Techniques of assessing small airways dysfunction

Microscopic Small Airway Abnormalities Identified in Early Idiopathic Pulmonary Fibrosis In Vivo Using Endobronchial Optical Coherence Tomography

Rationale: Idiopathic pulmonary fibrosis (IPF) affects the subpleural lung but is considered to spare small airways. Micro-computed tomography (micro-CT) studies demonstrated small airway reduction in end-stage IPF explanted lungs, raising questions about small airway involvement in early-stage disease. Endobronchial optical coherence tomography (EB-OCT) is a volumetric imaging modality that detects microscopic features from subpleural to proximal airways. Objectives: In this study, EB-OCT was used to evaluate small airways in early IPF and control subjects in vivo. Methods: EB-OCT was performed in 12 subjects with IPF and 5 control subjects (matched by age, sex, smoking history, height, and body mass index). Subjects with IPF had early disease with mild restriction (FVC: 83.5% predicted), which was diagnosed per current guidelines and confirmed by surgical biopsy. EB-OCT volumetric imaging was acquired bronchoscopically in multiple, distinct, bilateral lung locations (total: 97 sites). IPF imaging sites were classified by severity into affected (all criteria for usual interstitial pneumonia present) and less affected (some but not all criteria for usual interstitial pneumonia present). Bronchiole count and small airway stereology metrics were measured for each EB-OCT imaging site. Measurements and Main Results: Compared with the number of bronchioles in control subjects (mean = 11.2/cm3; SD = 6.2), there was significant bronchiole reduction in subjects with IPF (42% loss; mean = 6.5/cm3; SD = 3.4; P = 0.0039), including in IPF affected (48% loss; mean: 5.8/cm3; SD: 2.8; P < 0.00001) and IPF less affected (33% loss; mean: 7.5/cm3; SD: 4.1; P = 0.024) sites. Stereology metrics showed that IPF-affected small airways were significantly larger, more distorted, and more irregular than in IPF-less affected sites and control subjects. IPF less affected and control airways were statistically indistinguishable for all stereology parameters (P = 0.36-1.0). Conclusions: EB-OCT demonstrated marked bronchiolar loss in early IPF (between 30% and 50%), even in areas minimally affected by disease, compared with matched control subjects. These findings support small airway disease as a feature of early IPF, providing novel insight into pathogenesis and potential therapeutic targets.

Small airways disease in chronic obstructive pulmonary disease

INTRODUCTION

Small airway disease (SAD) represents a common and critical feature of Chronic Obstructive Pulmonary Disease (COPD). Introduced in the '60s, SAD has gradually gained increasing interest as assessment methodologies have improved. Chronic exposure to smoking and noxious particles or gases induces inflammation and remodeling, leading to airway obstruction and SAD, eventually resulting in complete airway loss.

AREAS COVERED

A literature search up to June 2024 was performed in PubMed to identify articles on SAD and airway diseases mainly COPD, but also to the extent that it seemed relevant in the uncontrolled/severe asthma field, where SAD is better studied. We provide clinicians and translational scientists with a comprehensive analysis of the existing literature on SAD in COPD, concentrating on the underlying pathophysiological mechanisms, diagnostic techniques, and current pharmacological approaches targeting airflow obstruction in small airways.

EXPERT OPINION

Small airways are the primary site for the onset and progression of airflow obstruction in patients with COPD, with significant clinical consequences associated with poor lung function, hyperinflation, and impaired quality of life. The early identification of individuals with subclinical SAD may allow us to prevent its further progress from airway loss and potential development of emphysema and choose the appropriate therapeutic approach.

Machine learning for accurate detection of small airway dysfunction-related respiratory changes: an observational study

BACKGROUND

The use of machine learning(ML) methods would improve the diagnosis of small airway dysfunction(SAD) in subjects with chronic respiratory symptoms and preserved pulmonary function(PPF). This paper evaluated the performance of several ML algorithms associated with the impulse oscillometry(IOS) analysis to aid in the diagnostic of respiratory changes in SAD. We also find out the best configuration for this task.

METHODS

IOS and spirometry were measured in 280 subjects, including a healthy control group (n = 78), a group with normal spirometry (n = 158) and a group with abnormal spirometry (n = 44). Various supervised machine learning (ML) algorithms and feature selection strategies were examined, such as Support Vector Machines (SVM), Random Forests (RF), Adaptive Boosting (ADABOOST), Navie Bayesian (BAYES), and K-Nearest Neighbors (KNN).

RESULTS

The first experiment of this study demonstrated that the best oscillometric parameter (BOP) was R5, with an AUC value of 0.642, when comparing a healthy control group(CG) with patients in the group without lung volume-defined SAD(PPFN). The AUC value of BOP in the control group was 0.769 compared with patients with spirometry defined SAD(PPFA) in the PPF population. In the second experiment, the ML technique was used. In CGvsPPFN, RF and ADABOOST had the best diagnostic results (AUC = 0.914, 0.915), with significantly higher accuracy compared to BOP (p < 0.01). In CGvsPPFA, RF and ADABOOST had the best diagnostic results (AUC = 0.951, 0.971) and significantly higher diagnostic accuracy (p < 0.01). In the third, fourth and fifth experiments, different feature selection techniques allowed us to find the best IOS parameters (R5, (R5-R20)/R5 and Fres). The results demonstrate that the performance of ADABOOST remained essentially unaltered following the application of the feature selector, whereas the diagnostic accuracy of the remaining four classifiers (RF, SVM, BAYES, and KNN) is marginally enhanced.

CONCLUSIONS

IOS combined with ML algorithms provide a new method for diagnosing SAD in subjects with chronic respiratory symptoms and PPF. The present study's findings provide evidence that this combination may help in the early diagnosis of respiratory changes in these patients.

Evaluating the clinical utility of small airway function assessment for early diagnosis of GOLD stage 0 chronic obstructive pulmonary disease

OBJECTIVE

To investigate the clinical utility of small airway function indices for early identification of GOLD stage 0 chronic obstructive pulmonary disease (COPD).

METHODS

This retrospective study enrolled 137 participants at our institution between January 2017 and December 2018, comprising 40 healthy controls, 46 individuals with GOLD stage 0 COPD, and 51 patients with established COPD. Pulmonary function was assessed using the PowerCube spirometry system (GANSHORN, Germany). Parameters evaluated included forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), FEV1/FVC ratio, and small airway function indicators.

RESULTS

The COPD cohort exhibited significantly lower values across all lung function measures compared to the other two groups, particularly for dynamic lung volume parameters such as FEV1%predicted and FEV1/FVC%. Small airway function indices, including FEV3%predicted, FEF75%predicted, FEF50%predicted, FEF25%predicted, and MMEF%predicted, were markedly decreased in the COPD group (all p-values <0.001). Receiver operating characteristic (ROC) curve analysis demonstrated that MMEF/FVC% and FEV3/FVC% had high diagnostic accuracy for COPD, with MMEF/FVC% exhibiting the optimal sensitivity and specificity.

CONCLUSION

Small airway function indices, especially MMEF/FVC%, can serve as effective tools for early identification of GOLD stage 0 COPD. Incorporation of these findings into clinical practice may facilitate early diagnosis and intervention, thereby improving treatment outcomes and patient quality of life.

Update on advances in cystic fibrosis towards a cure and implications for primary care clinicians

During the past quarter century, the diagnosis and treatment of cystic fibrosis (CF) have been transformed by molecular sciences that initiated a new era with discovery of the cystic fibrosis transmembrane conductance regulator (CFTR) gene. The knowledge gained from that breakthrough has had dramatic clinical impact. Although once a diagnostic dilemma with long delays, preventable deaths, and irreversible pathology, CF can now be routinely diagnosed shortly after birth through newborn screening programs. This strategy of pre-symptomatic identification has eliminated the common diagnostic "odyssey" that was a failure of the healthcare delivery system causing psychologically traumatic experiences for parents. Therapeutic advances of many kinds have culminated in CFTR modulator treatment that can reduce the effects of or even correct the molecular defect in the chloride channel -the basic cause of CF. This astonishing advance has transformed CF care as described fully herein. Despite this impressive progress, there are challenges and controversies in the delivery of care. Issues include how best to achieve high sensitivity newborn screening with acceptable specificity; what course of action is appropriate for children who are identified through the unavoidable incidental findings of screening tests (CFSPID/CRMS cases and heterozygote carriers); how best to ensure genetic counseling; when to initiate the very expensive but life-saving CFTR modulator drugs; how to identify new CFTR modulator drugs for patients with non-responsive CFTR variants; how to adjust other therapeutic modalities; and how to best partner with primary care clinicians. Progress always brings new challenges, and this has been evident worldwide for CF. Consequently, this article summarizes the major advances of recent years along with controversies and describes their implications with an international perspective.

Free-Breathing Functional Pulmonary Proton MRI: A Novel Approach Using Voxel-Wise Lung Ventilation (VOLVE) Assessment in Healthy Volunteers and Patients With Chronic Obstructive Pulmonary Disease

BACKGROUND

In respiratory medicine, there is a need for sensitive measures of regional lung function that can be performed using standard imaging technology, without the need for inhaled or intravenous contrast agents.

PURPOSE

To describe VOxel-wise Lung VEntilation (VOLVE), a new method for quantifying regional lung ventilation (V) and perfusion (Q) using free-breathing proton MRI, and to evaluate VOLVE in healthy never-smokers, healthy people with smoking history, and people with chronic obstructive pulmonary disease (COPD).

STUDY TYPE

Prospective pilot.

POPULATION

Twelve healthy never-smoker participants (age 30.3 ± 12.5 years, five male), four healthy participants with smoking history (>10 pack-years) (age 42.5 ± 18.3 years, one male), and 12 participants with COPD (age 62.8 ± 11.1 years, seven male).

FIELD STRENGTH/SEQUENCE

Single-slice free-breathing two-dimensional fast field echo sequence at 3 T.

ASSESSMENT

A novel postprocessing was developed to evaluate the MR signal changes in the lung parenchyma using a linear regression-based approach, which makes use of all the data in the time series for maximum sensitivity. V/Q-weighted maps were produced by computing the cross-correlation, lag and gradient between the respiratory/cardiac phase time course and lung parenchyma signal time courses. A comparison of histogram median and skewness values and spirometry was performed.

STATISTICAL TESTS

Kruskal-Wallis tests with Dunn's multiple comparison tests to compare VOLVE metrics between groups; Spearman correlation to assess the correlation between MRI and spirometry-derived parameters; and Bland-Altman analysis and coefficient of variation to evaluate repeatability were used. A P-value <0.05 was considered significant.

