Determinants of lung function development from birth to age 5 years: an interrupted time series analysis of a South African birth cohort

BACKGROUND

Early life is a key period that determines long-term health. Lung development in childhood predicts lung function attained in adulthood and morbidity and mortality across the life course. We aimed to assess the effect of early-life lower respiratory tract infection (LRTI) and associated risk factors on lung development from birth to school age in a South African birth cohort.

METHODS

We prospectively followed children enrolled in a population-based cohort from birth (between March 5, 2012 and March 31, 2015) to age 5 years with annual lung function assessment. Data on multiple early-life exposures, including LRTI, were collected. The effect of early-life risk factors on lung function development from birth to age 5 years was assessed using the Generalised Additive Models for Location, Scale and Shape and Interrupted Time Series approach.

FINDINGS

966 children (475 [49·2%] female, 491 [50·8%] male) had lung function measured with oscillometry, tidal flow volume loops, and multiple breath washout. LRTI occurred in 484 (50·1%) children, with a median of 2·0 LRTI episodes (IQR 1·0-3·0) per child. LRTI was independently associated with altered lung function, as evidenced by lower compliance (0·959 [95% CI 0·941-0·978]), higher resistance (1·028 [1·016-1·041]), and higher respiratory rate (1·018 [1·063-1·029]) over 5 years. Additional impact on lung function parameters occurred with each subsequent LRTI. Respiratory syncytial virus (RSV) LRTI was associated with lower expiratory flow ratio (0·97 [0·95-0·99]) compared with non-RSV LRTI. Maternal factors including allergy, smoking, and HIV infection were also associated with altered lung development, as was preterm birth, low birthweight, female sex, and coming from a less wealthy household.

INTERPRETATION

Public health interventions targeting LRTI prevention, with RSV a priority, are vital, particularly in low-income and middle-income settings.

FUNDING

UK Medical Research Council Grant, The Wellcome Trust, The Bill & Melinda Gates Foundation, US National Institutes of Health Human Heredity and Health in Africa, South African Medical Research Council, Hungarian Scientific Research Fund, and European Respiratory Society.

Lung function changes in children exposed to mine fire smoke in infancy

BACKGROUND AND OBJECTIVE

Chronic, low-intensity air pollution exposure has been consistently associated with reduced lung function throughout childhood. However, there is limited research regarding the implications of acute, high-intensity air pollution exposure. We aimed to determine whether there were any associations between early life exposure to such an episode and lung growth trajectories.

METHODS

We conducted a prospective cohort study of children who lived in the vicinity of the Hazelwood coalmine fire. Lung function was measured using respiratory oscillometry. Z-scores were calculated for resistance (R5 ) and reactance at 5 Hz (X5 ) and area under the reactance curve (AX). Two sets of analyses were conducted: (i) linear regression to assess the cross-sectional relationship between post-natal exposure to mine fire-related particulate matter with an aerodynamic diameter of less than 2.5 micrometres (PM2.5 ) and lung function at the 7-year follow-up and (ii) linear mixed-effects models to determine whether there was any association between exposure and changes in lung function between the 3- and 7-year follow-ups.

RESULTS

There were no associations between mine fire-related PM2.5 and any of the lung function measures, 7-years later. There were moderate improvements in X5 (β: -0.37 [-0.64, -0.10] p = 0.009) and AX (β: -0.40 [-0.72, -0.08] p = 0.014), between the 3- and 7-year follow-ups that were associated with mean PM2.5 , in the unadjusted and covariance-adjusted models. Similar trends were observed with maximum PM2.5 .

CONCLUSION

There was a moderate improvement in lung stiffness of children exposed to PM2.5 from a local coalmine fire in infancy, consistent with an early deficit in lung function at 3-years after the fire that had resolved by 7-years.

Risk factors for poorer respiratory outcomes in adolescents and young adults born preterm

RATIONALE

The respiratory outcomes for adult survivors of preterm birth in the postsurfactant era are wide-ranging with prognostic factors, especially those encountered after the neonatal period, poorly understood.

OBJECTIVES

To obtain comprehensive 'peak' lung health data from survivors of very preterm birth and identify neonatal and life-course risk factors for poorer respiratory outcomes in adulthood.

METHODS

127 participants born ≤32 weeks gestation (64%, n=81 with bronchopulmonary dysplasia (BPD), initially recruited according to a 2 with-BPD:1 without-BPD strategy), and 41 term-born controls completed a lung health assessment at 16-23 years, including lung function, imaging and symptom review. Risk factors assessed against poor lung health included neonatal treatments, respiratory hospitalisation in childhood, atopy and tobacco smoke exposure.

MEASUREMENTS AND MAIN RESULTS

Young adults born prematurely had greater airflow obstruction, gas trapping and ventilation inhomogeneity, in addition to abnormalities in gas transfer and respiratory mechanics, compared with term. Beyond lung function, we observed greater structural abnormalities, respiratory symptoms and inhaled medication use. A previous respiratory admission was associated with airway obstruction; mean forced expiratory volume in 1 s/forced vital capacity z-score was -0.561 lower after neonatal confounders were accounted for (95% CI -0.998 to -0.125; p=0.012). Similarly, respiratory symptom burden was increased in the preterm group with a respiratory admission, as was peribronchial thickening (6% vs 23%, p=0.010) and bronchodilator responsiveness (17% vs 35%, p=0.025). Atopy, maternal asthma and tobacco smoke exposure did not influence lung function or structure at 16-23 years in our preterm cohort.

CONCLUSIONS

Even after accounting for the neonatal course, a respiratory admission during childhood remained significantly associated with reduced peak lung function in the preterm-born cohort, with the largest difference seen in those with BPD. A respiratory admission during childhood should, therefore, be considered a risk factor for long-term respiratory morbidity in those born preterm, especially for individuals with BPD.

Oscillometry and spirometry are not interchangeable when assessing the bronchodilator response in children and young adults born preterm

INTRODUCTION

The European Respiratory Society Oscillometry Taskforce identified that clinical correlates of bronchodilator responses are needed to advance oscillometry in clinical practice. The understanding of bronchodilator-induced oscillometry changes in preterm lung disease is poor. Here we describe a comparison of bronchodilator assessments performed using oscillometry and spirometry in a population born very preterm and explore the relationship between bronchodilator-induced changes in respiratory function and clinical outcomes.

METHODS

Participants aged 6-23 born ≤32 (N = 288; 132 with bronchopulmonary dysplasia) and ≥37 weeks' gestation (N = 76, term-born controls) performed spirometry and oscillometry. A significant bronchodilator response (BDR) to 400 μg salbutamol was classified according to published criteria.

RESULTS

A BDR was identified in 30.9% (n = 85) of preterm-born individuals via spirometry and/or oscillometry, with poor agreement between spirometry and oscillometry definitions (k = 0.26; 95% confidence interval [CI] 0.18-0.40, p < .001). Those born preterm with a BDR by oscillometry but not spirometry had increased wheeze (33% vs. 11%, p = .010) and baseline resistance (Rrs5 z-score mean difference (MD) = 0.86, 95% CI 0.07-1.65, p = .025), but similar baseline spirometry to the group without a BDR (forced expiratory volume in 1 s [FEV1 ] z-score MD = -0.01, 95% CI -0.66 to 0.68, p > .999). Oscillometry was more feasible than spirometry (95% success rate vs. 85% (FEV1 ), 69% (forced vital capacity) success rate, p < .001), however being born preterm did not affect test feasibility.

CONCLUSION

In the preterm population, oscillometry is a feasible and clinically useful supportive test to assess the airway response to inhaled salbutamol. Changes measured by oscillometry reflect related but distinct physiological changes to those measured by spirometry, and thus these tests should not be used interchangeably.

Elevated leukotriene B4 and 8-isoprostane in exhaled breath condensate from preterm-born infants

BACKGROUND

Inflammation and oxidative stress play a key role in the development of bronchopulmonary dysplasia (BPD), possibly contributing to persistent respiratory morbidity after preterm birth. We aimed to assess if inflammatory markers were elevated in exhaled breath condensate (EBC) of infants born very prematurely (< 32 weeks gestation) at 12-16 corrected months of age, and if increased levels were associated with BPD diagnosis and respiratory morbidity.

