Which reference equation should we use for interpreting spirometry values for First Nations Australians? A cross-sectional study.

OBJECTIVES: To evaluate the suitability of the Global Lung Function Initiative (GLI)-2012 other/mixed and GLI-2022 global reference equations for evaluating the respiratory capacity of First Nations Australians. DESIGN, SETTING: Cross-sectional study; analysis of spirometry data collected by three prospective studies in Queensland, the Northern Territory, and Western Australia between March 2015 and December 2022. PARTICIPANTS: Opportunistically recruited First Nations participants in the Indigenous Respiratory Reference Values study (Queensland, Northern Territory; age, 3-25 years; 18 March 2015 - 24 November 2017), the Healthy Indigenous Lung Function Testing in Adults study (Queensland, Northern Territory; 18 years or older; 14 August 2019 - 15 December 2022) and the Many Healthy Lungs study (Western Australia; five years or older; 10 October 2018 - 7 November 2021). MAIN OUTCOME MEASURES: Goodness of fit to spirometry data for each GLI reference equation, based on mean Z-score and its standard deviation, and proportions of participants with respiratory parameter values within 1.64 Z-scores of the mean value. RESULTS: Acceptable and repeatable forced expiratory volume in the first second (FEV1) values were available for 2700 First Nations participants in the three trials; 1467 were classified as healthy and included in our analysis (1062 children, 405 adults). Their median age was 12 years (interquartile range, 9-19 years; range, 3-91 years), 768 (52%) were female, and 1013 were tested in rural or remote areas (69%). Acceptable and repeatable forced vital capacity (FVC) values were available for 1294 of the healthy participants (88%). The GLI-2012 other/mixed and GLI-2022 global equations provided good fits to the spirometry data; the race-neutral GLI-2022 global equation better accounted for the influence of ageing on FEV1 and FVC, and of height on FVC. Using the GLI-2012 other/mixed reference equation and after adjusting for age, sex, and height, mean FEV1 (estimated difference, -0.34; 95% confidence interval [CI], -0.46 to -0.22) and FVC Z-scores (estimated difference, -0.45; 95% CI, -0.59 to -0.32) were lower for rural or remote than for urban participants, but their mean FEV1/FVC Z-score was higher (estimated difference, 0.14; 95% CI, 0.03-0.25). CONCLUSION: The normal spirometry values of healthy First Nations Australians may be substantially higher than previously reported. Until more spirometry data are available for people in urban areas, the race-neutral GLI-2022 global or the GLI-2012 other/mixed reference equations can be used when assessing the respiratory function of First Nations Australians.

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 (ß: -0.37 [-0.64, -0.10] p = 0.009) and AX (ß: -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.

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.

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.

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 PM2.5 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 PM2.5 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 PM2.5 (daily average or peak). CONCLUSION: There was no detectable effect of in utero exposure to PM2.5 from a local coalmine fire on post-natal lung function 7-years later. However, statistical power was limited.

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.

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.

Asthma and allergies in a cohort of adolescents conceived with ART.

RESEARCH QUESTION: Are asthma and allergies more common in adolescents conceived with assisted reproductive technologies (ART) compared with adolescents conceived without? DESIGN: The Growing Up Healthy Study (GUHS) is a prospective cohort study including ART-conceived offspring born between 1991 and 2001 in Perth, Australia. Their long-term health outcomes, including asthma and allergy parameters, were compared with those of their counterparts conceived without ART from the Raine Study Generation 2 (Gen2), born in 1989-1991. At age 14, 152 GUHS and 1845 Gen2 participants completed the following assessments: the International Studies of Asthma and Allergies in Childhood (ISAAC) questionnaire, spirometry, methacholine challenge testing and skin prick testing (SPT). RESULTS: No differences were detected in the prevalence of current asthma (7.7% versus 10.8%, adjusted odds ratio [aOR] 0.82 (95% CI 0.44-1.52), P = 0.530). Spirometry-measured lung volumes were larger in the ART adolescents. Bronchial hyperresponsiveness was less prevalent in the ART cohort (8.8 versus 18.6%, P = 0.006). Current allergic rhinoconjunctivitis (ARC) rates were significantly higher in the ART cohort (32.4% versus 25.2%, aOR 1.52 [95% CI 1.03-2.26], P = 0.036), with no cohort differences in atopic dermatitis. Food allergies were more prevalent in the ART cohort (20.7 versus 10.9%, aOR 1.89 [95% CI 1.17-3.06], P = 0.010) with more adolescents having a positive SPT (68.0% versus 45.4%, aOR 3.03 [95% 1.99-4.63], P < 0.001). CONCLUSIONS: This study reports no differences in asthma prevalence, slightly altered lung function, an increase in ARC, food allergies and positive SPT in the ART-conceived adolescents. These findings are important to families and healthcare providers and may open up possibilities for targeted screening and treatment. Further studies are required to confirm these findings.