RESULTS

Significant differences between the groups were found for ventilation between healthy never-smoker and COPD groups (median XCCV, LagV, and GradV) and perfusion (median XCCQ, LagQ, and GradQ). Minimal bias and no significant differences between intravisit scans were found (P range = 0.12-0.97).

DATA CONCLUSION

This preliminary study showed that VOLVE has potential to provide metrics of function quantification.

LEVEL OF EVIDENCE

2 TECHNICAL EFFICACY: Stage 1.

Beyond forced exhalation: impulse oscillometry as a promising tool for bronchial hyperresponsiveness evaluation

Introduction: The multiple forced expiratory maneuvers that must be performed during methacholine test require a high degree of collaboration and can lead to fatigue. However, impulse oscillometry (IOS) is a noninvasive test, quick and easy to perform, that does not require effort-dependent maneuvers. Objectives: The primary endpoint was to evaluate the relationship between IOS and spirometry during the methacholine test. The secondary endpoint was to study the predictive value of baseline IOS in the development of bronchial hyperreactivity. Methods: Observational, prospective, cross-sectional study, with recruitment of consecutive patients from the pulmonology department with clinical suspicion of bronchial asthma with negative bronchodilator test and normal FeNO. Results: Twenty-five patients were included, with a mean age of 49 ± 18 years. Thirteen patients (52%) had a positive methacholine test. The correlation between IOS indices and FEV1 was significant (p < 0.05) in all cases. The indices with the highest predictive power were R5-20 and AX. The optimal cutoff points were an increase of greater than 32.96% in R5, greater than 120.83% for X5, an increase of 30.30 [kPa l-1s-1] in R5-20, and an increase of 1.01 [kPa l-1] for AX. Baseline oscillometry demonstrated a strong predictive value in the development of bronchial hyperreactivity, with a sensitivity of 61.5% and a specificity of 91.7%, using the cut-off point of 160.0% for R5. Conclusions: IOS may be a valuable alternative to forced spirometry in detecting bronchial hyperreactivity during the methacholine test, showing a good correlation between both tests.

Oscillometry-Defined Small Airway Dysfunction in Patients with Chronic Obstructive Pulmonary Disease

BACKGROUND

The prevalence of small airway dysfunction (SAD) in patients with chronic obstructive pulmonary disease (COPD) across different ethnicities is poorly understood. This study aimed to estimate the prevalence of SAD in stable COPD patients.

METHODS

We conducted a cross-sectional study of 196 consecutive stable COPD patients. We measured pre- and post-bronchodilator (BD) lung function and respiratory impedance. The severity of COPD and lung function abnormalities was graded in accordance with the Global Initiative for Chronic Obstructive Lung Disease (GOLD) guidelines. SAD was defined as either difference in whole-breath resistance at 5 and 19 Hz > upper limit of normal or respiratory system reactance at 5 Hz < lower limit of normal.

RESULTS

The cohort consisted of 95.9% men, with an average age of 66.3 years. The mean forced expiratory volume 1 second (FEV1) % predicted was 56.4%. The median COPD assessment test (CAT) scores were 14. The prevalence of post-BD SAD across the GOLD grades 1 to 4 was 14.3%, 51.1%, 91%, and 100%, respectively. The post-BD SAD and expiratory flow limitation at tidal breath (EFLT) were present in 62.8% (95% confidence interval [CI], 56.1 to 69.9) and 28.1% (95% CI, 21.9 to 34.2), respectively. COPD patients with SAD had higher CAT scores (15.5 vs. 12.8, p<0.01); poor lung function (FEV1% predicted 46.6% vs. 72.8%, p<0.01); lower diffusion capacity for CO (4.8 mmol/min/kPa vs. 5.6 mmol/min/kPa, p<0.01); hyperinflation (ratio of residual volume to total lung capacity % predicted: 159.7% vs. 129%, p<0.01), and shorter 6-minute walk distance (367.5 m vs. 390 m, p=0.02).

CONCLUSION

SAD is present across all severities of COPD. The prevalence of SAD increases with disease severity. SAD is associated with poor lung function and higher symptom burden. Severe SAD is indicated by the presence of EFLT.

Respiratory function after 30+ years following sulfur mustard exposure in survivors in Sweden

Background

Sulfur mustard (SM) exposure causes acute and chronic respiratory diseases. The extent of small airway dysfunction (SAD) in individuals exposed to SM is unclear. This study evaluated and compared SAD in SM-exposed and SM-unexposed participants using noninvasive lung function tests assessing small airway function.

Methods

This retrospective cohort study involved SM-exposed (n = 15, mean age: 53 ± 8 years) and SM-unexposed (n = 15, mean age: 53 ± 7 years) Kurdish-Swedish individuals in Sweden. Small airway resistance and reactance were assessed using impulse oscillometry (IOS). Nitrogen (N2) multiple breath washout (MBW) was employed to assess lung ventilation heterogeneity. The gas-exchanging capacity of the lungs was assessed using the diffusing capacity of the lungs for the carbon monoxide (DLCO) test. Lung function outcomes were reported as absolute values and z-scores. Group comparisons were performed using the Mann-Whitney U test.

Results

No statistically significant differences in age, height, or body mass index were observed between the two groups. IOS showed significantly increased small airway resistance, while N2MBW exhibited significantly increased global and acinar ventilation heterogeneity in SM-exposed individuals compared to that in unexposed individuals. SAD was identified in 14 of 15 SM-exposed individuals, defined as at least one abnormal IOS difference between resistance at 5 and 20 Hz (R5-R20) and/or area of reactance (AX) or N2MBW lung's acinar zone (Sacin), and DLCO adjusted to the alveolar volume (DLCO/VA) outcome. Of these 14 individuals, only 5 demonstrated concordant findings across the IOS and N2MBW tests.

Conclusion

Exposure to SM was positively associated with long-term impairment of respiratory tract function in the small airways in the majority of the previously SM-exposed individuals in the present study. Furthermore, both IOS and N2MBW should be employed to detect SAD in SM-exposed survivors as they provide complementary information. Identifying and characterizing the remaining pathology of the small airways in survivors of SM exposure is a first step toward improved treatment and follow-up.

Delphi Consensus on Clinical Applications of GOLD 2023 Recommendations in COPD Management: How Aligned are Recommendations with Clinical Practice?

INTRODUCTION

The objective of this Delphi study was to understand and assess the level of consensus among respiratory experts on the clinical application of GOLD 2023 recommendations in management of patients with chronic obstructive pulmonary disease (COPD).

METHODS

The study comprised two online surveys and a participant meeting with 34 respiratory experts from 16 countries. Responses of 73 questions were recorded using a Likert scale ranging from 0 (disagreement) to 9 (agreement). The consensus threshold was 75%.

RESULTS

Survey 1 and survey 2 had 34 and 32 participants, respectively; and 25 attended the participant meeting. Consensus was reached on survey 1: 28/42; survey 2: 18/30 close-ended questions. A consensus was reached on the clinical relevance of most updates in definitions and diagnosis of COPD. Mixed results for the treatment recommendations by GOLD were noted: 74% agreed with the recommendation to initiate treatment with dual bronchodilators for group E patients; 63% agreed for including inhaled corticosteroids (ICS)/long-acting β2 agonist(LABA)/ Long-acting muscarinic receptor antagonists (LAMA) as a treatment option for GOLD B patients. Also, consensus lacked on removing ICS + LABA as an initial therapeutic option, in countries with challenges in access to other treatment option;. 88% agreed that they use GOLD recommendations in their daily clinical practice.

CONCLUSIONS

This Delphi study demonstrated a high level of consensus regarding key concepts of GOLD 2023 report, with most participants favoring recent updates in definitions, diagnosis, management, and prevention of COPD. More evidence on the etiotype based management and treatment options for group B and E are required which could further strengthen clinical application of the GOLD report.

Burden, clinical features, and outcomes of post-tuberculosis chronic obstructive lung diseases

PURPOSE OF REVIEW

Post-tuberculosis lung disease (PTLD) is an increasingly recognized and debilitating consequence of pulmonary tuberculosis (PTB). In this review, we provide a comprehensive overview of PTLD with airflow obstruction (PTLD-AFO), focusing on its burden, pathophysiology, clinical manifestations, diagnostic methods, and management strategies.

RECENT FINDINGS

The relationship between PTLD and airflow obstruction is complex and multifactorial. Approximately 60% of the patients with PTLD have some spirometric abnormality. Obstruction is documented in 18-22% of PTLD patients. The host susceptibility and host response to mycobacterium drive the pathogenic mechanism of PTLD. A balance between inflammatory, anti-inflammatory, and fibrotic pathways decides whether an individual with PTB would have PTLD after microbiological cure. An obstructive abnormality in PTLD-AFO is primarily due to destruction of bronchial walls, aberrant healing, and reduction of mucosal glands. The most common finding on computed tomography (CT) of thorax in patients with PTLD-AFO is bronchiectasis and cavitation. Therefore, the 'Cole's vicious vortex' described in bronchiectasis applies to PTLD. A multidisciplinary approach is required for diagnosis and treatment. The disability-adjusted life-years (DALYs) attributed to PTLD represent about 50% of the total estimated burden of DALYs due to tuberculosis (TB). Patients with PTLD require comprehensive care that includes psychosocial support, pulmonary rehabilitation, and vaccination against respiratory pathogens. In the absence of trials evaluating different treatments for PTLD-AFO, therapy is primarily symptomatic.

SUMMARY

PTLD with airflow obstruction has considerable burden and causes a significant morbidity and mortality. However, many aspects of PTLD-AFO still need to be answered. Studies are required to evaluate different phenotypes, especially concerning Aspergillus -related complications. The treatment should be personalized based on the predominant phenotype of airflow obstruction. Extensive studies to understand the exact burden, pathogenesis, and treatment of PTBLD-AFO are needed.