METHODS

EBC samples and respiratory questionnaires were collected from 15 term-born infants and 33 preterm-born infants, 12 with a neonatal BPD diagnosis. EBC samples were analysed for leukotriene B4 (inflammation) and 8-isoprostane (oxidative stress) concentrations using enzyme-linked immune-assays. Differences between groups were analysed by Kruskal-Wallis Test with post-hoc comparisons, independent samples t-test or Mann-Whitney U test depending on normality of the data.

RESULTS

Leukotriene B4 and 8-isoprostane levels were elevated in exhaled breath condensate of preterm-born infants compared to those born at term (mean difference [95% CI]; 1.52 [0.45, 2.59], p = 0.02; 0.77 [0.52, 1.02], p < 0.001, respectively). Leukotriene B4 and 8-isoprostane levels were independent of BPD diagnosis and respiratory morbidity over the first year of life.

CONCLUSIONS

Infants born very prematurely exhibit elevated markers of airway neutrophilic inflammation and oxidative stress beyond the first year of life, regardless of a neonatal diagnosis of chronic lung disease or respiratory morbidity during infancy. These findings may have implications for future lung health.

TRIAL REGISTRATION

N/A.

Factors influencing participation in home, school, and community settings by children and adolescents with neuromuscular disorders: A qualitative descriptive study

AIM

This study explored how children and adolescents with a neuromuscular disorder (NMD) and their parents experienced barriers and enablers to the child's participation.

METHOD

This was a qualitative descriptive design. Fourteen semi-structured interviews were conducted (n = 13 mothers, n = 4 fathers, n = 8 children and adolescents) including one to three family members for each interview according to their preference. Data were analysed by content analysis, using the family of Participation-Related Constructs (fPRC), to characterize the components of participation.

RESULTS

Meaningful participation was illustrated in the personal categories of the fPRC including the child's sense of self, preferences, and competence to perform activities. Enablers and barriers related to adaptive equipment and activity modification, social relationships, inclusion, accessibility to venues, social attitudes, and policies.

INTERPRETATION

Personal motivators are critical to understanding what participation is meaningful to children and adolescents with NMDs. Social and physical supports within the child's immediate environment as well as accessibility and advocacy more widely in the community enable participation. The fPRC is a useful tool for understanding participation in these children; it informs how to support participation and suggests domains for evaluation in future intervention studies. Advocacy for participation should consider targets in the immediate and broader environments.

WHAT THIS PAPER ADDS

The family of Participation-Related Constructs classified the components of participation for children and adolescents with neuromuscular disorders. Meaningful participation involved a complex interaction between personal and environmental factors. Barriers to participation included poor accessibility, lack of equipment, and social exclusion.

No association between in utero exposure to emissions from a coalmine fire and post-natal lung function

BACKGROUND AND OBJECTIVE

Studies linking early life exposure to air pollution and subsequent impaired lung health have focused on chronic, low-level exposures in urban settings. We aimed to determine whether in utero exposure to an acute, high-intensity air pollution episode impaired lung function 7-years later.

METHOD

We conducted a prospective cohort study of children who lived in the vicinity of a coalmine fire. Respiratory function was measured using the forced oscillation technique (FOT). Z-scores for resistance at 5 Hz (R₅), reactance at 5 Hz (X₅) and area under the reactance curve (AX) were calculated. Two sets of analyses were conducted to address two separate questions: (1) whether mine fire exposure (a binary indicator; conceived after the mine fire vs in utero exposed) was associated with the respiratory Z-scores; (2) whether there was any dose-response relationship between fire-related PM_2.5 exposure and respiratory outcomes among those exposed.

RESULTS

Acceptable lung function measurements were obtained from 79 children; 25 unexposed and 54 exposed in utero. Median (interquartile range) for daily average and peak PM_2.5 for the exposed children were 4.2 (2.6 - 14.2) and 88 (52-225) µg/m³ respectively. There were no detectable differences in Z-scores between unexposed and exposed children. There were no associations between respiratory Z-scores and in utero exposure to PM_2.5 (daily average or peak).

CONCLUSION

There was no detectable effect of in utero exposure to PM_2.5 from a local coalmine fire on post-natal lung function 7-years later. However, statistical power was limited.

Multi-ancestry genome-wide association analyses improve resolution of genes and pathways influencing lung function and chronic obstructive pulmonary disease risk

Lung-function impairment underlies chronic obstructive pulmonary disease (COPD) and predicts mortality. In the largest multi-ancestry genome-wide association meta-analysis of lung function to date, comprising 580,869 participants, we identified 1,020 independent association signals implicating 559 genes supported by ≥2 criteria from a systematic variant-to-gene mapping framework. These genes were enriched in 29 pathways. Individual variants showed heterogeneity across ancestries, age and smoking groups, and collectively as a genetic risk score showed strong association with COPD across ancestry groups. We undertook phenome-wide association studies for selected associated variants as well as trait and pathway-specific genetic risk scores to infer possible consequences of intervening in pathways underlying lung function. We highlight new putative causal variants, genes, proteins and pathways, including those targeted by existing drugs. These findings bring us closer to understanding the mechanisms underlying lung function and COPD, and should inform functional genomics experiments and potentially future COPD therapies.

Longitudinal effects of prenatal exposure to plastic-derived chemicals and their metabolites on asthma and lung function from childhood into adulthood

BACKGROUND AND OBJECTIVE

Environmental exposure to phthalates and bisphenol A (BPA), chemicals used in the production of plastics, may increase risk for asthma and allergies. However, little is known about the long-term effects of early life exposure to these compounds. We investigated if prenatal exposure to these compounds was associated with asthma, allergy and lung function outcomes from early childhood into adulthood in a cohort study.

METHODS

Maternal serum samples collected from 846 pregnant women in the Raine Study were assayed for BPA and phthalate metabolites. The children of these women were followed up at 5, 13 and 22 years where spirometry and respiratory questionnaires were conducted to determine asthma and allergy status. Lung function trajectories were derived from longitudinal spirometry measurements. Multinomial logistic regression and weighted quantile sum regression was used to test associations of individual and chemical mixtures with asthma phenotypes and lung function trajectories.

RESULTS

Effects of prenatal BPA and phthalates on asthma phenotypes were seen in male offspring, where BPA was associated with increased risk for persistent asthma, while mono-iso-butyl phthalate and mono-iso-decyl phthalate was associated with increased risk for adult asthma. Prenatal BPA had no effect on lung function trajectories, but prenatal phthalate exposure was associated with improved lung function.

CONCLUSION

Prenatal BPA exposure was associated with increased likelihood of persistent asthma in males, while prenatal phthalate exposure was associated with increased likelihood of adult asthma in males. Results suggest that prenatal exposure to prenatal BPA and phthalates affect asthma risk, particularly in males, however lung function was not adversely affected.

Association between early respiratory viral infections and structural lung disease in infants with cystic fibrosis

BACKGROUND

Infants with cystic fibrosis (CF) develop structural lung disease early in life, and viral infections are associated with progressive lung disease. We hypothesized that the presence of respiratory viruses would be associated with structural lung disease on computed tomography (CT) of the chest in infants with CF.

METHODS

Infants with CF were enrolled before 4 months of age. Multiplex PCR assays were performed on nasal swabs to detect respiratory viruses during routine visits and when symptomatic. Participants underwent CT imaging at approximately 12 months of age. Associations between Perth-Rotterdam Annotated Grid Morphometric Analysis for CF (PRAGMA-CF) CT scores and respiratory viruses and symptoms were assessed with Spearman correlation coefficients.

RESULTS

Sixty infants were included for analysis. Human rhinovirus was the most common virus detected, on 28% of tested nasal swabs and in 85% of participants. The median (IQR) extent of lung fields that was healthy based on PRAGMA-CF was 98.7 (0.8)%. There were no associations between PRAGMA-CF and age at first virus, or detection of any virus, including rhinovirus, respiratory syncytial virus, or parainfluenza. The extent of airway wall thickening was associated with ever having wheezed (ρ = 0.31, p = 0.02) and number of encounters with cough (ρ = 0.25, p = 0.0495).

