The prevalence of small airways disease in adult asthma: A systematic literature review

Managing Small Airway Disease in Patients with Severe Asthma: Transitioning from the "Silent Zone" to Achieving "Quiet Asthma"

Background/Objectives: Several studies have demonstrated the positive clinical and functional impact of adding Long-Acting Muscarinic Antagonist (LAMA) to Inhaled Corticosteroids (ICS) and Long-Acting Beta-Agonists (LABA) therapy in the treatment of severe asthma. Aim and objectives: To demonstrate that treating Small Airways Disease (SAD) in severe asthma patients who are candidates for biologics can improve respiratory symptoms, lung function, and airways inflammation, potentially avoiding or delaying the use of biological therapy. Methods: Thirty-two severe asthma patients with SAD were transitioned from separate inhalers for ICS/LABA and LAMA to extrafine single-inhaler beclomethasone, formoterol, and glycopyrronium. None of these patients underwent biological therapy before the study. Follow-up evaluations were conducted at baseline (T0) and three months after initiation (T3). Assessments included clinical evaluations, spirometry, oscillometry, and inflammation markers. Results: Transitioning to single-inhaler triple therapy from T0 to T3 resulted in significant improvements in Asthma Control Test (ACT) and SAD parameters, including increased Forced Expiratory Volume in the mid-range of lung capacity and improved airway resistance and reactance measurements using impulse oscillometry. A significant reduction in airway inflammation was evidenced by lower levels of Fractional Exhaled Nitric Oxide 350 (FeNO 350) (p < 0.001 for all). Conclusions: Adopting a single-inhaler triple therapy notably enhanced clinical control and small airway function in patients with severe asthma and SAD, supporting the positive impact of target-therapy for the achievement of a stable state termed "Quiet Asthma".

Predicting parameters of airway dynamics generated from inspiratory and expiratory plethysmographic airway loops, differentiating subtypes of chronic obstructive diseases

BACKGROUND

The plethysmographic shift volume-flow loop (sRaw-loop) measured during tidal breathing allows the determination of several lung function parameters such as the effective specific airway resistance (sReff), calculated from the ratio of the integral of the resistive aerodynamic specific work of breathing (sWOB) and the integral of the corresponding flow-volume loop. However, computing the inspiratory and expiratory areas of the sRaw-loop separately permits the determination of further parameters of airway dynamics. Therefore, we aimed to define the discriminating diagnostic power of the inspiratory and expiratory sWOB (sWOBin, sWOBex), as well as of the inspiratory and expiratory sReff (sReff IN and sReff EX), for discriminating different functional phenotypes of chronic obstructive lung diseases.

METHODS

Reference equations were obtained from measurement of different databases, incorporating 194 healthy subjects (35 children and 159 adults), and applied to a collective of 294 patients with chronic lung diseases (16 children with asthma, aged 6-16 years, and 278 adults, aged 17-92 years). For all measurements, the same type of plethysmograph was used (Jaeger Würzburg, Germany).

RESULTS

By multilinear modelling, reference equations of sWOBin, sWOBex, sReff IN and sReff EX were derived. Apart from anthropometric indices, additional parameters such as tidal volume (VT), the respiratory drive (P0.1), measured by means of a mouth occlusion pressure measurement 100 ms after inspiration and the mean inspiratory flow (VT/TI) were found to be informative. The statistical approach to define reference equations for parameters of airway dynamics reveals the interrelationship between covariants of the actual breathing pattern and the control of breathing.

CONCLUSIONS

We discovered that sWOBin, sWOBex, sReff IN and sReff EX are new discriminating target parameters, that differentiate much better between chronic obstructive diseases and their subtypes, especially between chronic obstructive pulmonary disease (COPD) and asthma-COPD overlap (ACO), thus strengthening the concept of precision medicine.

Identification and treatment of persistent small airway dysfunction in paediatric patients with asthma: a retrospective cohort study

BACKGROUND

Asthma is a common respiratory disease. In asthma, the small airways have more intensive inflammation and prominent airway remodelling, compared to the central airways. We aimed to investigate the predictive value of risk factors and the fractional concentration of exhaled nitric oxide (FeNO) for persistent small airway dysfunction (p-SAD), and compare the effects of different treatment modalities.

METHODS

This retrospective cohort study included 248 children with asthma (aged 4-11 years). Binary logistic regression was used to analyse the risk factors for p-SAD. Correlations among FEV1/FVC, small airway function parameters, and FeNO levels in patients with asthma were analysed using Spearman's rank correlation. The receiver operating characteristic curve and the Delong test were used to analyse the predictive value of FeNO for p-SAD. Differences in the treatment effects of inhaled corticosteroids (ICS) and ICS with a long-acting beta-agonist (ICS/LABA) on p-SAD were analysed using Fisher's exact test.

