Techniques of assessing small airways dysfunction

Small airway disease and its predictors in patients with rheumatoid arthritis

BACKGROUND

Rheumatoid arthritis (RA) is a connective tissue disease, characterized by symmetric peripheral polyarthritis. Extra-articular disease occurs in approximately 50% of the patients with lung being a common site. The presence of functional or morphological abnormalities in small airways has recently been noted in patients with RA but its exact prevalence and clinical significance is still a subject of debate. This study was aimed to determine the prevalence of small airway disease (SAD) in patients with RA and the factors influencing it.

METHODS

Fifty consecutive patients with RA were included in this cross-sectional observational study. All patients were subjected to pulmonary function tests (PFT) including Spirometry and Forced Oscillation technique (FOT). Those with features of SAD on PFT were subjected to High-Resolution Computed Tomography (HRCT) of the chest.

RESULTS

Spirometry was suggestive of SAD in 17 patients, with 34% prevalence and FOT was abnormal in 9 patients, with 18% prevalence in the study population. Of 17 patients with SAD on spirometry, 8 (47.05%) patients showed mosaic attenuation, a sign of SAD on the HRCT chest. On univariate analysis, age, Disease Activity Score (DAS-28), joint erosions on X-ray, RF and anti-CCP were found to be associated with SAD.

CONCLUSION

SAD was present in one-third of the patients with RA, even in those with short duration of disease, low to moderate disease activity and no respiratory symptoms. It is thus inferred that the complete workup of RA patients should include pulmonary function assessment.

Forced Expiratory Flow at 25%-75% Links COPD Physiology to Emphysema and Disease Severity in the SPIROMICS Cohort

BACKGROUND

Forced expiratory volume in 1 second (FEV₁) is central to the diagnosis of chronic obstructive pulmonary disease (COPD) but is imprecise in classifying disease burden. We examined the potential of the maximal mid-expiratory flow rate (forced expiratory flow rate between 25% and 75% [FEF_25%-75%]) as an additional tool for characterizing pathophysiology in COPD.

OBJECTIVE

To determine whether FEF_25%-75% helps predict clinical and radiographic abnormalities in COPD.

STUDY DESIGN AND METHODS

The SubPopulations and InteRediate Outcome Measures In COPD Study (SPIROMICS) enrolled a prospective cohort of 2978 nonsmokers and ever-smokers, with and without COPD, to identify phenotypes and intermediate markers of disease progression. We used baseline data from 2771 ever-smokers from the SPIROMICS cohort to identify associations between percent predicted FEF_25%-75% (%predFEF_25%-75%) and both clinical markers and computed tomography (CT) findings of smoking-related lung disease.

RESULTS

Lower %predFEF_25-75% was associated with more severe disease, manifested radiographically by increased functional small airways disease, emphysema (most notably with homogeneous distribution), CT-measured residual volume, total lung capacity (TLC), and airway wall thickness, and clinically by increased symptoms, decreased 6-minute walk distance, and increased bronchodilator responsiveness (BDR). A lower %predFEF_25-75% remained significantly associated with increased emphysema, functional small airways disease, TLC, and BDR after adjustment for FEV₁ or forced vital capacity (FVC).

INTERPRETATION

The %predFEF_25-75% provides additional information about disease manifestation beyond FEV₁. These associations may reflect loss of elastic recoil and air trapping from emphysema and intrinsic small airways disease. Thus, %predFEF_25-75% helps link the anatomic pathology and deranged physiology of COPD.

Self-reported exercise-induced dyspnea and airways obstruction assessed by oscillometry and spirometry in adolescents

BACKGROUND

Self-reported exercise-induced dyspnea (EID) is common among adolescents. Possible underlying pathologies are exercise-induced bronchoconstriction (EIB) and laryngeal obstruction (EILO). The forced oscillation technique (FOT) may evaluate exercise-induced changes in airway caliber.

AIM

To investigate in adolescents the relationship between EID, EIB (post-exercise fall in forced expiratory volume in 1s (FEV₁ )≥10%), EILO, and post-exercise challenge changes in FOT parameters.

METHODS

One hundred and forty-three subjects (97 with EID) of 13-15 years old underwent a standardized exercise challenge with FOT measurement and spirometry repeatedly performed between 2 and 30 min post-exercise. EILO was studied in a subset of 123 adolescents. Subjects showing greater changes than the healthy subgroup in the modulus of the inspiratory impedance were considered FOT responders.

RESULTS

EID-nonEIB subjects presented similar post-exercise changes in all FOT parameters to nonEID-nonEIB adolescents. Changes in all FOT parameters correlated with FEV₁ fall. 45 of 97 EID subjects responded neither by FEV₁ nor FOT to exercise. 19 and 18 subjects responded only by FEV₁ (onlyFEV₁ responders) or FOT (onlyFOTresponders), respectively. Only a lower baseline forced vital capacity (FVC)%predicted and a higher FEV₁ /FVC distinguished the onlyFEV₁ responders from onlyFOTresponders. FOT parameters did not present specific post-exercise patterns in EILO subjects.

CONCLUSION

FOT can be used to identify post-exercise changes in lower airway function. However, EID has a modest relation with both FEV₁ and FOT responses, highlighting the need for objective testing. More research is needed to understand whether onlyFEV₁ responders and onlyFOTresponders represent different endotypes.

Long-term Ozone Exposure and Small Airways Dysfunction: The China Pulmonary Health (CPH) Study

RATIONALE

It remains unknown whether long-term ozone exposure can impair lung function.

OBJECTIVES

To investigate the associations between long-term ozone exposure and adult lung function in China.

METHODS

Lung function results and diagnosis of small airways dysfunction (SAD) were collected from a cross-sectional study, China Pulmonary Health Study (N=50,991). We used multivariate linear and logistic regression models to examine the associations of long-term ozone exposure with lung function parameters and SAD, respectively, adjusting for demographic characteristics, individual risk factors, and longitudinal trend. We then performed a stratification analysis by chronic obstructive pulmonary disease (COPD).

MEASUREMENTS AND MAIN RESULTS

We observed each 1-standard deviation (SD, 4.9 ppb) increase in warm-season ozone concentrations was associated with a 14.2 mL/s [95% confidence interval (CI): 8.8, 19.6] decrease in forced expiratory flow at 75th percentile of vital capacity and a 29.5 mL/s (95% CI: 19.6, 39.5) decrease in mean forced expiratory flow between the 25th and 75th percentile of vital capacity. The odds ratio of SAD was 1.09 (95% CI: 1.06, 1.11) for a 1-SD increase in warm-season ozone concentrations. Meanwhile, we observed a significant association with a decreased ratio of expiratory volume in 1 second to forced vital capacity (FEV1/FVC) but not with FEV1 or FVC. The association estimates were greater in the COPD group than in the non-COPD group.

CONCLUSION

We found independent associations of long-term ozone exposure with impaired small airways function and higher SAD risks, while the associations with airflow obstruction were weak. COPD patients appear to be more vulnerable.

Airway mucin MUC5AC and MUC5B concentrations and the initiation and progression of chronic obstructive pulmonary disease: an analysis of the SPIROMICS cohort

BACKGROUND

We previously described the contributions of increased total airway mucin concentrations to the pathogenesis and diagnosis of the chronic bronchitic component of chronic obstructive pulmonary disease (COPD). Here, we investigated the relative contribution of each of the major airway gel-forming mucins, MUC5AC and MUC5B, to the initiation, progression, and early diagnosis of airways disease in COPD.

METHODS

SPIROMICS was a multicentre, observational study in patients aged 40-80 years recruited from six clinical sites and additional subsites in the USA. In this analysis, MUC5AC and MUC5B were quantitated by stable isotope-labelled mass spectrometry in induced sputum samples from healthy never-smokers, ever-smokers at risk for COPD, and ever-smokers with COPD. Participants were extensively characterised using results from questionnaires, such as the COPD assessment test (CAT) and St George's Respiratory Questionnaire; quantitative CT, such as residual volume/total lung capacity ratio (RV/TLC) and parametric response mapping-functional small airway disease (PRM-fSAD); and pulmonary function tests, such as FEV1, forced vital capacity (FVC), and forced expiratory flow, midexpiratory phase (FEF25-75%). Absolute concentrations of both MUC5AC and MUC5B were related to cross-sectional (baseline, initial visit) and 3-year follow-up longitudinal data, including lung function, small airways obstruction, prospective acute exacerbations, and smoking status as primary outcomes. This study is registered with ClinicalTrials.gov (NCT01969344).

FINDINGS

This analysis included 331 participants (mean age 63 years [SEM 9·40]), of whom 40 were healthy never-smokers, 90 were at-risk ever-smokers, and 201 were ever-smokers with COPD. Increased MUC5AC concentrations were more reliably associated with manifestations of COPD than were MUC5B concentrations, including decreased FEV1 and FEF25-75%, and increased prospective exacerbation frequency, RV/TLC, PRM-fSAD, and COPD assessment scores. MUC5AC concentrations were more reactive to cigarette smoke exposure than were MUC5B concentrations. Longitudinal data from 3-year follow-up visits generated a multivariate-adjusted odds ratio for two or more exacerbations of 1·24 (95% CI 1·04-1·47, p=0·015) for individuals with high baseline MUC5AC concentration. Increased MUC5AC, but not MUC5B, concentration at baseline was a significant predictor of FEV1, FEV1/FVC, FEF25-75%, and CAT score decline during the 3-year follow-up. Moreover, current smokers in the at-risk group showed raised MUC5AC concentrations at initial visits and decreased lung function over 3 years. By contrast, former smokers in the at-risk group showed normal MUC5AC concentrations at the initial visit and preserved lung function over 3 years.

INTERPRETATION

These data indicate that increased MUC5AC concentration in the airways might contribute to COPD initiation, progression, exacerbation risk, and overall pathogenesis. Compared with MUC5B, greater relative changes in MUC5AC concentrations were observed as a function of COPD severity, and MUC5AC concentration seems to be an objective biomarker to detect disease in at-risk and pre-COPD individuals. These data suggest that MUC5AC-producing pathways could be potential targets for future therapeutic strategies. Thus, MUC5AC could be a novel biomarker for COPD prognosis and for testing the efficacy of therapeutic agents.

