital diaphragmatic hernia. Undertaking physiological studies, we have increased the understanding of the premature baby's response to resuscitation and evaluated interventions in the delivery suite. Mechanical ventilation modes have been optimised and randomised controlled trials (RCTs) with short- and long-term outcomes undertaken. Our studies highlighted respiratory syncytial virus lower respiratory tract infections (LRTIs) and other respiratory viral LRTIs had an adverse impact on respiratory outcomes of prematurely born infants, who we demonstrated have a functional and genetic predisposition to respiratory viral LRTIs. We have described the long-term respiratory outcomes for children with sickle cell disease and importantly identified influencing factors. In conclusion, it is essential to undertake long term follow up of infants at high risk of chronic respiratory morbidity if effective preventative strategies are to be developed.

Influence of bronchopulmonary dysplasia on lung function in adolescents who were born extremely prematurely

OBJECTIVES

To assess if a previous diagnosis of bronchopulmonary dysplasia (BPD) was associated with poorer lung function at 16 to 19 years of age, regardless of whether postnatal corticosteroids had been administered.

WORKING HYPOTHESIS

Infants with BPD will have poorer lung function at 16 to 19 years of age.

STUDY DESIGN

Prospective follow-up study.

PATIENT-SUBJECT SELECTION

One hundred and sixty-one participants aged between 16 and 19 years who were born at less than 29 weeks of gestation; 87 had had BPD.

METHODOLOGY

Lung function was assessed by spirometry (FEV₁ , FVC, FEV₁ /FVC, FEF₇₅ , FEF₅₀ , FEF₂₅ , FEF_{25 -75} , PEF), impulse oscillometry (R5Hz and R20Hz), plethysmography (FRC_pleth , TLC_pleth , RV_pleth ), diffusion capacity of the lungs for carbon monoxide (D_L CO, D_L CO/VA) and lung clearance index (LCI). Questionnaires were used to quantify respiratory symptoms and a shuttle sprint test to assess exercise capacity.

RESULTS

At 16 to 19 years, those who had had a diagnosis of BPD had poorer airway function (FEV₁ , FEF₇₅ , FEF₅₀ , FEF_{25 -75} ) compared to those without. FVC and D_L CO were also poorer in those who had BPD. Those differences remained significant after adjusting for sex, gestational age, and maternal smoking. When excluding those who had received postnatal corticosteroids, differences remained significant in FEV₁ , FVC, and FEF₇₅ . There were no significant differences in exercise capacity or respiratory symptoms between those with and without BPD.

CONCLUSIONS

In adolescents and young adults born prematurely, those who had BPD had poorer lung function compared to those without, regardless of whether they had received postnatal corticosteroids.

Longitudinal changes in lung function in very prematurely born young people receiving high-frequency oscillation or conventional ventilation from birth

OBJECTIVE

To examine changes in lung function over time in extremely prematurely born adolescents.

WORKING HYPOTHESIS

Changes in lung function during adolescence would vary by ventilation mode immediately after birth.

STUDY DESIGN

Longitudinal follow-up study.

PATIENT SUBJECT SELECTION

Participants from the United Kingdom Oscillation Study who were randomized at birth to high-frequency oscillation (HFO) or conventional ventilation (CV) were assessed at 11-14 years (n = 319) and at 16-19 years (n = 159).

METHODOLOGY

Forced expiratory flow (FEF), forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC), and lung volumes including functional residual capacity (FRC) were reported as z-scores. The diffusion capacity of the lungs for carbon monoxide (DLCO) was measured. Lung function trajectories were compared by mode of ventilation using mixed models. Changes in z-scores were scaled to 5-year average follow-up.

RESULTS

There were significant changes in the mean FEF75, FEF50, FEF25, FEV1, FVC, and DLCO z-scores within the CV and HFO cohorts, but no significant differences in the changes between the two groups. The mean FRC z-score increased in both groups, with an average change of greater than one z-score. The mean FEV1/FVC z-score increased significantly in the CV group, but not in the HFO group (difference in slopes: p = 0.02). Across the population, deterioration in lung function was associated with male sex, white ethnicity, lower gestational age at birth, postnatal corticosteroids, oxygen dependency at 36 weeks postmenstrual age, and lower birth weight, but not ventilation mode.

CONCLUSIONS

There was little evidence that the mode of ventilation affected changes in lung function over time.