RESULTS

Asthmatic children with older age of receiving the regular treatment (OR 1.782, 95% CI 1.082-2.935), with younger age at the time of onset of suspected asthma symptoms (OR 0.602, 95% CI 0.365-0.993), with longer duration of using ICS or ICS/LABA (OR 1.642, 95% CI 1.170-2.305) and with worse asthma control (OR 3.893, 95% CI 1.699-8.922) had increased risk for p-SAD. Significant negative correlations of small airway function parameters with FeNO at a 200 mL/s flow rate (FeNO200), and the concentration of nitric oxide in the alveolar or acinar region (CaNO) were observed. The areas under the curve of FeNO200 (cut-off:10.5ppb), CaNO (cut-off:5.1ppb), and FeNO200 combined with CaNO were 0.743, 0.697, and 0.750, respectively, for asthma with p-SAD. After using ICS or ICS/LABA, switching to ICS/LABA was easier than continuing with ICS to improve small airway dysfunction (SAD) in the 8th month.

CONCLUSIONS

Paediatric asthma with p-SAD is associated with older age at receiving regular treatment, younger age at the time of onset of suspected asthma symptoms, longer duration of using ICS or ICS/LABA, worse asthma control, and higher FeNO200 and CaNO levels, all of which can be combined with small airway function indicators to distinguish p-SAD from asthma. ICS/LABA improves SAD better than ICS alone.

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.

Impulse oscillometry defined small airway dysfunction in asthmatic patients with normal spirometry: Prevalence, clinical associations, and impact on asthma control

BACKGROUND

The small-airway dysfunction (SAD), detected with impulse oscillometry (IOS) methods, has been recently better characterized in patients with asthma. However, little is known about SAD in asthmatic patients with normal spirometry (NS).

OBJECTIVE

In this study, we aimed to investigate, in an unselected sample of 321 patients with physician-diagnosed asthma and NS, prevalence, clinical characterization, and impact on asthma control of IOS-defined SAD. As a secondary objective of the study, we focused on comparing the difference between IOS- and spirometry-defined SAD.

METHODS

Consecutive patients with a previous diagnosis of asthma but normal spirometry at the moment of the enrollment were stratified by the presence of IOS-defined SAD (difference in resistance at 5 Hz and at 20 Hz [R5-R20] greater than 0.07 kPa x s x L-1). We have also assessed the presence of SAD defined by spirometry, according to FEF 25-75 < 65% of the predicted. Clinical and laboratory features were collected, and univariable and multivariable analyses were used to analyze cross-sectional associations between clinical variables and outcomes (SAD).

RESULTS

IOS-defined SAD was present in 54.1% of the cohort. In contrast, spirometry-defined SAD was present in only 10% of patients. Subjects with IOS-defined SAD showed less well-controlled asthma and a higher mean inhaled corticosteroid dosage use compared with subjects without SAD (both P < .001). Overweight (odds ratio [OR], 1.14; 95% CI, 1.05-1.23), exacerbation history (OR, 3.06; 95% CI, 1.34-6.97), asthma-related night awakenings (OR, 6.88; 95% CI, 2.13-22.23), exercise-induced asthma symptoms (OR, 33.5; 95% CI, 9.51-117.8), and controlled asthma (OR, 0.22; 95% CI, 0.06-0.84) were independently associated with SAD.

CONCLUSIONS

Asthmatic patients with IOS-defined SAD showed less well-controlled asthma, more severe exacerbations and higher mean inhaled corticosteroid dosage. We confirmed exercise-induced asthma, asthma-related night awakenings, exacerbation history, and overweight as independently associated with SAD, while showing well-controlled asthma as inversely associated. SAD may be overlooked by standard spirometry.

Small airways dysfunction: The importance of utilising Z-scores to define MMEF abnormalities in clinical practice

Background

The small airways comprise the largest cross-sectional area of the lungs, however, assessing and reporting abnormalities for this region of the bronchial tree has been practically and scientifically uncertain.

Methods

Using routinely collected spirometry data for patients with either asthma or COPD, the accuracy of % predicted values for defining small airways dysfunction was assessed. A z-score of ≤ -1.645 of the maximal-mid expiratory flow (MMEF) was used as the gold standard for defining abnormality in the small airways.

Results

Records of 3396 patients were included in the analysis. The false positive (FP) rates were 24.6 %, 16.1 %, 11.5 %, or 7.9 % when the % predicted value of 80 %, 70 %, 65 %, or 60 % were used, respectively. Sex, age, and BMI were associated with FP rates. Males were more likely to be categorised as FP with odds ratio (OR) between 1.10 and 1.49 across % predicted groups. Age was associated with FP rates with an OR between 1.01 and 1.08. The BMI was also associated with FP rates with an OR of 1.03 across all % predicted groups. Assessing the association of age groups with FP rate showed that those above 60 years old were more likely to be categorised as FP with an OR between 1.23 and 73.2 compared to those less than 30 years old.