FUNDING

National Institutes of Health; National Heart, Lung, and Blood Institute.

Small-airway disease and its reversibility in human immunodeficiency virus-infected children on highly active antiretroviral therapy: A cross-sectional study in an African setting

BACKGROUND:

Lung function abnormalities may occur in children with human immunodeficiency virus (HIV) infection. Small-airway disease (SAD) precedes abnormalities in forced expiratory volume in 1 s (FEV ₁).

OBJECTIVE:

This study aims to assess the presence and reversibility of SAD in HIV-infected children using the Global Lung Function Initiative standards.

METHODS:

A cross-sectional study was conducted over 6 months at the Paediatric HIV Clinic of the University of Nigeria Teaching Hospital in Enugu, Southeast Nigeria. Eligible consenting children with HIV infection were recruited. Lung function was measured, and the reversibility of FEV₁ and forced vital capacity (FVC) was assessed at 12% while that of forced expiratory flow between 25% and 75% (FEF_25-75) was assessed at 12%, 15%, and 20%. Predictors of abnormal Z-score values were determined by multivariate linear and logistic regressions. Statistically significant values were set at P < 0.05.

RESULTS:

The mean Z-score for FEV₁, FVC, and FEF_25-75 was − 2.19, −1.86, and − 1.60, respectively. Most patients (73%) had abnormal FEV₁, while 52% had abnormal FEF_25-75. Significant changes in FEV₁ (P = 0.001) and FEF_25-75 (P < 0.001) occurred after the bronchodilator response (BDR) test. Of the children whose FEV₁ showed positive BDR, 70.9% had low zFEV_1; 50% had low zFEF_25-75, while all had low FEV_1. Nutritional status (Z-score for body mass index) was significantly associated with low FEV_1.

CONCLUSIONS:

Abnormal FEF_25-75 as a marker of SAD and FEV₁ with a positive BDR are common in HIV-infected children. These lung function abnormalities justify long-term follow-up for these patients.

Why We Should Target Small Airways Disease in Our Management of Chronic Obstructive Pulmonary Disease

For more than 50 years, small airways disease has been considered a key feature of chronic obstructive pulmonary disease (COPD) and a major cause of airway obstruction. Both preventable and treatable, small airways disease has important clinical consequences if left unchecked. Small airways disease is associated with poor spirometry results, increased lung hyperinflation, and poor health status, making the small airways an important treatment target in COPD. The early detection of small airways disease remains the key barrier; if detected early, treatments designed to target small airways may help reduce symptoms and allow patients to maintain their activities. Studies are needed to evaluate the possible role of new drugs and novel drug formulations, inhalers, and inhalation devices for treating small airways disease. These developments will help to improve our management of small airways disease in patients with COPD.

Asthma, bronchial hyperresponsiveness, allergy and lung function development until early adulthood: A systematic literature review

BACKGROUND

It is unclear in which periods of life lung function deficits develop, and whether these are affected by risk factors such as asthma, bronchial hyper-responsiveness (BHR) and allergic comorbidity. The goal of this systematic review was to identify temporal associations of asthma, BHR and allergic comorbidity with large and small lung function development from birth until peak function in early adulthood.

METHODS

We searched MEDLINE, EMBASE, Web of Science and CINAHL for papers published before 01.01.2020 on risk factors and lung function measurements of large and small airways. Studies were required to report lung function at any time point or interval from birth until peak lung function (age 21-26) and include at least one candidate risk factor.

RESULTS

Of the 45 papers identified, 44 investigated cohorts and one was a clinical trial with follow-up. Asthma, wheezing, BHR and allergic sensitization early in life and to multiple allergens were associated with a lower lung function growth of large and small airways during early childhood compared with the control populations. Lung function development after childhood in subjects with asthma or persistent wheeze, although continuing to grow at a lower level, largely tracked parallel to non-affected individuals until peak function was attained.

CLINICAL IMPLICATIONS AND FUTURE RESEARCH

Deficits in lung function growth develop in early childhood, and children with asthma, BHR and early-life IgE (poly)sensitization are at risk. This period is possibly a critical window of opportunity to identify at-risk subjects and provide treatment aimed at preventing long-term sequelae of lung function.

Novel measure of lung function for assessing disease activity in asthma

Introduction

In asthma, lung function measures are often discordant with clinical features such as disease activity or control.

Methods

We investigated a novel technique that provides a measure (σCL) of unevenness (inhomogeneity) in lung inflation/deflation. In particular, we compared σCL with FEV₁% predicted (FEV₁%pred) as measures of disease activity in the asthmatic lung.

Results

σCL correlated modestly with FEV₁%pred. However, σCL is not simply a proxy for FEV₁%pred as the effects of salbutamol on the two parameters were unrelated. Importantly, σCL reflected disease control better than FEV₁.

Discussion

We conclude that σCL shows promise as an objective measure of disease activity in asthma.

Seven Pillars of Small Airways Disease in Asthma and COPD: Supporting Opportunities for Novel Therapies

Identification of pathologic changes in early and mild obstructive lung disease has shown the importance of the small airways and their contribution to symptoms. Indeed, significant small airways dysfunction has been found prior to any overt airway obstruction being detectable by conventional spirometry techniques. However, most therapies for the treatment of obstructive lung disease target the physiological changes and associated symptoms that result from chronic lung disease, rather than directly targeting the specific underlying causes of airflow disruption or the drivers of disease progression. In addition, although spirometry is the current standard for diagnosis and monitoring of response to therapy, the most widely used measure, FEV1 , does not align with the pathologic changes in early or mild disease and may not align with symptoms or exacerbation frequency in the individual patient. Newer functional and imaging techniques allow more effective assessment of small airways dysfunction; however, significant gaps in our understanding remain. Improving our knowledge of the role of small airways dysfunction in early disease in the airways, along with the identification of novel end points to measure subclinical changes in this region (ie, those not captured as symptoms or identified through standard FEV1), may lead to the development of novel therapies that directly combat early airways disease processes with a view to slowing disease progression and reversing damage. This expert opinion paper discusses small airways disease in the context of asthma and COPD and highlights gaps in current knowledge that impede earlier identification of obstructive lung disease and the development and standardization of novel small airways-specific end points for use in clinical trials.

Association of fine particulate matter air pollution and its constituents with lung function: The China Pulmonary Health study

The associations of long-term exposure to various constituents of fine particulate matter (≤2.5 μm in aerodynamic diameter, PM_2.5) air pollution with lung function were not clearly elucidated in developing countries. The aim was to evaluate the associations of long-term exposure to main constituents of PM_2.5 with lung function in China. This is a nationwide, cross-sectional analysis among 50,991 study participants from the China Pulmonary Health study. Multivariable linear regression models were used to obtain differences of forced expiratory volume in 1 s (FEV₁), forced vital capacity (FVC), FEV₁/FVC, peak expiratory flow (PEF), and forced expiratory flow at 25-75% of exhaled FVC (FEF_25-75%) associated with an interquartile range (IQR) change of PM_2.5 or its constituents. Residential annual PM_2.5 levels varied from 26 μg/m³ to 92 μg/m³ (average: 53 μg/m³). An IQR increase of PM_2.5 concentrations was associated with lower FEV₁ (19.82 mL, 95% CI: 11.30-28.33), FVC (17.45 mL, 95% CI: 7.16-27.74), PEF (86.64 mL/s, 95% CI: 59.77-113.52), and FEF_25-75% (31.93 mL/s, 95% CI: 16.64-47.22). Black carbon, organic matter, ammonium, sulfate, and nitrate were negatively associated with most lung function indicators, with organic matter and nitrate showing consistently larger magnitude of associations than PM_2.5 mass. This large-scale study provides first-hand epidemiological evidence that long-term exposure to ambient PM_2.5 and some constituents, especially organic matter and nitrate, were associated with lower large- and small- airway function.

Predicting Lung Deposition of Extrafine Inhaled Corticosteroid-Containing Fixed Combinations in Patients with Chronic Obstructive Pulmonary Disease Using Functional Respiratory Imaging: An In Silico Study

Background: Functional respiratory imaging (FRI) is a computational fluid dynamics-based technique using three-dimensional models of human lungs and formulation profiles to simulate aerosol deposition. Methods: FRI was used to evaluate lung deposition of extrafine beclomethasone dipropionate (BDP)/formoterol fumarate (FF)/glycopyrronium bromide (GB) and extrafine BDP/FF delivered through pressurized metered dose inhalers and to compare results with reference gamma scintigraphy data. FRI combined high-resolution computed tomography scans of 20 patients with moderate-to-severe chronic obstructive pulmonary disease (mean forced expiratory volume in 1 second 42% predicted) with in silico computational flow simulations, and incorporated drug delivery parameters to calculate aerosol airway deposition. Inhalation was simulated using profiles obtained from real-life measurements. Results: Total lung deposition (proportion deposited in intrathoracic region) was similarly high for both products, with mean ± standard deviation (SD) values of 31.0% ± 5.7% and 28.1% ± 5.2% (relative to nominal dose) for BDP/FF/GB and BDP/FF, respectively. Pairwise comparison of the deposition of BDP and FF gave a mean intrathoracic BDP/FF/GB:BDP/FF deposition ratio of 1.10 (p = 0.0405). Mean intrathoracic, central and peripheral deposition ratios for BDP were 1.09 (95% confidence interval [CI]: 1.05-1.14), 0.92 (95% CI: 0.89-0.96), and 1.20 (95% CI: 1.15-1.26), respectively, and for FF were 1.11 (95% CI: 1.07-1.15), 0.94 (95% CI: 0.91-0.98), and 1.21 (95% CI: 1.15-1.27), within the bioequivalence range (0.80-1.25) for intrathoracic and central regions, and slightly exceeding the upper boundary in the peripheral region. Mean ± SD central:peripheral deposition (C:P) was 0.48 ± 0.13 for BDP/FF/GB and 0.62 ± 0.17 for BDP/FF, indicating a higher proportion of drug deposition in the small airways than in the large airways. Conclusion: FRI demonstrated similar deposition patterns for extrafine BDP/FF/GB and BDP/FF, with both having a high lung deposition. Moreover, the deposition patterns of BDP and FF were similar in both products. Furthermore, the C:P ratios of both products indicated a high peripheral deposition, supporting small airway targeting and delivery of these two extrafine fixed combinations, with a small difference in ratios potentially due to mass median aerodynamic diameters.