Small airways in asthma: From inflammation and pathophysiology to treatment response

Small airways are characterized as those with an inner diameter less than 2 mm and constitute a major site of pathology and inflammation in asthma disease. It is estimated that small airways dysfunction may occur before the emergence of noticeable symptoms, spirometric abnormalities and imaging findings, thus characterizing them as "the quiet or silent zone" of the lungs. Despite their importance, measuring and quantifying small airways dysfunction presents a considerable challenge due to their inaccessibility in usual functional measurements, primarily due to their size and peripheral localization. Several pulmonary function tests have been proposed for the assessment of the small airways, including impulse oscillometry, nitrogen washout, body plethysmography, as well as imaging methods. Nevertheless, none of these methods has been established as the definitive "gold standard," thus, a combination of them should be used for an effective assessment of the small airways. Widely used asthma treatments seem to also affect several parameters of the small airways. Emerging biologic treatments show promising results in reducing small airways inflammation and remodelling, providing evidence for potential alterations in the disease's progression and outcomes. These novel therapies have implications not only in the clinical aspects of asthma but also in its inflammatory and functional aspects.

Deep learning parametric response mapping from inspiratory chest CT scans: a new approach for small airway disease screening

OBJECTIVES

Parametric response mapping (PRM) enables the evaluation of small airway disease (SAD) at the voxel level, but requires both inspiratory and expiratory chest CT scans. We hypothesize that deep learning PRM from inspiratory chest CT scans can effectively evaluate SAD in individuals with normal spirometry.

METHODS

We included 537 participants with normal spirometry, a history of smoking or secondhand smoke exposure, and divided them into training, tuning, and test sets. A cascaded generative adversarial network generated expiratory CT from inspiratory CT, followed by a UNet-like network predicting PRM using real inspiratory CT and generated expiratory CT. The performance of the prediction is evaluated using SSIM, RMSE and dice coefficients. Pearson correlation evaluated the correlation between predicted and ground truth PRM. ROC curves evaluated predicted PRMfSAD (the volume percentage of functional small airway disease, fSAD) performance in stratifying SAD.

RESULTS

Our method can generate expiratory CT of good quality (SSIM 0.86, RMSE 80.13 HU). The predicted PRM dice coefficients for normal lung, emphysema, and fSAD regions are 0.85, 0.63, and 0.51, respectively. The volume percentages of emphysema and fSAD showed good correlation between predicted and ground truth PRM (|r| were 0.97 and 0.64, respectively, p < 0.05). Predicted PRMfSAD showed good SAD stratification performance with ground truth PRMfSAD at thresholds of 15%, 20% and 25% (AUCs were 0.84, 0.78, and 0.84, respectively, p < 0.001).

CONCLUSION

Our deep learning method generates high-quality PRM using inspiratory chest CT and effectively stratifies SAD in individuals with normal spirometry.

The Role of Small Airway Disease in Pulmonary Fibrotic Diseases

Small airway disease (SAD) is a pathological condition that affects the bronchioles and non-cartilaginous airways 2 mm or less in diameter. These airways play a crucial role in respiratory function and are often implicated in various pulmonary disorders. Pulmonary fibrotic diseases are characterized by the thickening and scarring of lung tissue, leading to progressive respiratory failure. We aimed to present the link between SAD and fibrotic lung conditions. The evidence suggests that SAD may act as a precursor or exacerbating factor in the progression of fibrotic diseases. Patients with fibrotic conditions often exhibit signs of small airway dysfunction, which can contribute to worsening respiratory symptoms and decreased lung function. Moreover, individuals with advanced SAD are at a heightened risk of developing fibrotic changes in the lung. The interplay between inflammation, environmental factors, and genetic predisposition further complicates this association. The early detection and management of SAD can potentially mitigate the progression of fibrotic diseases, highlighting the need for comprehensive clinical evaluation and research. This review emphasizes the need to understand the evolving connection between SAD and pulmonary fibrosis, urging further detailed research to clarify the causes and potential treatment between the two entities.

Reference equations using segmented regressions for impulse oscillometry in healthy subjects aged 2.7-90 years

Background

Published reference equations for impulse oscillometry (IOS) usually encompass a specific age group but not the entire lifespan. This may lead to discordant predicted values when two or more non-coincident equations can be applied to the same person, or when a person moves from one equation to the next non-convergent equation as he or she gets older. Thus, our aim was to provide a single reference equation for each IOS variable that could be applied from infancy to old age.

Methods

This was an ambispective cross-sectional study in healthy nonsmokers, most of whom lived in Mexico City, who underwent IOS according to international standards. A multivariate piecewise linear regression, also known as segmented regression, was used to obtain reference equations for each IOS variable.

Results

In a population of 830 subjects (54.0% female) aged 2.7 to 90 years (54.8% children ≤12 years), segmented regression estimated two breakpoints for age in almost all IOS variables, except for R5-R20 in which only one breakpoint was detected. With this approach, multivariate regressions including sex, age, height and body mass index as independent variables were constructed, and coefficients for calculating predicted value, lower and upper limits of normal, percentage of predicted and z-score were obtained.

Conclusions

Our study provides IOS reference equations that include the major determinants of lung function, i.e. sex, age, height and body mass index, that can be easily implemented for subjects of almost any age.

Computer-assisted evaluation of small airway disease in CT scans of Iran-Iraq war victims of chemical warfare by a locally developed software: comparison between different quantitative methods

OBJECTIVE

Diagnosis of small airway disease on computed tomography (CT) scans is challenging in patients with a history of chemical warfare exposure. We developed a software package based on different methodologies to identify and quantify small airway disease in CT images. The primary aim was to identify the best automatic methodology for detecting small airway disease in CT scans of Iran-Iraq War victims of chemical warfare.

METHODS

This retrospective case-control study enrolled 46 patients with a history of chemical warfare exposure and 27 controls with inspiratory/expiratory (I/E) CT scans and spirometry tests. Image data were automatically segmented, and inspiratory images were registered into the expiratory images' frame using the locally developed software. Parametric response mapping (PRM) and air trapping index (ATI) mapping were performed on the CT images. Conventional QCT methods, including expiratory/inspiratory mean lung attenuation (E/I MLA) ratio, normal density E/I (ND E/I) MLA ratio, attenuation volume Index (AVI), %low attenuation areas (LAA) < -856 in exhale scans, and %LAA < -950 in inhale scans were also computed. QCT measurements were correlated with spirometry results and compared across the two study groups.

RESULTS

The correlation analysis showed a significant negative relationship between three air trapping (AT) measurements (PRM, ATI, and %LAAExp < -856) and spirometry parameters (Fev1, Fvc, Fev1/Fvc, and MMEF). Moreover, %LAAExp < -856 had the highest significant negative correlation with Fev1/Fvc (r = -0.643, P-value < 0.001). Three AT measurements demonstrated a significant difference between the study groups. The E/I ratio was also significantly different between the two groups (P-value < 0.001). Binary logistic regression models showed PRMFsad, %LAAExp < -856, and ATI as significant and strong predictors of the study outcome. Optimal cut-points for PRMFsad = 19%, %LAAExp < -856 = 23%, and ATI = 27% were identified to classify the participants into two groups with high accuracy.

CONCLUSION

QCT methods, including PRM, ATI, and %LAAExp < -856 can greatly advance the identification and quantification of SAD in chemical warfare victims. The results should be verified in well-designed prospective studies involving a large population.

Association between clinical, serological, functional and radiological findings and ventilatory distribution heterogeneity in patients with rheumatoid arthritis

BACKGROUND

In rheumatoid arthritis (RA), the involvement of the pulmonary interstitium can lead to structural changes in the small airways and alveoli, leading to reduced airflow and maldistribution of ventilation. The single-breath nitrogen washout (SBN2W) test is a measure of the ventilatory distribution heterogeneity and evaluates the small airways. This study aimed to find out which clinical, serological, functional and radiological findings are useful to identify RA patients with pathological values of the phase III slope (SIII) measured by the SBN2W test.

METHODS

This was a cross-sectional study in which RA patients were assessed using the Health Assessment Questionnaire-Disability Index (HAQ-DI) and the Clinical Disease Activity Index (CDAI) and underwent serological analysis of autoantibodies and inflammatory markers. In addition, they underwent pulmonary function tests (including the SBN2W test) and chest computed tomography (CT).

RESULTS

Of the 60 RA patients evaluated, 39 (65%) had an SIII >120% of the predicted value. There were significant correlations between SIII and age (r = 0.56, p<0.0001), HAQ-DI (r = 0.34, p = 0.008), forced vital capacity (FVC, r = -0.67, p<0.0001), total lung capacity (r = -0.46, p = 0.0002), residual volume/total lung capacity (TLC) (r = 0.44, p = 0.0004), and diffusing capacity of the lungs for carbon monoxide (r = -0.45, p = 0.0003). On CT scans, the subgroup with moderate/severe disease had a significantly higher SIII than the normal/minimal/mild subgroup (662 (267-970) vs. 152 (88-283)% predicted, p = 0.0004). In the final multiple regression model, FVC, extent of moderate/severe involvement and age were associated with SIII, explaining 59% of its variability.

CONCLUSIONS

In patients with RA, FVC, extent of lung involvement and age, all of which are easily obtained variables in clinical practice, identify poorly distributed ventilation. In addition, the presence of respiratory symptoms and deteriorated physical function are closely related to the distribution of ventilation in these patients.

Quantitative analyzes of the variability in airways via four-dimensional dynamic ventilation CT in patients with chronic obstructive pulmonary disease: correlation with spirometry data and severity of airflow limitation

Background

In chronic obstructive pulmonary disease (COPD) patients, the diagnosis and assessment of disease severity are mainly based on spirometry, which may lead to misjudgments due to poor patient compliance. Thoracic four-dimensional dynamic ventilation computed tomography (4D-CT) provides more airway data approximating true physiological function than conventional CT. We aimed to determine dynamic changes in airways to elucidate the pathological mechanism underlying COPD and predict the severity of airflow limitation in patients.

Methods

Forty-two COPD patients underwent 4D-CT and spirometry. The minimum lumen diameter changed with the breathing cycle in 4th-generation airways and was continuously measured in the apical (RB1), lateral (RB4) and posterior basal segments (RB10) of the right lung. The minimum lumen diameter in the peak inspiration and peak expiration as well as the peak expiratory/peak inspiratory ratio (E/I ratio), and dynamic coefficient of variance (CV) were calculated.

Results

Correlations of FEV1% with the CV of minimum lumen diameter in RB1 (ρ=-0.473, P=0.002) and in RB10 (ρ=-0.480, P=0.005) were observed, suggesting that the dynamic variability in 4th-generation airways was associated with airflow limitation in COPD patients. The CV of the minimum lumen diameter in RB1 significantly differed between the GOLD I + II and GOLD III + IV groups {8.59 [interquartile range (IQR), 6.63-14.86] vs. 14.64 (10.65-25.88), respectively; P=0.016}, suggesting that the dynamic CV in RB1 increased significantly in the GOLD III + IV group, which had worse pulmonary ventilation function. Based on the receiver operating characteristic (ROC) curve analysis, CV-RB1 predicted FEV1% <50% with an optimal cut-off of 9.43% [sensitivity 85.7%, specificity 57.1%, area under the curve (AUC) 0.717].