Conclusion

When assessing the small airways in clinical practice or for scientific purposes, the % predicted values overestimate the actual impairment leading to FP interpretation. Utilising z-score values are recommended to assess the small airways using the spirometric index, MMEF.

Construction of a Diagnostic Algorithm for Diagnosis of Adult Asthma Using Machine Learning with Random Forest and XGBoost

An evidence-based diagnostic algorithm for adult asthma is necessary for effective treatment and management. We present a diagnostic algorithm that utilizes a random forest (RF) and an optimized eXtreme Gradient Boosting (XGBoost) classifier to diagnose adult asthma as an auxiliary tool. Data were gathered from the medical records of 566 adult outpatients who visited Kindai University Hospital with complaints of nonspecific respiratory symptoms. Specialists made a thorough diagnosis of asthma based on symptoms, physical indicators, and objective testing, including airway hyperresponsiveness. We used two decision-tree classifiers to identify the diagnostic algorithms: RF and XGBoost. Bayesian optimization was used to optimize the hyperparameters of RF and XGBoost. Accuracy and area under the curve (AUC) were used as evaluation metrics. The XGBoost classifier outperformed the RF classifier with an accuracy of 81% and an AUC of 85%. A combination of symptom-physical signs and lung function tests was successfully used to construct a diagnostic algorithm on importance features for diagnosing adult asthma. These results indicate that the proposed model can be reliably used to construct diagnostic algorithms with selected features from objective tests in different settings.

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.

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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

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Oscillometry in severe asthma: the state of the art and future perspectives

INTRODUCTION

Approximately 3-10% of people with asthma have severe asthma (SA). Patients with SA have greater impairment in daily life and much higher costs. Even if asthma affects the entire bronchial tree, small airways have been recognized as the major site of airflow limitation. There are several tools for studying small airway dysfunction (SAD), but certainly the most interesting is oscillometry. Despite several studies, the clinical usefulness of oscillometry in asthma is still in question. This paper aims to provide evidence supporting the use of oscillometry to improve the management of SA in clinical practice.

AREAS COVERED

In the ATLANTIS study, SAD was strongly evident across all severity. Various tools are available for evaluation of SAD, and certainly an integrated use of these can provide complete and detailed information. However, the most suitable method is oscillometry, implemented for clinical routine by using either small pressure impulses or small pressure sinusoidal waves.

EXPERT OPINION

Oscillometry, despite its different technological implementations is the best tool for determining the impact of SAD on asthma and its control. Oscillometry will also be increasingly useful for choosing the appropriate drug, and there is ample room for a more widespread diffusion in clinical practice.

[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.

Associations between short-term exposure to ambient air pollution and lung function in adults

BACKGROUND

Evidence of the acute effects of high-level air pollution on small airway function and systemic inflammation in adults is scarce.

OBJECTIVE

To examined the associations of short-term (i.e., daily) exposure to multiple air pollutants with lung function and inflammatory markers.

METHODS

We assessed short-term (daily) effects of air pollutants, including particulate matter with aerodynamic diameter less than 2.5 μm (PM_2.5) and 10 μm (PM₁₀), nitrogen dioxide (NO₂), sulfur dioxide (SO₂) and carbon monoxide (CO), on lung function and peripheral immune cell counts over various lag times using generalized linear regression models.

RESULTS

A total of 4764 adults were included from the general community-dwelling population in Shanghai, China. Exposure to air pollutants and lung function were negatively correlated. Decline in FEF between 25% and 75% of vital capacity (FEF_25-75%) were found associated with PM_2.5, SO₂, and CO, and decline in forced expiratory volume in 3 s (FEV₃) to forced vital capacity (FVC) ratio were associated with all examined pollutants, indicating obstruction in small airways. Obstructed airflow in large and middle airways as indicated by decline in FEV₁/FVC were also associated with all pollutants. In subgroup analysis, significant negative associations between the five pollutants and SAD parameters were found only in males but not in females. The difference in the associations of SO₂ with FEF_75% between males and females achieved statistical significance. Additionally, all examined pollutants were significantly associated with lower peripheral neutrophil count.

IMPACT STATEMENT

Acute exposure to air pollutants were associated with airflow-limitation. Both small airways and proximal airways were affected. Acute exposure to air pollutants were accompanied with a lower neutrophil count.

Small airway dysfunction in asthmatic patients treated with as-needed SABA monotherapy: A perfect storm

BACKGROUND

Short-acting beta agonist (SABA)-only treatment is associated with poor asthma control and adverse clinical outcomes. The importance of small airway dysfunction (SAD) is increasingly recognized in asthma, but less is known in patients using SABA-only therapy. We aimed to investigate the impact of SAD on asthma control in an unselected cohort of 60 adults with physician-diagnosed intermittent asthma treated with as-needed SABA monotherapy.