Small airway dysfunction and poor asthma control: a dangerous liaison

Asthma is a common chronic condition, affecting approximately 339 million people worldwide. The main goal of the current asthma treatment guidelines is to achieve clinical control, encompassing both the patient symptoms and limitations and the future risk of adverse asthma outcomes. Despite randomized controlled trials showing that asthma control is an achievable target, a substantial proportion of asthmatics remain poorly controlled in real life. The involvement of peripheral small airways has recently gained greater recognition in asthma, and many studies suggest that the persistent inflammation at these sites leads to small airway dysfunction (SAD), strongly contributing to a worse asthma control. Overall, the impulse oscillometry (IOS), introduced in the recent years, seems to be able to sensitively assess small airways, while conventional spirometry does not. Therefore, IOS may be of great help in characterizing SAD and guiding therapy choice. The aim of this article is to review the literature on SAD and its influence on asthma control, emphasizing the most recent evidence.

Blood eosinophils, FeNO and small airways dysfunction in predicting airway hyperresponsiveness in patients with asthma-like symptoms

PURPOSE

In patients with suspected asthma and no airflow limitation in spirometry, methacholine challenge testing (MCT) for airway hyperresponsiveness (AHR) is an option of documenting variable airflow limitation. The goal of the study was to assess the ability of blood eosinophils, fractional concentration of exhaled nitric oxide (FeNO) and distal airways function to discriminate patients with AHR from those with normal airway responsiveness (AR).

METHODS

We analyzed baseline data from 42 participants who underwent MCT because of asthma-like symptoms and no airflow limitation in spirometry.

RESULTS

Eosinophil count was higher among participants with borderline AHR comparing to those with normal AR (340 cells/µL, IQR 285-995 vs. 125 cells/µL, IQR 75-180, post-hoc p = 0.041). FeNO and percent predicted of functional residual volume (FRC%pred) were higher in participants with moderate-marked AHR compared to those with normal AR (40 ppb, IQR 30.5-100.5 vs. 18 ppb, IQR 13-50, post-hoc p = 0.008; 140.1%±17.0% vs. 107.3%±20.7%, post-hoc p < 0.001, respectively). Percentage predicted of the maximal expiratory flow at 25% of the forced vital capacity (MEF₂₅%pred) was lower in participants with mild AHR and borderline AHR compared to those with normal AR (72.9%±16.9% vs. 113.0%±36.8%, post-hoc p = 0.017; 73.3%±15.9% vs. 113.0%±36.8%, post-hoc p = 0.045; respectively). Level of AHR correlated with eosinophil count, FeNO, MEF₂₅%pred, forced expiratory flow between 25% and 75% of vital capacity (FEF_25-75%pred), FRC%pred and specific airway resistance (sR_aw).

CONCLUSIONS

Blood eosinophils, FeNO and small airways dysfunction markers are related to the level of AR to methacholine in patients with asthma-like symptoms and no airflow limitation in spirometry.

Causal Effects of Body Mass Index on Airflow Obstruction and Forced Mid-Expiratory Flow: A Mendelian Randomization Study Taking Interactions and Age-Specific Instruments Into Consideration Toward a Life Course Perspective

Obesity has complex links to respiratory health. Mendelian randomization (MR) enables assessment of causality of body mass index (BMI) effects on airflow obstruction and mid-expiratory flow. In the adult SAPALDIA cohort, recruiting 9,651 population-representative samples aged 18–60 years at baseline (female 51%), BMI and the ratio of forced expiratory volume in 1 second (FEV₁) to forced vital capacity (FVC) as well as forced mid-expiratory flow (FEF25–75%) were measured three times over 20 follow-up years. The causal effects of BMI in childhood and adulthood on FEV1/FVC and FEF25–75% were assessed in predictive (BMI averaged over 1st and 2nd, lung function (LF) averaged over 2nd and 3rd follow-up; N = 2,850) and long-term cross-sectional models (BMI and LF averaged over all follow-ups; N = 2,728) by Mendelian Randomization analyses with the use of weighted BMI allele score as an instrument variable and two-stage least squares (2SLS) method. Three different BMI allele scores were applied to specifically capture the part of BMI in adulthood that likely reflects tracking of genetically determined BMI in childhood. The main causal effects were derived from models containing BMI (instrumented by BMI genetic score), age, sex, height, and packyears smoked as covariates. BMI interactions were instrumented by the product of the instrument (BMI genetic score) and the relevant concomitant variable. Causal effects of BMI on FEV1/FVC and FEF25–75% were observed in both the predictive and long-term cross-sectional models. The causal BMI- LF effects were negative and attenuated with increasing age, and stronger if instrumented by gene scores associated with childhood BMI. This non-standard MR approach interrogating causal effects of multiplicative interaction suggests that the genetically rooted part of BMI patterns in childhood may be of particular relevance for the level of small airway function and airflow obstruction later in life. The methodological relevance of the results is first to point to the importance of a life course perspective in studies on the etiological role of BMI in respiratory health, and second to point out novel methodological aspects to be considered in future MR studies on the causal effects of obesity related phenotypes.

Ventilation Heterogeneity in Asthma and COPD: The Value of the Poorly Communicating Fraction as the Ratio of Total Lung Capacity to Alveolar Volume

BACKGROUND

The ventilation heterogeneity (VH) is reliably assessed by the multiple-breath nitrogen washout (MBNW), which provides indices of conductive (Scond) and acinar (Sacin) VH as well as the lung clearance index (LCI), an index of global VH. VH can be alternatively measured by the poorly communicating fraction (PCF), that is, the ratio of total lung capacity by body plethysmography to alveolar volume from the single-breath lung diffusing capacity measurement.

OBJECTIVES

Our objective was to assess VH by PCF and MBNW in patients with asthma and with COPD and to compare PCF and MBNW parameters in both patient groups.

METHOD

We studied 35 asthmatic patients and 45 patients with COPD. Each patient performed spirometry, body plethysmography, diffusing capacity, and MBNW test.

RESULTS

Compared to COPD patients, asthmatics showed a significantly lesser degree of airflow obstruction and lung hyperinflation. In asthmatic patients, both PCF and LCI and Sacin values were significantly lower than the corresponding ones of COPD patients. In addition, in both patient groups, PCF showed a positive correlation with LCI (p < 0.05) and Sacin (p < 0.05), but not with Scond. Lastly, COPD patients with PCF >30% were highly likely to have a value ≥2 of the mMRC dyspnea scale.

CONCLUSIONS

These results showed that PCF, a readily measure derived from routine pulmonary function testing, can provide a comprehensive measure of both global and acinar VH in asthma and in COPD patients and can be considered as a comparable tool to the well-established MBNW technique.

Chronic exposure to diesel exhaust may cause small airway wall thickening without lumen narrowing: a quantitative computerized tomography study in Chinese diesel engine testers

Background

Diesel exhaust (DE) is a major source of ultrafine particulate matters (PM) in ambient air and contaminates many occupational settings. Airway remodeling assessed using computerized tomography (CT) correlates well with spirometry in patients with obstructive lung diseases. Structural changes of small airways caused by chronic DE exposure is unknown. Wall and lumen areas of 6th and 9th generations of four candidate airways were quantified using end-inhalation CT scans in 78 diesel engine testers (DET) and 76 non-DETs. Carbon content in airway macrophage (CCAM) in sputum was quantified to assess the dose-response relationship.

Results

Environmental monitoring and CCAM showed a much higher PM exposure in DETs, which was associated with higher wall area and wall area percent for 6th generation of airways. However, no reduction in lumen area was identified. No study subjects met spirometry diagnosis of airway obstruction. This suggested that small airway wall thickening without lumen narrowing may be an early feature of airway remodeling in DETs. The effect of DE exposure status on wall area percent did not differ by lobes or smoking status. Although the trend test was of borderline significance between categorized CCAM and wall area percent, subjects in the highest CCAM category has a 14% increase in wall area percent for the 6th generation of airways compared to subjects in the lowest category. The impact of DE exposure on FEV1 can be partially explained by the wall area percent with mediation effect size equal to 20%, P_perm = 0.028).

Conclusions

Small airway wall thickening without lumen narrowing may be an early image feature detected by CT and underlie the pathology of lung injury in DETs. The pattern of changes in small airway dimensions, i.e., thicker airway wall without lumen narrowing caused by occupational DE exposure was different to that (i.e., thicker airway wall with lumen narrowing) seen in our previous study of workers exposed to nano-scale carbon black aerosol, suggesting constituents other than carbon cores may contribute to such differences. Our study provides some imaging indications of the understanding of the pulmonary toxicity of combustion derived airborne particulate matters in humans.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12989-021-00406-1.

Outdoor pollen-related changes in lung function and markers of airway inflammation: A systematic review and meta-analysis

BACKGROUND

Experimental challenge studies have shown that pollen can have early and delayed effects on the lungs and airways. Here, we qualitatively and quantitatively synthesize the evidence of outdoor pollen exposure on various lung function and airway inflammation markers in community-based studies.

METHODS

Four online databases were searched: Medline, Web of Science, CINAHL and Google Scholar. The search strategy included terms relating to both exposure and outcomes. Inclusion criteria were human-based studies published in English that were representative of the community. Additionally, we only considered cross-sectional or short-term longitudinal studies which investigated pollen exposure by levels or season. Study quality assessment was performed using the Newcastle-Ottawa scale. Meta-analysis was conducted using random-effects models.