Conclusions

4D-CT might be an available method to help diagnose and evaluate the severity of COPD.

Prevalence of small airway dysfunction in the Swiss PneumoLaus Cohort

Background

Recent evidence identified exposure to particulate matter of size ≤2.5 µm (PM2.5) as a risk factor for high prevalence of small airway dysfunction (SAD). We assessed the prevalence of SAD in a European region with low air pollution levels.

Methods

SAD was defined as a maximum mid-expiratory flow (MMEF) <65% of predicted value (PV) or MMEF

Results

Among 3351 participants (97.6% Caucasian, 55.7% female sex, mean age 62.7 years), we observed MMEF <65% PV in 425 (12.7%) and MMEF 65 years only. In an area where ambient PM2.5 concentration was <15 µg·m-3 during the observation period (2010 and 2020), ≥72% of participants with SAD were ever-smokers.

Conclusions

The observed low prevalence of SAD of 5.0-12.7% depending on criteria employed may be related to lower PM2.5 exposure. Smoking was the main factor associated with SAD in an area with low PM2.5 exposure. Employing a MMEF threshold <65% PV carries a risk of SAD overdiagnosis in elderly individuals.

Collapse

Key Words Collapse

MESH Headings Collapse

Grants Collapse

Affiliation(s)

Brice Touilloux Division of Pulmonology, Department of Medicine, Lausanne University Hospital (CHUV) and University of Lausanne (UNIL), Lausanne, Switzerland Division of Pulmonology, Department of Medicine and Specialties, Fribourg Hospital, Fribourg, Switzerland
Cedric Bongard Division of Pulmonology, Department of Medicine, Lausanne University Hospital (CHUV) and University of Lausanne (UNIL), Lausanne, Switzerland
Benoit Lechartier Division of Pulmonology, Department of Medicine, Lausanne University Hospital (CHUV) and University of Lausanne (UNIL), Lausanne, Switzerland
Minh Khoa Truong Division of Pulmonology, Department of Medicine, Lausanne University Hospital (CHUV) and University of Lausanne (UNIL), Lausanne, Switzerland
Pedro Marques-Vidal Division of Internal Medicine, Department of Medicine, CHUV and UNIL, Lausanne, Switzerland
Peter Vollenweider Division of Internal Medicine, Department of Medicine, CHUV and UNIL, Lausanne, Switzerland
Julien Vaucher Division of Internal Medicine, Department of Medicine, CHUV and UNIL, Lausanne, Switzerland Division of Internal Medicine, Department of Medicine and Specialties, Fribourg Hospital, Fribourg, Switzerland University of Fribourg, Fribourg, Switzerland
Alessio Casutt Division of Pulmonology, Department of Medicine, Lausanne University Hospital (CHUV) and University of Lausanne (UNIL), Lausanne, Switzerland Division of Pneumology, Ospedale Regionale di Lugano, Ente Ospedaliero Cantonale, Lugano, Switzerland These authors contributed equally
Christophe von Garnier Division of Pulmonology, Department of Medicine, Lausanne University Hospital (CHUV) and University of Lausanne (UNIL), Lausanne, Switzerland These authors contributed equally

Collapse

Detection of Small Airway Dysfunction in Asthmatic Patients by Spirometry and Impulse Oscillometry System

BACKGROUND

There is no gold standard in diagnosing SAD. Indicators of SAD are considered: (a) a value <65% of predicted values of two of three measures, FEF25-75, FEF50 e FEF75 (FEF+); (b) a value of FEV3/FEV6 < LLN (FEV3/FEV6+); (c) an IOS value of R5-R20 >0.07 kPa·s·L-1 (R5-R20+).

AIM AND OBJECTIVES

The aim of the study was to ascertain, in asthmatic patients, whether spirometry and IOS indicators agree in detecting SAD. We also assessed the relationship between spirometry and IOS indicators and clinical features of asthma.

METHODS

We prospectively recruited adult asthmatic patients. Anthropometric and clinical characteristics were recorded. All patients performed spirometry and IOS tests.

RESULTS

We enrolled 301 asthmatic patients (179 females; mean age 50 ± 16 years) with normal to moderately severe degree of airway obstruction; 91% were non-smokers, 74% were atopic, 28% had an exacerbation in the previous year, and 18% had a poor asthma control by ACT. SAD was diagnosed in 62% of patients through FEF+, in 40% through FEV3/FEV6+ and in 41% through R5-R20+. κ values were 0.49 between FEF+ and FEV3/FEV6+, 0.20 between FEF+ and R5-R20+, 0.07 between FEV3/FEV6+ and R5-R20+. R5-R20+ but not FEF+ and FEV3/FEV6+ was significantly associated with ACT score (p < 0.05).

CONCLUSIONS

Our study shows that in mild to moderately severe asthmatic patients, spirometry and IOS indicators are complementary in diagnosing SAD. Additionally, IOS indicator, but not spirometry ones, was related to asthma control.

[Small airway: from definition to treatment]

The small airway, present since the origins of humanity and described barely a century ago, has recently been discovered as the anatomical site where inflammation begins in some obstructive lung diseases, such as asthma and Chronic Obstructive Pulmonary Disease (COPD), per se. Small airway dysfuction was identified in up to 91% of asthmatic patients and in a large proportion of COPD patients. In subjects without pathology, small airway represent 98.8% (approximately 4500 ml) of the total lung volume, contributing only between 10-25% of the total lung resistance; however, in subjects with obstruction, it can represent up to 90% of the total resistance. Despite this, its morphological and functional characteristics allow its dysfunction to remain undetected by conventional diagnostic methods, such as spirometry. Hence the importance of this review, which offers an overview of the tools available to assess small airway dysfunction and the possible therapies that act in this silent zone.

Comparative assessment of small airway dysfunction by impulse oscillometry and spirometry in chronic obstructive pulmonary disease and asthma with and without fixed airflow obstruction

Background

Small airways play a major role in the pathogenesis and prognosis of chronic obstructive pulmonary disease (COPD) and asthma. More data on small airway dysfunction (SAD) using spirometry and impulse oscillometry (IOS) in these populations are required. The objective of this study was to compare the two methods, spirometry and IOS, for SAD detection and its prevalence defined by spirometry and IOS in subjects with COPD and asthma with and without fixed airflow obstruction (FAO).

Design

This is a cross-sectional study.

Methods

Spirometric and IOS parameters were compared across four groups (COPD, asthma with FAO, asthma without FAO, and healthy subjects). SAD defined by spirometry and IOS criteria were compared.

Results

A total of 262 subjects (67 COPD, 55 asthma with FAO, 101 asthma without FAO, and 39 healthy controls) were included. The prevalence of SAD defined by using IOS and spirometry criteria was significantly higher in patients with COPD (62.7 and 95.5%), asthma with FAO (63.6 and 98.2%), and asthma without FAO (38.6 and 19.8%) in comparison with healthy control (7.7 and 2.6%). IOS is more sensitive than spirometry in the detection of SAD in asthma without FAO (38.6% vs. 19.8%, p = 0.003) However, in subjects with FAO (COPD and asthma with FAO), spirometry is more sensitive than IOS to detect SAD (95.5% vs. 62.7%, p < 0.001 and 98.2% vs. 63.6%, p < 0.001, respectively).

Conclusion

Small airway dysfunction was significantly detected in COPD and asthma with and without FAO. Although IOS shows more sensitivity than spirometry in the detection of SAD in asthma without FAO, spirometry is more sensitive than IOS in patients with FAO including COPD and asthma with FAO.

Analysis of influencing factors and a predictive model of small airway dysfunction in adults

BACKGROUND

Small airway dysfunction (SAD) is a widespread but less typical clinical manifestation of respiratory dysfunction. In lung diseases, SAD can have a higher-than-expected impact on lung function. The aim of this study was to explore risk factors for SAD and to establish a predictive model.

METHODS

We included 1233 patients in the pulmonary function room of TangDu Hospital from June 2021 to December 2021. We divided the subjects into a small airway disorder group and a non-small airway disorder group, and all participants completed a questionnaire. We performed univariate and multivariate analyses to identify the risk factors for SAD. Multivariate logistic regression was performed to construct the nomogram. The performance of the nomogram was assessed and validated by the Area under roc curve (AUC), calibration curves, and Decision curve analysis (DCA).

RESULTS

One. The risk factors for small airway disorder were advanced age (OR = 7.772,95% CI 2.284-26.443), female sex (OR = 1.545,95% CI 1.103-2.164), family history of respiratory disease (OR = 1.508,95% CI 1.069-2.126), history of occupational dust exposure (OR = 1.723,95% CI 1.177-2.521), history of smoking (OR = 1.732,95% CI 1.231-2.436), history of pet exposure (OR = 1.499,95% CI 1.065-2.110), exposure to O₃ (OR = 1.008,95% CI 1.003-1.013), chronic bronchitis (OR = 1.947,95% CI 1.376-2.753), emphysema (OR = 2.190,95% CI 1.355-3.539) and asthma (OR = 7.287,95% CI 3.546-14.973). 2. The AUCs of the nomogram were 0.691 in the training set and 0.716 in the validation set. Both nomograms demonstrated favourable clinical consistency. 3.There was a dose‒response relationship between cigarette smoking and SAD; however, quitting smoking did not reduce the risk of SAD.

CONCLUSION

Small airway disorders are associated with age, sex, family history of respiratory disease, occupational dust exposure, smoking history, history of pet exposure, exposure to O₃, chronic bronchitis, emphysema, and asthma. The nomogram based on the above results can effectively used in the preliminary risk prediction.

Small airways disease in patients with alpha-1 antitrypsin deficiency

Alpha-1 antitrypsin deficiency (AATD) is a genetic disorder, characterized by panacinar emphysema mainly in the lower lobes, and predisposes to chronic obstructive pulmonary disease (COPD) at a younger age, especially in patients with concomitant cigarette smoking. Alpha-1 antitrypsin (a1-AT) is a serine protease inhibitor that mainly blocks neutrophil elastase and maintains protease/antiprotease balance in the lung and AATD is caused by mutations in the SERPINA1 gene that encodes a1-AT protein. PiZZ is the most common genotype associated with severe AATD, leading to reduced circulating levels of a1-AT. Besides its antiprotease function, a1-AT has anti-inflammatory and antioxidative effects and AATD results in defective innate immunity. Protease/antiprotease imbalance affects not only the lung parenchyma but also the small airways and recent studies have shown that AATD is associated with small airway dysfunction. Alterations in small airways structure with peripheral ventilation inhomogeneities may precede emphysema formation, providing a unique opportunity to detect early disease. The aim of the present review is to summarize the current evidence for the contribution of small airways disease in AATD-associated lung disease.