METHODS

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

RESULTS

SAD was present in 73% of the cohort. Compared with patients without SAD, adults with SAD had a higher number of severe exacerbations (65.9% versus 25.0%, p < 0.05), higher use of annual SABA canisters (median (IQR), 3 (1.75-3) versus 1 (1-2), p < 0.001), and significantly less well-controlled asthma (11.7% versus 75.0%, p < 0.001). Spirometry parameters were similar between patients with IOS-defined SAD and those without SAD. The multivariable logistic regression analysis showed that exercise-induced bronchoconstriction symptoms (EIB, odds ratio [OR] 31.18; 95%CI:4.85-365.00) and night awakenings due to asthma (OR 30.30; 95%CI:2.61-1141.00) were independent predictors of SAD, with a high predictive power of the model incorporating these baseline predictors (AUC 0.92).

CONCLUSIONS

EIB and nocturnal symptoms are strong predictors of SAD in asthmatic patients using as-needed SABA-monotherapy, helping to distinguish subjects with SAD among patients with asthma when IOS cannot be performed.

Anatomical and histopathological approaches to asthma phenotyping

Asthma is typically characterized by variable respiratory symptoms and airflow limitation. Along with the pathophysiology and symptoms are immunological and inflammatory processes. The last decades research has revealed that the immunology of asthma is highly heterogeneous. This has clinical consequences and identification of immunological phenotypes is currently used to guide biological treatment. The focus of this review is on another dimension of asthma diversity, namely anatomical heterogeneity. Immunopathological alterations may go beyond the central airways to also involve the distal airways, the alveolar parenchyma, and pulmonary vessels. Also, extrapulmonary tissues are affected. The anatomical distribution of inflammation in asthma has remained relatively poorly discussed despite its potential implication on both clinical presentation and response to treatment. There is today evidence that a significant proportion of the asthma patients has small airway disease with type 2 immunity, eosinophilia and smooth muscle infiltration of mast cells. The small airways in asthma are also subjected to remodelling, constriction, and luminal plugging, events that are likely to contribute to the elevated distal airway resistance seen in some patients. In cases when the inflammation extends into the alveolar parenchyma alveolar FCER1-high mast cells, eosinophilia, type 2 immunity and activated alveolar macrophages, together with modest interstitial remodelling, create a complex immunopathological picture. Importantly, the distal lung inflammation in asthma can be pharmacologically targeted by use of inhalers with more distal drug deposition. Biological treatments, which are readily distributed to the distal lung, may also be beneficial in eligible patients with more severe and anatomically widespread 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.

Small airway disease and asthma control

AIM

Maximum mid-expiratory flow (MMEF) is one of the pulmonary function tests that report small airway disease. Our study aimed to investigate the role of MMEF values in asthma control, the prevalence of small airway disease, and their effect on asthma control in patients with asthma with normal forced expiratory volume in one second (FEV₁) values.

MATERIAL AND METHOD

Patients who presented to the Chest Diseases outpatient clinic of our hospital between 2018 and 2019 and were diagnosed as having asthma were included in the study. The characteristics of the patients, pulmonary function tests, their asthma treatment, and asthma control test (ACT) scores were recorded. Patients with FEV₁ <80 in the pulmonary function test, those with additional lung disease, those who had an attack in the last 4 weeks, and patients who smoked were excluded from the study. MMEF <65 was defined as small airway disease.

RESULTS

The MMEF% and MMEF (L/s) values of the group with uncontrolled asthma were found to be statistically significantly lower than those of the controlled asthma group (p = 0.016 and p = 0.003, respectively). MMEF% and MMEF (L/s) values in those with wheezing were found to be significantly lower compared with those without wheezing (p = 0.025 and p = 0.049, respectively). The MMEF% and MMEF (L/s) values of the patients with nocturnal symptoms were found to be statistically significantly lower than in patients without nocturnal symptoms (p = 0.023 and p = 0.041, respectively). ACT values of patients with MMEF <65 were found to be statistically lower than those of patients with MMEF >65 (0.047).

CONCLUSION

Considering small airway disease in patients with asthma may be beneficial in clinical practice.

Fixed-dose combination fluticasone/formoterol for asthma treatment in a real-world setting: meta-analysis of exacerbation rates and asthma control

BACKGROUND

Treatment guidelines for asthma management are derived almost exclusively from the results of controlled clinical trials undertaken in carefully selected patient populations; meaning that their outcomes may not reflect the true performance of treatments when used in general daily medical practice. The aim of this meta-analysis was to combine the results of observational studies investigating the fluticasone propionate/formoterol (FP/FORM) fixed-dose combination in real-world asthma patients.

METHODS

A systemic literature review was completed in March 2019 using the PubMed database. We identified 394 studies. Five studies, which included a total of 4756 patients treated with FP/FORM, were judged eligible and included in the meta-analysis.