RESULTS

We included 27 of 6551 studies identified from the search. Qualitative synthesis indicated associations between pollen exposure and predominantly type-2 inflammation in both the upper and lower airways, but little evidence for lung function changes. People with ever asthma and/or seasonal allergic rhinitis (SAR) were at higher risk of such airway inflammation. Meta-analysis confirmed a positive relationship between pollen season, eosinophilia and eosinophil cationic protein (ECP) in people with ever SAR but the results between studies were highly variable. Heterogeneity was reduced after further subgrouping by age, and the forest plots indicated that eosinophilic airway inflammation to outdoor pollen exposure increased with age.

CONCLUSION

Among people with ever asthma and ever SAR, exposure to increased ambient pollen triggers type-2 upper and lower airway inflammation rather than a non-specific or innate inflammation. These findings can lead to the formulation of specific pollen immunotherapy for susceptible individuals. Future research should be directed towards investigating lagged associations and effect modifications using larger and more generalized populations.

SYSTEMATIC REVIEW REGISTRATION

CRD42020146981 (PROSPERO).

Small Airways Disease, Biomarkers and COPD: Where are We?

The response to treatment and progression of Chronic Obstructive Pulmonary Disease (COPD) varies significantly. Small airways disease (SAD) is being increasingly recognized as a key pathological feature of COPD. Studies have brought forward pathological evidence of small airway damage preceding the development of emphysema and the detection of obstruction using traditional spirometry. In recent years, there has been a renewed interest in the early detection of SAD and this has brought along an increased demand for physiological tests able to identify and quantify SAD. Early detection of SAD allows early targeted therapy and this suggests the potential for altering the course of disease. The aim of this article is to review the evidence available on the physiological testing of small airways. The first half will focus on the role of lung function tests such as maximum mid-expiratory flow, impulse oscillometry and lung clearance index in detecting and quantifying SAD. The role of Computed Tomography (CT) as a radiological biomarker will be discussed as well as the potential of recent CT analysis software to differentiate normal aging of the lungs to pathology. The evidence behind SAD biomarkers sourced from blood as well as biomarkers sourced from sputum and broncho-alveolar lavage (BAL) will be reviewed. This paper focuses on CC-16, sRAGE, PAI-1, MMP-9 and MMP-12.

Structure and function of small airways in asthma patients revisited

Small airways (<2 mm in diameter) are probably involved across almost all asthma severities and they show proportionally more structural and functional abnormalities with increasing asthma severity. The structural and functional alterations of the epithelium, extracellular matrix and airway smooth muscle in small airways of people with asthma have been described over many years using in vitro studies, animal models or imaging and modelling methods. The purpose of this review was to provide an overview of these observations and to outline several potential pathophysiological mechanisms regarding the role of small airways in asthma.

Small-airway dysfunction in paediatric asthma

PURPOSE OF REVIEW

Asthma is a chronic inflammatory airway disorder that can involve the entire bronchial tree. Increasing evidence shows that ventilation heterogeneity and small airway dysfunction are relevant factors in the pathogenesis of asthma and represent a hallmark in adults with persistent asthma. Little is known about the contribution of peripheral airway impairment in paediatric asthma, mainly due to the inaccessibility to evaluation by noninvasive techniques, which have only been widely available in recent years.

RECENT FINDINGS

Emerging evidence suggests that small airways are affected from the early stages of the disease in childhood-onset asthma. Conventional lung function measurement, using spirometry, is unable to sensitively evaluate small airway function and may become abnormal only once there is a significant burden of disease. Recent studies suggest that chronic inflammation and dysfunction in the small airways, as detected with new advanced techniques, are risk factors for asthma persistence, asthma severity, worse asthma control and loss of pulmonary function with age, both in adults and children. Knowing the extent of central and peripheral airway involvement is clinically relevant to achieve asthma control, reduce bronchial hyper-responsiveness and monitor response to asthma treatment.

SUMMARY

This review outlines the recent evidence on the role of small airway dysfunction in paediatric asthma development and control, and addresses how the use of new diagnostic techniques available in outpatient clinical settings, namely impulse oscillometry and multiple breath washout, could help in the early detection of small airway impairment in children with preschool wheezing and school-age asthma and potentially guide asthma treatment.

Is hyperpolarised gas magnetic resonance imaging a valid and reliable tool to detect lung health in cystic fibrosis patients? a cosmin systematic review

This paper systematically reviewed the literature reporting the validity and reliability of hyperpolarised gas MRI as a marker of lung health in cystic fibrosis (CF). MEDLINE, EMBASE and grey literature were searched for studies assessing the measurement properties of hyperpolarised helium-3 or xenon-129 MRI. The COSMIN risk of bias tool was used to critically appraise eligible studies. Findings show hyperpolarised gas MRI was able to detect structural and functional abnormalities in the lungs, detect response to treatments, and is more sensitive than FEV₁ in detecting ventilation defects in CF patients. There was moderately robust evidence for construct validity of hyperpolarised gas MRI, although evidence for other types of validity is currently low. Nonetheless, high quality studies concluded that hyperpolarised gas MRI is a reliable tool and test results are reproducible in CF patients. Hyperpolarised gas MRI is a promising tool for detecting early CF pulmonary disease and for longitudinal monitoring of CF.

The diagnosis of asthma. Can physiological tests of small airways function help?

Asthma is a common, chronic, and heterogeneous disease with a global impact and substantial economic costs. It is also associated with significant mortality and morbidity and the burden of undiagnosed asthma is significant. Asthma can be difficult to diagnose as there is no gold standard test and, while spirometry is central in diagnosing asthma, it may not be sufficient to confirm or exclude the diagnosis. The most commonly reported spirometric measures (forced expiratory volume in one second (FEV₁) and forced vital capacity assess function in the larger airways. However, small airway dysfunction is highly prevalent in asthma and some studies suggest small airway involvement is one of the earliest disease manifestations. Moreover, there are new inhaled therapies with ultrafine particles that are specifically designed to target the small airways. Potentially, tests of small airways may more accurately diagnose early or mild asthma and assess the response to treatment than spirometry. Furthermore, some assessment techniques do not rely on forced ventilatory manoeuvres and may, therefore, be easier for certain groups to perform. This review discusses the current evidence of small airways tests in asthma and future research that may be needed to further assess their utility.

Lung Deposition Using the Respimat® Soft Mist™ Inhaler Mono and Fixed-Dose Combination Therapies: An In Vitro/In Silico Analysis

Tiotropium and olodaterol are mainstay treatments for chronic obstructive pulmonary disease (COPD) and yield important clinical improvements, especially when used in fixed-dose combination. Whilst previous studies have shown consistent delivery of tiotropium to the lungs with the Respimat^® inhaler, no such study has been carried out for olodaterol or the components of their fixed-dose combination (TIO/OLO). Combining in vitro and in silico models, we measured the amount of drug retained in the mouth-throat area, entering the trachea and reaching the lung periphery. We applied a hybrid deposition model that considered the experimentally determined output of an Alberta throat model (in vitro - dose to lung) combined with a computational fluid dynamic model of the lungs (in silico). Regardless of the COPD breathing pattern, ≥50% of the nominal dose of either tiotropium, olodaterol, or TIO and OLO in the fixed-dose combination reached the lung. Of the dose reaching the lungs, greater than 50% is deposited in the lung periphery (from generation 8 onwards). Our study demonstrated that aerosol delivery via the Respimat inhaler achieved high deposition deep into the lung periphery with all formulations evaluated.

Physiological tests of small airways function in diagnosing asthma: a systematic review

BACKGROUND

Asthma is a common, heterogeneous disease that is characterised by chronic airway inflammation and variable expiratory airflow limitation. Current guidelines use spirometric measures for asthma assessment. This systematic review aimed to assess whether the most commonly reported tests of small airways function could contribute to the diagnosis of asthma.

METHODS

Standard systematic review methodology was used, and a range of electronic databases was searched (Embase, MEDLINE, CINAHL, CENTRAL, Web of Science, DARE). Studies that included physiological tests of small airways function to diagnose asthma in adults were included, with no restrictions on language or date. The risk of bias and quality assessment tools used were Agency for Healthcare Research and Quality tool for cross-sectional studies and Quality Assessment of Diagnostic Accuracy Studies 2 for diagnostic test accuracy (DTA) studies.

RESULTS

7072 studies were identified and 10 studies met review criteria. 7 included oscillation techniques and 5 included maximal mid-expiratory flow (MMEF). Studies were small and of variable quality. In oscillometry, total resistance (R5) and reactance at 5 Hz (X5) was altered in asthma compared with healthy controls. The percentage predicted of MMEF was lower in patients with asthma compared with controls in all studies and lower than the % predicted forced expiratory volume in 1 s. In DTA of oscillometry, R5 showed a sensitivity between 69% and 72% and specificity between 61% and 86%.

CONCLUSION

There were differences in the results of physiological tests of small airway function in patients with asthma compared with controls. However, studies are small and heterogeneous. Further studies are needed to assess the effectiveness of these tests on a larger scale, including studies to determine which test methodology is the most useful in asthma.

Small Airway Disease in Pediatric Asthma: the Who, What, When, Where, Why, and How to Remediate. A Review and Commentary

Asthma affects all portions of the airways. Small airways, however, comprise a substantial component of the conducting lung air flow. In asthma, inflammatory processes can affect the whole respiratory tract, from central to peripheral/small airways. The emphasis in adult and pediatric respiratory disease clinics is to focus on large airway obstruction and reversibility. This information, although valuable, underemphasizes a large portion of the conduction airway of asthmatics. Standard descriptions of asthma management focus on a multiple medication approaches. We particularly focused on the management of asthma in the international guidelines for the Global Initiative for Asthma (GINA). Overall, however, minimal attention is placed on the small airway pool in asthma medical management. We took the opportunity to thoroughly review and present specific data from the adult asthma literature which supported the concept that small airway abnormalities may play a role in the pathogenesis and clinical expression of asthma. Based on the conclusions of the adult asthma literature, we here present a thorough review of the literature as it relates to small airway disease in children with asthma. We used, collectively, individual data sources of data to expand the information available from standard diagnostic techniques, especially spirometry, in the evaluation of small airway disease. As the pharmacological approaches to moderate to severe asthma are advancing rapidly into the realm of biologics, we sought to present potential pharmacological options for small airway dysfunction in pediatrics prior to biological modifier intervention.