CONCLUSIONS

Infants with CF had minimal structural lung disease. We did not find an association between respiratory viruses and CT abnormalities. Wheezing and frequency of cough were associated with early structural changes.

Development of a Symptom-Based Tool for Screening of Children at High Risk of Preschool Asthma

IMPORTANCE

Despite advances in asthma therapeutics, the burden remains highest in preschool children; therefore, it is critical to identify primary care tools that distinguish preschool children at high risk for burdensome disease for further evaluation. Current asthma prediction tools, such as the modified Asthma Predictive Index (mAPI), require invasive tests, limiting their applicability in primary care and low-resource settings.

OBJECTIVE

To develop and evaluate the use of a symptom-based screening tool to detect children at high risk of asthma, persistent wheeze symptoms, and health care burden.

DESIGN, SETTING, AND PARTICIPANTS

The cohort for this diagnostic study included participants from the CHILD Study (n = 2511) from January 1, 2008, to December 31, 2012, the Raine Study from January 1, 1989, to December 31, 2012 (n = 2185), and the Canadian Asthma Primary Prevention Study (CAPPS) from January 1, 1989, to December 31, 1995 (n = 349), with active follow-up to date. Data analysis was performed from November 1, 2019, to May 31, 2022.

EXPOSURES

The CHILDhood Asthma Risk Tool (CHART) identified factors associated with asthma in patients at 3 years of age (timing and number of wheeze or cough episodes, use of asthma medications, and emergency department visits or hospitalizations for asthma or wheeze) to identify children with asthma or persistent symptoms at 5 years of age.

MAIN OUTCOMES AND MEASURES

Within the CHILD Study cohort, CHART was evaluated against specialist clinician diagnosis and the mAPI. External validation was performed in both a general population cohort (Raine Study [Australia]) and a high-risk cohort (CAPPS [Canada]). Predictive accuracy was measured by sensitivity, specificity, area under the receiver operating characteristic curve (AUROC), and positive and negative predicted values.

RESULTS

Among 2511 children (mean [SD] age at 3-year clinic visit, 3.08 [0.17] years; 1324 [52.7%] male; 1608 of 2476 [64.9%] White) with sufficient questionnaire data to apply CHART at 3 years of age, 2354 (93.7%) had available outcome data at 5 years of age. CHART applied in the CHILD Study at 3 years of age outperformed physician assessments and the mAPI in predicting persistent wheeze (AUROC, 0.94; 95% CI, 0.90-0.97), asthma diagnosis (AUROC, 0.73; 95% CI, 0.69-0.77), and health care use (emergency department visits or hospitalization for wheeze or asthma) (AUROC, 0.70; 95% CI, 0.61-0.78). CHART had a similar predictive performance for persistent wheeze in the Raine Study (N = 2185) in children at 5 years of age (AUROC, 0.82; 95% CI, 0.79-0.86) and CAPPS (N = 349) at 7 years of age (AUROC, 0.87; 95% CI, 0.80-0.94).

CONCLUSIONS AND RELEVANCE

In this diagnostic study, CHART was able to identify children at high risk of asthma at as early as 3 years of age. CHART could be easily incorporated as a routine screening tool in primary care to identify children who need monitoring, timely symptom control, and introduction of preventive therapies.

ERS/ATS technical standard on interpretive strategies for routine lung function tests

BACKGROUND

Appropriate interpretation of pulmonary function tests (PFTs) involves the classification of observed values as within/outside the normal range based on a reference population of healthy individuals, integrating knowledge of physiological determinants of test results into functional classifications and integrating patterns with other clinical data to estimate prognosis. In 2005, the American Thoracic Society (ATS) and European Respiratory Society (ERS) jointly adopted technical standards for the interpretation of PFTs. We aimed to update the 2005 recommendations and incorporate evidence from recent literature to establish new standards for PFT interpretation.

METHODS

This technical standards document was developed by an international joint Task Force, appointed by the ERS/ATS with multidisciplinary expertise in conducting and interpreting PFTs and developing international standards. A comprehensive literature review was conducted and published evidence was reviewed.

RESULTS

Recommendations for the choice of reference equations and limits of normal of the healthy population to identify individuals with unusually low or high results are discussed. Interpretation strategies for bronchodilator responsiveness testing, limits of natural changes over time and severity are also updated. Interpretation of measurements made by spirometry, lung volumes and gas transfer are described as they relate to underlying pathophysiology with updated classification protocols of common impairments.

CONCLUSIONS

Interpretation of PFTs must be complemented with clinical expertise and consideration of the inherent biological variability of the test and the uncertainty of the test result to ensure appropriate interpretation of an individual's lung function measurements.

O-087 Asthma and allergies in a cohort of adolescents conceived after assisted reproductive technologies (ART)

Study question

Are adolescents conceived after assisted reproductive technologies (ART) at an increased risk of asthma and allergies, compared to their counterparts conceived without ART?

Summary answer

No difference in asthma prevalence, better lung-function, and an increase in allergic rhinoconjunctivitis, food allergies and positive skin-prick tests are reported in the ART cohort.

What is known already

Over 8 million children have been born after conception with ART worldwide. Emerging evidence shows an increased risk of atopic disorders, such as asthma and allergies, in such children, potentially due to epigenetic alterations or underlying parental subfertility and perinatal risk factors. Studies to date are highly heterogeneous, including non-standardized diagnostic tools, non-representative reference populations, and lacking appropriate covariate adjustment. With the increase in atopic disorders worldwide, and the burden they bring to the life of individuals and to society, in combination with the increase in ART, it is important to further investigate the risk of atopy in such offspring.

Study design, size, duration

The Growing Up Healthy Study (GUHS) is a prospective study that recruited 303 offspring conceived after ART (aged 13-21), born 1991-2001 in Western Australia. Their health parameters, including asthma and allergy assessments, were compared with those of counterparts conceived without ART, from the Raine Study Generation 2 (Gen2). The 2,868 Gen2 participants are representative of the local population. At age 14 (2013-2017), 152 GUHS participants replicated atopy assessments previously completed by similarly aged Gen2 participants.

Participants/materials, setting, methods

Asthma and allergy assessments consisted of a parent-completed modified version of the ‘International Studies of Asthma and Allergies in Childhood’ (ISAAC) questionnaire, spirometry, methacholine challenge- and skin-prick testing (SPT). Chi2, Fisher’s Exact and Mann-Whitney U tests, performed in SPSS V25, examined cohort differences, and generalized estimating equations adjusted for (a subset of) the following covariates: sex, age, height, singleton pregnancy, gestational age, birthweight, mode of delivery, primary caregiver smoking, and being an only child.

Main results and the role of chance

Current asthma and asthma severity, based on the ISAAC questionnaire, appeared similar between the cohorts. Lung function (mean Forced Expiratory Volume [FEV1], Forced Vital Capacity [FVC] and FEV1/FVC ratio) was better in the ART cohort (3.10 vs. 2.96 L, p = 0.011; 3.72 vs. 3.29 L, p &lt; 0.001; 85.5 vs. 91.8%, p &lt; 0.001, respectively). No difference in mean Forced Expiratory Flow was reported. Bronchial hyperresponsiveness was significantly less prevalent in the ART cohort (8.8% vs.18.6% p = 0.006).

Current allergic rhinoconjunctivitis (ARC) rates were significantly higher in the ART cohort (32.4% vs. 25.2%, aOR 1.52 [1.03-2.26], p = 0.036), while prevalence of current atopic dermatitis did not differ. Food allergies were twice as prevalent in the ART cohort (20.7 vs. 10.9%, aOR 1.89 [1.17-3.06], p = 0.010). Significantly more GUHS participants had a positive SPT (68.0% vs. 45.4%, aOR 3.034 [1.989-4.628], p &lt; 0.001). The percentage of polysensitisation (&gt; 1 allergen) did not differ between the cohorts. Sub-analyses comparing offspring conceived after in vitro fertilisation (IVF)[n = 100] and intracytoplasmic sperm injection (ICSI)[n = 40], and fresh and frozen embryo transfers (ETs n = 82, FETs n = 58) within the ART cohort, showed no significant differences, although all allergy outcomes appeared more prevalent in the ET group.