RESULTS

The estimated severe asthma exacerbation rate was 11.47% (95% CI, 5.8 to 18.72%), calculated from the random effect model. A sensitivity analysis excluding 2 studies (one was an outlier, and the exacerbation rate for the studied treatment alone could not be determined in the other) showed a 7.04% rate of severe asthma exacerbations. The estimated relative risk of the incidence of severe asthma exacerbations was 0.323 (95% CI, 0.159 to 0.658). The estimated asthma control rate was 60.6% (95% CI, 55.7% to 65.6%). The odds of achieving asthma control significantly increased by FP/FORM compared with pre-study conditions (estimated odds ratio: 2.214 [95% CI, 1.292 to 3.795]; p < 0.001).

CONCLUSIONS

The findings of this meta-analysis confirm the effectiveness of FP/FORM for the treatment of asthma patients in a real-world setting beyond the limitations of RCTs.

In young children with asthma, obesity, and uncontrolled disease are highly associated with peripheral airway impairment

BACKGROUND

Despite the fact that impulse oscillometry (IOS)-determined peripheral airway impairment (PAI) phenotype is a major risk factor for uncontrolled asthma, IOS is seldom used clinically.

OBJECTIVE

To identify clinical characteristics that can best identify the PAI phenotype.

METHODS

Clinical characteristics and spirometry results were compared in 227 patients with asthma with the PAI phenotype determined by resistance and reactance values that exceeded IOS‑predictive normal values using Gochicoa-Rangel equations. Logistic regression analyses determined factors associated with PAI phenotype, with risk classification based on predicted probability from the final adjusted model.

RESULTS

Analysis for identifying PAI, present in 37% of our population, revealed statistically significant odds ratio (OR) for age (4-7 years), of 3.75 (1.47-9.55) (P = .006), obesity OR of 2.59 (1.36-4.96) (P = .004), uncontrolled asthma OR of 2.77 (1.34-5.74) (P = .006), and abnormal forced expiratory flow between 25% and 75% (FEF25%-75%) (<65%) OR of 4.22 (1.59-11.20) (P = .004). For identifying PAI in those considered well controlled, key characteristics were age (4-7 years), OR of 2.81 (1.10-7.18) (P = .03), and obesity, OR of 2.18 (1.09-4.39) (P = .03). For those 4 to 7 years old, who were obese and had uncontrolled disease, probability of PAI was greater than or equal to 80%, regardless of FEF 25%-75%. Probabilities from logistic regression analyses to identify PAI were associated with an area under the curve of 0.750, and applying standard threshold of greater than or equal to 0.50 probability for identification produced sensitivity at 49.4%, specificity at 85.3%, positive predictive value at 66.1%, negative predictive value at 74.4%, and accuracy at 72.1%.

CONCLUSION

Clinical characteristics of age at 4 to 7 years, obesity, uncontrolled asthma, and FEF 25%-75% (<65%) identify PAI with high specificity and accuracy. This approach offers the clinician a practical method for strongly considering the presence of PAI when IOS is not available.

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.

Monoclonal antibodies targeting small airways: a new perspective for biological therapies in severe asthma

Small airway dysfunction (SAD) in asthma is characterized by the inflammation and narrowing of airways with less of 2 mm in diameter between generations 8 and 23 of the bronchial tree. It is now widely accepted that small airways are involved in the pathogenesis of asthma and are a major determinant of airflow obstruction in this disease. 

In recent years, specialized tests have been developed, such as Impulse Oscillometry (IOS) and Multiple Breath Nitrogen Washout (MBNW) tests, which have been deemed more accurate in detecting SAD than conventional spirometry. Clinical studies show that SAD is associated with more severe bronchial hyperresponsiveness, worse asthma control, and a higher risk of exacerbations. Recent data from a large cohort study showed that the prevalence of SAD in asthma patients increases with asthma severity. Overall, SAD seems to represent a treatable trait, which makes it appealing for asthma control optimization and exacerbation rate reduction, especially in moderate-to-severe asthma.

Biologic agents are now available for the treatment of different severe asthma phenotypes and endotypes. However, the effect of these therapies on SAD remains poorly characterized. Literature showing that biologic agents can also favorably improve small airway function is accumulating. In particular, anti-IL5 agents (mepolizumab and benralizumab) seems to have a greater impact on SAD as compared to other biological agents, but direct comparisons in prospective randomized controlled trials are lacking.

In this mini-review article, we address the latest evidence on the effect of biological therapies on SAD in patients with severe asthma.

