ATS/ERS Statement: Raised Volume Forced Expirations in Infants: Guidelines for Current Practice

Role of body mass index in unbalanced (dysanaptic) lung growth of healthy infants

RATIONALE

Imbalance between forced expiratory volume in the first second (FEV1) and forced vital capacity (FVC) (dysanapsis) has been reported in children who are obese. This dysanaptic growth might begin at an early age, although there are no data on children younger than 6 years.

OBJETIVES

To assess whether body mass index (BMI) and early weight gain, in healthy infants born at term, plays a significant role in the imbalance between FEV1 and FVC, even in the absence of obesity.

METHODS

Lung function was measured by means of raised volume rapid thoracic compression in 69 healthy infants born at term from the Nutrition in Early Life and Asthma cohort. Dysanapsis was defined as zFVC >0.674, zFEV0 .5 ≥-1.645, and FEV0 .5/FVC ≤-1.645. Weight gain (g/day) and growth rate (cm/year) were calculated as the difference between weight and length on the test date and those at birth. To assess the relationship between zBMI and dysanapsis, a receiver operating characteristic curve was performed. Multivariable analysis was carried out by means of linear regressions (one for each lung function index) and by logistic regression for dysanapsis (yes/no).

RESULTS

Higher zBMI was associated with risk of dysanapsis (odds ratio: 3.53, [95% confidence interval: 1.30; 9.66]; p = .014): Each additional zBMI unit was associated with ~10 mL higher FVC and with ~3.5% lower FEV0.5/FVC. Weight gain was associated with lower FEV0.5/FVC ratio.

CONCLUSION

Dysanaptic development of lung function begins very early in infancy and is related with weight gain and body mass index, even in the absence of obesity.

Defining and Promoting Pediatric Pulmonary Health: Developing Biomarkers for Pulmonary Health

Children with inherited and/or acquired respiratory disorders often arrive in adolescence and adulthood with diminished lung function that might have been detected and prevented had better mechanisms been available to identify and to assess progression of disease. Fortunately, advances in genetic assessments, low-cost diagnostics, and minimally- invasive novel biomarkers are being developed to detect and to treat respiratory diseases before they give rise to loss of life or lung function. This paper summarizes the Developing Biomarkers for Pulmonary Health sessions of the National Heart, Lung, and Blood Institute- sponsored 2021 Defining and Promoting Pediatric Pulmonary Health workshop. These sessions discussed genetic testing, pulse oximetry, exhaled nitric oxide, and novel biomarkers related to childhood lung diseases.

Prematurity-associated wheeze: current knowledge and opportunities for further investigation

Prematurity-associated wheeze is a common complication of preterm birth, with significant impact on the health and healthcare utilization of former preterm infants. This wheezing phenotype remains poorly understood and difficult to predict. This review will discuss the current state of the literature on prematurity-associated wheeze. We will discuss etiology and pathophysiology, and offer two conceptual models for the pathogenesis of this complex condition. This review will also identify current methods of ascertainment, and discuss the strengths and limitations of each. We will explore research-backed approaches to prevention and management, and finally suggest both pre-clinical and clinical avenues for investigation. An in-depth understanding of prematurity-associated wheeze will aid clinicians in its diagnosis and management, and inspire scientists to pursue much-needed further study into causes and prevention of this common and impactful condition. IMPACT: There is no recent, concise review on the current state of research on prematurity-associated wheeze, which is a rapidly evolving area of study. This article highlights causal models of wheeze, methods of ascertainment, management strategies for the clinician, and opportunities for further research for the physician scientist.

Forced expiratory flows and diffusion capacity in infants born from mothers with pre-eclampsia

RATIONALE

Animal models suggest pre-eclampsia (Pre-E) affects alveolar development, but data from humans are lacking.

OBJECTIVE

Assess the impact of Pre-E on airway function, diffusion capacity, and respiratory morbidity in preterm and term infants born from mothers with Pre-E.

METHODS

Infants born from mothers with and without Pre-E were recruited for this study; term and preterm infants were included in both cohorts. Respiratory morbidity in the first 12 months of life was assessed through monthly phone surveys. Raised volume rapid thoracoabdominal compression and measurement of diffusion capacity of the lung to carbon monoxide (DLCO) were performed at 6 months corrected age.

MEASUREMENTS AND MAIN RESULTS

There were 146 infants in the Pre-E cohort and 143 in the control cohort. The Pre-E cohort was further divided into nonsevere (N = 41) and severe (N = 105) groups. There was no significant difference in DLCO and DLCO/alveolar volume among the three groups. Forced vital capacity was similar among the three groups, but the nonsevere Pre-E group had significantly higher forced expiratory flows than the other two groups. After adjusting for multiple covariates including prematurity, the severe Pre-E group had a lower risk for wheezing in the first year of life compared to the other two groups.

CONCLUSIONS

Pre-E is not associated with reduced DLCO, lower forced expiratory flows, or increased wheezing in the first year of life. These results differ from animal models and highlight the complex relationships between Pre-E and lung function and respiratory morbidity in human infants.

Bronchodilator responsiveness and dysanapsis in bronchopulmonary dysplasia

Background

The incidence of bronchopulmonary dysplasia (BPD) following preterm birth is increasing. Bronchodilators are often used to treat patients with BPD with little evidence to guide therapy. The aim of this study was to test the hypothesis that there are infant pulmonary function test (iPFT) parameters that can predict subsequent bronchodilator response in infants with BPD.

Methods

Subjects in this study were part of a patient group in which we reported three BPD phenotypes (obstructive, restrictive and mixed) based on iPFT data. From that group, a cohort of 93 patients with iPFT data including bronchodilator response was eligible for this study.

Results

Bronchodilator responsiveness was found in 59 people (63%) in the cohort. There were no differences in demographics between the responders and non-responders. There was no difference in forced vital capacity (FVC) between the two groups. Responders had significantly lower forced expiratory volume in 0.5 s (FEV0.5) and FEV0.5/FVC (p<0.005) and greater indices of hyperinflation than did non-responders (p<0.005). Logistic regression modelling found that pre-bronchodilator FEV0.5 and functional residual capacity/total lung capacity were significantly associated with bronchodilator response. The magnitude of response to bronchodilators was negatively correlated (R= −0.49, R2= 0.24, p<0.001) with the FEV0.5. The median dysanapsis ratio in responders (0.08, 95% CI 0.05–0.19) was significantly (p=0.005) smaller than in non-responders (0.18, 95% CI 0.06–0.38).

Conclusion

These findings demonstrate that there are pulmonary function test parameters associated with bronchodilator response. Responders had evidence of greater dysanaptic lung growth than non-responders.

Air pollution exposure impairs lung function in infants

Aim

To assess associations between air pollution exposure and infant lung function.

Methods

Healthy infants from Stockholm were recruited to two cohorts (n = 99 and n = 78). Infant spirometry included plethysmography and raised volume forced expiratory flows. In pooled analyses, lung function at ~6 months of age was related to time‐weighted average air pollution levels at residential addresses from birth until the lung function test. The pollutants included particulate matter with an aerodynamic diameter < 10 μm (PM₁₀) or <2.5 μm and nitrogen dioxide.

Results

There were significant inverse relations between air pollution exposure during infancy and forced expiratory volume at 0.5 s (FEV_0.5) as well as forced vital capacity (FVC) for all pollutants. For example, the decline was 10.1 ml (95% confidence interval 1.3–18.8) and 10.3 ml (0.5–20.1) in FEV_0.5 and FVC, respectively, for an interquartile increment of 5.3 μg/m³ in PM₁₀. Corresponding associations for minute ventilation and functional residual capacity were 43.3 ml/min (−9.75–96.3) and 0.84 ml (−4.14–5.82).

Conclusions

Air pollution exposure was associated with impaired infant lung function measures related to airway calibre and lung volume, suggesting that comparatively low levels of air pollution negatively affect lung function in early life.

Relationship between lung function and exhaled volatile organic compounds in healthy infants

OBJECTIVE

The aim of this study is to assess, for the first time, the relationship between the volatilome and lung function in healthy infants, which may be of help for the early detection of certain respiratory diseases. Lung function tests are crucial in chronic respiratory diseases diagnosis. Moreover, volatile organic compounds (VOCs) analysis in exhaled breath is a noninvasive technique that enables the monitorization of oxidative stress, typical of some forms of airway inflammation.

METHODS

Lung function was studied in 50 healthy infants of 3-8 months of age and the following parameters were obtained: forced vital capacity (FVC), forced expiratory volume at 0.5 s (FEV_0.5 ), forced expiratory flow at 75% of FVC (FEF₇₅ ), forced expiratory flow at 25%-75% of FVC (FEF_25-75 ), and FEV_0.5 /FVC. Lung function was measured according to the raised volume rapid thoracoabdominal compression technique. In addition, a targeted analysis of six endogenous VOCs (acetone, isoprene, decane, undecane, tetradecane, and pentadecane) in the exhaled breath of the children was carried out by means of thermal desorption coupled gas chromatography-single quadrupole mass spectrometry system.