Prevalence and features of IOS-defined small airway disease across asthma severities

BACKGROUND

Impulse oscillometry (IOS) is a noninvasive method based on the forced oscillation technique able to detect small airway dysfunction (SAD) in asthma. We aimed to analyze the prevalence and the functional features of IOS-defined SAD across the different Global Initiative for Asthma (GINA) steps.

METHODS

A cross-sectional, single-center study in which 400 consecutive adult patients with physician-diagnosed, community-managed asthma underwent standard spirometry and IOS, and were stratified by stepwise GINA classification. SAD was defined by IOS as a fall in resistance from 5 to 20 Hz [R5-R20]>0.07kPa × s × L^-1.

RESULTS

The prevalence of IOS-defined SAD ranged between 58.3% (GINA step 2) and 78.6% (GINA step 5), without statistically significant difference within GINA steps (p > 0.05 in all comparisons). Isolated SAD (i.e. without proximal airways involvement) was similarly represented across GINA steps 2-4. Peripheral airways resistance (R5-R20) tended to a progressive increase with the worsening of GINA steps, and was significantly higher in steps 4-5 compared to the other steps (p < 0.05). The proportion of patients with FEF_25-75%-defined SAD (<60%) was lower than the IOS-defined one in GINA steps 2-4 (p < 0.05). Only non-significant or weak inverse correlations between R5-R20 and FEF_25-75% were observed within each GINA step, with the exception of GINA step 5, which showed a strong, inverse correlation (r = -0.80, p = 0.0005).

CONCLUSIONS

This study shows that first, IOS-defined SAD is overwhelmingly present across asthma severities; second, airways resistance increases with the worsening of GINA steps; and third, SAD may be overlooked by standard spirometry, especially in milder asthma.

A Systematic Review of the Use of Physiological Tests Assessing the Acute Response to Treatment During Exacerbations of COPD (with a Focus on Small Airway Function)

Exacerbations are prevalent in Chronic Obstructive Pulmonary Disease (COPD) patients and associated with poor clinical outcomes. Currently, there is a lack of sensitive and specific tools that can objectively identify exacerbations and assess their progress or treatment response. FEV₁ is often reported as a study outcome, but it has significant limitations. Studies have suggested that small airways measures might provide physiological biomarkers during exacerbations. Therefore, this study was done to assess which physiological tests of small airways function have been used in the acute setting during exacerbations of COPD and the evidence to support their use. An electronic databases search was conducted in April 2019. A standard systematic review methodology was used. Eligible studies were those of ≥10 participants that compared at least one small airway test with FEV₁ to assess response to treatment with baseline and a follow-up measurement ≤2 months after. Analyses were narrative. Of 1436 screened studies, seven studies were eligible. There was heterogeneity in which tests of small airways were used and three different small airways measures were reported. Studies were small (including 20 to 87 subjects). Six articles reported improvements in small airway measurements during the recovery from exacerbation which correlated with FEV₁. Included studies varied in their timing and duration of the assessment. There is some evidence to support the use of small airway tests in acute exacerbations of COPD. However, studies have been small with different tests being utilized. Further studies to determine the usefulness of each test may be of interest.

Extended nitric oxide analysis in patients with chronic rhinosinusitis with nasal polyps, with or without associated asthma

Chronic rhinosinusitis with nasal polyps (CRSwNP) is a complex inflammatory disease highly impacting patient's quality of life, and associated with lower airway inflammation often evolving into asthma. Exhaled nitric oxide (FE_NO) is a non-invasive tool to assess Type 2 airway inflammation and its extended analysis allows to differentiate between alveolar concentration (CalvNO) and bronchial output (JawNO). It is also possible to assess the sino-nasal production of nitric oxide (nNO). We studied extended nitric oxide production in patients with CRSwNP with or without associated asthma. Consecutive adult patients with CRSwNP, with or without asthma, and 15 healthy controls were enrolled. Exclusion criteria were: smoking, uncontrolled asthma, recent upper or lower airway infections and oral corticosteroid therapy in the 4 weeks preceding clinical evaluation. Patients' demographic and clinical data were collected; patients underwent pulmonary function tests and extended nitric oxide analysis including nasal nNO assessment. A total of 125 subjects were enrolled (15 healthy controls; 69 with CRSwNP and asthma, and 41 with CRSwNP only). FE_NO, JawNO and CalvNO values were higher, while nNO was lower, in all patients with CRSwNP compared to healthy controls; no difference was found in CalvNO between patients with concomitant asthma and non-asthmatic subjects; in asthmatic patients, FE_NO and JawNO were significantly higher, while nNO values was lower, compared to patients with CRSwNP only. These results suggest that CRSwNP could be the first manifestation of a more complex systemic inflammatory pathology driven by Type 2 inflammation. An 'inflammatory gradient' hypothesis could describe a pattern of inflammation in CRSwNP patients that starts distally in the alveoli. Finally, our study indirectly reinforces the concept that novel biological drugs could become valid therapeutic options for nasal polyposis.

Lung function deterioration in school children with cystic fibrosis

INTRODUCTION

Lung disease in cystic fibrosis (CF) begins early in life but the capabilities for detecting abnormalities of pulmonary dysfunction in children remain limited.

OBJECTIVE

The study aimed to evaluate the early progression of lung function by the analysis of pulmonary hyperinflation, ventilation inhomogeneity (VI), trapped gas and airway obstruction with age.

METHODS

One hundred CF children aged 7 to 18, divided into two groups aged 7 to 12 (n = 40) and 13 to 18 (n = 60), were enrolled. Patients performed multiple-breath nitrogen washout (MBNW) tests and plethysmography for measurements of lung clearance index (LCI), functional residual capacity (FRC_pleth , FRC_MBNW ), volume of trapped gas (V_T ), total resistance, and effective and specific effective airway resistance (R_eff , sR_eff ).

RESULTS

We obtained a positive correlation of FRC_pleth , FRC_MBNW , and LCI with age. A linear correlation between FRC_MBNW and FRC_pleth (P < .0001) was observed. VI was higher in the group of older patients (9.79 in the group aged 7-12 and 11.67 in the group aged 13-18). An increased effective specific airway resistance >2 (z-score) was present in 58% of all subjects (50% and 63.3%, respectively). Pulmonary hyperinflation (FRC_pleth >2 z-score) was observed in 33% of all patients: 25% and 36.6%, respectively. Trapped gas (V_T  > 2 z-score) was present in 18% of all children: 30% and 10%, respectively.

CONCLUSION

A gradual decline in lung function is associated with an increase in VI, airway obstruction, pulmonary hyperinflation and development of trapped gas. In children who cannot perform either spirometry or plethysmography, MBNW can deliver a measurement of LCI connecting with VI as well as FRC_MBNW to indicate indirectly the increase of hyperinflation.

Prevalence and risk factors of small airway dysfunction, and association with smoking, in China: findings from a national cross-sectional study

BACKGROUND

Small airway dysfunction is a common but neglected respiratory abnormality. Little is known about its prevalence, risk factors, and prognostic factors in China or anywhere else in the world. We aimed to estimate the prevalence of small airway dysfunction using spirometry before and after bronchodilation, both overall and in specific population subgroups; assess its association with a range of lifestyle and environmental factors (particularly smoking); and estimate the burden of small airway dysfunction in China.

METHODS

From June, 2012, to May, 2015, the nationally representative China Pulmonary Health study invited 57 779 adults to participate using a multistage stratified sampling method from ten provinces (or equivalent), and 50 479 patients with valid lung function testing results were included in the analysis. We diagnosed small airway dysfunction on the basis of at least two of the following three indicators of lung function being less than 65% of predicted: maximal mid-expiratory flow, forced expiratory flow (FEF) 50%, and FEF 75%. Small airway dysfunction was further categorised into pre-small airway dysfunction (defined as having normal FEV1 and FEV1/forced vital capacity [FVC] ratio before bronchodilator inhalation), and post-small airway dysfunction (defined as having normal FEV1 and FEV1/FVC ratio both before and after bronchodilator inhalation). Logistic regression yielded adjusted odds ratios (ORs) for small airway dysfunction associated with smoking and other lifestyle and environmental factors. We further estimated the total number of cases of small airway dysfunction in China by applying present study findings to national census data.

FINDINGS

Overall the prevalence of small airway dysfunction was 43·5% (95% CI 40·7-46·3), pre-small airway dysfunction was 25·5% (23·6-27·5), and post-small airway dysfunction was 11·3% (10·3-12·5). After multifactor regression analysis, the risk of small airway dysfunction was significantly associated with age, gender, urbanisation, education level, cigarette smoking, passive smoking, biomass use, exposure to high particulate matter with a diameter less than 2·5 μm (PM2·5) concentrations, history of chronic cough during childhood, history of childhood pneumonia or bronchitis, parental history of respiratory diseases, and increase of body-mass index (BMI) by 5 kg/m2. The ORs for small airway dysfunction and pre-small airway dysfunction were similar, whereas larger effect sizes were generally seen for post-small airway dysfunction than for either small airway dysfunction or pre-small airway dysfunction. For post-small airway dysfunction, cigarette smoking, exposure to PM2·5, and increase of BMI by 5 kg/m2 were significantly associated with increased risk, among preventable risk factors. There was also a dose-response association between cigarette smoking and post-small airway dysfunction among men, but not among women. We estimate that, in 2015, 426 (95% CI 411-468) million adults had small airway dysfunction, 253 (238-278) million had pre-small airway dysfunction, and 111 (104-126) million had post-small airway dysfunction in China.

INTERPRETATION

In China, spirometry-defined small airway dysfunction is highly prevalent, with cigarette smoking being a major modifiable risk factor, along with PM2·5 exposure and increase of BMI by 5 kg/m2. Our findings emphasise the urgent need to develop and implement effective primary and secondary prevention strategies to reduce the burden of this condition in the general population.