Small airway dysfunction in idiopathic pulmonary fibrosis

It is generally accepted that the pathophysiology of idiopathic pulmonary fibrosis (IPF) can be attributed to impaired lung interstitium and alveoli, while airway involvement has rarely been reported. In the present study, we aimed to investigate the actual occurrence of IPF comorbid small airway dysfunction (SAD) and its impact on survival. Data from inpatients diagnosed with IPF at Shanghai Pulmonary Hospital (Shanghai, China) from 2011 to 2021 were retrospectively collected and analyzed. Lung function parameters were used to assess SAD. A total of 243 IPF patients were included in this retrospective study, and 84 cases (84/243, 34.57%) were diagnosed with SAD. The lung histopathology showed that all 48 cases undergoing lung transplantation presented various degrees of airway lesions, of which 18 patients (18/48, 37.5%) diagnosed with SAD before lung transplantation had a higher proportion of airway distortion and obliteration. The possible risk factors associated with IPF comorbid SAD were smoking, male, younger age, and high CT fibrosis and emphysema scores. By univariate Fine-Grey regression, the hazard ratio (HR) of IPF comorbid SAD was 1.725 (95% CI 1.071, 2.777, p < 0.05). After adjusting the CTPF model and GAP model, the value of HR was 1.714 (95% CI 1.043, 2.816, p < 0.05) and 1.731 (95% CI 1.074, 2.788, p < 0.05), respectively. These findings suggested that IPF comorbid SAD was an independent risk factor for the mortality of IPF patients.

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.

A novel computed tomography radiomic nomogram for early evaluation of small airway dysfunction development

The common respiratory abnormality, small airway dysfunction (fSAD), is easily neglected. Its prognostic factors, prevalence, and risk factors are unclear. This study aimed to explore the early detection of fSAD using radiomic analysis of computed tomography (CT) images to predict fSAD progress. The patients were divided into fSAD and non-fSAD groups and divided randomly into a training group (n = 190) and a validation group (n = 82) at a 7:3 ratio. Lung kit software was used for automatic delineation of regions of interest (ROI) on chest CT images. The most valuable imaging features were selected and a radiomic score was established for risk assessment. Multivariate logistic regression analysis showed that age, radiomic score, smoking, and history of asthma were significant predictors of fSAD (P < 0.05). Results suggested that the radiomic nomogram model provides clinicians with useful data and could represent a reliable reference to form fSAD clinical treatment strategies.

Exposure to second-hand smoke is an independent risk factor of small airway dysfunction in non-smokers with chronic cough: A retrospective case-control study

Objectives

This study aimed to identify the potential risk factors for small airway dysfunction (SAD) in non-smokers with chronic cough.

Methods

Non-smokers with chronic cough who underwent lung function tests at Xiangya Hospital from May 2019 to May 2020 were enrolled, and divided into the derivation and validation cohorts based on their hospital admission time. SAD was determined based on the presence of at least two of the following three indicators of lung function being less than 65% of predicted: maximal mid-expiratory flow, forced expiratory flow at 50% of forced vital capacity (FVC), and forced expiratory flow at 75% of FVC. Clinical data of these patients were collected. Risk factors for SAD were identified by logistic regression analysis in the derivation cohort and further confirmed in the validation cohort.

Results

In total, 316 patients (152 in the non-SAD group and 164 in the SAD group) were included in the derivation cohort. Compared with the non-SAD group, the SAD group had a higher proportion of female patients (82.3 vs. 59.2%, P < 0.001), was more commonly exposed to second-hand smoke (SHS) (61.6 vs. 27.6%, P < 0.001), and tended to be older (median age, 45.5 vs. 40.0 years old, P = 0.004). The median FVC, forced expiratory volume in one second (FEV₁) % pred, FEV₁/FVC ratio, and peak expiratory flow (PEF) % pred were slightly lower in the SAD group. Multivariable logistic analysis showed that exposure to SHS was an independent risk factor (OR 4.166 [95% CI 2.090–8.302], P < 0.001) for SAD in non-smokers with chronic cough after adjusting for related variables. In the validation cohort (n = 146), patients with SHS exposure had a relative risk of 1.976 (95% CI 1.246–3.135, P = 0.004) for SAD compared to those without SHS exposure. Multivariable logistic analysis consistently confirmed that exposure to SHS was an independent risk factor (OR 3.041 [95% CI 1.458–6.344], P = 0.003) for SAD in non-smokers.

Conclusions

Exposure to SHS is independently associated with a higher risk of SAD in non-smokers with chronic cough. Reduction in SHS exposure may ameliorate lung function, thus lowering the risk of irreversible airway obstruction.

Real-life effectiveness of dupilumab in patients with mild to moderate bronchial asthma comorbid with CRSwNP

BACKGROUND

Dupilumab, an anti-IL-4α receptor antibody, is a new treatment for severe or refractory asthma. However, real-world evidence on the efficacy of dupilumab in patients with mild to moderate bronchial asthma is lacking.