RESULTS

A negatively significant relationship has been observed between levels of acetone, tetradecane, and pentadecane in exhaled breath and several of the lung function parameters. Levels of acetone (feature m/z = 58) were significantly negatively associated with FVC and FVE_0.5 , levels of tetradecane (feature m/z = 71) with FEV_0.5, and levels of pentadecane (feature m/z = 71) with FEV_0.5 and FEF_25-75 .

CONCLUSION

The findings of this study highlight a significant association between VOCs related to oxidative stress and lung function in healthy infants.

Development of Lung Function in Preterm Infants During the First Two Years of Life

INTRODUCTION

It remains unclear if prematurity itself can influence post delivery lung development and particularly, the bronchial size.

AIM

To assess lung function during the first two years of life in healthy preterm infants and compare the measurements to those obtained in healthy term infants during the same time period.

METHODS

This observational longitudinal study assessed lung function in 74 preterm (30+0 to 35+6 weeks' gestational age) and 76 healthy term control infants who were recruited between 2011 and 2013. Measurements of tidal breathing, passive respiratory mechanics, tidal and raised volume forced expirations (V'maxFRC and FEF_25-75, respectively) were undertaken following administration of oral chloral hydrate sedation according to ATS/ERS recommendations at 6- and 18-months corrected age.

RESULTS

Lung function measurements were obtained from the preterm infants and full term controls initially at 6 months of age. Preterm infants had lower absolute and adjusted values (for gestational age, postnatal age, sex, body size, and confounding factors) for respiratory compliance and V'maxFRC. At 18 months corrected postnatal age, similar measurements were repeated in 57 preterm infants and 61 term controls. A catch-up in tidal volume, respiratory mechanics parameters, FEV_0.5 and forced expiratory flows was seen in preterm infants.

CONCLUSION

When compared with term controls, the lower forced expiratory flows observed in the healthy preterm group at 6 months was no longer evident at 18 months corrected age, suggesting a catch-up growth of airway function.

Respiratory Follow Up of the Premature Neonates-Rationale and Practical Issues

The aim of the review was to present the state of knowledge about the respiratory pathology in former premature neonates (children that were born preterm-before 37 weeks of gestation-and are examined and evaluated after 40 weeks corrected age) other than chronic lung disease, in order to provide reasons for a respiratory follow-up program for this category of patients. After a search of the current evidence, we found that premature infants are prone to long-term respiratory consequences due to several reasons: development of the lung outside of the uterus, leading to dysmaturation of the structures, pulmonary pathology due to immaturity, infectious agents or mechanical ventilation and deficient control of breathing. The medium- to long-term respiratory consequences of being born before term are represented by an increased risk of respiratory infections (especially viral) during the first years of life, a risk of recurrent wheezing and asthma and a decrease in pulmonary volumes and airway flows. Late preterm infants have risks of pulmonary long-term consequences similar to other former premature infants. Due to all the above risks, premature neonates should be followed in an organized fashion, being examined at regular time intervals from discharge from the maternity hospital until adulthood-this could lead to an early detection of the risks and preventive therapies in order to improve their prognosis and assure a normal and productive life. The difficulties related to establishing such programs are represented by the insufficient standardization of the data gathering forms, clinical examinations and lung function tests, but it is our belief that if more premature infants are followed, the experience will allow standards to be established in these fields and the methods of data gathering and evaluation to be unified.

The Nutrition in Early Life and Asthma (NELA) birth cohort study: Rationale, design, and methods

BACKGROUND

Primary prevention strategies for asthma are lacking. Its inception probably starts in utero and/or during the early postnatal period as the developmental origins of health and disease (DOHaD) paradigm suggests.

OBJECTIVES

The main objective of Nutrition in Early Life and Asthma (NELA) cohort study is to unravel whether the following factors contribute causally to the developmental origins of asthma: (1) maternal obesity/adiposity and foetal growth; (2) maternal and child nutrition; (3) outdoor air pollution; (4) endocrine disruptors; and (5) maternal psychological stress. Maternal and offspring biological samples are used to assess changes in offspring microbiome, immune system, epigenome and volatilome as potential mechanisms influencing disease susceptibility.

POPULATION

Randomly selected pregnant women from three health areas of Murcia, a south-eastern Mediterranean region of Spain, who fulfilled the inclusion criteria were invited to participate at the time of the follow-up visit for routine foetal anatomy scan at 19-22 weeks of gestation, at the Maternal-Fetal Medicine Unit of the "Virgen de la Arrixaca" University Clinical Hospital over a 36-month period, from March 2015 to April 2018.

DESIGN

Prospective, population-based, maternal-child, birth cohort study.

METHODS

Questionnaires on exposures and outcome variables were administered to mothers at 20-24 gestation week; 32-36 gestation week; and delivery. Children were surveyed at birth, 3 and 18 months of age and currently at 5 years. Furthermore, physical examinations were performed; and different measurements and biological samples were obtained at these time points.

PRELIMINARY RESULTS

Among the 1350 women invited to participate, 738 (54%) were finally enrolled in the study and 720 of their children were eligible at birth. The adherence was high with 612 children (83%) attending the 3 months' visit and 532 children (72%) attending the 18 months' visit.

CONCLUSION

The NELA cohort will add original and unique knowledge to the developmental origins of asthma.

Bronchopulmonary dysplasia-A historical perspective

Bronchopulmonary dysplasia (BPD) was first described by Northway et al in 1967. This article describes the evolution of our understanding of the pathophysiology of BPD and the approaches to treatments of this illness developed over the past fifty years. These interventions had their roots in the understanding of the principles of the surface tension present at air-liquid interfaces, which were developed over 150 years before BPD's initial description. Improving outcomes in neonatal care have led to greater survival of preterm and very preterm infants, and to an evolution of the pathogenesis and pathology of BPD, from an illness caused primarily by barotrauma and oxygen toxicity to one of interruption of lung development. While the incidence of BPD has remained about the same in recent decades, this is because survival of infants born at lower gestational ages is increasing. Understanding of molecular, genetic and physiologic mechanisms has led to newer treatments that have mitigated some of the harmful effects of prolonged mechanical ventilation. Recognition of BPD as a chronic multi-system disease has resulted in further improvements in care after discharge from neonatal intensive care. Since many of the origins of chronic obstructive lung disease in adults are based in childhood respiratory illnesses, improving outcomes of BPD in infancy and childhood will undoubtedly lead to improved respiratory outcomes in the adults that these children will become.

Hyperinflation is associated with increased respiratory rate and is a more sensitive measure of cystic fibrosis lung disease during infancy compared to forced expiratory measures

BACKGROUND

The goal of this study was to identify clinical features associated with abnormal infant pulmonary function tests (iPFTs), specifically functional residual capacity (FRC), in infants with cystic fibrosis (CF) diagnosed via newborn screen (NBS). We hypothesized that poor nutritional status in the first 6-12 months would be associated with increased FRC at 12-24 months.

METHODS

This study utilized a combination of retrospectively and prospectively collected data from ongoing research studies and iPFTs performed for clinical indications. Demographic and clinical features were obtained from the electronic medical record. Forced expiratory flows and volumes were obtained using the raised volume rapid thoracoabdominal technique (RVRTC) and FRC was measured via plethysmography.

RESULTS

A total of 45 CF NBS infants had iPFTs performed between 12 and 24 months. Mean forced vital capacity, forced expiratory volume in 0.5 s, and forced expiratory flows were all within normal limits. In contrast, the mean FRC z-score was 2.18 (95% confidence interval [CI] = 1.48, 2.88) and the mean respiratory rate (RR) z-score was 1.42 (95% CI = 0.95, 1.89). There was no significant association between poor nutritional status and abnormal lung function. However, there was a significant association between higher RR and increased FRC, and a RR cutoff of 36 breaths/min resulted in 92% sensitivity to detect hyperinflation with 32% specificity.

CONCLUSION

These results suggest that FRC is a more sensitive measure of early CF lung disease than RVRTC measurements and that RR may be a simple, noninvasive clinical marker to identify CF NBS infants with hyperinflation.

Distinct lung function and bronchodilator responses between term and preterm young children with recurrent wheezing

BACKGROUND

Recurrent or unresolved wheezing is a common complaint in certain young children populations, especially those born preterm. Using infant lung function testing, we aimed to distinguish the differences between term and preterm young children with recurrent wheezing.

METHODS

Children under 2 years of corrected age were enrolled if they had 3 or more wheezing episodes during the enrollment period. Healthy term controls of comparable age were also recruited for reference. Measurements of lung function were made, including tidal breathing, passive respiratory mechanics, and forced tidal and raised-volume expiration. For children with recurrent wheezing, raised-volume forced expiration was repeated after an adequate delivery of bronchodilator nebulization was achieved.