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.

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.

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 (PM2.5 ). 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 PM2.5 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.

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.

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.

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.

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.

Early life exposure to coal mine fire smoke emissions and altered lung function in young children.

BACKGROUND AND OBJECTIVE: Long-term respiratory risks following exposure to relatively short periods of poor air quality early in life are unknown. We aimed to evaluate the association between exposure to a 6-week episode of air pollution from a coal mine fire in children aged <2 years, and their lung function 3 years after the fire. METHODS: We conducted a prospective cohort study. Individual exposure to 24-h average and peak concentrations of particulate matter with an aerodynamic diameter <2.5 µm in diameter (PM2.5 ) during the fire were estimated using dispersion and chemical transport modelling. Lung function was measured using the forced oscillation technique (FOT), generating standardized Z-scores for resistance and reactance at a frequency of 5 Hz (Rrs5 and Xrs5 ), and area under the reactance curve (AX). We used linear regression models to assess the associations between PM2.5 exposure and lung function, adjusted for potential confounders. RESULTS: Of the 203 infants originally recruited, 84 aged 4.3 ± 0.5 years completed FOT testing. Median (interquartile range, IQR) for average and peak PM2.5 were 7.9 (6.8-16.8) and 103.4 (60.6-150.7) µg/m3 , respectively. The mean ± SD Z-scores for Rrs5 , Xrs5 and AX were 0.56 ± 0.80, -0.76 ± 0.88 and 0.72 ± 0.92, respectively. After adjustment for potential confounders including maternal smoking during pregnancy, a 10 µg/m3 increase in average PM2.5 was significantly associated with worsening AX (ß-coefficient: 0.260; 95% CI: 0.019, 0.502), while the association between a 100-µg/m3 increase in peak PM2.5 and AX was borderline (0.166; 95% CI: -0.002, 0.334). CONCLUSION: Infant exposure to coal mine fire emissions could be associated with long-term impairment of lung reactance.

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.

Intra-breath measures of respiratory mechanics in healthy African infants detect risk of respiratory illness in early life.

Lower respiratory tract illness (LRTI) is a leading cause of mortality and morbidity in children. Sensitive and noninvasive infant lung function techniques are needed to measure risk for and impact of LRTI on lung health. The objective of this study was to investigate whether lung function derived from the intra-breath forced oscillation technique (FOT) was able to identify healthy infants at risk of LRTI in the first year of life.Lung function was measured with the novel intra-breath FOT, in 6-week-old infants in a South African birth cohort (Drakenstein Child Health Study). LRTI during the first year was confirmed by study staff. The association between baseline lung function and LRTI was assessed with logistic regression and odds ratios determined using optimal cut-off values.Of the 627 healthy infants with successful lung function testing, 161 (24%) had 238 LRTI episodes subsequently during the first year. Volume dependence of respiratory resistance (ΔR) and reactance (ΔX) was associated with LRTI. The predictive value was stronger if LRTI was recurrent (n=50 (31%): OR 2.5, ΔX), required hospitalisation (n=38 (16%): OR 5.4, ΔR) or was associated with wheeze (n=87 (37%): OR 3.9, ΔX).Intra-breath FOT can identify healthy infants at risk of developing LRTI, wheezing or severe illness in the first year of life.

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; fres = 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.