Limitations, reasons for caution

Despite substantial study size, numbers did not allow for adjustment for all covariates. Sub-analyses (IVF vs. ICSI and ET vs. FET), were conducted with limited power and require replication in larger cohorts. Both cohorts were largely of Caucasian decent (&gt;88.0%), which reduces applicability of findings to other ethnicities.

Wider implications of the findings

Reassuringly, adolescents conceived after ART had better lung-function than their counterparts and no differences in asthma prevalence. The reported increase in allergies in ART conceived adolescents is of importance to families and healthcare providers, and opens possibilities for targeted screening and treatment. Further studies are required to confirm our findings.

Trial registration number

Not applicable

Clinical significance and applications of oscillometry

Recently, “Technical standards for respiratory oscillometry” was published, which reviewed the physiological basis of oscillometric measures and detailed the technical factors related to equipment and test performance, quality assurance and reporting of results. Here we present a review of the clinical significance and applications of oscillometry. We briefly review the physiological principles of oscillometry and the basics of oscillometry interpretation, and then describe what is currently known about oscillometry in its role as a sensitive measure of airway resistance, bronchodilator responsiveness and bronchial challenge testing, and response to medical therapy, particularly in asthma and COPD. The technique may have unique advantages in situations where spirometry and other lung function tests are not suitable, such as in infants, neuromuscular disease, sleep apnoea and critical care. Other potential applications include detection of bronchiolitis obliterans, vocal cord dysfunction and the effects of environmental exposures. However, despite great promise as a useful clinical tool, we identify a number of areas in which more evidence of clinical utility is needed before oscillometry becomes routinely used for diagnosing or monitoring respiratory disease.

This paper provides a current review of the interpretation, clinical significance and application of oscillometry in respiratory medicine, with special emphasis on limitations of evidence and suggestions for future research.https://bit.ly/3GQPViA

Does machine learning have a role in the prediction of asthma in children?

Asthma is the most common chronic lung disease in childhood. There has been a significant worldwide effort to develop tools/methods to identify children's risk for asthma as early as possible for preventative and early management strategies. Unfortunately, most childhood asthma prediction tools using conventional statistical models have modest accuracy, sensitivity, and positive predictive value. Machine learning is an approach that may improve on conventional models by finding patterns and trends from large and complex datasets. Thus far, few studies have utilized machine learning to predict asthma in children. This review aims to critically assess these studies, describe their limitations, and discuss future directions to move from proof-of-concept to clinical application.

Characterization of lung function trajectories and associated early life predictors in an Australian birth cohort study

Background

There is growing evidence that lung function in early life predicts later lung function. Adverse events over the lifespan might influence an individual's lung function trajectory, resulting in poor respiratory health. The aim of this study is to identify early-life risk factors and their impact on lung function trajectories to prevent long term lung impairments.

Methods

Our study included participants from the Raine Study – a prospective pregnancy cohort -with at least two spirometry measurements. Lung function trajectories from the six to 22-year follow-ups were characterised using finite mixture modelling. Multinomial logistic regression analyses were used to evaluate the association between early-life predictors and lung function trajectories.

Main results

A total of 1512 participants (768 males, 744 females), representing 53% of the whole cohort, were included in this analysis. Four lung function trajectories of FEV1, FVC and FEV1/FVC (z-scores) were identified. FEV1 and FVC trajectories were categorised as: “very low”, “low”, “average”, and “above average”, respectively. Based on their shape, lung function trajectories of FEV1/FVC were categorised as “very low”, “low-average”, “average-low”, and “average”. Asthma and maternal smoke were identified as risk factors for low lung function trajectories in this cohort, as well as early-life exposure to PM2.5Absorbance.

Conclusions

Early-life risk factors may influence lung function trajectories over time. Nonetheless, identifying children who have a high risk of having low lung function trajectories should be prioritised to prevent deficits in later life.

The ventilatory response to hypoxia is blunted in some preterm infants during the second year of life

BACKGROUND

Preterm birth and subsequent neonatal ventilatory treatment disrupts development of the hypoxic ventilatory response (HVR). An attenuated HVR has been identified in preterm neonates, however it is unknown whether the attenuation persists into the second year of life. We investigated the HVR at 12-15 months corrected postnatal age and assessed predictors of a blunted HVR in those born very preterm (<32 weeks gestation).

METHODS

HVR was measured in infants born very preterm. Hypoxia was induced with a three-step reduction in their fraction of inspired oxygen (F_IO₂) from 0.21 to 0.14. Respiratory frequency (f), tidal volume (V _T), minute ventilation (V _E), inspiratory time (t _I), expiratory time (t _E), V _T/t _I, t_I/t _TOT, V _T/t _TOT, area under the low-volume loop and peak tidal expiratory flow (PTEF) were measured at the first and third minute of each F_IO₂. The change in respiratory variables over time was assessed using a repeated measures ANOVA with Greenhouse-Geisser correction. A blunted HVR was defined as a <10% rise in V _E, from normoxia. The relationship between neonatal factors and the magnitude of HVR was assessed using Spearman correlation.

RESULTS

Thirty nine infants born very preterm demonstrated a mean (SD) HVR of 11.4 (10.1)% (increase in V _E) in response to decreasing F_IO₂ from 0.21 to 0.14. However, 17 infants (44%) failed to increase V _E by ≥10% (range -14% to 9%) and were considered to have a blunted response to hypoxia. Males had a smaller HVR than females [ΔV _E (-9.1%; -15.4, -2.8; p = 0.007)].

CONCLUSION

Infants surviving very preterm birth have an attenuated ventilatory response to hypoxia that persists into the second year of life, especially in males.

Quality of life is poorly correlated to lung disease severity in school-aged children with cystic fibrosis

BACKGROUND

There is no data exclusively on the relationship between health-related quality-of-life (HRQOL) and lung disease severity in early school-aged children with cystic fibrosis (CF). Using data from the Australian Respiratory Early Surveillance Team for Cystic Fibrosis (AREST CF) we assessed the relationships between HRQOL, lung function and structure.

METHODS

125 children aged 6.5-10 years enrolled in the AREST CF program were included from CF clinics at Royal Children's Hospital (RCH), Melbourne (n = 66) and Perth Children's Hospital (PCH), Perth (n = 59), Australia. Demographics, HRQOL measured by Cystic Fibrosis Questionnaire-Revised (CFQ-R), spirometry, multiple-breath washout (MBW) and chest CT were collected across two years. Correlation between CFQ-R scores and lung structure/function parameters and agreement between parent-proxy and child-reported HRQOL were evaluated.

RESULTS

No correlation was observed between most CFQ-R domain scores and FEV1 z-scores, excepting weak-positive correlation with parent CFQ-R Physical (rho = 0.21, CI 0.02-0.37), and Weight (rho = 0.21, CI 0.03-0.38) domain and child Body domain (rho = 0.26, CI 0.00-0.48). No correlation between most CFQ-R domain scores and LCI values was noted excepting weak-negative correlation with parent Respiratory (rho = -0.23, CI ^-0.41-^-0.05), Emotional (rho = -0.24, CI ^-0.43-^-0.04), and Physical (-0.21, CI ^-0.39-^-0.02) domains. Furthermore, structural lung disease on CT data demonstrated little to no association with CFQ-R parent and child domain scores. Additionally, no agreement between child self-report and parent-proxy CFQ-R scores was observed across the majority of domains and visits.

CONCLUSION

HRQOL correlated poorly with lung function and structure in early school-aged children with CF, hence clinical trials should consider these outcomes independently when determining study end-points.