RESULTS

In total, 68 young children (40 with recurrent wheezing and 28 healthy controls) were recruited. Among children with recurrent wheezing, 23 preterm children (preterm group), and 17 term children (term group) were enrolled. Compared with healthy controls, both the term and preterm groups had lower lung function as measured by absolute values and z scores. The term group performed worse than the preterm group with regard to forced vital capacity, forced expiratory volume at 0.5 s (FEV_0.5), and peak expiratory flow. Following bronchodilator nebulization, the term group had significantly higher increases in FEV_0.5 and forced mid-expiratory flow than the preterm group.

CONCLUSION

Young children with recurrent wheezing, especially term infants, demonstrated lower lung function than healthy controls. Moreover, the term group evidenced greater responsiveness to bronchodilators than the preterm group. The distinct bronchodilator responses may offer further information to guide the diagnosis and treatment of young children with recurrent wheezing.

The Use of Infant Pulmonary Function Tests in the Diagnosis of Neuroendocrine Cell Hyperplasia of Infancy

BACKGROUND

Infant pulmonary function tests (iPFTs) in subjects with neuroendocrine cell hyperplasia of infancy (NEHI) have demonstrated significant expiratory airflow obstruction and air trapping.

RESEARCH QUESTION

Can indexes from iPFTs be used in the diagnosis of NEHI?

STUDY DESIGN AND METHODS

This is an observational case-control study evaluating iPFT results from a registry of patients assessed at the Hadassah Hebrew University Medical Center between 2008 and 2018. We used the Kruskal-Wallis H test to compare iPFT results in infants with NEHI with those in two infants in a disease control group (infants evaluated for recurrent wheezing and infants evaluated owing to prematurity) and those in a spirometry control group of infants with normal expiratory airflow. Receiver operating characteristic (ROC) curves were used to assess the diagnostic accuracy of the iPFT indexes.

RESULTS

We evaluated iPFT data in 481 infants (15, NEHI; 292, wheezing; 128, premature; and 46, control group). Infants with NEHI had significantly increased trapped air volumes (median functional residual capacity measured with baby-body plethysmograph [FRC_pleth] was 199% predicted; median ratio of residual volume to total lung capacity was 59% predicted) when compared with results in all evaluated groups of infants (P < .001), including multiple pairwise comparisons. Airflow limitation was demonstrated in infants with NEHI when compared with the infants in the spirometry control group but was similar to that in the two infants in the disease control group. FRC_pleth had the best discriminatory ability for NEHI diagnosis, with an FRC_pleth ≥ 150% predicted demonstrating a ROC of 0.91 (95% CI, 0.82-1.00), sensitivity of 86.7% (95% CI, 59.5%-98.3%), and specificity of 95.5% (95% CI, 93.2%-97.3%).

INTERPRETATION

Findings on iPFTs of markedly increased air trapping, out of proportion to the degree of airflow limitation, are characteristic of infants with NEHI. iPFT results demonstrating an FRC_pleth ≥ 150% predicted are highly specific for NEHI and may aid in early diagnosis. Further research is required to confirm these findings in a prospective cohort and to understand the pathophysiologic explanation for these findings.

Time to get serious about the detection and monitoring of early lung disease in cystic fibrosis

Structural and functional defects within the lungs of children with cystic fibrosis (CF) are detectable soon after birth and progress throughout preschool years often without overt clinical signs or symptoms. By school age, most children have structural changes such as bronchiectasis or gas trapping/hypoperfusion and lung function abnormalities that persist into later life. Despite improved survival, gains in forced expiratory volume in one second (FEV₁) achieved across successive birth cohorts during childhood have plateaued, and rates of FEV₁ decline in adolescence and adulthood have not slowed. This suggests that interventions aimed at preventing lung disease should be targeted to mild disease and commence in early life. Spirometry-based classifications of 'normal' (FEV₁≥90% predicted) and 'mild lung disease' (FEV₁ 70%-89% predicted) are inappropriate, given the failure of spirometry to detect significant structural or functional abnormalities shown by more sensitive imaging and lung function techniques. The state and readiness of two imaging (CT and MRI) and two functional (multiple breath washout and oscillometry) tools for the detection and monitoring of early lung disease in children and adults with CF are discussed in this article.Prospective research programmes and technological advances in these techniques mean that well-designed interventional trials in early lung disease, particularly in young children and infants, are possible. Age appropriate, randomised controlled trials are critical to determine the safety, efficacy and best use of new therapies in young children. Regulatory bodies continue to approve medications in young children based on safety data alone and extrapolation of efficacy results from older age groups. Harnessing the complementary information from structural and functional tools, with measures of inflammation and infection, will significantly advance our understanding of early CF lung disease pathophysiology and responses to therapy. Defining clinical utility for these novel techniques will require effective collaboration across multiple disciplines to address important remaining research questions. Future impact on existing management burden for patients with CF and their family must be considered, assessed and minimised.To address the possible role of these techniques in early lung disease, a meeting of international leaders and experts in the field was convened in August 2019 at the Australiasian Cystic Fibrosis Conference. The meeting entitiled 'Shaping imaging and functional testing for early disease detection of lung disease in Cystic Fibrosis', was attended by representatives across the range of disciplines involved in modern CF care. This document summarises the proceedings, key priorities and important research questions highlighted.

Lung function testing and inflammation markers for wheezing preschool children: A systematic review for the EAACI Clinical Practice Recommendations on Diagnostics of Preschool Wheeze

BACKGROUND

Preschool wheeze is highly prevalent; 30%-50% of children have wheezed at least once before age six. Wheezing is not a disorder; it is a symptom of obstruction in the airways, and it is essential to identify the correct diagnosis behind this symptom. An increasing number of studies provide evidence for novel diagnostic tools for monitoring and predicting asthma in the pediatric population. Several techniques are available to measure airway obstruction and airway inflammation, including spirometry, impulse oscillometry, whole-body plethysmography, bronchial hyperresponsiveness test, multiple breath washout test, measurements of exhaled NO, and analyses of various other biomarkers.

METHODS

We systematically reviewed all the existing techniques available for measuring lung function and airway inflammation in preschool children to assess their potential and clinical value in the routine diagnostics and monitoring of airway obstruction.

RESULTS

If applicable, measuring FEV1 using spirometry is considered useful. For those unable to perform spirometry, whole-body plethysmography and IOS may be useful. Bronchial reversibility to beta2-agonist and hyperresponsiveness test with running exercise challenge may improve the sensitivity of these tests.

CONCLUSIONS

The difficulty of measuring lung function and the lack of large randomized controlled trials makes it difficult to establish guidelines for monitoring asthma in preschool children.

The remaining barriers to normalcy in CF: Advances in assessment of CF lung disease

Despite early diagnosis of cystic fibrosis (CF) through newborn screening, a substantial proportion of infants and young children with CF still demonstrate physiologic and structural evidence of lung disease progression, such as obstructive airway disease and bronchiectasis. The growing availability of highly effective CF transmembrane conductance regulatory modulator therapy to the vast majority of people with CF has led to the potential to alter the natural history of CF lung disease, but to assess the full impact of these therapies on CF lung disease and to help guide treatment, sensitive measures of early and mild disease are needed. Chest imaging using computed tomography or magnetic resonance imaging is one approach, but technologic barriers and/or concern about exposure to ionizing radiation may limit its use. However, advances in physiologic measurement techniques and exhaled breath analysis offer another option for assessment of CF lung disease.

Early disease surveillance in young children with cystic fibrosis: A qualitative analysis of parent experiences

BACKGROUND

Sensitive measures of early lung disease are being integrated into therapeutic trials and clinical practice in cystic fibrosis (CF). The impact of early disease surveillance (EDS) using these novel and often intensive techniques on young children and their families is not well researched.

METHODS

The Australian Respiratory Early Surveillance Team for Cystic Fibrosis (AREST CF) has operated a combined clinical and research early disease surveillance program, based around annual chest CT scan, bronchoscopy and lung function from newborn screening diagnosis until age 6 years, for over two-decades. To explore parental experiences of EDS in their child, a qualitative study was conducted using audio-recorded, semi-structured interviews in n=46 mothers and n=21 fathers of children (aged 3-months to six years) attending CF centres in Perth and Melbourne, Australia. Themes were developed iteratively using thematic analysis and assessed for validity and confirmability.

RESULTS

Parents' experiences were positive overall; affording a sense of control over CF, disease knowledge, and belief that EDS was in the best interests of their child. Challenges included poor understanding about EDS measures leading to anxiety and distress, self-blame surrounding adverse findings, and emotional burden of surveillance visits. Tailored information regarding the practical and psychosocial aspects of EDS were endorsed.

CONCLUSION

While experiences were generally positive there is need for information and psychosocial support for parents to mitigate anxiety and develop positive coping strategies surrounding surveillance procedures and results. Managing expectations regarding risks and benefits of disease surveillance in clinical and research settings are important aspects of care.