Corticosteroids in the prevention and treatment of infants with bronchopulmonary dysplasia: Part I. systemic corticosteroids

Bronchopulmonary dysplasia (BPD) is the most significant respiratory complication of prematurity, and its consequences last from birth into adulthood. Unfortunately, the dramatic improvements in the management of premature infants have not led to a decreased incidence of BPD, or to breakthroughs in treatments offered for this long-lasting chronic respiratory disorder. Over recent decades the pathological picture of BPD has changed from inflammation, interstitial fibrosis and emphysema attributed to volu-, barotrauma and oxygen toxicity to larger, simplified alveoli and dysmorphic vessels related to arrested alveolarization and vasculogenesis with inflammation maintaining a central role. Corticosteroids (CSs) play a key role in the development of respiratory epithelial cells and lung maturation. These potent anti-inflammatory agents have long been used for the prevention and treatment of BPD; however, the risk/benefit ratio of their use remains unresolved. CSs administered antenatally have contributed to reduce mortality and respiratory distress syndrome, no such effect on BPD reduction has been observed. Postnatal systemic CSs reduced the rate and severity of BPD, yet their long-term neurodevelopmental and respiratory consequences markedly limit routine administration. This is the first in a two-part State-of-the-Art series that reviews the latest relevant clinical trials investigating the short-term and long-term effects of CSs in the prevention and treatment of BPD.

Prenatal exposure to arsenic and lung function in children from the New Hampshire Birth Cohort Study

Prenatal arsenic exposure is associated with an increased risk of lung cancer along with multiple non-carcinogenic outcomes, including respiratory diseases in arsenic-contaminated areas. Limited epidemiologic data exist on whether in utero arsenic exposure influences lung development and subsequent respiratory health. We investigated the association between gestational arsenic exposure and childhood lung function in the New Hampshire Birth Cohort Study. Urinary arsenic speciation including inorganic arsenic (iAs), monomethylarsonic acid (MMA), dimethylarsinic acid (DMA) and arsenobetaine was measured in maternal urine samples collected during pregnancy and spirometry was performed in offspring at a median age of 7.4 years. Forced vital capacity (FVC), forced expiratory volume in the first second of exhalation (FEV1), and forced expiratory flow between 25% and 75% of FVC (FEF25-75) standardized z-scores were assessed in linear models as dependent variables with the log2-transformed summation of urinary arsenic species (ΣAs = iAs + MMA + DMA) corrected for specific gravity as an independent variable and with adjustment for maternal smoking status, children's age, sex and height. Among the 358 children in the study, a doubling of ΣAs was associated with a -0.08 (ß) decrease in FVC z-scores (95% confidence interval (CI) from -0.14 to -0.01) and -0.10 (ß) (95% CI from -0.18 to -0.02) decrease in FEV1 z-scores. The inverse association appeared stronger among those mothers with lower secondary methylation index (urinary DMA/MMA), especially among girls. No association was observed for FEF25-75 z-scores. Our results suggest that gestation arsenic exposure at levels relevant to the general US population during the vulnerable period of lung formation may adversely affect lung function in childhood.

Intrauterine growth retardation and lung function of very prematurely born young people

OBJECTIVES

To assess if intrauterine growth retardation (IUGR) was associated with reduced lung function at 16-19 years.

WORKING HYPOTHESIS

Very prematurely born young people who had IUGR would have reduced lung function postpuberty.

STUDY DESIGN

Prospective follow-up study.

PATIENT-SUBJECT SELECTION

One hundred and fifty-nine 16-19 year olds born before 29 weeks of gestation; 37 had IUGR.

METHODOLOGY

Lung function tests were performed: spirometry was used to assess forced expiratory volume in one second (FEV1), forced expiratory flow at 75%, 50% and 25% of expired vital capacity (FEF75, FEF50 and FEF25), peak expiratory flow (PEF) and forced vital capacity (FVC). Functional residual capacity (FRCpleth) total lung capacity (TLCpleth) and residual volume (RVpleth) were measured. Alveolar function was assessed by diffusion capacity within the lungs of carbon monoxide (DLCO). Impulse oscillometry was used to assess respiratory resistance and lung clearance index to assess ventilation homogeneity. Exercise capacity was assessed using a shuttle sprint test.

RESULTS

After adjustment for BMI, the mean FEV-1/FVC, FEF75, FEF25-75, FRCpleth and RVpleth were poorer in those who had had IUGR, with differences between 0.56 and 0.75 z-scores. After further adjustment for BPD and postnatal corticosteroid use, only the difference in RVpleth z-scores remained statistically significant, adjusted difference (95% CI): 0.66 (0.18,1.13). Exercise capacity was lower in those with IUGR and this was more pronounced in males (p=0.04).

CONCLUSIONS

At 16-19 years of age, those who had IUGR had poorer lung function and exercise capacity compared with those with adequate intrauterine growth.

Postnatal dexamethasone exposure and lung function in adolescents born very prematurely

We previously demonstrated corticosteroid administration on the neonatal intensive care unit was associated with reduced lung function at 11 to 14 years of age in children born very prematurely. The objective of this observational study was to assess if lung function remained impaired at 16 to 19 years of age in those who had received postnatal corticosteroids and whether the trajectory of lung function with increasing age differed between those who had and had not received corticosteroids. One hundred and fifty-nine children born prior to 29 weeks of gestational age had comprehensive lung function measurements; 49 had received postnatal dexamethasone. Lung function outcomes were compared between those who had and had not received postnatal dexamethasone after adjustment for neonatal factors. Forced expiratory flow at 75%, 50%, 25% and 25-75% of the expired vital capacity, forced expiratory volume in one second, peak expiratory flow and forced vital capacity and lung volumes (total lung capacity and residual volume) were assessed. The majority of results were significantly lower in those who received dexamethasone (between 0.61 to 0.78 standard deviations). Lung function reduced as the number of courses of dexamethasone increased. Between 11 and 14 years and 16 to 19 years, lung function improved in the unexposed group, but forced expiratory flow at 75% of the expired vital capacity and forced expiratory volume in one second deteriorated in those who had received postnatal corticosteroids (p = 0.0006). These results suggest that prematurely born young people who received postnatal corticosteroids may be at risk of premature onset of chronic obstructive pulmonary disease.