Lung inflammation and simulated airway resistance in infants with cystic fibrosis

Cystic fibrosis (CF) is characterized by small airway disease; but central airways may also be affected. We hypothesized that airway resistance estimated from computational fluid dynamic (CFD) methodology in infants with CF was higher than controls and that early airway inflammation in infants with CF is associated with airway resistance. Central airway models with a median of 51 bronchial outlets per model (interquartile range 46,56) were created from chest computed tomography scans of 18 infants with CF and 7 controls. Steady state airflow into the trachea was simulated to estimate central airway resistance in each model. Airway resistance was increased in the full airway models of infants with CF versus controls and in models trimmed to 33 bronchi. Airway resistance was associated with markers of inflammation in bronchoalveolar lavage fluid obtained approximately 8 months earlier but not with markers obtained at the same time. In conclusion, airway resistance estimated by CFD modeling is increased in infants with CF compared to controls and may be related to early airway inflammation.

Addressing Race in Pulmonary Function Testing by Aligning Intent and Evidence With Practice and Perception

The practice of using race or ethnicity in medicine to explain differences between individuals is being called into question because it may contribute to biased medical care and research that perpetuates health disparities and structural racism. A commonly cited example is the use of race or ethnicity in the interpretation of pulmonary function test (PFT) results, yet the perspectives of practicing pulmonologists and physiologists are missing from this discussion. This discussion has global relevance for increasingly multicultural communities in which the range of values that represent normal lung function is uncertain. We review the underlying sources of differences in lung function, including those that may be captured by race or ethnicity, and demonstrate how the current practice of PFT measurement and interpretation is imperfect in its ability to describe accurately the relationship between function and health outcomes. We summarize the arguments against using race-specific equations as well as address concerns about removing race from the interpretation of PFT results. Further, we outline knowledge gaps and critical questions that need to be answered to change the current approach of including race or ethnicity in PFT results interpretation thoughtfully. Finally, we propose changes in interpretation strategies and future research to reduce health disparities.

Associations between respiratory and vascular function in early childhood

BACKGROUND AND OBJECTIVE

The link between respiratory and vascular health is well documented in adult populations. Impaired lung function is consistently associated with thicker arteries and higher incidence of cardiovascular disease. However, there are limited data on this relationship in young children and the studies that exist have focussed on populations at high risk of cardiorespiratory morbidity. We determined if an association exists between respiratory and cardiovascular function in young children and, if so, whether it is confounded by known cardiorespiratory risk factors.

METHODS

Respiratory and vascular data from a prospective cohort study established to evaluate the health implications 3 years after coal mine fire smoke exposure in children aged 3-5 years were used. Respiratory function was measured using the forced oscillation technique and included resistance at 5 Hz (R₅ ), reactance at 5 Hz (X₅ ) and area under the reactance curve (AX). Vascular health was measured by carotid intima-media thickness (ultrasound) and pulse wave velocity (arterial tonometry). Regression analyses were used to examine the relationship between the respiratory Z-scores and cardiovascular measures. Subsequent analyses were adjusted for potential confounding by maternal smoking during pregnancy, maternal education and exposure to fine particulate matter <2.5 μm in aerodynamic diameter (PM_2.5 ).

RESULTS

Peripheral lung function (X₅ and AX), but not respiratory system resistance (R₅ ), was associated with vascular function. Adjustment for maternal smoking, maternal education and early life exposure to PM_2.5 had minimal effect on these associations.

CONCLUSION

These observations suggest that peripheral lung stiffness is associated with vascular stiffness and that this relationship is established early in life.

Variants associated with HHIP expression have sex-differential effects on lung function

Background: Lung function is highly heritable and differs between the sexes throughout life. However, little is known about sex-differential genetic effects on lung function. We aimed to conduct the first genome-wide genotype-by-sex interaction study on lung function to identify genetic effects that differ between males and females. Methods: We tested for interactions between 7,745,864 variants and sex on spirometry-based measures of lung function in UK Biobank (N=303,612), and sought replication in 75,696 independent individuals from the SpiroMeta consortium. Results: Five independent single-nucleotide polymorphisms (SNPs) showed genome-wide significant (P<5x10 -8) interactions with sex on lung function, and 21 showed suggestive interactions (P<1x10 -6). The strongest signal, from rs7697189 (chr4:145436894) on forced expiratory volume in 1 second (FEV 1) (P=3.15x10 -15), was replicated (P=0.016) in SpiroMeta. The C allele increased FEV 1 more in males (untransformed FEV 1 β=0.028 [SE 0.0022] litres) than females (β=0.009 [SE 0.0014] litres), and this effect was not accounted for by differential effects on height, smoking or pubertal age. rs7697189 resides upstream of the hedgehog-interacting protein ( HHIP) gene and was previously associated with lung function and HHIP lung expression. We found HHIP expression was significantly different between the sexes (P=6.90x10 -6), but we could not detect sex differential effects of rs7697189 on expression. Conclusions: We identified a novel genotype-by-sex interaction at a putative enhancer region upstream of the HHIP gene. Establishing the mechanism by which HHIP SNPs have different effects on lung function in males and females will be important for our understanding of lung health and diseases in both sexes.

Official ERS technical standard: Global Lung Function Initiative reference values for static lung volumes in individuals of European ancestry

BACKGROUND

Measurement of lung volumes across the life course is critical to the diagnosis and management of lung disease. The aim of the study was to use the Global Lung Function Initiative methodology to develop all-age multi-ethnic reference equations for lung volume indices determined using body plethysmography and gas dilution techniques.

METHODS

Static lung volume data from body plethysmography and gas dilution techniques from individual, healthy participants were collated. Reference equations were derived using the LMS (lambda-mu-sigma) method and the generalised additive models of location shape and scale programme in R. The impact of measurement technique, equipment type and being overweight or obese on the derived lung volume reference ranges was assessed.

RESULTS

Data from 17 centres were submitted and reference equations were derived from 7190 observations from participants of European ancestry between the ages of 5 and 80 years. Data from non-European ancestry populations were insufficient to develop multi-ethnic equations. Measurements of functional residual capacity (FRC) collected using plethysmography and dilution techniques showed physiologically insignificant differences and were combined. Sex-specific reference equations including height and age were developed for total lung capacity (TLC), FRC, residual volume (RV), inspiratory capacity, vital capacity, expiratory reserve volume and RV/TLC. The derived equations were similar to previously published equations for FRC and TLC, with closer agreement during childhood and adolescence than in adulthood.

CONCLUSIONS

Global Lung Function Initiative reference equations for lung volumes provide a generalisable standard for reporting and interpretation of lung volumes measurements in individuals of European ancestry.

Pulmonary Gas Exchange Improves over the First Year in Preterm Infants with and without Bronchopulmonary Dysplasia

BACKGROUND

Right shift of the peripheral oxyhaemoglobin saturation (SpO2) versus inspired oxygen pressure (PIO2) curve is a sensitive marker of pulmonary gas exchange.

OBJECTIVES

The aim of this study was to assess the impact of prematurity and bronchopulmonary dysplasia (BPD) on gas exchange and right-to-left shunt in the neonatal period, and its evolution over the first year of life.

METHOD

We assessed shift and shunt in extremely preterm (EP) and very preterm (VP) infants at 36 and 44 weeks' postmenstrual age (PMA), and at 1-year corrected postnatal age (cPNA). PIO2 was decreased stepwise to achieve SpO2 between 85 and 98%. Shift and shunt were calculated from paired SpO2/PIO2 measurements using customized software. Results were examined cross-sectionally at each time point, and longitudinally using generalized linear regression. Term infants were assessed at 44 wk PMA as a comparative reference.

RESULTS

Longitudinal modelling showed continuous decline in shift in EP and VP infants during the first year of life. There was no difference in shift compared to term infants at 44 wk PMA (p = 0.094). EP infants with BPD had higher shift than infants without BPD at 36 wk PMA (p < 0.001) and 44 wk PMA (p = 0.005) but not at 1-year cPNA.