Preschool Asthma Symptoms in Children Born Preterm: The Relevance of Lung Function in Infancy

Background: The aim of the study is to assess whether lung function of infants born preterm predicts wheezing in pre-school age. Methods: A survey of the core wheezing questionnaire of the International Study on Asthma and Allergy in Children was administered to parents of preterm newborns, to whom lung function tests were performed at a corrected age of six months, and who, at the time of the survey, were between three and nine years of age. Results: Low values of all lung function parameters measured, except FVC, were predictors of wheezing at some time in life, (FEV0.5 OR: 0.62 (95%CI 0.39; 0.995); FEV0.5/FVC OR: 0.73 (0.54; 0.99)) FEF75 OR: 0.60 [0.37; 0.93]; FEF25-75 OR: 0.57 (0.37; 0.89)); and of wheezing in the past year (FEV0.5 OR: 0.36 (0.17; 0.76); FEV0.5/FVC OR: 0.59 (0.38; 0.93); FEF75 OR: 0.38 [0.19; 0.76]; FEF25-75 OR: 0.35 (0.17; 0.70). In addition, FEV0.5/FVC values lower than the lowest limit of normality, were predictive of hospital admissions due to wheezing (OR: 3.07; (1.02; 9.25)). Conclusions: Limited lung function in infancy is predictive of both future wheezing and hospitalization for a wheezing episode.

Care recommendations for the respiratory complications of esophageal atresia-tracheoesophageal fistula

Tracheoesophageal fistula (TEF) with esophageal atresia (EA) is a common congenital anomaly that is associated with significant respiratory morbidity throughout life. The objective of this document is to provide a framework for the diagnosis and management of the respiratory complications that are associated with the condition. As there are no randomized controlled studies on the subject, a group of experts used a modification of the Rand Appropriateness Method to describe the various aspects of the condition in terms of their relative importance, and to rate the available diagnostic methods and therapeutic interventions on the basis of their appropriateness and necessity. Specific recommendations were formulated and reported as Level A, B, and C based on whether they were based on "strong", "moderate" or "weak" agreement. The tracheomalacia that exists in the site of the fistula was considered the main abnormality that predisposes to all other respiratory complications due to airway collapse and impaired clearance of secretions. Aspiration due to impaired airway protection reflexes is the main underlying contributing mechanism. Flexible bronchoscopy is the main diagnostic modality, aided by imaging modalities, especially CT scans of the chest. Noninvasive positive airway pressure support, surgical techniques such as tracheopexy and rarely tracheostomy are required for the management of severe tracheomalacia. Regular long-term follow-up by a multidisciplinary team was considered imperative. Specific templates outlining the elements of the clinical respiratory evaluation according to the patients' age were also developed.

Infant spirometry as a predictor of lung function at early childhood in cystic fibrosis patients

BACKGROUND

Infant pulmonary function testing using the raised volume rapid thoracoabdominal compression (RVRTC) technique requires sedation and is time consuming. Many cystic fibrosis (CF) centers do not have access to equipment and the utility of routine testing remains to be determined. We aimed to assess whether RVRTC tests performed during infancy predict spirometry at early school age.

METHODS

The RVRTC-based forced expiratory flow measures in infants were compared to the first adequately performed spirometry at school age. All tests were carried out during routine clinic visits and expressed as age related z-scores; only test occasions where patients were considered stable were included in the analysis.

RESULTS

47 patients had useable infant RVRTC as well as matching school age spirometry data. There was weak correlation between infant FEV_0.5 and early school age FEV₁ (R = 0.29, p = 0.05). Four infants had significantly low zFEV_0.5 (zFEV_0.5 < -1.96), of which one of those remained under that limit at childhood. Changes in spirometry between infancy and early childhood were negatively correlated to baseline FEV_0.5 (R = 0.61 p<0.001) reflecting that the change was driven by where individuals started off with. There was no difference in clinical characteristics between those improving, those with stable or deteriorating in lung function.

CONCLUSION

Infant RVRTC measures were not predictive of pulmonary function in early school age, likely due to the high proportion of measures of forced expiratory flows within the normal range at both time points.

Early Neonatal Oxygen Exposure Predicts Pulmonary Morbidity and Functional Deficits at 1 Year

OBJECTIVE

To evaluate the predictive value of cumulative oxygen exposure thresholds over the first 2 postnatal weeks, linking them to bronchopulmonary dysplasia (BPD) and 1-year pulmonary morbidity and lung function in extremely low gestational age newborns.

STUDY DESIGN

Infants (N = 704) enrolled in the Prematurity and Respiratory Outcomes Program, a multicenter prospective cohort study, that survived to discharge were followed through their neonatal intensive care unit hospitalization to 1-year corrected age. Cumulative oxygen exposure (Oxygen_AUC14) thresholds were derived from univariate models of BPD, stratifying infants into high-, intermediate-, and low-oxygen exposure groups. These groups were then used in multivariate logistic regressions to prospectively predict post-prematurity respiratory disease (PRD), respiratory morbidity score (RMS) in the entire cohort, and pulmonary function z scores (N = 108 subset of infants) at 1-year corrected age.

RESULTS

Over the first 14 postnatal days, infants exposed to high oxygen averaged ≥33.1% oxygen, infants exposed to intermediate oxygen averaged 29.1%-33.1%, and infants exposed to low oxygen were below both cutoffs. In multivariate models, infants exposed to high oxygen showed increased PRD and RMS, whereas infants exposed to intermediate oxygen demonstrated increased moderate/severe RMS. Infants in the high/intermediate groups had decreased forced expiratory volume at 0.5 seconds/forced vital capacity ratio.

CONCLUSIONS

Oxygen_AUC14 establishes 3 thresholds of oxygen exposure that risk stratify infants early in their neonatal course, thereby predicting short-term (BPD) and 1-year (PRD, RMS) respiratory morbidity. Infants with greater Oxygen_AUC14 have altered pulmonary function tests at 1 year of age, indicating early evidence of obstructive lung disease and flow limitation, which may predispose extremely low gestational age newborns to increased long-term pulmonary morbidity.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT01435187.

Vitamin C to Pregnant Smokers Persistently Improves Infant Airway Function to 12 Months of Age: A Randomised Trial

BACKGROUND

Vitamin C (500 mg·day-1) supplementation for pregnant smokers has been reported to increase newborn pulmonary function and infant forced expiratory flows (FEFs) at 3 months of age. Its effect on airway function through 12 months of age has not been reported.

OBJECTIVE

To assess whether vitamin C supplementation to pregnant smokers is associated with a sustained increased airway function in their infants through 12 months of age.

METHODS

This is a prespecified secondary outcome of a randomised, double-blind, placebo-controlled trial that randomised 251 pregnant smokers between 13 and 23 weeks of gestation: 125 to 500 mg·day-1 vitamin C and 126 to placebo. Smoking cessation counselling was provided. FEFs performed at 3 and 12 months of age were analysed by repeated measures analysis of covariance.

RESULTS

FEFs were performed in 222 infants at 3 months and 202 infants at 12 months of age. The infants allocated to vitamin C had significantly increased FEFs over the first year of life compared to those allocated to placebo. The overall increased flows were: 40.2 mL·sec-1 for FEF75 (adjusted 95% CI for difference 6.6 to 73.8; p=0.025); 58.3 mL·sec-1 for FEF50 (95% CI 10.9 to 105.8; p=0.0081); and 55.1 mL·sec-1 for FEF25-75 (95% CI, 9.7 to 100.5; p=0.013).

CONCLUSIONS

In offspring of pregnant smokers randomised to vitamin C versus placebo, vitamin C during pregnancy was associated with a small but significantly increased airway function at 3 and 12 months of age, suggesting a potential shift to a higher airway function trajectory curve. Continued follow-up is underway.

Therapy at 30 days of life predicts lung function at 6 to 12 months in infants with congenital diaphragmatic hernia

INTRODUCTION

Congenital diaphragmatic hernia (CDH) is associated with variable degrees of lung hypoplasia. Pulmonary support at 30 days postnatal age was found to be the strongest predictor of inpatient mortality and morbidity among CDH infants and was also associated with higher pulmonary morbidity at 1 and 5 years. It is not known, however, if there is a relationship between the need for medical therapy at 30 days of life and subsequent abnormalities in lung function as reflected in infant pulmonary function test (iPFT) measurements.

OBJECTIVE

We hypothesized that CDH infants who require more intensive therapy at 30 days would have more abnormal iPFT values at the time of their first infant pulmonary function study, reflecting the more severe spectrum of lung hypoplasia.

METHODS

A single-institution chart review of all CDH survivors who were enrolled in a Pulmonary Hypoplasia Program (PHP) through July 2019, and treated from 2002 to 2019 was performed. All infants were divided into groups based on their need for noninvasive (supplemental oxygen, high flow therapy, noninvasive mechanical ventilation) or invasive (mechanical ventilation, extracorporeal membrane oxygenation) respiratory assistance, bronchodilators, diuretic use, and pulmonary hypertension (PH) therapy (inhaled and/or systemic drugs) at 30 days. Descriptive and statistical analyses were performed between groups comparing subsequent lung function measurements.