Monitoring small airway dysfunction in connective tissue disease-related interstitial lung disease: a retrospective and prospective study

BACKGROUND

Small airway dysfunction (SAD), a hallmark of early lung function abnormality, is a major component of several chronic respiratory disorders. The role of SAD in patients with connective tissue disease-related interstitial lung disease (CTD-ILD) has not been explored.

METHODS

We conducted a two-parts (retrospective and prospective) study to collect pulmonary function tests from CTD-ILD patients. SAD was defined as at least two of the three measures (MMEF, FEF 50%, and FEF 75%) must be 65% of predicted values. Spearman correlation coefficient was used to evaluate association between SAD and other pulmonary function parameters. Mixed effects regression modeling analysis was used to assess response to treatment.

RESULTS

CTD-ILD patients with SAD and without SAD were compared in this study. In the retrospective study, pulmonary function tests (PFTs) from 491 CTD-ILD patients were evaluated, SAD were identified in 233 (47.5%). CTD-ILD patients with SAD were less smokers (17.6% vs. 27.9%, p = 0.007) and more females (74.3% vs. 64.0%, p = 0.015) than those without SAD. CTD-ILD patients with SAD had lower vital capacity (% predicted FVC, 70.4 ± 18.3 vs. 80.0 ± 20.9, p < 0.001) and lower diffusion capacity (% predicted DLCO, 58.8 ± 19.7 vs. 63.8 ± 22.1, p = 0.011) than those without SAD. Among 87 CTD-ILD patients prospectively enrolled, significant improvement in % predicted FVC was observed at 12-months follow-up (6.37 ± 1.53, p < 0.001 in patients with SAD; 5.13 ± 1.53, p = 0.002 in patients without SAD), but not in diffusion capacity and SAD parameters.

CONCLUSION

In our cohort, about half of CTD-ILD patients have SAD, which is less frequent in smokers and more common in female patients. CTD-ILD patients with SAD have worse pulmonary function compared to those without SAD. Improvement of FVC but no improvement of SAD was observed in CTD-ILD patients after treatment.

Functional imaging in asthma and COPD: design of the NOVELTY ADPro substudy

The NOVEL observational longiTudinal studY (NOVELTY; ClinicalTrials.gov identifier NCT02760329) is a global, prospective, observational study of ∼12 000 patients with a diagnosis of asthma and/or COPD. Here, we describe the design of the Advanced Diagnostic Profiling (ADPro) substudy of NOVELTY being conducted in a subset of ∼180 patients recruited from two primary care sites in York, UK. ADPro is employing a combination of novel functional imaging and physiological and metabolic modalities to explore structural and functional changes in the lungs, and their association with different phenotypes and endotypes. Patients participating in the ADPro substudy will attend two visits at the University of Sheffield, UK, 12±2 months apart, at which they will undergo imaging and physiological lung function testing. The primary end-points are the distributions of whole lung functional and morphological measurements assessed with xenon-129 magnetic resonance imaging, including ventilation, gas transfer and airway microstructural indices. Physiological assessments of pulmonary function include spirometry, bronchodilator reversibility, static lung volumes via body plethysmography, transfer factor of the lung for carbon monoxide, multiple-breath nitrogen washout and airway oscillometry. Fractional exhaled nitric oxide will be measured as a marker of type-2 airways inflammation. Regional and global assessment of lung function using these techniques will enable more precise phenotyping of patients with physician-assigned asthma and/or COPD. These techniques will be assessed for their sensitivity to markers of early disease progression.

Impaired exercise capacity in individuals with non-obstructive small airway dysfunction

Background

Whether individuals with non-obstructive spirometry-defined small airway dysfunction (SAD) have impaired exercise capacity is unclear, particularly in never-smokers. This study clarifies the degree of impaired exercise capacity and its potential cause in individuals with non-obstructive SAD.

Methods

This community-based, multiyear cross-sectional study analyzed data collected in Guangdong, China from 2012-2019 by the National Science and Technology Support Plan Program. Measurements of exercise capacity [peak work rate and peak oxygen uptake ( V ˙ O 2peak )] in participants with non-obstructive spirometry-defined SAD (n=157) were compared with those in controls (n=85) and Global Initiative for Chronic Obstructive Lung Disease (GOLD) I patients (n=239). Subgroup analyses were performed by smoking status.

Results

The risk of impaired exercise capacity was significantly higher in participants with non-obstructive SAD [ V ˙ O 2peak <84%predicted, adjusted odds ratio (aOR) =2.53; 95% confidence interval (CI): 1.42-4.52] than in controls but was not significantly different from that in GOLD I patients. Results were consistent within subgroups of smoking status (ever-smokers: non-obstructive SAD vs. controls, aOR =2.44; 95% CI: 1.08-5.51; never-smokers: non-obstructive SAD vs. controls, aOR =2.38, 95% CI: 1.02-5.58). Participants with non-obstructive SAD had a significantly lower peak work rate (β=-10.5; 95% CI: -16.3 to -4.7) and V ˙ O 2peak (%predicted, β=-4.0; 95% CI: -7.7 to -0.2) and tended to have higher ventilatory equivalents for carbon dioxide at the ventilatory threshold ( V ˙ E / V ˙ CO 2AT , β=1.1; 95% CI: -0.1 to 2.3) when compared with controls. Both peak work rate and V ˙ O 2peak were negatively correlated with V ˙ E / V ˙ CO 2AT .

Conclusions

Although not meeting the current criteria for chronic obstructive pulmonary disease, individuals with non-obstructive SAD have impaired exercise capacity that may be associated with ventilatory inefficiency regardless of smoking status.

HRCT quantitative analysis of airway remodeling and airway trapping in the small airway asthma phenotype and its correlation with pulmonary function

OBJECTIVES

We aimed to explore whether large airway remodeling and small airway structural changes exist in subjects with small airway asthma phenotype and to evaluate the relationships between quantitative high-resolution computed tomography (qHRCT) parameters and lung function.

METHODS

We enrolled 15 subjects with small airway asthma phenotype and 18 healthy controls. The two groups were matched by age, sex and body square area (BSA) with propensity score matching (PSM). Pulmonary function and qHRCT parameters [wall thickness (WT), wall area (WA), lumen area (LA), wall area percentage (WA%) of the 4th-6th generations in the right upper lobe apical segmental bronchus (RB1), adjusted by BSA, WT/BSA, WA/BSA, and LA/BSA, relative volume change -860 HU to -950 HU (RVC_{-860 to -950}) and the expiration to inspiration ratio of mean lung density (MLD_E/I)) were compared between the groups. Correlation analysis was employed to assess the relationship between qHRCT parameters and pulmonary function.

RESULTS

The small airway asthma phenotype had significantly higher WA%, RVC_{-860 to -950} and MLD_E/I and lower LA/BSA than the healthy control. Additionally, we found moderate to strong correlations between impulse oscillation (IOS) indices and WA6% and WT6/BSA. No significant correlation was found between bronchial parameters and air trapping parameters (p > 0.05).

CONCLUSIONS

Combining physiological tests with imaging approaches can lead to better evaluation of small airway disfunction (SAD) in asthmatic patients. Additionally, despite nonexistent airflow obstruction in patients with small airway asthma phenotype, large airway remodeling and small airway structural changes may appear simultaneously in the early stage of disease.

Peribronchiolar Metaplasia: A Marker of Cigarette Smoke-Induced Small Airway Injury in a Rural Cohort

Background

Peribronchiolar metaplasia (PBM) is considered a reaction to injury characterized by the proliferation of bronchiolar epithelium into immediately adjacent alveolar walls. While an association of PBM with diffuse interstitial lung diseases has been recognized, the clinical significance of PBM remains uncertain.

Methods

A cohort (n = 352) undergoing surgical resection of a lung nodule/mass in a rural area was retrospectively reviewed. Multivariate logistic regression analysis was performed to determine the association of PBM with clinical, physiological, radiographic, and histologic endpoints.

Results

In the total study cohort, 9.1% were observed to have PBM as a histologic finding in resected lung tissue (n = 32). All but one of these patients with PBM were ever-smokers with a median of 42 pack years. Clinical COPD was diagnosed in two-thirds of patients with PBM. Comorbid gastroesophageal reflux disease (GERD) was significantly associated with PBM. All patients with PBM demonstrated radiologic and histologic evidence of emphysema. Measures of pulmonary function were not impacted by PBM. Mortality was not associated with the histologic observation of PBM. In a logistic regression model, centrilobular-ground glass opacity interstitial lung abnormality and traction bronchiectasis on the CT scan of the chest and histologic evidence of fibrosis, desquamative interstitial pneumonia and anthracosis all strongly predicted PBM in the cohort.

Conclusion

A constellation of radiologic and histologic smoking-related abnormalities predicted PBM in study cohort. This confirms a co-existence of lung tissue responses to smoking including PBM, emphysema, and fibrosis. Acknowledging the physiologically "silent" nature of small airway dysfunction on pulmonary function testing, our findings support PBM as a histologic marker of small-airway injury associated with cigarette smoking.

Monitoring practices of chronic lung allograft dysfunction in pediatric lung transplantation

INTRODUCTION

Chronic lung allograft dysfunction (CLAD) continues to negatively impact the survival of pediatric lung transplant (LTx) recipients. Current consensus guidelines are adult-focused. We sought to examine CLAD detection and monitoring practices at pediatric LTx programs.

METHODS

We conducted a survey among the International Pediatric Lung Transplant Collaborative. Questions consisted of practitioner's experience, LTx program demographics, and querying tests used for CLAD surveillance and detection. Investigations queried included: chest x-ray (CXR), chest computed tomography (CT), lung magnetic resonance imaging (MRI), ventilation/perfusion scanning, conventional pulmonary function testing (PFT), multiple breath washout (MBW), infant/preschool PFT, bronchoalveolar lavage, transbronchial biopsies (TBBx), or other tissue sampling techniques. Preferences for certain modalities over others were questioned based on a five-point Likert scale.