CONCLUSIONS

In the absence of lung disease, prematurity per se did not result in reduced gas exchange at 1-year cPNA. We report ongoing, significant improvements in pulmonary gas exchange in all preterm infants during the first year of life, despite evidence of early deficits in gas exchange in EP infants with BPD.

Lung abnormalities do not influence aerobic capacity in school children born preterm

PURPOSE

Children born preterm have impaired lung function and altered lung structure. However, there are conflicting reports on how preterm birth impacts aerobic exercise capacity in childhood. We aimed to investigate how neonatal history and a diagnosis of bronchopulmonary dysplasia (BPD) impact the relationship between function and structure of the lung, and aerobic capacity in school-aged children born very preterm.

METHODS

Preterm children (≤ 32 w completed gestation) aged 9-12 years with (n = 38) and without (n = 35) BPD, and term-born controls (n = 31), underwent spirometry, lung volume measurements, gas transfer capacity, a high-resolution computer tomography (CT) scan of the chest, and an incremental treadmill exercise test.

RESULTS

Children born preterm with BPD had an elevated breathing frequency to tidal volume ratio compared to term controls (76% vs 63%, p = 0.002). The majority (88%) of preterm children had structural changes on CT scan. There were no differences in peak V̇O₂ (47.1 vs 47.7 mL/kg/min, p = 0.407) or oxygen uptake efficiency slope when corrected for body weight (67.6 vs 67.3, p = 0.5) between preterm children with BPD and term controls. There were no differences in any other exercise outcomes. The severity of structural lung disease was not associated with exercise outcomes in this preterm population.

CONCLUSION

Children born preterm have impaired lung function, and a high prevalence of structural lung abnormalities. However, abnormal lung function and structure do not appear to impact on the aerobic exercise capacity of preterm children at school age.

Variants associated with HHIP expression have sex-differential effects on lung function

Background: Lung function is highly heritable and differs between the sexes throughout life. However, little is known about sex-differential genetic effects on lung function. We aimed to conduct the first genome-wide genotype-by-sex interaction study on lung function to identify genetic effects that differ between males and females. Methods: We tested for interactions between 7,745,864 variants and sex on spirometry-based measures of lung function in UK Biobank (N=303,612), and sought replication in 75,696 independent individuals from the SpiroMeta consortium. Results: Five independent single-nucleotide polymorphisms (SNPs) showed genome-wide significant (P<5x10 -8) interactions with sex on lung function, and 21 showed suggestive interactions (P<1x10 -6). The strongest signal, from rs7697189 (chr4:145436894) on forced expiratory volume in 1 second (FEV 1) (P=3.15x10 -15), was replicated (P=0.016) in SpiroMeta. The C allele increased FEV 1 more in males (untransformed FEV 1 β=0.028 [SE 0.0022] litres) than females (β=0.009 [SE 0.0014] litres), and this effect was not accounted for by differential effects on height, smoking or pubertal age. rs7697189 resides upstream of the hedgehog-interacting protein ( HHIP) gene and was previously associated with lung function and HHIP lung expression. We found HHIP expression was significantly different between the sexes (P=6.90x10 -6), but we could not detect sex differential effects of rs7697189 on expression. Conclusions: We identified a novel genotype-by-sex interaction at a putative enhancer region upstream of the HHIP gene. Establishing the mechanism by which HHIP SNPs have different effects on lung function in males and females will be important for our understanding of lung health and diseases in both sexes.

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.

Association between diesel engine exhaust exposure and lung function in Australian gold miners

Previous studies have reported that miners (and other workers) exposed to high levels of diesel engine exhaust (DEE) have an increased risk of lung function decline. The main objective of this study was to evaluate associations between exposure to different components associated with DEE in relation to lung function across a 12-h working shift. Eighty underground gold miners and twenty surface miners completed spirometry and questionnaires at the beginning and end of their 12 h work shift. Personal exposure to elemental carbon (EC), volatile organic compounds (VOCs), nitrogen dioxide (NO₂), particle size and particle number were monitored during their shift. Multiple regression models were used to examine the associations between DEE and lung function, adjusting for a range of covariates. Underground miners were exposed to higher levels of EC, VOCs, NO₂, and particle number and larger mean particle size than surface miners. Cross-shift reduction in Z-score value of FEV₁/FVC in underground miners was statistically significantly greater than those of surface miners. The cross-shift change in Z-score value of FEV₁/FVC was associated with exposure to higher concentration of EC and particle number, but not with VOCs, NO₂ and particle size. Occupational exposure to diesel engine exhaust in current Australian gold mines is substantial. Exposures were higher in underground miners and had a negative association with their lung function over a single 12-h shift.

Structural determinants of long-term functional outcomes in young children with cystic fibrosis

Background

Accelerated lung function decline in individuals with cystic fibrosis (CF) starts in adolescence with respiratory complications being the most common cause of death in later life. Factors contributing to lung function decline are not well understood, in particular its relationship with structural lung disease in early childhood. Detection and management of structural lung disease could be an important step in improving outcomes in CF patients.

Methods

Annual chest computed tomography (CT) scans were available from 2005 to 2016 as a part of the AREST CF cohort for children aged 3 months to 6 years. Annual spirometry measurements were available for 89.77% of the cohort (167 children aged 5–6 years) from age 5 to 15 years through outpatient clinics at Perth Children's Hospital (Perth, Australia) and The Royal Children's Hospital in Melbourne (Melbourne, Australia) (697 measurements, mean±sd age 9.3±2.1 years).

Results

Children with a total CT score above the median at age 5–6 years were more likely to have abnormal forced expiratory volume in 1 s (FEV1) (adjusted hazard ratio 2.67 (1.06–6.72), p=0.037) during the next 10 years compared to those below the median chest CT score. The extent of all structural abnormalities except bronchial wall thickening were associated with lower FEV1 Z-scores. Mucus plugging and trapped air were the most predictive sub-score (adjusted mean change −0.17 (−0.26 – −0.07) p<0.001 and −0.09 (−0.14 – −0.04) p<0.001, respectively).

Discussion

Chest CT identifies children at an early age who have adverse long-term outcomes. The prevention of structural lung damage should be a goal of early intervention and can be usefully assessed with chest CT. In an era of therapeutics that might alter disease trajectories, chest CT could provide an early readout of likely long-term success.

Technical standards for respiratory oscillometry

Oscillometry (also known as the forced oscillation technique) measures the mechanical properties of the respiratory system (upper and intrathoracic airways, lung tissue and chest wall) during quiet tidal breathing, by the application of an oscillating pressure signal (input or forcing signal), most commonly at the mouth. With increased clinical and research use, it is critical that all technical details of the hardware design, signal processing and analyses, and testing protocols are transparent and clearly reported to allow standardisation, comparison and replication of clinical and research studies. Because of this need, an update of the 2003 European Respiratory Society (ERS) technical standards document was produced by an ERS task force of experts who are active in clinical oscillometry research.The aim of the task force was to provide technical recommendations regarding oscillometry measurement including hardware, software, testing protocols and quality control.The main changes in this update, compared with the 2003 ERS task force document are 1) new quality control procedures which reflect use of "within-breath" analysis, and methods of handling artefacts; 2) recommendation to disclose signal processing, quality control, artefact handling and breathing protocols (e.g. number and duration of acquisitions) in reports and publications to allow comparability and replication between devices and laboratories; 3) a summary review of new data to support threshold values for bronchodilator and bronchial challenge tests; and 4) updated list of predicted impedance values in adults and children.

Normative data for multiple breath washout outcomes in school-aged Caucasian children

Background

The multiple breath nitrogen washout (N2MBW) technique is increasingly used to assess the degree of ventilation inhomogeneity in school-aged children with lung disease. However, reference values for healthy children are currently not available. The aim of this study was to generate reference values for N2MBW outcomes in a cohort of healthy Caucasian school-aged children.