RESULTS

A total of 382 infants (median gestational age [GA] 38.4 [interquartile range (IQR) = 37.1-39] weeks, 41.8% female, 70.9% Caucasian) with CDH were enrolled in the PHP through July 2019, and 118 infants underwent iPFT. The median age of the first iPFT was 6.6 (IQR = 5.3-11.7) months. Those requiring any pulmonary support at 30 days had a higher functional residual capacity (FRC) (z) (P = .03), residual volume (RV) (z) (P = .008), ratio of RV to total lung capacity (RV/TLC) (z) (P = .0001), and ratio of FRC to TLC (FRC/TLC) (z) (P = .001); a lower forced expiratory volume at 0.5 seconds (FEV0.5) (z) (P = .03) and a lower respiratory system compliance (Crs) (P = .01) than those who did not require any support. Similarly, those requiring diuretics and/or PH therapy at 30 days had higher fractional lung volumes, lower forced expiratory flows and Crs than infants who did not require such support (P < .05).

CONCLUSIONS

Infants requiring any pulmonary support, diuretics and/or PH therapy at 30 postnatal days have lower forced expiratory flows and higher fractional lung volumes, suggesting a greater degree of lung hypoplasia. Our study suggests that the continued need for PH, diuretic or pulmonary support therapy at 30 days can be used as additional risk-stratification measurements for evaluation of infants with CDH.

Risk factors affecting postoperative pulmonary function in congenital diaphragmatic hernia

Purpose

It is well known that congenital diaphragmatic hernia (CDH) in infants impacts pulmonary function rehabilitation after surgery. However, the risk factors of postoperative pulmonary function are still unclear. In this research, we analyzed the potential risk factors of postoperative pulmonary function in CDH patients in order to improve the clinical management of CDH patients.

Methods

Thirty-three cases CDH infants followed were enrolled from November 2016 to September 2018. Clinical data were reviewed. Tidal breathing pulmonary function testing was performed after surgery. Correlation between pulmonary function and clinical characteristics was evaluated using multivariate analysis of variance.

Results

Pulmonary dysfunction was detected in 87.9% patients (29 of 33). The defect size was found to be significantly larger in patients with obstructed and mixed ventilatory disorders (P = 0.001). Diagnosis of gestational age (GA) was also significantly earlier compared to restrictive ventilatory disorders (P = 0.001). Larger defect size, and earlier prenatal diagnosis of GA were detected in severe obstructive ventilatory disorders (P = 0.007, P = 0.001, retrospectively).

Conclusion

Most patients had various degrees of pulmonary dysfunction after surgery. Patients with larger defect size and earlier diagnosis time might be vulnerable to severe obstructive and mixed ventilatory disorders.

Standardization of Spirometry 2019 Update. An Official American Thoracic Society and European Respiratory Society Technical Statement

Background: Spirometry is the most common pulmonary function test. It is widely used in the assessment of lung function to provide objective information used in the diagnosis of lung diseases and monitoring lung health. In 2005, the American Thoracic Society and the European Respiratory Society jointly adopted technical standards for conducting spirometry. Improvements in instrumentation and computational capabilities, together with new research studies and enhanced quality assurance approaches, have led to the need to update the 2005 technical standards for spirometry to take full advantage of current technical capabilities.Methods: This spirometry technical standards document was developed by an international joint task force, appointed by the American Thoracic Society and the European Respiratory Society, with expertise in conducting and analyzing pulmonary function tests, laboratory quality assurance, and developing international standards. A comprehensive review of published evidence was performed. A patient survey was developed to capture patients' experiences.Results: Revisions to the 2005 technical standards for spirometry were made, including the addition of factors that were not previously considered. Evidence to support the revisions was cited when applicable. The experience and expertise of task force members were used to develop recommended best practices.Conclusions: Standards and consensus recommendations are presented for manufacturers, clinicians, operators, and researchers with the aims of increasing the accuracy, precision, and quality of spirometric measurements and improving the patient experience. A comprehensive guide to aid in the implementation of these standards was developed as an online supplement.

Effect of acute respiratory infections in infancy on pulmonary function test at 3 years of age: a prospective birth cohort study

INTRODUCTION

Acute respiratory infections (ARIs) in infancy may have a long-term impact on the developing respiratory system. We planned a prospective cohort study to determine the impact of ARI during infancy on the pulmonary function test indices at 3 years of age.

METHODS

A cohort of normal, full-term newborns were followed up 6 monthly and during ARI episodes. Infant pulmonary function tests (IPFTs) were performed at baseline and each follow-up visit using tidal breathing flow-volume loop, rapid thoracoabdominal compression (RTC) and raised volume RTC manoeuvres. During each ARI episode, nasopharyngeal aspirates were tested for respiratory pathogens by real-time PCR.

RESULTS

We screened 3421 neonates; 310 were enrolled; IPFT was performed in 225 (boys: 125 (55.6%)) at 3 years. During infancy, 470 ARI episodes were documented in 173 infants. At 3 years, children with history of any ARI episode during infancy had lower forced expiratory volume in 1 s (FEV_1.0), forced expiratory volume in 0.75 s (FEV_0.75), forced expiratory volume in 0.5 s (FEV_0.5), forced expiratory flow between 25% and 75% of FVC (FEF_25-75), and maximal expiratory flow at 25% of FVC (MEF₂₅) as compared with those without any ARI episode during infancy. The ratio of tidal expiratory flow (TEF) at 25% or 50% of tidal expiratory volume to peak TEF (TEF₅₀ or TEF₂₅/peak TEF) at 3 years was significantly increased in children who had ARI in infancy.

CONCLUSIONS

ARI during infancy is associated with impaired pulmonary function indices such as increased resistance and decreased forced expiratory flow and volume at 3 years of age.

Association between thoracic musculoskeletal abnormalities and lung function in preterm infants

INTRODUCTION

In view of the difficulties and risks of performing lung function tests in infants and the hypothesis that children with abnormal pulmonary test may exhibit thoracic musculoskeletal alterations.

OBJECTIVES

This study aimed to determine the frequency of abnormal lung function and their relationship.

MATERIALS AND METHODS

This was a cross-sectional study with children from 6 to 12 months of corrected age, born at a gestational age of <37 weeks and with a birthweight ≤1500 g, who were subjected to a lung function test and photogrammetry--an objective and non-invasive procedure. To verify the association between the thoracic musculoskeletal abnormalities and measure changes in lung function, univariate linear regression was used. The level of statistical significance was setted at P < 0.05.

RESULTS

Of the 38 infants, 12 (31.6%) exhibited abnormal lung function, including 9 (23.7%) with obstructive function and 3 (7.9%) with restrictive function. A significant association was noted between forced expiratory volume at 0.5 second <-2 z score and the acromion/xiphoid process/acromion angle (β = 4.935); forced vital capacity <-2 z score and the angle of the manubrium/left acromion/trapezium (β = 0.033) and forced expiratory volume at 0.5 second and forced vital capacity ratio <-2 z score and the inframammillary point/xiphoid process/inframammillary point angle (β = 0.043).

CONCLUSION

Preterm infants with very low birthweight presented a high frequency of abnormal lung function, particularly obstructive type and thoracic musculoskeletal abnormalities were associated with changes in lung function.

Evolution and Determinants of Lung Function until Late Infancy among Infants Born Preterm

To investigate the evolution of lung function in preterm infants with and without bronchopulmonary dysplasia (BPD) and to determine the perinatal characteristics associated with indexes of lung function in later infancy. Longitudinal lung function assessments were performed at approximately 6, 12, 18, and 24 months of corrected age in preterm infants. Perinatal characteristics were further analyzed to ascertain the determinants of lung function indexes. Although all preterm infants (n = 121; 61 without BPD and 60 with BPD) exhibited decreased lung function in early infancy (6 months of age), after body length was adjusted for, only infants with BPD exhibited poor performance. Furthermore, the lung function of infants with mild to moderate BPD caught up gradually, but the generally poor lung function performance of infants with severe BPD, especially in forced expiratory flow, persisted until later age (24 months). Regarding perinatal characteristics, the z-score of body length at the time of examination and total number of days on positive-pressure ventilation are the major determinants of lung function in later infancy.

Exhaled Nitric Oxide in Wheezy Infants Predicts Persistent Atopic Asthma and Exacerbations at School Age

BACKGROUND

There are limited data assessing the predictive value of fraction of exhaled nitric oxide (FENO) in infants/toddlers with recurrent wheezing for asthma at school age.

OBJECTIVES

In a cohort of infants/toddlers with recurrent wheezing determine the predictive values of sedated single-breath FENO (SB-FENO) and awake tidal-breathing mixed-expired FENO (tidal-FENO) for active asthma, severe exacerbations, and lung function at age 6 years.