RESULTS

Twenty-four of 25 programs responded. Chest CT and CXR are used generally for both CLAD surveillance and detection. No programs use lung MRI clinically, it may have some utility in the future. While all centers use conventional PFT, MBW, and infant/preschool PFT are used in one-fifth and one-third of centers, respectively. While the majority of programs use TBBx, only 41.7% would obtain a diagnosis based on tissue histopathology over noninvasive techniques if CLAD is suspected. Utilization of biomarkers is still limited.

CONCLUSIONS

Our results indicate continued use of conventional PFT along with chest CT and less so CXR for CLAD detection and monitoring in the large majority of centers. Infant/preschool PFT and novel methods such as MBW are used in a few centers only. Respondents agreed there is a timely need for pediatric consensus guidelines on CLAD detection and monitoring.

Adverse roles of mast cell chymase-1 in COPD

BACKGROUND

COPD is the third leading cause of death worldwide. Cigarette smoke (CS)-induced chronic inflammation inducing airway remodelling, emphysema and impaired lung function is the primary cause. Effective therapies are urgently needed. Human chymase (hCMA)1 and its orthologue mCMA1/mouse mast cell protease (mMCP)5 are exocytosed from activated mast cells and have adverse roles in numerous disorders, but their role in COPD is unknown.

METHODS

We evaluated hCMA1 levels in lung tissues of COPD patients. We used mmcp5-deficient (-/-) mice to evaluate this protease's role and potential for therapeutic targeting in CS-induced experimental COPD. In addition, we used ex vivo/in vitro studies to define mechanisms.

RESULTS

The levels of hCMA1 mRNA and CMA1+ mast cells were increased in lung tissues from severe compared to early/mild COPD patients, non-COPD smokers and healthy controls. Degranulated mast cell numbers and mMCP5 protein were increased in lung tissues of wild-type mice with experimental COPD. mmcp5 -/- mice were protected against CS-induced inflammation and macrophage accumulation, airway remodelling, emphysema and impaired lung function in experimental COPD. CS extract challenge of co-cultures of mast cells from wild-type, but not mmcp5 -/- mice with wild-type lung macrophages increased in tumour necrosis factor (TNF)-α release. It also caused the release of CMA1 from human mast cells, and recombinant hCMA-1 induced TNF-α release from human macrophages. Treatment with CMA1 inhibitor potently suppressed these hallmark features of experimental COPD.

CONCLUSION

CMA1/mMCP5 promotes the pathogenesis of COPD, in part, by inducing TNF-α expression and release from lung macrophages. Inhibiting hCMA1 may be a novel treatment for COPD.

Lung structure and function on MRI in preterm born school children with and without BPD: A feasibility study

BACKGROUND AND OBJECTIVE

The most common respiratory complication of prematurity is bronchopulmonary dysplasia (BPD), leading to structural lung changes and impaired respiratory outcomes. However, also preterm children without BPD may show similar adverse respiratory outcomes. There is a need for a safe imaging modality for preterm children with and without BPD for disease severity assessment and risk stratification. Our objective was to develop a magnetic resonance imaging (MRI) protocol in preterm children with and without BPD at school age.

METHODS

Nine healthy volunteers (median age 11.6 [range: 8.8-12.8] years), 11 preterm children with BPD (11.0 [7.2-15.6] years), and 9 without BPD (11.1 [10.7-12.6] years) underwent MRI. Images were scored on hypo- and hyperintense abnormalities, bronchopathy, and architectural distortion. MRI data were correlated to spirometry. Ventilation and perfusion defects were analyzed using Fourier Decomposition (FD) MRI.

RESULTS

On MRI, children with BPD had higher %diseased lung (9.1 (interquartile range [IQR] 5.9-11.6)%) compared to preterm children without BPD (3.4 (IQR 2.5-5.4)%, p < 0.001) and healthy volunteers (0.4 (IQR 0.1-0.8)%, p < 0.001). %Diseased lung correlated negatively with %predicted FEV₁ (r = -0.40, p = 0.04), FEV₁ /FVC (r = -0.49, p = 0.009) and FEF₇₅ (r = -0.63, p < 0.001). Ventilation and perfusion defects on FD sequence corresponded to hypointense regions on expiratory MRI.

CONCLUSION

Chest MRI can identify structural and functional lung damage at school age in preterm children with and without BPD, showing a good correlation with spirometry. We propose MRI as a sensitive and safe imaging method (without ionizing radiation, contrast agents, or the use of anesthesia) for the long-term follow-up of preterm children.

Effect of Dornase Alfa on the Lung Clearance Index in Children with Cystic Fibrosis: A Lesson from a Case Series

BACKGROUND

Dornase alfa (DNase) is the only mucus-degrading agent that has proven efficacy in cystic fibrosis (CF). Few studies have evaluated the effects of DNase on the lung clearance index (LCI). We report the experience of two CF centers in which LCI monitoring was used to evaluate the efficacy of DNase therapy.

METHODS

This is a prospective and observational study, evaluating the effects of DNase therapy on LCI values in three CF children followed at CF centers in Florence and Catania, Italy. In both centers, LCI was performed routinely, every 3-6 months, based on the clinical picture and severity of the lung disease. In this study, we evaluated the LCI before and after long-term DNase therapy.

RESULTS

DNase improved LCI values in the absence of respiratory exacerbations: in case n. 1 LCI decreased by 39% in 16 months (from 11.1 to 6.8); in case n. 2 by 20% in 12 months (from 9.3 to 7.4); in case n. 3 by 24% in 16 months (from 9.3 to 7.0).

CONCLUSIONS

This case series confirms the efficacy of DNase therapy in CF children, as demonstrated by the LCI reduction in treated patients. Furthermore, our results suggest that LCI is a sensitive marker of disease and can be used for the evaluation of response to treatment.

HDAC6 inhibitor ACY-1083 shows lung epithelial protective features in COPD

Airway epithelial damage is a common feature in respiratory diseases such as COPD and has been suggested to drive inflammation and progression of disease. These features manifest as remodeling and destruction of lung epithelial characteristics including loss of small airways which contributes to chronic airway inflammation. Histone deacetylase 6 (HDAC6) has been shown to play a role in epithelial function and dysregulation, such as in cilia disassembly, epithelial to mesenchymal transition (EMT) and oxidative stress responses, and has been implicated in several diseases. We thus used ACY-1083, an inhibitor with high selectivity for HDAC6, and characterized its effects on epithelial function including epithelial disruption, cytokine production, remodeling, mucociliary clearance and cell characteristics. Primary lung epithelial air-liquid interface cultures from COPD patients were used and the impacts of TNF, TGF-β, cigarette smoke and bacterial challenges on epithelial function in the presence and absence of ACY-1083 were tested. Each challenge increased the permeability of the epithelial barrier whilst ACY-1083 blocked this effect and even decreased permeability in the absence of challenge. TNF was also shown to increase production of cytokines and mucins, with ACY-1083 reducing the effect. We observed that COPD-relevant stimulations created damage to the epithelium as seen on immunohistochemistry sections and that treatment with ACY-1083 maintained an intact cell layer and preserved mucociliary function. Interestingly, there was no direct effect on ciliary beat frequency or tight junction proteins indicating other mechanisms for the protected epithelium. In summary, ACY-1083 shows protection of the respiratory epithelium during COPD-relevant challenges which indicates a future potential to restore epithelial structure and function to halt disease progression in clinical practice.

Impulse Oscillometry, Small Airways Disease, and Extra-Fine Formulations in Asthma and Chronic Obstructive Pulmonary Disease: Windows for New Opportunities

In recent years, the perspective of management of respiratory disease has been gradually changing in light of the increasing evidence of small airways as the major site of airflow obstruction contributing to the development of both COPD and asthma already in early stages of disease. First and foremost, the evidence is redefining disease severity, identifying small airways disease phenotypes and early signs of disease, and revising prevalence and overall epidemiological data as well. Much effort has been put toward the instrumental assessment of small airways’ involvement and early detection. Several clinical trials have evaluated the advantage of extra-fine formulations which can best target the small airways in uncontrolled asthma and severe COPD. Here, we briefly present a practical overview of the role of the small airways in disease, the most appropriate diagnostic methods for quantifying their impairment, and provide some insight into the costs of respiratory management in Italy, especially in sub-optimally controlled disease.

Reference equations for oscillometry and their differences among populations: a systematic scoping review

Respiratory oscillometry is gaining global attention over traditional pulmonary function tests for its sensitivity in detecting small airway obstructions. However, its use in clinical settings as a diagnostic tool is limited because oscillometry lacks globally accepted reference values. In this scoping review, we systematically assessed the differences between selected oscillometric reference equations with the hypothesis that significant heterogeneity existed between them. We searched bibliographic databases, registries and references for studies that developed equations for healthy adult populations according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. A widely used Caucasian model was used as the standard reference and compared against other models using Bland-Altman and Lin's concordance correlational analyses. We screened 1202 titles and abstracts, and after a full-text review of 67 studies, we included 10 in our analyses. Of these, three models had a low-to-moderate agreement with the reference model, particularly those developed from non-Caucasian populations. Although the other six models had a moderate-to-high agreement with the standard model, there were still significant sex-specific variations. This is the first systematic analysis of the heterogeneity between oscillometric reference models and warrants the validation of appropriate equations in clinical applications of oscillometry to avoid diagnostic errors.

An a Priori Approach to Small Airway Dysfunction in Pediatric Asthmatics

Small airway dysfunction remains a stepchild in the pediatric asthma care pathway. In brief, elements of the pulmonary function test (PFT) concerning smaller airway data remain less utilized. To further the value of the standard PFT we underwent a prospective Proof of Concept (POC) project, utilizing the outpatient performance of PFT tests in children 6–18 years during a 15-month period. The goal of the study was to determine if a priori the PFT represented a small airway disease pattern or not. Only the pulmonary function was used to make that distinction. Children 6–18 years with asthma who completed a PFT had their PFT as being characterized with or without a small airway dysfunction (SAD) designation, coded in the electronic medical record as an a priori decision using the code J98.4 (other disorders of lung) as a marker for electronic medical records retrieval. Subsequently, the results were analyzed between a group of 136 children designated (a priori) as having no small airway dysfunction in comparison to 91 children a priori designated as having small airway dysfunction. The a priori designation groups were post hoc compared for large and smaller airway function differences. Both large and smaller airway dysfunction were highly significantly different between the 2 groups, based solely on the initial division of the total group based on the decision the PFT represented a small airway pattern. We concluded the baseline pulmonary function test used in the evaluation of pediatric asthma has readily identifiable information regarding the presence of small airway dysfunction, and we characterized what was unique on the PFT based on that SAD classification

The association between small airway dysfunction and aging: a cross-sectional analysis from the ECOPD cohort

BACKGROUND

Aging has been evidenced to bring about some structural and functional lung changes, especially in COPD. However, whether aging affects SAD, a possible precursor of COPD, has not been well characterized.