FUNDING

Ministry of Science and Technology of China; National Natural Science Foundation of China; National Health Commission of China.

Investigating outcome measures for assessing airway clearance techniques in adults with cystic fibrosis: protocol of a single-centre randomised controlled crossover trial

Introduction

Airway clearance techniques (ACTs) are a gold standard of cystic fibrosis management; however, the majority of research evidence for their efficacy is of low standard; often attributed to the lack of sensitivity from outcome measures (OMs) used historically. This randomised controlled trial (RCT) investigates these standard OMs (sputum weight, forced expiratory volume in 1 s) and new OMs (electrical impedance tomography (EIT), multiple breath washout (MBW) and impulse oscillometry (IOS)) to determine the most useful measures of ACT.

Methods and analysis

This is a single-centre RCT with crossover design. Participants perform MBW, IOS and spirometry, and then are randomised to either rest or supervised ACT lasting 30–60 min. MBW, IOS and spirometry are repeated immediately afterwards. EIT and sputum are collected during rest/ACT. On a separate day, the OMs are performed with the other intervention. Primary endpoint is difference in change in OMs before and after ACT/rest. Sample size was calculated with 80% power and significance of 5% for each OM (target n=64).

Ethics and dissemination

Ethics approval was gained from the London–Chelsea Research Ethics Committee (reference 16/LO/0995, project ID 154635). Dissemination will involve scientific conference presentation and publication in a peer-reviewed journal.

Trial registration numbers

ISRCTN11220163 and NCT02721498.

Using Novel Computed Tomography Analysis to Describe the Contribution and Distribution of Emphysema and Small Airways Disease in Chronic Obstructive Pulmonary Disease

Rationale: Chronic obstructive pulmonary disease (COPD) is characterized by airflow limitation, caused by emphysema and small airways disease (SAD). Computed tomography (CT) coupled with image analysis enables the quantification of these abnormalities; however, the optimum method for doing so has not been determined.Objectives: This study aims to compare two CT quantitative analysis techniques, disease probability measure (DPM) and parametric response mapping (PRM), and assess their relationship with specific physiological measures of SAD.Methods: Subjects with mild to moderate COPD, never smokers, and healthy ex-smokers were recruited. Each had airway oscillometry and multiple-breath nitrogen washout, measuring peripheral airway resistance, peripheral airway reactance, and acinar airway inhomogeneity. Subjects also had an inspiratory and expiratory chest CT, with DPM and PRM analysis performed by coregistering images and classifying each voxel as normal, emphysema, or nonemphysematous gas trapping related to SAD.Results: Thirty-eight subjects with COPD, 18 never smokers, and 23 healthy ex-smokers were recruited. There were strong associations between DPM and PRM analysis when measuring gas trapping (ρ = 0.87; P < 0.001) and emphysema (ρ = 0.99; P < 0.001). DPM assigned significantly more voxels as emphysema and gas trapped than PRM (P < 0.001). Both techniques showed significantly greater emphysema and gas trapping in subjects with COPD than in never smokers and ex-smokers (P < 0.001). All CT measures had significant associations with peripheral airway resistance and reactance, with disease probability measure of nonemphysematous gas trapping related to SAD having the strongest independent association with peripheral airway resistance (β = 0.42; P = 0.001) and peripheral airway reactance (β = 0.41; P = 0.001). Emphysema measures had the strongest associations with acinar airway inhomogeneity (β = 0.35-0.38).Conclusions: These results provide further validation for the use of DPM/PRM analysis in COPD by demonstrating significant relationships with specific physiological measures of SAD.

End-expiratory lung volume assessment using helium and carbon dioxide in an experimental model of pediatric capnoperitoneum

BACKGROUND

Capnoperitoneum during laparoscopy leads to cranial shift of the diaphragm, loss in lung volume, and risk of impaired gas exchange. Infants are susceptible to these changes and bedside assessment of lung volume during laparoscopy might assist with optimizing the ventilation. Thus, the primary aim was to investigate the monitoring value of a continuous end-expiratory lung volume (EELV) assessment method based on CO₂ dynamics ( EELV CO 2 ) in a pediatric capnoperitoneum model by evaluating the correlation and trending ability against helium washout (EELV_He ).

METHODS

Intra-abdominal pressure (IAP) was randomly varied between 0, 6, and 12 mm Hg with CO₂ insufflation, while positive end-expiratory pressure (PEEP) levels of 3, 6, and 9 cm H₂ O were randomly applied in eight anesthetized and mechanically ventilated chinchilla rabbits. Concomitant EELV CO 2 and EELV_He and lung clearance index (LCI) were obtained under each experimental condition.

RESULTS

Significant correlations were found between EELV CO 2 and EELV_He before capnoperitoneum (r = .85, P < .001), although increased IAP distorted this relationship. The negative influence of IAP was counteracted by the application of PEEP 9, which restored the correlation between EELV CO 2 and EELV_He and resulted in 100% concordance rate between the methods regarding changes in lung volume. EELV_He and LCI showed a curvilinear relationship, and an EELV_He of approximately 20 mL kg^-1 , determined with a receiver operating characteristic curve, was associated with near-normal LCI values.

CONCLUSION

In this animal model of pediatric capnoperitoneum, reliable assessment of changes in EELV based on EELV CO 2 requires an open lung strategy, defined as EELV above approximately 20 mL kg^-1 .

Prevalence and clinical correlates of small airway obstruction in patients with systemic sclerosis

OBJECTIVES

This study aims to assess the prevalence and clinical correlates of small airway obstruction (SAO) in patients with systemic sclerosis (SSc).

METHODS

Sixty-nine consecutive patients with SSc (63 women and 6 men) were included. Lung function tests, including assessment of lung diffusing capacity, were performed in all patients. Patients were considered to have SAO when the maximal expiratory flow at 25% of the forced vital capacity (MEF₂₅) was lower than 60% as predicted. High-resolution computed tomography (HRCT) of the lung was performed in all patients with MEF₂₅ < 60%. We assessed the relationship of SAO in our patients with large airway obstruction, decreased lung diffusing capacity, HRCT findings, disease duration, disease subtype, scleroderma-specific antibodies, and smoking.

RESULTS

SAO was noticed in 46/69 (66.6%) of patients with SSc. Restrictive lung disease was found in 4/69 (5.8%), obstruction of large airways in 18/69 (26.1%), and decreased lung diffusing capacity in 47/69 (68.1%) of patients. No difference in gender, age, disease duration, disease subtype, and scleroderma-specific antibodies was found between patients with and without SAO. Eighteen out of forty-six (39.1%) patients with SAO had decreased forced expiratory volume in 1 sec (FEV₁) and the Tiffeneau-Pinelli index, indicating presence of coexistent large airway obstruction. Twenty out of forty-six (43.5%) patients with SAO had associated decreased lung diffusing capacity, while 8/46 (17.4%) of patients had isolated SAO. HRCT patterns of interstitial lung disease (ILD) were found more frequently in patients with SAO and decreased lung diffusing capacity, compared with patients with SAO and normal diffusing capacity (75% vs 11.5%, p = 0.008). We have noticed that tobacco smokers among SSc patients with SAO have more common associated obstructive lung disease on spirometry (58.8% vs 15.4%, p = 0.004). On the other hand, isolated SAO and SAO associated with impaired diffusing capacity were equally frequent among smokers and non-smokers.

CONCLUSION

Patients with SSc have commonly SAO. It can be considered clinical feature of undiagnosed asthma or chronic obstructive pulmonary disease (COPD), if isolated or associated with large airway obstruction, especially in tobacco smokers. On the other hand, SAO associated with decreased lung diffusing capacity was found to be not related to smoking, and may indicate a possible prominent bronchiolar involvement within SSc-related interstitial lung disease Key Points • Small airway obstruction in patients with systemic sclerosis can be considered a clinical feature of undiagnosed obstructive lung disease, if isolated or associated with large airway obstruction, especially in tobacco smokers. • Obstruction of small airways, associated with decreased lung diffusing capacity, may indicate a possible prominent bronchiolar involvement within systemic sclerosis-related interstitial lung disease.

Feasibility of Aerosolized Alpha-1 Antitrypsin as a Therapeutic Option

Inhalation therapy is integral in the management of patients with chronic obstructive pulmonary disease (COPD). Specifically, intravenous augmentation therapy is available to patients with alpha-1 antitrypsin deficiency (AATD), although there is insufficient alpha-1 antitrypsin (AAT) delivery to the lungs to modify airways inflammation. In contrast, the inhaled route allows replacement therapy to reach the target site of action and with higher AAT levels. Patients certainly support the inhalation route as an alternative to intravenous injections, obviating repetitive needle insertion and allowing treatment empowerment rather than dependency on traveling to specialized units. The difficulty with inhalation has been the ability to target the formulation to the pathophysiological site of disease: the emphysematous lung parenchyma of the small alveolated airways. Recent advances have suggested nebulizers as being able to deliver an adequate dose, consistently and reproducibly, and, coupled with developments in formulation science, allowed replacement therapy to reach the epithelial lining fluid of the small airways. The bench science has been translated to the first randomized, placebo-controlled clinical trial to study the effects of nebulized AAT, which, although not meeting the primary endpoint of prolonging time to first exacerbation, showed this treatment modality was safe and achievable in a large patient cohort. Indeed, learning from this trial suggests the importance of choosing the right clinical endpoints, and recent key advances in lung physiology indices allow better assessment of the "silent zone" of small airways disease. Knowledge from other respiratory diseases will complement treating patients with AATD, where there is considerable innovation in aerosol science and inhalation medicine directed at utilizing the inhaled route. Indeed, it could be postulated that the inhaled route may not only achieve local pulmonary therapeutic benefit, but through systemic absorption and controlled pharmacokinetic profiling, the formulation may reach and treat liver disease.