METHODS

In 44 infants/toddlers, SB-FENO was measured under sedation at 50 mL/sec in conjunction with forced expiratory flow and volume measurements, and tidal-FENO was measured during awake tidal breathing. Clinical outcomes and lung function were assessed at age 6 years in 36 subjects.

RESULTS

Enrollment SB-FENO was significantly higher among subjects with active asthma at age 6 years than among subjects without asthma (36.4 vs. 16.9 ppb, p < 0.0001), and the odds of asthma was 7.6 times greater (OR 7.6; 95% CI 1.8-31.6) for every 10 ppb increase in enrollment SB-FENO. A ROC analysis demonstrated that an enrollment SB-FENO > 31.5 ppb predicted active asthma at age 6 years with an area under the curve (AUC) of 0.92 (95% CI: 0.82-1). SB-FENO was also higher among subjects who experienced severe asthma exacerbations during the year preceding age of 6 years. SB-FENO at enrollment and lung function measures at age 6 years were modestly correlated (FEV1: r = -0.4; FEF25-75: r = -0.41; FEV1/FVC ratio: r=-0.46), and SB-FENO was significantly higher among subjects with bronchodilator responsiveness (BDR) at age 6 years. Tidal-FENO was not predictive of active asthma, exacerbations, or lung function at age 6 years.

CONCLUSION

In wheezy infants/toddlers, SB-FENO was predictive of school-age asthma and associated with lung function measures at age 6 years.

Impact of early caffeine therapy in preterm newborns on infant lung function

OBJECTIVE

To know the effect of caffeine therapy on infant lung function in preterm infants with a gestational age less than 31 weeks.

MATERIAL AND METHODS

Forced vital capacity (FVC), forced expiratory volume at 0.5 seconds (FEV_0.5 ), and forced expiratory flows were measured by raised volume rapid thoracoabdominal compression technique; functional residual capacity was measured by plethysmography (FRC_pleth ). Compliance of the respiratory system was measured by a single interruption technique (Crs). The Student t test was used to compare lung function measurements between the two groups: treated versus nontreated with caffeine. A multivariate analysis was carried out considering each and every lung function parameter (z-score) as the dependent variable; and gender, gestational age, birth weight (z-score), corrected age, invasive mechanical ventilation (yes/no), and bronchopulmonary dysplasia (BPD) diagnosis (yes/no) as independent ones. Additionally, stratified analyses by BPD diagnosis were performed.

RESULTS

The multivariate analysis showed significant higher z-scores of FVC and FEV_0.5 in preterm infants treated with caffeine (P = .004 and P = .024, respectively). This result only being significant in the group of non-BPD infants (P = .021 and P = .042), after stratifying by BPD diagnosis. Differences were not found in z-scores of FEV0.5/FVC, FEF75, FEF25-75, FRCpleth, nor Crs.

CONCLUSION

Lung function (FVC and FEV_0.5 ) is improved in infants born under 31 weeks of gestation when treated with caffeine. This improvement is driven by the group of infants who did not suffer from BPD. Overall, our results show that there is an early beneficial effect of caffeine treatment in infant lung function.

Forced expiratory flows and volumes in a Swedish cohort of healthy term infants

BACKGROUND

The use of pulmonary function tests (PFTs) in infants has increased during the last decades, making the need for equipment- and ethnic-specific reference data mandatory for appropriate interpretation of the results.

AIM

Our aim was to investigate how well the already published reference equations for infant spirometry fit a healthy population of Swedish infants.

METHOD

We performed forced tidal and raised volume expiratory maneuvers in healthy infants using Jaeger BabyBody equipment.

RESULTS

PFT data were collected from 91 healthy infants aged between 3 months to 2 years at 143 occasions. Mean (standard deviation) z-scores were 0.68(1.33) for maximal flow at functional residual capacity (V'_max FRC), -0.15(0.96) for forced vital capacity (FVC), 0.40(1.33) for the forced expired volume in the initial 0.5 seconds (FEV_0.5 ) and 0.52(0.93) for the ratio FEV_0.5 /FVC, respectively. Z-scores for all indices but FEV_0.5 /FVC were highly dependent on length.

CONCLUSIONS

We have shown that the use of previously published reference equations may result in an age-related misinterpretation of lung function measure in a Swedish infant population.

Nebulized step-down budesonide vs. fluticasone in infantile asthma: A retrospective cohort study

The United States Food and Drug Administration has approved budesonide in infantile asthma but nebulization of infants under budesonide has the risk of relapse of asthma. The objective of the present study was to compare the effectiveness and safety of fluticasone step-down treatment with budesonide step-down treatment in infantile asthma. The data of 778 infants with confirmed asthma were included in the analysis. Infants who had received nebulized 500 µg budesonide twice daily for 6 weeks followed by 250 µg budesonide twice daily for 6 weeks were included in the BS group (n=389), while infants who had received nebulized 250 µg fluticasone twice daily for 6 weeks followed by 125 µg fluticasone twice daily for 6 weeks were included in the FC group (n=389). The data of lung function tests and a safety study were collected and analyzed. Budesonide treatment achieved a reduced specific airway resistance (sRaw; 1.28±0.11 vs. 1.21±0.10 kPa/sec; P<0.0001, q=13.45) and improved forced expiratory volume in 1 sec (FEV1; 0.977±0.068 vs. 0.997±0.085 l/sec; P<0.0001, q=5.54). In addition, fluticasone treatment achieved a reduced sRaw (1.27±0.1 vs. 1.23±0.11 kPa/sec, P<0.0001, q=7.39) and improved FEV1 (0.971±0.069 vs. 0.992±0.085 l/sec; P=0.0003, q=5.46). Of note, the efficacy of budesonide to reduce sRaw (P=0.008, q=3.69) and improve FEV1 (P<0.0001, q=6.93) was greater than that of fluticasone. The budesonide treatment group had more post-treatment symptom-free days than the fluticasone treatment group (165.56±23.15 vs. 112.21±9.45 days; P<0.0001). The step-down approach of budesonide nebulization may better support the functional and clinical outcomes with an increased number of post-treatment symptom-free days compared with fluticasone in infantile asthma (level of evidence, 3).

Oral Vitamin C (500 mg/d) to Pregnant Smokers Improves Infant Airway Function at 3 Months (VCSIP). A Randomized Trial

Rationale: We reported a randomized trial demonstrating daily supplemental vitamin C to pregnant smokers significantly improved newborn pulmonary function tests. The current study tests these results in a new cohort using infant pulmonary function tests. Objectives: To determine if infants of pregnant smokers randomized to daily supplemental vitamin C would have improved forced expiratory flows (FEFs) at 3 months of age compared with those randomized to placebo, and to investigate the association of the α5 nicotinic acetylcholine receptor. Methods: A randomized, double-blind, placebo-controlled trial was conducted at three centers. Two hundred fifty-one pregnant smokers were randomized at 13-23 weeks of gestation: 125 randomized to vitamin C (500 mg/d) and 126 to placebo. Measurements and Main Results: The primary outcome was FEF75 at 3 months of age performed with the raised volume rapid thoracic compression technique (Jaeger/Viasys). FEF50 and FEF25-75 obtained from the same expiratory curves were prespecified secondary outcomes. The infants of pregnant smokers randomized to vitamin C (n = 113) had the following FEFs at 3 months of age compared with those randomized to placebo (n =  109) as measured by FEF75 (200.7 vs. 188.7 ml/s; adjusted 95% confidence interval [CI] for difference, -3.33 to 35.64; P = 0.10), FEF50 (436.7 vs. 408.5 ml/s; adjusted 95% CI for difference, 6.10-61.30; P = 0.02), and FEF25-75 (387.4 vs. 365.8 ml/s; adjusted 95% CI for difference, 0.92-55.34; P = 0.04). Infant FEFs seemed to be negatively associated with the maternal risk alleles for the α5 nicotinic acetylcholine receptor (rs16969968). Conclusions: Although the primary outcome of FEF75 was not improved after vitamin C supplementation to pregnant smokers, the predetermined secondary outcomes FEF50 and FEF25-75 were significantly improved. These results extend our previous findings and demonstrate improved airway function (FEF50 and FEF25-75) at 3 months of age in infants after vitamin C supplementation to pregnant smokers. Clinical trial registered with www.clinicaltrials.gov (NCT01723696).

Lung Function in Infants with Sickle Cell Anemia

Lung volumes and forced expiratory flows were evaluated in 22 infants with sickle cell anemia and compared with a control group. Forced expiratory flows showed significantly lower values in the sickle cell group. The majority of infants had normal lung function, and obstruction was the most common pattern of abnormality.

Early respiratory viral infections in infants with cystic fibrosis

BACKGROUND

Viral infections contribute to morbidity in cystic fibrosis (CF), but the impact of respiratory viruses on the development of airway disease is poorly understood.