A prenatally disrupted airway epithelium orchestrates the fetal origin of asthma in mice

BACKGROUND

Prenatal challenges such as maternal stress perception increase the risk and severity of asthma during childhood. However, insights into the trajectories and targets underlying the pathogenesis of prenatally triggered asthma are largely unknown. The developing lung and immune system may constitute such targets.

OBJECTIVE

Here we have aimed to identify the differential sex-specific effects of prenatal challenges on lung function, immune response, and asthma severity in mice.

METHODS

We generated bone marrow chimeric (BMC) mice harboring either prenatally stress-exposed lungs or a prenatally stress-exposed immune (hematopoietic) system and induced allergic asthma via ovalbumin. Next-generation sequencing (RNA sequencing) of lungs and assessment of airway epithelial barrier function in ovalbumin-sensitized control and prenatally stressed offspring was also performed.

RESULTS

Profoundly enhanced airway hyperresponsiveness, inflammation, and fibrosis were exclusively present in female BMC mice with prenatally stress-exposed lungs. These effects were significantly perpetuated if both the lungs and the immune system had been exposed to prenatal stress. A prenatally stress-exposed immune system alone did not suffice to increase the severity of these asthma features. RNA sequencing analysis of lungs from prenatally stressed, non-BMC, ovalbumin-sensitized females unveiled a deregulated expression of genes involved in asthma pathogenesis, tissue remodeling, and tight junction formation. It was also possible to independently confirm a tight junction disruption. In line with this, we identified an altered perinatal and/or postnatal expression of genes involved in lung development along with an impaired alveolarization in female prenatally stressed mice.

CONCLUSION

Here we have shown that the fetal origin of asthma is orchestrated by a disrupted airway epithelium and further perpetuated by a predisposed immune system.

Lung function and respiratory outcomes in teenage boys and girls born very prematurely

OBJECTIVES

Male sex in prematurely born infants has been associated with worse respiratory outcomes in early childhood.

WORKING HYPOTHESIS

Respiratory outcomes at 11 to 14 years of age in children born very prematurely and routinely exposed to antenatal corticosteroids and postnatal surfactant would differ according to sex.

STUDY DESIGN

Analysis of follow-up data.

PATIENT-SUBJECT SELECTION

Three hundred and nineteen children born before 29 weeks of gestational age from the United Kingdom Oscillation Study.

METHODOLOGY

Spirometry was used to assess forced expiratory flow at 75%, 50%, and 25% of expired vital capacity (FEF₇₅ , FEF₅₀ , and FEF₂₅ ), forced expiratory volume in 1 second (FEV₁ ), peak expiratory flow (PEF), and forced vital capacity (FVC). Lung volumes were measured using a helium dilution technique (FRC_He ) and by plethysmography (FRC_pleth ). Total lung capacity (TLC) and residual volume (RV) were calculated. Mean lung function measurements were compared using linear mixed models and reported as unadjusted and adjusted for neonatal and age 11 to 14 years factors. The participants also completed health questionnaires and provided a urine sample for assessment of passive or active smoking.

RESULTS

Three (FEF₂₅ , FEF_25-75 , FEV₁ ) lung function measures showed significant differences in favor of females after adjustment. The percentage of children with abnormal lung function (below 5th centile for normal) had adjusted differences between 10 and 30 percentage points, for example, for FEF₂₅ 15% females compared with 26% males.

CONCLUSIONS

Among extremely prematurely born school children airway function was significantly worse in males.

Advances in treating bronchopulmonary dysplasia

Introduction: Bronchopulmonary dysplasia (BPD) is a common long-term adverse complication of very premature delivery. Affected infants can suffer chronic respiratory morbidities including lung function abnormalities and reduced exercise capacity even as young adults. Many studies have investigated possible preventative strategies; however, it is equally important to identify optimum management strategies for infants with evolving or established BPD. Areas covered: Respiratory support modalities and established and novel pharmacological treatments. Expert opinion: Respiratory support modalities including proportional assist ventilation and neurally adjusted ventilatory assist are associated with short term improvements in oxygenation indices. Such modalities need to be investigated in appropriate RCTs. Many pharmacological treatments are routinely used with a limited evidence base, for example diuretics. Stem cell therapies in small case series are associated with promising results. More research is required before it is possible to determine if such therapies should be investigated in large RCTs with long-term outcomes.