Methods

N2MBW data from healthy Caucasian school-age children between 6 and 18 years old were collected from four experienced centres. Measurements were performed using an ultrasonic flowmeter (Exhalyzer D, Eco Medics AG, Duernten, Switzerland) and were analysed with commercial software (Spiroware version 3.2.1, Eco Medics AG). Normative values and upper limits of normal (ULN) were generated for lung clearance index (LCI) at 2.5% (LCI2.5%) and at 5% (LCI5%) of the initial nitrogen concentration and for moment ratios (M1/M0 and M2/M0). A prediction equation was generated for functional residual capacity (FRC).

Results

Analysis used 485 trials from 180 healthy Caucasian children aged from 6 to 18 years old. While LCI increased with age, this increase was negligible (0.04 units·year–1 for LCI2.5%) and therefore fixed ULN were defined for this age group. These limits were 7.91 for LCI2.5%, 5.73 for LCI5%, 1.75 for M1/M0 and 6.15 for M2/M0, respectively. Height and weight were found to be independent predictors of FRC.

Conclusion

We report reference values for N2MBW outcomes measured on a commercially available ultrasonic flowmeter device (Exhalyzer D, Eco Medics AG) in healthy school-aged children to allow accurate interpretation of ventilation distribution outcomes and FRC in children with lung disease.

Upper Airway Pathology Contributes to Respiratory Symptoms in Children Born Very Preterm

OBJECTIVE

To evaluate the role of upper airway dysfunction, indicated by altered vocal quality (dysphonia), on the respiratory symptoms of children surviving very preterm birth.

STUDY DESIGN

Children born <32 weeks of gestation participated in 2 separate assessments during midchildhood. The first visit assessed voice quality by a subjective evaluation using the Consensus Auditory-Perceptual Evaluation of Voice and a computerized analysis of the properties of the voice via the Acoustic Voice Quality Index. The second assessment recorded parentally reported respiratory symptoms and measures of lung function, including spirometry, lung volumes, oscillatory mechanics, and a cardiopulmonary exercise test.

RESULTS

Preterm children (n = 35; median gestation 24.3 weeks) underwent paired voice and lung assessments at approximately 11 years of age. Preterm children with dysphonia (n = 25) reported significantly more respiratory symptoms than those with normal voices (n = 10) including wheeze (92% vs 40%; P = .001) and asthma diagnosed by a physician (60% vs 10%; P = .007). Lung function outcomes were generally not different between the dysphonic group and the group with normal voice (P > .05), except for the oscillatory mechanics measures, which were all at least 0.5 z score lower in the dysphonic group (Xrs₈ mean difference = -0.91 z scores, P = .003; f_res = 1.06 z scores, P = .019; AX = -0.87 z scores, P = .010; Rrs₈ = 0.63 z scores, P = .068).

CONCLUSIONS

The upper airway may play a role in the respiratory symptoms experienced by some very preterm children and should be considered by clinicians, especially when symptoms are in the presence of normal lung function and are refractory to treatment.

An urgent need for African spirometry reference equations: the Paediatric and Adult African Spirometry study

BACKGROUND: The GLI₂₀₁₂ (Global Lung Initiative 2012) has provided the largest data set to date for multi-ethnic spirometry reference equations; however, data on African populations are limited. In pulmonary function testing, diagnosis of lung disorder is based on comparing the individual's lung function to a reference appropriate for sex and ethnicity.METHODS: We conducted a systematic review of studies reporting spirometry results in healthy children and adults in Africa. Data from these studies were collated for Z-scores of forced expiratory volume in 1 sec (zFEV₁), forced vital capacity (zFVC) and zFEV₁/FVC compared to GLI reference equations.RESULTS: Nine studies, covering a total of 4750 individuals from North, South, East, West and Central Africa (52% were female), were reviewed. Marked differences were noted between individuals from North Africa and sub-Saharan Africa. The Southern zFEV₁ (-0.12 ± 0.98), zFVC (-0.15 ± 0.98) and zFEV₁/FVC (0.05 ± 0.89), Central zFEV₁ (-0.16 ± 0.79), zFVC (-0.09 ± 0.83) and zFEV₁/FVC (-0.17 ± 0.71) and East African zFEV₁ (0.10 ± 0.88), zFVC (0.16 ± 0.85) and zFEV₁/FVC (-0.10 ± 0.95) cohorts had an excellent fit with the GLI-African American. The West African showed a poor fit to all reference equations. The North African group showed the best fit for the GLI Caucasian zFEV₁ (-0.12 ± 1.37), zFVC (-0.26 ± 1.36) and zFEV₁/FVC (0.25 ± 1.11). The zFEV₁/FVC ratios were stable across all the populations.CONCLUSION: Current evidence seems to support the use of GLI₂₀₁₂ reference values in North African and sub-Saharan African populations after taking into account ethnic correction factors.

Long-term medical and psychosocial outcomes in congenital diaphragmatic hernia survivors

OBJECTIVE

Survival rates for congenital diaphragmatic hernia (CDH) are increasing. The long-term outcomes of CDH survivors were compared with a healthy control group to assess the morbidity for guidance of antenatal counselling and long-term follow-up programmes.

PARTICIPANTS AND DESIGN

Participants born with CDH in Western Australia 1993-2008 were eligible with matched controls from the general population. Participants had comprehensive lung function tests, echocardiogram, low-dose chest CT scan and completed a Strengths and Difficulties Questionnaire (SDQ) and quality of life (QOL) questionnaire.

RESULTS

34 matched case-control pairs were recruited. Demographic data between groups were similar. Cases were smaller at follow-up (weight Z-score of -0.2vs0.3; p=0.03; height Z-score of -0.3vs0.6; p=0.01). Cases had lower mean Z-scores for forced expiratory volume in 1 s (FEV₁) (-1.49 vs -0.01; p=0.004), FEV₁/forced vital capacity (-1.92 vs -1.2; p=0.009) and forced expiratory flow at 25-75% (FEF25-75) (-1.18vs0.23; p=0.007). Cases had significantly worse respiratory mechanics using forced oscillation technique. Subpleural triangles architectural distortion, linear opacities and scoliosis on chest CT were significantly higher in cases. Prosthetic patch requirement was associated with worse lung mechanics and peak cough flow. Cases had significantly higher rates of gastro-oesophageal reflux disease (GORD) and GORD medication usage. Developmental delay was significantly higher in cases. More cases had a total difficulties score in the high to very high range (25% vs 0%, p=0.03) on the SDQ and reported lower objective QOL scores (70.2 vs 79.8, p=0.02).

CONCLUSION

Survivors of CDH may have significant adverse long-term medical and psychosocial issues that would be better recognised and managed in a multidisciplinary clinic.

Preschool Multiple-Breath Washout Testing. An Official American Thoracic Society Technical Statement

BACKGROUND

Obstructive airway disease is nonuniformly distributed throughout the bronchial tree, although the extent to which this occurs can vary among conditions. The multiple-breath washout (MBW) test offers important insights into pediatric lung disease, not available through spirometry or resistance measurements. The European Respiratory Society/American Thoracic Society inert gas washout consensus statement led to the emergence of validated commercial equipment for the age group 6 years and above; specific recommendations for preschool children were beyond the scope of the document. Subsequently, the focus has shifted to MBW applications within preschool subjects (aged 2-6 yr), where a "window of opportunity" exists for early diagnosis of obstructive lung disease and intervention.

METHODS

This preschool-specific technical standards document was developed by an international group of experts, with expertise in both custom-built and commercial MBW equipment. A comprehensive review of published evidence was performed.

RESULTS

Recommendations were devised across areas that place specific age-related demands on MBW systems. Citing evidence where available in the literature, recommendations are made regarding procedures that should be used to achieve robust MBW results in the preschool age range. The present work also highlights the important unanswered questions that need to be addressed in future work.

CONCLUSIONS

Consensus recommendations are outlined to direct interested groups of manufacturers, researchers, and clinicians in preschool device design, test performance, and data analysis for the MBW technique.

Effect of Albuterol Premedication vs Placebo on the Occurrence of Respiratory Adverse Events in Children Undergoing Tonsillectomies: The REACT Randomized Clinical Trial

IMPORTANCE

Tonsillectomy is a common pediatric procedure for the treatment of sleep-disordered breathing and chronic tonsillitis. Up to half of children having this procedure experience a perioperative respiratory adverse event.