METHODS

Infants with CF identified by newborn screening were enrolled prior to 4 months of age to participate in a prospective observational study at 4 centers. Clinical data were collected at clinic visits and weekly phone calls. Multiplex PCR assays were performed on nasopharyngeal swabs to detect respiratory viruses during routine visits and when symptomatic. Participants underwent bronchoscopy with bronchoalveolar lavage (BAL) and a subset underwent pulmonary function testing. We present findings through 8.5 months of life.

RESULTS

Seventy infants were enrolled, mean age 3.1 ± 0.8 months. Rhinovirus was the most prevalent virus (66%), followed by parainfluenza (19%), and coronavirus (16%). Participants had a median of 1.5 viral positive swabs (range 0-10). Past viral infection was associated with elevated neutrophil concentrations and bacterial isolates in BAL fluid, including recovery of classic CF bacterial pathogens. When antibiotics were prescribed for respiratory-related indications, viruses were identified in 52% of those instances.

CONCLUSIONS

Early viral infections were associated with greater neutrophilic inflammation and bacterial pathogens. Early viral infections appear to contribute to initiation of lower airway inflammation in infants with CF. Antibiotics were commonly prescribed in the setting of a viral infection. Future investigations examining longitudinal relationships between viral infections, airway microbiome, and antibiotic use will allow us to elucidate the interplay between these factors in young children with CF.

Validation of the GOLD 2017 and new 16 subgroups (1A-4D) classifications in predicting exacerbation and mortality in COPD patients

BACKGROUND AND OBJECTIVE

A multidimensional assessment of COPD was recommended by the Global Initiative for Chronic Obstructive Lung Disease (GOLD) in 2013 and revised in 2017. We examined the ability of the GOLD 2017 and the new 16 subgroup (1A-4D) classifications to predict clinical outcomes, including exacerbation and mortality, and compared them with the GOLD 2013 classifications.

METHODS

Patients with COPD were recruited from January 2006 to December 2017. The predictive abilities of grades 1-4 and groups A-D were examined through a logistic regression analysis with receiver operating curve estimations and area under the curve (AUC).

RESULTS

A total of 553 subjects with COPD were analyzed. The mortality rate was 48.6% during a median follow-up period of 5.2 years. Both the GOLD 2017 and the 2013 group A-D classifications had good predictive ability for total and severe exacerbations, for which the AUCs were 0.79 vs 0.77 and 0.79 vs 0.78, respectively. The AUCs for the GOLD 2017 groups A-D, grades 1-4, and the GOLD 2013 group A-D classifications were 0.70, 0.66, and 0.70 for all-cause mortality and 0.73, 0.71, and 0.74 for respiratory cause mortality, respectively. Combining the spirometric staging with the grouping for the GOLD 2017 subgroups (1A-4D), the all-cause mortality rate for group B and D patients was significantly increased from subgroups 1B-4B (27.7%, 50.6%, 53.3%, and 69.2%, respectively) and groups 1D-4D (55.0%, 68.8%, 82.1%, and 90.5%, respectively). The AUCs of subgroups (1A-4D) were 0.73 and 0.77 for all-cause and respiratory mortality, respectively; the new classification was determined more accurate than the GOLD 2017 for predicting mortality (P<0.0001).

CONCLUSION

The GOLD 2017 classification performed well by identifying individuals at risk of exacerbation, but its predictive ability for mortality was poor among COPD patients. Combining the spirometric staging with the grouping increased the predictive ability for all-cause and respiratory mortality.

SUMMARY AT A GLANCE

We validate the ability of the GOLD 2017 and 16 subgroup (1A-4D) classifications to predict clinical outcome for COPD patients. The GOLD 2017 classification performed well by identifying individuals at risk of exacerbation, but its predictive ability for mortality was poor. The new 16 subgroup (1A-4D) classification combining the spirometric 1-4 staging and the A-D grouping increased the predictive ability for mortality and was better than the GOLD 2017 for predicting all-cause and respiratory mortality among COPD patients.

Airway function in infancy is linked to airflow measurements and respiratory symptoms from childhood into adulthood

INTRODUCTION

Increasing evidence suggests that poor lung function in adulthood is determined very early in life. Our study aims were: (1) identify factors associated with early infant lung function; (2) quantify the link between early infant lung function and early adult lung function; and (3) identify environmental and inherited factors which predict lung function throughout the post-natal growth period.

METHODS

In this longitudinal study, 253 individuals were recruited antenatally. Lung function and allergy testing occurred at 1, 6, 12 months, 6, 11, 18, and 24 years of age. The relationship between lung function at 1 month (V'maxFRC) and spirometry variables at each follow-up was evaluated. Early life predictors of spirometry were assessed longitudinally using linear mixed models.

RESULTS

V'maxFRC correlated positively with FEF25-75% at every assessment from 6 to 24 years and FEV₁ /FVC at 11 and 24 years and inversely with airway responsiveness at 6 and 18 years. Maternal asthma and smoking in pregnancy were associated with lower FEV₁ from 6 to 24 years (-99 mL, P = 0.03; -77 mL, P = 0.045 respectively). Lower V'maxFRC at 1 month was associated with asthma and wheeze through to 24 years.

CONCLUSION

Lung airflow measurements track from birth into early adulthood, suggesting a permanent and stable airway framework is laid down in the antenatal period. Lower infant airway function is associated with respiratory symptoms into adulthood, indicating the link is clinically important. Antenatal and early life exposures must be addressed in order to maximize airway growth and reduce lifelong respiratory compromise.

Reference equations for the interpretation of forced expiratory and plethysmographic measurements in infants

BACKGROUND

Pulmonary function testing is commonly performed for diagnosis and clinical management of respiratory diseases. It is important to use appropriate reference equations from healthy subjects for interpretation of data from infants with lung disease. This study aimed to determine if published reference equations were similar to forced flow measures and plethysmographic infant pulmonary function testing data collected in the Canadian Healthy Infant Longitudinal Development (CHILD) Study.

METHODS

Reference equations for five pulmonary function variables (FEV_0.5 , FVC, FEF_25-75 , FEV_0.5 /FVC ratio and plethysmography (FRC_pleth )) were developed using data from the nSpire system. New reference equations developed using healthy data from the CHILD Study were compared to previously published reference equations for forced flow and plethysmographic measures.

RESULTS

The current analysis included 131 infants (on 181 test occasions) with forced flow measures and 161 infants (on 246 test occasions) with plethysmography measures, aged 3-24 months. Age and length were major determinants of both forced flow and plethysmography measures. In addition, ethnicity (Caucasian vs non-Caucasian) was significantly associated with FEV_0.5 /FVC and FEF_25-75 measures. We found that the published reference equations based on custom-built equipment or commercially available systems provided poor fit to our current pulmonary function testing data, resulting in placing a large proportion of our healthy population outside the normal ranges.

CONCLUSIONS

Our current data support the need for population and device specific reference data for infant pulmonary function studies. By deriving new equipment-specific reference equations for our healthy population, we provide normative data to other centers utilizing this equipment.

Ventilation inhomogeneity in infants with recurrent wheezing

BACKGROUND

The care of infants with recurrent wheezing relies largely on clinical assessment. The lung clearance index (LCI), a measure of ventilation inhomogeneity, is a sensitive marker of early airway disease in children with cystic fibrosis, but its utility has not been explored in infants with recurrent wheezing.

OBJECTIVE

To assess ventilation inhomogeneity using LCI among infants with a history of recurrent wheezing compared with healthy controls.

METHODS

This is a case-control study, including 37 infants with recurrent wheezing recruited from outpatient clinics, and 113 healthy infants from a longitudinal birth cohort, the Canadian Healthy Infant Longitudinal Development study. All infants, at a time of clinical stability, underwent functional assessment including multiple breath washout, forced expiratory flows and body plethysmography.

RESULTS

LCI z-score values among infants with recurrent wheeze were 0.84 units (95% CI 0.41 to 1.26) higher than healthy infants (mean (95% CI): 0.26 (-0.11 to 0.63) vs -0.58 (-0.79 to 0.36), p<0.001)). Nineteen percent of recurrently wheezing infants had LCI values that were above the upper limit of normal (>1.64 z-scores). Elevated exhaled nitric oxide, but not symptoms, was associated with abnormal LCI values in infants with recurrent wheeze (p=0.05).

CONCLUSIONS

Ventilation inhomogeneity is present in clinically stable infants with recurrent wheezing.

Pulmonary function in former very low birth weight preterm infants in the first year of life

BACKGROUND

Pulmonary function in former preterm infants may be compromised during childhood.

OBJECTIVES

To assess pulmonary function in very-low-birth-weight preterm infants at 6-12 months of corrected age and analyze the factors associated with abnormal pulmonary function.

METHODS

Cross-sectional study with preterm infants at 6-12 months of corrected age with birth weight <1500 g. Children with malformations or affected by neuromuscular and respiratory diseases were excluded. Forced expiratory flows were assessed using the chest compression technique, and volumes were measured by total body plethysmography. Pulmonary function parameters in preterm infants were compared to a control group of same-aged children born at term.