Combined Forced Expiratory Volume in 1 Second and Forced Vital Capacity Bronchodilator Response, Exacerbations, and Mortality in Chronic Obstructive Pulmonary Disease

Rationale: The American Thoracic Society (ATS)/European Respiratory Society defines a positive bronchodilator response (BDR) by a composite of BDR in either forced expiratory volume in 1 second (FEV₁) and/or forced vital capacity (FVC) greater than or equal to 12% and 200 ml (ATS-BDR). We hypothesized that ATS-BDR components would be differentially associated with important chronic obstructive pulmonary disease (COPD) outcomes. Objectives: To examine whether ATS-BDR components are differentially associated with clinical, functional, and radiographic features in COPD. Methods: We included subjects with COPD enrolled in the COPDGene study. In the main analysis, we excluded subjects with self-reported asthma. We categorized BDR into the following: 1) No-BDR, no BDR in either FEV₁ or FVC; 2) FEV₁-BDR, BDR in FEV₁ but no BDR in FVC; 3) FVC-BDR, BDR in FVC but no BDR in FEV₁; and 4) Combined-BDR, BDR in both FEV₁ and FVC. We constructed multivariable logistic, linear, zero-inflated negative binomial, and Cox hazards models to examine the association of BDR categories with symptoms, computed tomography findings, change in FEV₁ over time, respiratory exacerbations, and mortality. We also created models using the ATS BDR definition (ATS-BDR) as the main independent variable. Results: Of 3,340 COPD subjects included in the analysis, 1,083 (32.43%) had ATS-BDR, 182 (5.45%) had FEV₁-BDR, 522 (15.63%) had FVC-BDR, and 379 (11.34%) had Combined-BDR. All BDR categories were associated with FEV₁ decline compared with No-BDR. Compared with No-BDR, both ATS-BDR and Combined-BDR were associated with higher functional residual capacity %predicted, greater internal perimeter of 10 mm, and greater 6-minute-walk distance. In contrast to ATS-BDR, Combined-BDR was independently associated with less emphysema (adjusted beta regression coefficient, -1.67; 95% confidence interval [CI], -2.68 to -0.65; P = 0.001), more frequent respiratory exacerbations (incidence rate ratio, 1.25; 95% CI, 1.03-1.50; P = 0.02) and severe exacerbations (incidence rate ratio, 1.34; 95% CI, 1.05-1.71; P = 0.02), and lower mortality (adjusted hazards ratio, 0.76; 95% CI, 0.58-0.99; P = 0.046). Sensitivity analysis that included subjects with self-reported history of asthma showed similar findings. Conclusions: BDR in both FEV₁ and FVC indicates a COPD phenotype with asthma-like characteristics, and provides clinically more meaningful information than current definitions of BDR.

Association Between Bedroom Particulate Matter Filtration and Changes in Airway Pathophysiology in Children With Asthma

Importance

Fine particles (particulate matter 2.5 μm [PM2.5]), a ubiquitous air pollutant, can deposit in the small airways that play a vital role in asthma. It appears to be unknown whether the use of a PM2.5 filtration device can improve small airway physiology and respiratory inflammation in children with asthma.

Objective

To discover what pathophysiological changes in the small airways are associated with using a PM2.5-removing device in the bedrooms of children with asthma.

Design, Setting, and Participants

Children with mild or moderate asthma were enrolled in this double-blind, crossover study. The participants used a true filtration device and a sham filtration device in their bedrooms in a random order for 2 weeks each with a 2-week washout interval. The study was conducted in a suburb of Shanghai, China, during a low-ozone season.

Exposures

Ozone and PM2.5 were measured inside bedrooms and outside a window.

Main Outcomes and Measures

Impulse oscillometry, spirometry, and fractional exhaled nitric oxide were measured at the beginning and the end of each intervention. Peak expiratory flow was measured twice daily at home.

Results

Forty-three children (5-13 years old; 26 boys [60%]) participated. Outdoor 24-hour mean PM2.5 concentrations were moderately high, ranging from 28.6 to 69.8 μg/m3 (median, 53 μg/m3). During true filtration, bedroom PM2.5 concentrations were a mean (SD) of 63.4% (35.9%) lower than during sham filtration. Compared with sham filtration, true filtration was significantly associated with improved airway mechanics, reflected in a 24.4% (95% CI, 11.8%-37.1%) reduction in total airway resistance, a 43.5% (95% CI, 13.7%-73.3%) reduction in small airway resistance, a 22.2% (95% CI, 2.2%-42.2%) reduction in resonant frequency, and a 73.1% (95% CI, 0.3%-145.8%) increase in airway reactance. True filtration was also associated with significant improvements in fractional exhaled nitric oxide (a 27.6% [95% CI, 8.9%-42.4%] reduction) and peak expiratory flow (a 1.6% [95% CI, 0.8%-2.5%] increase). These improvements were significantly associated with bedroom PM2.5 reduction. Improvements in small airway function were nonsignificant (8.4% [95% CI, -1.4% to 18.3%]) in all participants but significant (13.2% [95% CI, 1.2%-25.1%]) in participants without eosinophilic airway inflammation at baseline. No improvements were observed for forced vital capacity, forced expiratory volume during the first second, and the ratio of these in all participants or subgroups.

Conclusions and Relevance

Per these results, indoor PM2.5 filtration can be a practical method to improve air flow in an asthmatic lung through improved airway mechanics and function as well as reduced inflammation. This warrants a clinical trial to confirm.

Trial Registration

ClinicalTrials.gov Identifier: NCT03282864.

Regional ventilation inhomogeneity in survivors of extremely preterm birth

INTRODUCTION

Survivors of extreme prematurity may have disrupted lung development. We hypothesized that the multiple breath washout (MBW) index Scond, which is intended to reflect ventilation inhomogeneity from the conducting airways, could be a sensitive marker of respiratory impairment in this group.

METHODS

Spirometry, TLco, and MBW were cross-sectionally evaluated at 8 to 14 years of age in children born at <28 weeks between 2004 and 2010 in Udine, Italy. Age-matched controls born at term were also included. Bronchopulmonary dysplasia (BPD) was defined as oxygen-dependence at 36 weeks postmenstrual age. The limits of normal were the 5th percentile of the reference population (Global Lung Initiative) for spirometry and TLco and the 95th percentile of controls for Lung Clearance Index, Scond, and Sacin from MBW.

RESULTS

Results were obtained in 47 extremely preterm children (53% boys, mean ± standard deviation age 11.3 ± 2.0 years, 40% with BPD) and 60 controls (50% boys, 11.6 ± 1.9 years). There were significant differences between preterm children and controls in all lung function outcomes, except for Sacin. Among children born <28 weeks, Scond tended to be frequently abnormal than FEV₁ z-score (29% vs 14%, P = .06). At multivariable linear regression, in the preterm group, current asthma was significantly associated with a higher Scond (B = 0.019, 95% confidence interval, 0.000-0.038), whereas BPD was not.

CONCLUSION

Almost a third of extremely preterm children at school age showed Scond alterations that affected also children without BPD. Longitudinal studies should clarify the prognostic meaning of Scond abnormalities in this group.

Characterizing the viscoelasticity of extra- and intra-parenchymal lung bronchi

Pulmonary disease is known to cause remodeling of tissue structure, resulting in altered viscoelastic properties; yet the foundation for understanding this phenomenon is still nascent and will enable scientific insights regarding lung functionality. In order to characterize the viscoelastic response of pulmonary airways, uniaxial tensile experiments are conducted on porcine extra- and intra-parenchymal bronchial regions, measuring both axially and circumferentially oriented tissue. Anisotropic and heterogeneous effects on preconditioning and hysteresis are substantial, linking to energy dissipation expectancies. Stress relaxation is rheologically modeled using several classical configurations of discrete spring and dashpot elements; among them, Standard Linear Solid (SLS) and Maxwell-Weichart exhibit better fit performance. Enhanced fractional order derivative SLS (FSLS) model is also evaluated through use of a hybrid spring-pot of order α. FSLS outperforms the conventional models, demonstrating superior representation of the stress-relaxation curve's initial value and non-linear asymptotic decent. FSLS parameters exhibit notable orientation- and region-specific values, trending with observed tissue structural constituents, such as glycosaminoglycan and collagen. To the best of our knowledge, this work is the first to characterize proximal and distal bronchial energy efficiency and contextualize tissue biochemical composition in view of experimental measures and viscoelastic trends. Results provide a foundation for future investigations, particularly for understanding the role of viscoelasticity in diseased states.

Pulmonary Function Changes in Chronic Obstructive Pulmonary Disease Patients According to Smoking Status

OBJECTIVES

The aim of our study was to examine pulmonary functions of patients from all stages of chronic obstructive pulmonary disease (COPD) according to their smoking status.

MATERIALS AND METHODS

A retrospective case-control study was carried out. Total of 148 patients were enrolled and divided into two groups in regards to their smoking status (quitters, n=68; non-quitters, n=80). Pulmonary function parameters, COPD assessment test score, Fagerström Nicotine Addiction Questionnaire score, smoking history and status were obtained from the electronic hospital data system. Patients' admission and 12-month data were recorded.

RESULTS

In non-quitters, the mean FEV1 values decreased from 2.32±1.14 to 2.24±1.12 (p<0.001). Particularly, in Stage-0, in the early high-risk group of COPD, the reduction in FEV1 was 90 mL, while the reduction was 70, 60, 40, and 40 mL in Stage-I, -II, -III, and -IV, respectively. In quitters, the mean FEV1 levels increased from 2.10±1.19 to 2.19±1.20 (p<0.001). For COPD patients overall, an average increase in FEV1 of 80-110 mL was observed. At the end of the 12 months follow-up, 17 (27.5%) of the non-quitters showed deterioration, and five (7.3%) of the quitters showed improvement in COPD stage.

CONCLUSION

FEV1 decline was accelerated in COPD patients who continued to smoke, whereas this decline was not prevented by inhaler treatments. The Global Initiative for Chronic Obstructive Lung Disease Stage-0 group, which is not included in the current guidelines, needs to be redefined. This group appears to be the most important group for implementing the smoking cessation and prevention strategy.