OBJECTIVE

We aimed to comprehensively assess the relationship between aging and SAD from computed tomography, impulse oscillometry, and spirometry perspectives in Chinese.

METHODS

We included 1859 participants from ECOPD, and used a linear-by-linear association test for evaluating the prevalence of SAD across various age subgroups, and multivariate regression models for determining the impact of age on the risk and severity of SAD. We then repeated the analyses in these subjects stratified by airflow limitation.

RESULTS

The prevalence of SAD increases over aging regardless of definitional methods. After adjustment for other confounding factors, per 10-yrs increase in age was significantly associated with the risk of CT-defined SAD (OR 2.57, 95% CI 2.13 to 3.10) and the increase in the severity of air trapping (β 2.09, 95% CI - 0.06 to 4.25 for LAA_-856), airway reactance (β - 0.02, 95% CI - 0.04 to - 0.01 for X5; β 0.30, 95% CI 0.13 to 0.47 for AX; β 1.75, 95% CI 0.85 to 2.66 for Fres), as well as the decrease in expiratory flow rates (β - 3.95, 95% CI - 6.19 to - 1.71 for MMEF%predicted; β - 5.42, 95% CI - 7.88 to - 2.95 for FEF₅₀%predicted) for SAD. All these associations were generally maintained in SAD defined by IOS or spirometry. After stratification of airflow limitation, we further found that the effect of age on LAA_-856 was the most significant among almost all subgroups.

CONCLUSIONS

Aging is significantly associated with the prevalence, increased risk, as well as worse severity of SAD. CT may be a more optimal measure to assess aging-related SAD. The molecular mechanisms for the role of aging in SAD need to be explored in the future. Trial registration Chinese Clinical Trial Registry ChiCTR1900024643. Registered on 19 July 2019.

Small airway dysfunction in Chinese patients with idiopathic pulmonary fibrosis

Background

Recent years, idiopathic pulmonary fibrosis (IPF) is thought to be a disease of alveoli as well as small airways. This study aimed to demonstrate the clinical feature, predictor, and prognosis of small airway dysfunction (SAD) in Chinese patients with IPF.

Methods

We enrolled 416 patients with IPF who hospitalized in Beijing Chao-Yang Hospital from 2000 to 2014 in this study, and the follow-up ended at December 2016. We collected demographic information, clinical examination results, spirometry results, HRCT results, and blood gas results during the study. Logistic regression analysis was used to identify the predictor for SAD. The COX proportional hazard model was used to analysis the prognosis effect of SAD.

Results

Among all the participants, 165 (39.66%) patients had SAD. FEV1 (% predicted) and FEV3/FVC were significantly associated with SAD in patients with IPF. IPF patients with lower FEV1 (% predicted, OR 30.04, 95% CI 9.61–93.90) and FEV3/FVC (OR 77.76, 95% CI 15.44–391.63) had increased risk for SAD. Patients with SAD were associated with significantly increased risk of mortality in patients with IPF (HR 1.73, 95% CI 1.02–2.92), as well as in IPF patients without other pulmonary comorbidities (COPD, emphysema, and asthma).

Conclusions

Spirometry-defined SAD was like 40% in patients with IPF. Lower FEV1 (% predicted) and FEV3/FVC were main predictors for SAD. IPF patients with SAD showed poorer prognosis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12890-022-02089-6.

Discordant Spirometry and Impulse Oscillometry Assessments in the Diagnosis of Small Airway Dysfunction

Background and objective: Spirometry is commonly used to assess small airway dysfunction (SAD). Impulse oscillometry (IOS) can complement spirometry. However, discordant spirometry and IOS in the diagnosis of SAD were not uncommon. We examined the association between spirometry and IOS within a large cohort of subjects to identify variables that may explain discordant spirometry and IOS findings. Methods: 1,836 subjects from the ECOPD cohort underwent questionnaires, symptom scores, spirometry, and IOS, and 1,318 subjects were examined by CT. We assessed SAD with R₅-R₂₀ > the upper limit of normal (ULN) by IOS and two of the three spirometry indexes (maximal mid-expiratory flow (MMEF), forced expiratory flow (FEF)_50%, and FEF_75%) < 65% predicted. Multivariate regression analysis was used to analyze factors associated with SAD diagnosed by only spirometry but not IOS (spirometry-only SAD) and only IOS but not spirometry (IOS-only SAD), and line regression was used to assess CT imaging differences. Results: There was a slight agreement between spirometry and IOS in the diagnosis of SAD (kappa 0.322, p < 0.001). Smoking status, phlegm, drug treatment, and family history of respiratory disease were factors leading to spirometry-only SAD. Spirometry-only SAD had more severe emphysema and gas-trapping than IOS-only SAD in abnormal lung function. However, in normal lung function subjects, there was no statistical difference in emphysema and gas-trapping between discordant groups. The number of IOS-only SAD was nearly twice than that of spirometry. Conclusion: IOS may be more sensitive than spirometry in the diagnosis of SAD in normal lung function subjects. But in patients with abnormal lung function, spirometry may be more sensitive than IOS to detect SAD patients with clinical symptoms and CT lesions.

The 5T approach in asthma: Triple Therapy Targeting Treatable Traits

Using a therapeutic strategy that is free from traditional diagnostic labels and based on the identification of "treatable traits" (TTs), which are influential in clinical presentations in each patient, might overcome the difficulties in identifying and validating asthma phenotypes and endotypes. Growing evidence is documenting the importance of using the triple therapy with ICS, LABA, and LAMAs in a single inhaler (SITT) in cases of asthma not controlled by ICS/LABA and in the prevention of exacerbations. The identification of TTs may overcome the possibility of using SITT without considering the specific needs of the patient. In effect, it allows a treatment strategy that is closer to the precision strategy now widely advocated for the management of patients with asthma. There are different TTs in asthma that may benefit from treatment with SITT, regardless of guideline recommendations. The airflow limitation and small airway dysfunction are key TTs that are present in different phenotypes/endotypes, do not depend on the degree of T2 inflammation, and respond better than other treatments to SITT. We suggest that the 5T (Triple Therapy Targeting Treatable Traits) approach should be applied to the full spectrum of asthma, not just severe asthma, and, consequently, SITT should begin earlier than currently recommended.

Lung disease burden assessment by oscillometry in a systematically disadvantaged urban population experiencing homelessness or at-risk for homelessness in Ottawa, Canada from a prospective observational study

Rationale

Oscillometry is an emerging technique that offers some advantages over spirometry as it does not require forced exhalation and may detect early changes in respiratory pathology. Obstructive lung disease disproportionately impacts people experiencing homelessness with a high symptoms burden, yet oscillometry is not studied in this population.

Objectives

To assess lung disease and symptom burden using oscillometry in people experiencing homelessness or at-risk of homelessness using a community-based participatory action research approach (The Bridge Model™).

Methods

Of 80 recruited, 55 completed baseline oscillometry, 64 completed spirometry, and all completed patient-reported outcomes with demographics, health, and respiratory symptom related questionnaires in the Participatory Research in Ottawa: Management and Point-of-Care for Tobacco Dependence project. Using a two-tail t-test, we compared mean oscillometry values for airway resistance (R_5–20), reactance area under the curve (A_x) and reactance at 5 Hz (X₅) amongst individuals with fixed-ratio method (FEV₁/FVC ratio < 0.70) and LLN (FEV₁/FVC ratio ≤ LLN) spirometry diagnosed chronic obstructive pulmonary disease (COPD). We compared mean oscillometry parameters based on participants’ COPD assessment test (CAT) scores using ANOVA test.

Results

There was no significant difference between the pre- and post- bronchodilator values of R_5–20 and A_x for the fixed ratio method (p = 0.63 and 0.43) and the LLN method (p = 0.45 and 0.36). There was a significant difference in all three of the oscillometry parameters, R_5–20, A_x and X₅, based on CAT score (p = 0.009, 0.007 and 0.05, respectively). There was a significant difference in R_5–20 and A_x based on the presence of phlegm (p = 0.03 and 0.02, respectively) and the presence of wheeze (p = 0.05 and 0.01, respectively). Oscillometry data did not correlate with spirometry data, but it was associated with CAT scores and correlated with the presence of self-reported symptoms of phlegm and wheeze in this population.

Conclusions

Oscillometry is associated with respiratory symptom burden and highlights the need for future studies to generate more robust data regarding the use of oscillometry in systematically disadvantaged populations where disease burden is disproportionately higher than the general population.

TrialRegistration: ClinicalTrails.gov—NCT03626064, Retrospective registered: August 2018, https://clinicaltrials.gov/ct2/show/NCT03626064

Development and Evaluation of a Small Airway Disease Index Derived From Modeling the Late-Expiratory Flattening of the Flow-Volume Loop

Excessive decrease in the flow of the late expiratory portion of a flow volume loop (FVL) or “flattening”, reflects small airway dysfunction. The assessment of the flattening is currently determined by visual inspection by the pulmonary function test (PFT) interpreters and is highly variable. In this study, we developed an objective measure to quantify the flattening. We downloaded 172 PFT reports in PDF format from the electronic medical records and digitized and extracted the expiratory portion of the FVL. We located point A (the point of the peak expiratory flow), point B (the point corresponding to 75% of the expiratory vital capacity), and point C (the end of the expiratory portion of the FVL intersecting with the x-axis). We did a linear fitting to the A-B segment and the B-C segment. We calculated: 1) the AB-BC angle (∠ABC), 2) BC-x-axis angle (∠BCX), and 3) the log ratio of the BC slope over the vertical distance between point A and x-axis [log (BC/A-x)]. We asked an expert pulmonologist to assess the FVLs and separated the 172 PFTs into the flattening and the non-flattening groups. We defined the cutoff value as the mean minus one standard deviation using data from the non-flattening group. ∠ABC had the best concordance rate of 80.2% with a cutoff value of 149.7°. We then asked eight pulmonologists to evaluate the flattening with and without ∠ABC in another 168 PFTs. The Fleiss’ kappa was 0.320 (lower and upper confidence intervals [CIs]: 0.293 and 0.348 respectively) without ∠ABC and increased to 0.522 (lower and upper CIs: 0.494 and 0.550) with ∠ABC. There were 147 CT scans performed within 6 months of the 172 PFTs. Twenty-six of 55 PFTs (47.3%) with ∠ABC <149.7° had CT scans showing small airway disease patterns while 44 of 92 PFTs (47.8%) with ∠ABC ≥149.7° had no CT evidence of small airway disease. We concluded that ∠ABC improved the inter-rater agreement on the presence of the late expiratory flattening in FVL. It could be a useful addition to the assessment of small airway disease in the PFT interpretation algorithm and reporting.