RESULTS

We studied 51 preterm and 37 infants born at term. Preterm infants had: gestational age at birth (30.0 ± 2.5 weeks), birth weight (1179 ± 247 g), 27.5% had bronchopulmonary dysplasia, and 45% received mechanical ventilation. Preterm infants had lower median z-scores in comparison to term infants for the following parameters (p < 0.05): FVC (-0.3 vs. 0.7), FEV_0.5 (-0.5 vs. 0.9), FEV_0.5/FVC (-0.6 vs. -0.5), FEF₅₀ (-0.4 vs. 0.9), FEF₇₅ (-0.3 vs. 0.8), FEF₈₅ (-0.1 vs. 0.6) and FEF_25-75 (-0.5 vs. 1.1). No term child had abnormal lung function, compared to 39.2% of preterm infants (p = 0.001). Factors associated with abnormal pulmonary function were lower gestational age at birth, small for gestational age, need for mechanical ventilation and presence of recurrent wheezing.

CONCLUSIONS

Preterms had a high prevalence of abnormal pulmonary function and lower pulmonary function in comparison to term infants. Prematurity, intrauterine growth restriction, respiratory support and recurrent wheezing were associated with abnormal pulmonary function.

Biomarkers of inflammation in infants with cystic fibrosis

Background

There are urgent needs for clinically relevant biomarkers to identify children with cystic fibrosis (CF) at risk for more progressive lung disease and to serve as outcome measures for clinical trials. Our objective was to investigate three targeted biomarkers in a population of asymptomatic CF infants.

Methods

Urine, blood and lung function data were collected for 2 years from clinically stable infants diagnosed with CF by newborn screening. A subset of CF infants had bronchoscopy with lavage performed at 6 months and 1 year. Urine was collected quarterly from healthy control infants. Expectorated sputum and urine were collected quarterly for 2 years from clinically stable CF adults. Desmosine, club cell secretory protein (CCSP) and cathepsin B concentrations were measured and compared. Mixed effects models were used to identify associations between biomarker concentrations and clinical characteristics. Receiver operator characteristic curves were generated to investigate the sensitivity and specificity of the biomarkers.

Results

Urinary cathepsin B was significantly higher in CF infants compared to healthy infants (p = 0.005). CF infant airway and urinary cathepsin B concentrations were significantly lower compared to adult CF subjects (p = 0.002 & p = 0.022, respectively). CF infant airway CCSP was significantly higher than adult CF subjects (p < 0.001). There was a significant correlation between CF infant plasma CCSP and BALF CCSP (p = 0.046). BALF CCSP was negatively associated with IL-8 (p = 0.017). There was no correlation between biomarker concentration and FEV_0.5.

Conclusions

Cathepsin B and CCSP show promise as biomarkers of inflammation in CF infants. Further study is needed.

Electronic supplementary material

The online version of this article (10.1186/s12931-017-0713-8) contains supplementary material, which is available to authorized users.

Early follow-up of lung disease in infants with cystic fibrosis using the raised volume rapid thoracic compression technique and computed tomography during quiet breathing

BACKGROUND

Among the different techniques used to monitor lung disease progression in infants with CF diagnosed by Newborn screening (NBS), raised volume-rapid thoracic compression (RVRTC) remains a promising tool. However, the need of sedation and positive pressure ventilation considerably limits its clinical use. We recently described a semi-quantitative method to evaluate air trapping by chest tomography during quite breathing without sedation (CTqb score). This parameter is the radiological sign of airway obstruction and could be also used for lung disease follow-up in infants with CF. However, its discriminative power compared with RVRTC and correlation with lung function parameters are not known.

OBJECTIVES

To compare the discriminative powers of the CTqb score and RVRTC parameters and to determine their correlation during the first year of life of infants with CF.

METHODS

In this multicenter longitudinal study, infants with CF diagnosed by NBS underwent RVRTC and CT during quite breathing at 10 ± 4 weeks (n = 30) and then at 13 ± 1 months of age (n = 28).

RESULTS

All RVRTC parameters and the CTqb score remained stable between evaluations. The CTqb score showed a higher discriminative power than forced expiratory volume in 0.5 s (FEV_0.5 ; the main RVRTC parameter) at both visits (66% and 50% of abnormal values vs 30% and 28%, respectively). No correlation was found between CTqb score and_, the different RVRTC parameters or the plethysmographic functional residual capacity, indicating that they evaluate different aspect of CF lung disease.

Raised-Volume Forced Expiratory Flow-Volume Curve in Healthy Taiwanese Infants

The raised-volume rapid thoracoabdominal compression (RVRTC) manoeuvre has been applied to obtain full forced expiratory flow-volume curves in infants. No reference data are available for Asian populations. This study was conducted to establish predictive reference equations for Taiwanese infants. Full-term infants without any chronic disease or major anomaly were enrolled from this cohort study. Full forced expiratory flow-volume curves were acquired using RVRTC manoeuvres through Jaeger's system. Tidal breath analysis, passive respiratory mechanics, and tidal forced expiratory flow-volume curves were performed and collected at the same measurement. Multiple linear analyses were used to model the variables. We performed 117 tests of RVRTC flow-volume curves in 97 infants. The results revealed that all parameters, except for FEV_0.5 /FVC, correlated highly and positively with body length. These parameters correlated significantly with other parameters of passive respiratory mechanics and tidal forced expiratory flow-volume curves. This is the first study to establish equipment-specific reference data of full forced expiration using RVRTC manoeuvres in Asian infants. The results revealed that parameters of RVRTC manoeuvres are moderately related to other parameters of infant lung function. These race-specific reference data can be used to more precisely and efficiently diagnose respiratory diseases in infants of Chinese ethnicity.

Feasibility of multiple breath washout measurements in infants with bronchiolitis: A pilot study

BACKGROUND

Lung clearance index (LCI) reflects ventilation inhomogeneity and is raised in obstructive airway disease. Feasibility of multiple breath washout (MBW) measurement during acute lung disease in infants is unknown. As a further measure of disease, exhaled nitric oxide (eNO) may paradoxically decrease in acute bronchiolitis. We hypothesized that MBW measurements were attainable in infants with bronchiolitis and that LCI was raised and eNO reduced, compared to normal controls.

METHODS

Infants with acute bronchiolitis were tested with sulfur hexafluoride (SF₆ ) MBW during hospitalization and compared to controls. Tidal breathing and eNO parameters were obtained. Measurements were performed during natural sleep.

RESULTS

Twenty-nine infants with bronchiolitis aged 3.7 ± 2.3 months (mean ± SD) and 23 controls aged 4.2 ± 2.5 months (P = 0.07) were evaluated. Fifteen of 29 (52%) infants with bronchiolitis and 19/23 (83%) controls achieved ≥2 valid MBW measurements. Reasons for test failure included waking up during facemask application and an irregular respiratory pattern. LCI was 8.4 ± 0.8 in the study group and 7.3 ± 0.7 in controls (P < 0.001). ENO was 2.3 ± 2.7 ppb in the study group and 7.9 ± 6.9 ppb in controls (P = 0.004).

CONCLUSION

MBW measurements during natural sleep are feasible but technically challenging in infants with acute bronchiolitis. LCI is raised compared to healthy controls. Larger trials, possibly using sedation protocols and shortened washout periods, are required to corroborate these findings. LCI can potentially serve as an objective indicator of severity and could be considered as a biomarker for future interventional trials.

Airway Microbiota in Bronchoalveolar Lavage Fluid from Clinically Well Infants with Cystic Fibrosis

Background

Upper airway cultures guide the identification and treatment of lung pathogens in infants with cystic fibrosis (CF); however, this may not fully reflect the spectrum of bacteria present in the lower airway. Our objectives were to characterize the airway microbiota using bronchoalveolar lavage fluid (BALF) from asymptomatic CF infants during the first year of life and to investigate the relationship between BALF microbiota, standard culture and clinical characteristics.

Methods

BALF, nasopharyngeal (NP) culture and infant pulmonary function testing data were collected at 6 months and one year of age during periods of clinical stability from infants diagnosed with CF by newborn screening. BALF was analyzed for total bacterial load by qPCR and for bacterial community composition by 16S ribosomal RNA sequencing. Clinical characteristics and standard BALF and NP culture results were recorded over five years of longitudinal follow-up.

Results

12 BALF samples were collected from 8 infants with CF. Streptococcus, Burkholderia, Prevotella, Haemophilus, Porphyromonas, and Veillonella had the highest median relative abundance in infant CF BALF. Two of the 3 infants with repeat BALF had changes in their microbial communities over six months (Morisita-Horn diversity index 0.36, 0.38). Although there was excellent percent agreement between standard NP and BALF cultures, these techniques did not routinely detect all bacteria identified by sequencing.

Conclusions

BALF in asymptomatic CF infants contains complex microbiota, often missed by traditional culture of airway secretions. Anaerobic bacteria are commonly found in the lower airways of CF infants.