Resistance of the respiratory system measured with forced oscillation technique (FOT) correlates with bronchial thermoplasty response

BACKGROUND

Bronchial Thermoplasty (BT) is an endoscopic treatment for severe asthma using radiofrequency energy to target airway remodeling including smooth muscle. The correlation of pulmonary function tests and BT response are largely unknown. Forced Oscillation Technique (FOT) is an effort-independent technique to assess respiratory resistance (Rrs) by using pressure oscillations including small airways.

AIM

To investigate the effect of BT on pulmonary function, assessed by spirometry, bodyplethysmography and FOT and explore associations between pulmonary function parameters and BT treatment response.

METHODS

Severe asthma patients recruited to the TASMA trial were analyzed in this observational cohort study. Spirometry, bodyplethysmography and FOT measurements were performed before and 6 months after BT. Asthma questionnaires (AQLQ/ACQ-6) were used to assess treatment response.

RESULTS

Twenty-four patients were analyzed. AQLQ and ACQ improved significantly 6 months after BT (AQLQ 4.15 (±0.96) to 4.90 (±1.14) and ACQ 2.64 (±0.60) to 2.11 (±1.04), p = 0.004 and p = 0.02 respectively). Pulmonary function parameters remained stable. Improvement in FEV₁ correlated with AQLQ change (r = 0.45 p = 0.03). Lower respiratory resistance (Rrs) at baseline (both 5 Hz and 19 Hz) significantly correlated to AQLQ improvement (r = - 0.52 and r = - 0.53 respectively, p = 0.01 (both)). Borderline significant correlations with ACQ improvement were found (r = 0.30 p = 0.16 for 5 Hz and r = 0.41 p = 0.05 for 19 Hz).

CONCLUSION

Pulmonary function remained stable after BT. Improvement in FEV₁ correlated with asthma questionnaires improvement including AQLQ. Lower FOT-measured respiratory resistance at baseline was associated with favorable BT response, which might reflect targeting of larger airways with BT.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02225392; Registered 26 August 2014.

Ventilation heterogeneity and oscillometry predict asthma control improvement following step-up inhaled therapy in uncontrolled asthma

BACKGROUND AND OBJECTIVE

Abnormal peripheral airway function is an important feature of asthma and relates to asthma symptoms and poor asthma control. We aimed to determine whether peripheral airway function, as measured by forced oscillatory impedance and multiple-breath nitrogen washout (MBNW), relates to symptom improvement in asthmatic participants with uncontrolled asthma, after stepping up to high-dose ICS/LABA treatment.

METHODS

A total of 19 subjects (14 females, mean age: 29.9 ± 13.6 years) with uncontrolled asthma, as defined by an ACQ5 > 1.5, taking 500 μg/day fluticasone equivalent or less, underwent spirometry, plethysmography, fractional exhaled FeNO, forced oscillatory resistance (Rrs_5Hz ) and reactance (Xrs_5Hz ), and indices of MBNW ventilation heterogeneity (lung clearance index (LCI), diffusion-convection-dependent (Sacin) and convection-dependent (Scond)). Measurements were made before and after 8 weeks of treatment with fluticasone/formoterol combination inhaler 250/10 μg, 2 puffs twice daily.

RESULTS

Treatment improved ACQ5 (P = 0.0002), FEV₁ (P = 0.02), FVC (P = 0.04), FeNO (P = 0.0008), Xrs_5Hz (P = 0.01), LCI (P = 0.0002), Sacin (P = 0.006) and Scond (P = 0.01). At baseline, ACQ5 correlated with Xrs_5Hz (r_s = 0.52, P = 0.03) and Rrs_5Hz (r_s = 0.55, P = 0.02). The improvement in ACQ5 was predicted by more abnormal baseline LCI (P = 0.03), Scond (P = 0.02) and Rrs_5Hz (P = 0.006). Baseline Scond was the best predictor of a clinically meaningful improvement in asthma control (ΔACQ > 0.5, ROC-AUC = 0.91, P = 0.007).

CONCLUSION

Step-up to high-dose combination treatment in uncontrolled asthma is associated with improved peripheral airway function as measured by Xrs_5Hz and MBNW. Baseline MBNW and FOT parameters correlated with the improvement in symptoms and may predict a positive response to up-titration in uncontrolled asthmatic patients.

Small Airway Disease Syndromes. Piercing the Quiet Zone

The role for direct assessment of small airway function in subjects with respiratory symptoms but normal airflow by spirometry is discussed. Small airway disease syndrome is described in numerous disease states using a multidisciplinary approach. Data demonstrate that small airway disease is related to presence of respiratory symptoms, exposure to inhaled toxins, presence of local and systemic inflammation, and presence of histologic abnormalities within the distal lung. Investigation of immunological derangements associated with distal airway dysfunction in the setting of normal spirometry may provide insight into pathophysiological mechanisms that are present at disease onset. For the purposes of this symposium, data were reviewed in selected clinical conditions (obesity, environmental inhalational injury, and cigarette smoking) that have been recently studied in the André Cournand Pulmonary Physiology Laboratory at Bellevue Hospital using the forced oscillation technique.

Clinical Characterization and Predictors of IOS-Defined Small-Airway Dysfunction in Asthma

BACKGROUND

The involvement of small airways has recently gained greater recognition in asthma. Impulse oscillometry (IOS) is a simple and noninvasive method based on the forced oscillation technique, for the detection of small-airway dysfunction (SAD).

OBJECTIVE

To identify the predictors of SAD in an unselected sample of 400 patients with physician-diagnosed asthma.

METHODS

All patients underwent standard spirometry and IOS at the first visit, and were stratified by the presence of SAD defined by IOS (fall in resistance from 5 to 20 Hz [R5-R20] > 0.07 kPa × s × L^-1). Univariable and multivariable analyses and classification tree method were used to analyze cross-sectional relationships between clinical variables and outcome (SAD).

RESULTS

SAD was present in 62% of the cohort. Subjects with SAD showed a less well-controlled asthma, according to the Global Initiative for Asthma definition, and a higher mean inhaled corticosteroid dosage use compared with subjects without SAD (both P < .001). Increased fractional exhaled nitric oxide (odds ratio [OR], 2.05; 95% CI, 1.14-3.70), female sex (OR, 2.27; 95% CI, 1.29-4.06), smoking (OR, 3.06; 95% CI, 1.60-6.05), older age (OR, 3.08; 95% CI, 1.77-5.49), asthma-related night awakenings (OR, 3.34; 95% CI, 1.85-6.17), overweight (OR, 3.64; 95% CI, 1.99-6.85), and exercise-induced asthma symptoms (OR, 6.39; 95% CI 3.65-11.45) were independent predictors of SAD. Classification tree analysis confirmed that exercise-induced asthma, overweight, asthma-related night awakenings, smoking, and older age have potential for clinical use in distinguishing patients with SAD from those without it.

CONCLUSIONS

We identified predictors of SAD and showed that especially exercise-induced asthma, overweight, asthma-related night awakenings, smoking, and older age were strongly associated with SAD.

Does the nitrogen single-breath washout test contribute to detecting pulmonary involvement in rheumatoid arthritis? A pilot study

Objective

There has been growing interest in studying small airway disease through measures of ventilation distribution, thanks to the resurgence of the nitrogen single-breath washout (N₂SBW) test. Therefore, this study evaluated the contribution of the N₂SBW test to the detection of pulmonary involvement in patients with rheumatoid arthritis (RA).

Results

Twenty-one patients with RA underwent clinical evaluation, pulmonary function tests (PFTs), including the N2_SBW test, and computed tomography (CT). The main tomographic findings were air trapping and bronchiectasis (57.1% and 23.8% of cases, respectively). According to the phase III slope of the N₂SBW (phase III slope), 11 and 10 patients had values < 120% predicted and > 120% predicted, respectively. Five patients with limited involvement on CT had a phase III slope > 120%. The residual volume/total lung capacity ratio was significantly different between patients with phase III slopes < 120% and > 120% (P = 0.024). Additionally, rheumatoid factor positivity was higher in patients with a phase III slope > 120% (P = 0.021). In patients with RA and airway disease on CT, the N₂SBW test detects inhomogeneity in the ventilation distribution in approximately half of the cases, even in those with normal conventional PFT results.

Assessing small airways dysfunction in asthma, asthma remission and healthy controls using particles in exhaled air

Asthma is a chronic disease, characterised by variable airflow obstruction and airway inflammation [1]. Small airways are thought to be a major site of pathology in asthma [2, 3]. There are different tools to assess small airways dysfunction (SAD), such as spirometry, body plethysmography, impulse oscillometry (IOS), multiple-breath nitrogen washout (MBNW), alveolar fraction of exhaled nitric oxide (F_ENO) and gas trapping assessed by high-resolution computed tomography (CT). However, there is no golden standard and some tests are difficult to perform [2, 3].

PExA mass can distinguish asthmatics from healthy individuals. Subjects with complete, but not clinical, asthma remission exhale more PExA mass compared to asthma. Higher PExA mass was associated with better function of both the small and large airways.http://bit.ly/2znHABg

Weight Status and Respiratory Health in Asthmatic Children

In this study,we explored the effect of adiposity as measured by BMI on lung function in 72 asthmatic school children (5-12 years) using baseline data from the Mediterranean diet enriched with fatty fish intervention study. Bronchial function was assessed using spirometry and fractional exhaled nitric oxide (FeNO). BMI categories were classified as normal and overweight/obese based on International Obesity Task Force cut-offs. Weak correlations were observed between BMI and FVC (p = 0.013) and FEV₁ (p = 0.026). Median FeNO was lower in the overweight/obese as compared to normal weight group (p = 0.027). Linear regression showed an increment in FEF_25-75% in the overweight/obese group as compared to normal weight after controlling for confounders namely age, height, sex, regular physical activity, medication and KIDMED score (p = 0.043; β = 11.65 units, 95% CI 0.36-22.94), although with no effect on FeNO. In conclusion, the findings of this study suggest that excess body weight could impact pulmonary dynamics in childhood asthma.