OBJECTIVE

To determine whether inhaled albuterol sulfate (salbutamol sulfate) premedication decreases the risk of perioperative respiratory adverse events in children undergoing anesthesia for tonsillectomy.

DESIGN, SETTING, AND PARTICIPANTS

A randomized, triple-blind, placebo-controlled trial (the Reducing Anesthetic Complications in Children Undergoing Tonsillectomies [REACT] trial) was conducted at Perth Children's Hospital (formerly Princess Margaret Hospital for Children), the only tertiary pediatric hospital in Western Australia. Participants included 484 children aged 0 to 8 years who were undergoing anesthesia for tonsillectomy. The study was conducted between July 15, 2014, and May 18, 2017.

INTERVENTIONS

Participants were randomized to receive either albuterol (2 actuations, 200 μg) or placebo before their surgery.

MAIN OUTCOMES AND MEASURES

Occurrence of perioperative respiratory adverse events (bronchospasm, laryngospasm, airway obstruction, desaturation, coughing, and stridor) until discharge from the postanesthesia care unit.

RESULTS

Of 484 randomized children (median [range] age, 5.6 [1.6-8.9] years; 285 [58.9%] boys), 479 data sets were available for intention-to-treat analysis. Perioperative respiratory adverse events occurred in 67 of 241 children (27.8%) receiving albuterol and 114 of 238 children (47.9%) receiving placebo. After adjusting for age, type of airway device, and severity of obstructive sleep apnea in a binary logistic regression model, the likelihood of perioperative respiratory adverse events remained significantly higher in the placebo group compared with the albuterol group (odds ratio, 2.8; 95% CI, 1.9-4.2; P < .001). Significant differences were seen in children receiving placebo vs albuterol in laryngospasm (28 [11.8%] vs 12 [5.0%]; P = .009), coughing (79 [33.2%] vs 27 [11.2%]; P < .001), and oxygen desaturation (54 [22.7%] vs 36 [14.9%]; P = .03).

CONCLUSIONS AND RELEVANCE

Albuterol premedication administered before tonsillectomy under general anesthesia in young children resulted in a clinically significant reduction in rates of perioperative respiratory adverse events compared with the rates in children who received placebo. Premedication with albuterol should be considered for children undergoing tonsillectomy.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry identifier: ACTRN12614000739617.

Identifying pediatric lung disease: A comparison of forced oscillation technique outcomes

RATIONALE

Increasing evidence suggests the forced oscillation technique (FOT) has the capacity to provide non-invasive monitoring and diagnosis of respiratory disease in young children. However, which FOT outcomes provide the most pertinent clinical information is currently unknown. The aim of this study was to determine which FOT outcomes were most sensitive for differentiating between health and specific childhood respiratory disease.

METHODS

Respiratory impedance was measured using a commercial device (i2M, Chess Medical, Belgium) in children aged between 3 and 7 years, who had been diagnosed with either cystic fibrosis (N = 84), asthma (N = 99) or were born very preterm (N = 114). Z-scores were calculated for respiratory system resistance (Rrs) and reactance (Xrs) at 6, 8, and 10 Hz, the resonance frequency (Fres), frequency dependence (Fdep_4-24 ), and area under the reactance curve (AX). Pairwise comparisons of the area under the receiver operating characteristic (ROC) curve were used to determine the most relevant FOT variables.

RESULTS AND CONCLUSIONS

The FOT outcomes best able to discern between health and disease were Fres (P < 0.0001) in cystic fibrosis, Fres (P < 0.0001) in asthma and Xrs₈ (P < 0.0001) in children born preterm. These findings suggest the utility of specific FOT outcomes is dependent on the respiratory disease being assessed. It is hoped that a disease-specific approach to interpreting FOT data can help further refine the FOT technique to aid in the diagnosis of children with pediatric respiratory disease.

Bronchodilator responsiveness in children with asthma is not influenced by spacer device selection

INTRODUCTION

Spacer devices optimize delivery of aerosol therapies and maximize therapeutic efficacy. We assessed the impact of spacer device on the prevalence and magnitude of bronchodilator response (BDR) in children with asthma.

METHODS

Children with physician confirmed asthma and parentally reported symptoms in the last 12 months were recruited for this study. Each participant completed two separate visits (5-10 days apart) with spirometry performed at baseline and following cumulative doses of salbutamol (200, 400, 800, and 200 μg) delivered by either a small volume disposable spacer or a large volume multi-use spacer. Spacer type was alternated for each participant during each visit. The primary outcome was the effect of spacer type on bronchodilator responsiveness. The secondary outcome was to assess the relationships between spacer device, salbutamol dose and the proportion of children with a clinically relevant BDR.

RESULTS

Thirty-two children (mean age 11.8 years) completed both visits. Change in lung function following bronchodilators was increased using the large volume spacer, for relative but not absolute increase in FEV₁ [mean difference (95% confidence intervals): 1.28% (0.02, 2.54; P = 0.047) and 0.013 L (-0.01, 0.04; P = 0.288)], respectively. There was no observed difference in FVC by spacer type. Overall, 59% (n = 19) of children exhibited a clinically relevant BDR at 400 µg of salbutamol for any spacer and was independent of spacer type.

CONCLUSION

Spacer device was not associated with clinically important differences in lung function following bronchodilator inhalation in children with asthma. At a recommended dose of 400 μg, some children with asthma may have their bronchodilator responsiveness misclassified.

Single-breath washout and association with structural lung disease in children with cystic fibrosis

BACKGROUND

In children with cystic fibrosis (CF) lung clearance index (LCI) from multiple-breath washout (MBW) correlates with structural lung disease. As a shorter test, single-breath washout (SBW) represents an attractive alternative to assess the ventilation distribution, however, data for the correlation with lung imaging are lacking.

METHODS

We assessed correlations between phase III slope (SIII) of double-tracer gas SBW, nitrogen MBW indices (LCI and moment ratios for overall ventilation distribution, Scond, and Sacin for conductive and mainly acinar ventilation, respectively) and structural lung disease assessed by chest computed tomography (CT) in children with CF.

RESULTS

In a prospective cross-sectional study data from MBW, SBW, and chest CT were obtained in 32 children with CF with a median (range) age of 8.2 (5.2-16.3) years. Bronchiectasis was present in 24 (75%) children and air trapping was present in 29 (91%). Median (IQR) SIII of SBW was -138.4 (150.6) mg/mol. We found no association between SIII with either the MBW outcomes or CT scores (n = 23, association with bronchiectasis extent r = 0.10, P = 0.64). LCI and Scond were associated with bronchiectasis extent (n = 23, r = 0.57, P = 0.004; r = 0.60, P = 0.003, respectively).

CONCLUSIONS

Acinar ventilation inhomogeneity measured by SBW was not associated with structural lung disease on CT. Double-tracer SBW added no benefit to indices measured by MBW.

Maternal Exposure to Indoor Air Pollution and Birth Outcomes

There is a growing body of research on the association between ambient air pollution and adverse birth outcomes. However, people in high income countries spend most of their time indoors. Pregnant women spend much of that time at home. The aim of this study was to investigate if indoor air pollutants were associated with poor birth outcomes. Pregnant women were recruited prior to 18 weeks gestation. They completed a housing questionnaire and household chemical use survey. Indoor pollutants, formaldehyde (HCHO), nitrogen dioxide (NO2) and volatile organic compounds (VOCs), were monitored in the women's homes at 34 weeks gestation. Gestational age (GA), birth weight (BW) and length (BL) and head circumference (HC) were collected from birth records. The associations between measured pollutants, and pollution surrogates, were analysed using general linear models, controlling for maternal age, parity, maternal health, and season of birth. Only HCHO was associated with any of the birth outcomes. There was a 0.044 decrease in BW z-score (p = 0.033) and 0.05 decrease in HC z-score (p = 0.06) for each unit increase in HCHO. Although HCHO concentrations were very low, this finding is consistent with other studies of formaldehyde and poor birth outcomes.