The disconnect between visual assessment of air trapping and lung physiology for assessment of small airway disease in scleroderma-related interstitial lung disease: An observation from the Scleroderma Lung Study II Cohort

OBJECTIVE

To explore the presence of small airway disease (SAD) and emphysema in scleroderma-related interstitial lung disease (SSc-ILD) and to evaluate the physiologic and clinical correlates of SAD in SSc-ILD.

METHODS

Thoracic high-resolution computed tomography (HRCT) images obtained from the Scleroderma Lung Study II (SLSII) participants were reviewed by a group of thoracic radiologists. The presence of SAD was assessed by visual assessment for air trapping. HRCT scans were also evaluated for the presence of emphysema. The association of the presence of air trapping and emphysema with physiological measures of airway disease and clinical variables was evaluated.

RESULTS

A total of 155 baseline HRCT scans were reviewed. For assessment of air trapping, images needed to be adequate end-expiratory examinations, leaving 123 scans. Air trapping was seen in 13/123 (10.6%) of the SSc-ILD cohort and was independent of smoking history, asthma or the presence of gastroesophageal reflux. Air trapping on HRCT was not associated with physiologic evidence of SAD. We also identified 8/155 (5.2%) patients with emphysema on HRCT, which was independent of SAD and found mostly in prior smokers.

CONCLUSION

We report the first study of air trapping on standardized, high-quality HRCT images as a reflection of SAD in a relatively large, well characterized SSc-ILD cohort. The presence of SAD in non-smoking SSc-ILD patients supports that SSc may cause not only restrictive lung disease (SSc-ILD), but also, to a lesser extent, obstructive disease. Physiologic measures alone may be inadequate to detect airway disease in patients with SSc-ILD.

Lung function in young adulthood: differences between males and females with asthma

Background

There are phenotypic differences in asthma in males and females. Differences in lung function between the sexes at the peak lung function level in young adulthood are so far not directly addressed. The aim of the present study was to assess lung function in early adulthood in males and females depending on asthma onset and remission.

Methods

Participants were included from the population-based birth cohort BAMSE and classified as having: never asthma, childhood asthma in remission, adolescent onset asthma or persistent asthma. Pre- and post-bronchodilator lung function (in Z-score) and lung clearance index (LCI) were measured at age 24 years. Lung function was compared stratified for sex between the never asthma and asthma groups univariately and in multiple linear regression analyses adjusted for maternal and paternal asthma, maternal smoking during pregnancy, secondary smoking, daily smoking, early respiratory syncytial virus infection, traffic pollution, childhood allergic sensitisation, and body mass index at age 24 years.

Results

All asthma phenotypes were associated with a lower forced expiratory volume in 1 s (FEV₁)/forced vital capacity (FVC) post-bronchodilation at 24 years. This was most pronounced in males with persistent asthma compared to males with never asthma (regression coefficient: −0.503; 95% CI: −0.708– −0.298). Childhood asthma (in remission or persistent) was associated with a lower FEV₁. After adjustment, the associations remained significant for males. For females, the significant associations with lower FEV₁ and FEV₁/FVC remained only for subjects with asthma in remission. Persistent asthma was associated with higher LCI in females.

Conclusions

In females, in contrast to males, the association between asthma and lower lung function was attenuated after adjustment for known risk factors.

Current or previous asthma is associated with lower lung function in early adulthood. In females, in contrast to males, the association between asthma and lower lung function is attenuated after adjustment for known risk factors.https://bit.ly/37vDzzu

Clinical characteristics associated with small airways disease in systemic sclerosis

Objective:

Pulmonary manifestations of systemic sclerosis are a major cause of morbidity and mortality. Small airways disease can cause dyspnea and pulmonary function test abnormalities. We aimed to determine the prevalence of small airways disease and describe the characteristics associated with small airways disease in a cohort of systemic sclerosis patients.

Methods:

We performed a retrospective cohort study of adults with systemic sclerosis who met American College of Rheumatology/European League Against Rheumatism 2013 classification criteria and were evaluated at our institution between November 2000 and November 2015. Patients with prior lung transplantation were excluded. Small airways disease was defined as the presence of one or more of the following: airway-centered fibrosis on surgical lung biopsy, forced expiratory volume at 25–75% ⩽ 50% on pulmonary function tests, and/or high-resolution computed tomography scan of the chest with bronchiolitis, mosaic attenuation, or air trapping on expiratory views. The primary outcome was small airways disease diagnosis. We performed multivariable logistic regression to determine the association of clinical variables with small airways disease.

Results:

One-hundred thirty-six systemic sclerosis patients were included; 55 (40%) had small airways disease. Compared to those without small airways disease, a significantly greater proportion of those with small airways disease had interstitial lung disease, chronic obstructive pulmonary disease, pulmonary hypertension, and gastroesophageal reflux disease. On multivariable analysis, pulmonary hypertension (odds ratio = 2.91, 95% confidence interval = 1.11–7.65, p-value = 0.03), gastroesophageal reflux disease (odds ratio = 2.70, 95% confidence interval = 1.08–6.79, p-value = 0.034), and anti-topoisomerase I (anti-Scl-70) antibody positivity (odds ratio = 0.42, 95% confidence interval = 0.19–0.93, p-value = 0.033) were associated with diagnosis of small airways disease.

Conclusion:

Small airways disease is prevalent among systemic sclerosis patients; those with pulmonary hypertension or gastroesophageal reflux disease may have a higher risk of small airways disease.

A study of pneumoproteins in crystalline silica exposed rock drillers

Objective: The objective was to assess serum concentrations of club cell protein 16 (CC-16) and the surfactant proteins A (SPs-A) and D (SP-D) in male rock drillers (N = 123) exposed to crystalline silica and in 48 occupationally non-exposed. Methods: The arithmetic mean (AM) duration of exposure was 10.7 years. The geometric mean (GM) crystalline silica exposure was 36 µg/m³ at the time of the study. The GM cumulative exposure was 239 µg/m³. Results: The concentrations of SP-D (GM 12.7 vs. 8.8 µg/L, p < 0.001) and SP-A (AM 1847 vs. 1378 ng/L, p = 0.051) were higher among rock drillers than among occupationally non-exposed. A positive significant association was observed between cumulative crystalline silica exposure and the SP-D concentrations (β = 0.07; p < 0.05). Rock drillers with small airway obstruction with maximal mid-expiratory flow % (MMEF%) <70% (N = 29) had higher SP-D concentrations than rock drillers with MMEF% ≥ 70% (N = 91) (GM 17.3 vs. 11.4 µg/L, p = 0.001). Rock drillers with MMEF% ≥70% (N = 91) had higher concentrations of SP-A (1957 vs. 1287 ng/L, p = 0.01) and SP-D (11.4 vs. 9.0 µg/L, p = 0.007) than non-exposed with MMEF% ≥70% (N = 39). Rock drillers with airway obstruction (FEV1/FVC < 0.70, N = 11) had significantly lower CC-16 concentrations than rock drillers with FEV1/FVC ≥0.70 (N = 109) after adjusting for relevant potential confounders (p = 0.02). Conclusion: The results indicate that pulmonary surfactant is a target for crystalline silica toxicity. The alterations appear to be driven by pulmonary alterations in the small airways and by exposure itself. Further studies on pneumoproteins and pulmonary function in other groups of workers exposed to crystalline silica are needed.

Small Airway Dysfunction in Cough Variant Asthma: Prevalence, Clinical, and Pathophysiological Features

Introduction: Small airway dysfunction (SAD) commonly presents in patients with classic asthma, which is associated with airway inflammation, disease severity, and asthma control. However, the prevalence of SAD, its relationship with cough severity and airway inflammation, and its development after antiasthmatic treatment in patients with cough variant asthma (CVA) need to be clarified. This study aimed to investigate the prevalence of SAD and its relationship with clinical and pathophysiological characteristics in patients with CVA and the change in small airway function after antiasthmatic treatment.

Methods: We retrospectively analyzed 120 corticosteroid-naïve patients with CVA who had finished a standard questionnaire and relevant tests in a specialist cough clinic, such as cough visual analog scale (VAS), differential cells in induced sputum, fractional exhaled nitric oxide (FeNO) measurement, spirometry, and airway hyper-responsiveness. Information of 1-year follow-up was recorded in a part of patients who received complete cough relief after 2 months of treatment. SAD was defined as any two parameters of maximal mid-expiratory flow (MMEF)% pred, forced expiratory flow at 50% of forced vital capacity (FEF50%) pred, and forced expiratory flow at 75% of forced vital capacity (FEF75%) pred measuring <65%.

Results: SAD occurred in 73 (60.8%) patients with CVA before treatment. The patients with SAD showed a significantly longer cough duration (24.0 vs. 6.0, p = 0.031), a higher proportion of women (78.1 vs. 59.6%, p = 0.029), older mean age (41.9 vs. 35.4, p = 0.005), and significantly lower forced expiratory volume in 1 s (FEV₁%) pred, FEV₁/FVC, MMEF% pred, FEF50% pred, FEF75% pred, PEF% pred, and PD20 (all p < 0.01) as compared with patients without SAD. There were no significant differences in cough VAS, sputum eosinophils count, FeNO, and TIgE level between patients with SAD and those without SAD. Among 105 patients who completed 2 months of antiasthmatic treatment and repeatedly experienced spirometry measurement, 57 (54.3%) patients still had SAD, despite a significant improvement in cough VAS, sputum eosinophils, FeNO, FEF50% pred, and PEF% pred (all p < 0.01). As compared with patients without SAD, patients with SAD showed no significant differences in the relapse rate (50.0 vs. 41.9%, p = 0.483) and wheeze development rate (10.4 vs. 0%, p = 0.063) during the follow-up.

Conclusions: Small airway dysfunction occurred in over half of patients with CVA and persisted after short-term antiasthmatic treatment, which showed distinctive clinical and pathophysiological features.