METHODS

We retrospectively evaluated the effects of dupilumab in 62 patients who received dupilumab for eosinophilic sinusitis comorbid with asthma at a single centre in Japan. Type 2 inflammatory markers, ACT, respiratory function tests, and forced oscillation technique (FOT) were analysed before, three months after, and one year after dupilumab administration, mainly in patients with mild to moderate asthma.

RESULTS

FEV1, %FEV1, %FVC, treatment steps for asthma and ACT improved significantly after three months of dupilumab treatment. FeNO was markedly decreased, whereas IgE and eosinophil counts showed no significant changes. Pre- and post-treatment respiratory resistance (Rrs) and respiratory reactance (Xrs) correlated significantly with FEV1. Improvement in %FEV1 was associated with higher FeNO and higher serum IgE before dupilumab treatment.

CONCLUSION

Dupilumab treatment for sinusitis may improve respiratory functions, asthma symptoms, and asthma treatment reduction, even if the associated bronchial asthma is not severe.

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.

An update on the currently available and emerging synthetic pharmacotherapy for uncontrolled asthma

INTRODUCTION

: The treatment of uncontrolled asthma has improved because of triple therapy that includes a long-acting muscarinic antagonist (LAMA) and biological drugs, but several patients are resistant to corticosteroids and/or cannot achieve adequate asthma control using such therapies.

AREAS COVERED

: Herein, the authors review the current and emerging synthetic pharmacotherapy for uncontrolled asthma to overcome obstacles and limitations of biological therapies. The authors also provide their expert perspectives and opinion on the treatment of uncontrolled asthma.

EXPERT OPINION

: LAMAs should be added to inhaled corticosteroid/long-acting β₂-agonist combinations much earlier than currently recommended by the Global Initiative for Asthma strategy because they can influence the course of small airways disease, reducing lung hyperinflation and improving asthma control. Biological therapies are a major advance in the treatment of severe asthma, but their use is still very limited for several reasons. An alternative to overcome the use of biological therapies is to synthesise compounds that target inflammation-signalling pathways. Several pathways have been identified as potential targets to design either therapeutic or prophylactic drugs against asthma. Some new compounds have already been tested in humans, but results have often been disappointing probably because existing phenotypic and endotypic variants may unpredictably limit the therapeutic value of blocking a specific pathway in most asthmatics, although there may be a substantial benefit for a subgroup of patients.

Small Airways: The “Silent Zone” of 2021 GINA Report?

Asthma is a chronic disease, affecting approximately 350 million people worldwide. Inflammation and remodeling in asthma involve the large airways, and it is now widely accepted that the small airways (those with an internal diameter <2 mm) are involved in the pathogenesis of asthma and are the major determinant of airflow obstruction in this disease. From a clinical perspective, small airways dysfunction (SAD) is associated with more severe bronchial hyperresponsiveness, worse asthma control and more exacerbations. Unlike the GOLD guidelines which, in their definition, identify COPD as a disease of the small airways, the Global Initiative for Asthma (GINA) guidelines do not refer to the prevalence and role of SAD in asthmatic patients. This decision seems surprising, given the growing body of compelling evidence accumulating pointing out the high prevalence of SAD in asthmatic patients and the importance of SAD in poor asthma control. Furthermore, and remarkably, SAD appears to possess the characteristics of a treatable pulmonary trait, making it certainly appealing for asthma control optimization and exacerbation rate reduction. In this mini-review article, we address the most recent evidence on the role of SAD on asthma control and critically review the possible inclusion of SAD among treatable pulmonary traits in international guidelines on asthma.

Spirometry parameters used to define small airways obstruction in population-based studies: systematic review

Background

The assessment of small airways obstruction (SAO) using spirometry is practiced in population-based studies. However, it is not clear what are the most used parameters and cut-offs to define abnormal results.

Methods

We searched three databases (Medline, Web of Science, Google Scholar) for population-based studies, published by 1 May 2021, that used spirometry parameters to identify SAO and/or provided criteria for defining SAO. We systematically reviewed these studies and summarised evidence to determine the most widely used spirometry parameter and criteria for defining SAO. In addition, we extracted prevalence estimates and identified associated risk factors. To estimate a pooled prevalence of SAO, we conducted a meta-analysis and explored heterogeneity across studies using meta regression.

Results

Twenty-five studies used spirometry to identify SAO. The most widely utilised parameter (15 studies) was FEF_25–75, either alone or in combination with other measurements. Ten studies provided criteria for the definition of SAO, of which percent predicted cut-offs were the most common (5 studies). However, there was no agreement on which cut-off value to use. Prevalence of SAO ranged from 7.5% to 45.9%. As a result of high heterogeneity across studies (I² = 99.3%), explained by choice of spirometry parameter and WHO region, we do not present a pooled prevalence estimate.

Conclusion

There is a lack of consensus regarding the best spirometry parameter or defining criteria for identification of SAO. The value of continuing to measure SAO using spirometry is unclear without further research using large longitudinal data.

PROSPERO registration number CRD42021250206

Supplementary Information

The online version contains supplementary material available at 10.1186/s12931-022-01990-2.

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.

Prognosis of bronchial asthma in children with different pulmonary function phenotypes: A real-world retrospective observational study

OBJECTIVE

To follow up on the changes in pulmonary function phenotypes in children with asthma in the first year after diagnosis, and explore the risk factors of poor control in children with good treatment compliance.

METHODS

Children who were diagnosed with asthma in the Respiratory Department of Shanghai Children's Medical Center from January 1, 2019 to December 31, 2020 and were re-examined every 3 months after diagnosis for 1 year were continuously included, regardless of gender. We collected the clinical data, analyzed clinical characteristics of the different pulmonary function phenotypes at baseline and explored risk factors of poor asthma control after 1 year of standardized treatment.

RESULTS

A total of 142 children with asthma were included in this study, including 54 (38.0%) with normal pulmonary function phenotype (NPF), 75 (52.8%) with ventilation dysfunction phenotype (VD), and 13 (9.2%) with small airway dysfunction phenotype (SAD) in the baseline. Among them, there were statistically significant differences in all spirometry parameters, age, and course of disease before diagnosis (P < 0.05), and a negative correlation between age (r ² = -0.33, P < 0.001), course of disease before diagnosis (r ² = -0.23, P = 0.006) and FEV₁/FVC. After 1-year follow-up, large airway function parameters and small airway function parameters were increased, fractional exhaled nitric oxide (FeNO) was decreased, the proportion of NPF was increased, the proportion of VD was decreased (P < 0.05), while there was no significant difference in the proportion of SAD. After 1 year of standardized treatment, 21 patients (14.8%) still had partly controlled or uncontrolled asthma. Our results showed that the more asthma attacks occurred within 1 year (OR = 6.249, 95% CI, 1.711-22.818, P = 0.006), the more times SAD presented at baseline and Assessment 1-4 (OR = 3.092, 95% CI, 1.222-7.825, P = 0.017), the higher the possibility of incomplete control of asthma.

CONCLUSION

About 15% of the children with good treatment compliance were still not completely controlled after 1 year of treatment, which is closely associated with persistent small airway dysfunction.

Mucus Plugs and Small Airway Dysfunction in Asthma, COPD, and Asthma-COPD Overlap

Purpose

There are reports concerning mucus plugs detected on high-resolution computed tomography images and airflow obstruction in asthma and chronic obstructive pulmonary disease (COPD). However, little is known about the associations between mucus plugs and small airway dysfunction (SAD). We evaluated the relationship between mucus plugs and pulmonary function in patients with asthma, COPD, and asthma-COPD overlap (ACO), and investigated the relevance to SAD and type 2 inflammation in a retrospective study.

Methods

Subjects included 49 asthmatic, 40 ACO, and 41 COPD patients. ACO was diagnosed based on the Japanese Respiratory Society ACO guidelines. Clinical and laboratory parameters, including blood eosinophil count, serum total IgE levels, fractional exhaled nitric oxide (FeNO), spirometry, and forced oscillation technique (FOT), were compared between patients with and without mucus plugs.

Results

Mucus plugs were found in 29 (59%) asthmatic, 25 (65%) ACO, 17 (41%) COPD patients. Patients with mucus plugs had reduced spirometry and larger FOT parameters, especially in COPD patients. Mucus scores correlated positively with IgE in ACO and FeNO in asthmatic patients, but not in COPD patients. Multivariate logistic regression analysis revealed that SAD parameters, including forced vital capacity and resonant frequency, a respiratory reactance parameter, were significantly associated with the presence of mucus plugs in the whole studied population.

Conclusions

SAD, rather than large airway dysfunction, was associated with mucus plugs in asthma, ACO, and COPD patients.

Clinical characteristics of and risk factors for small airway dysfunction detected by impulse oscillometry

BACKGROUND

Small airway dysfunction (SAD) is an early lesion of chronic respiratory disease that is best detected using impulse oscillometry (IOS). Few studies have investigated risk factors for IOS-defined SAD (IOS-SAD) in a large population. We aimed to explore the clinical features of and risk factors for IOS-SAD in a community-based population.

METHODS

We divided subjects into IOS-SAD and non-SAD groups based on a cutoff of >0.07 kPa/L/s in the difference between the resistance at 5 Hz versus the resistance at 20 Hz (R5-R20). All participants underwent spirometry, IOS, and completed a questionnaire; some participants underwent computed tomography (CT). We analyzed the risk factors for SAD based on binary logistic regression.

RESULTS

The total cohort comprised 1327 subjects. The prevalence of IOS-SAD was 32.9% (437/1327). Compared with the non-SAD group, the IOS-SAD group was older (64.0 ± 7.8 vs. 59.6 ± 7.8 years, p < 0.001), included less never-smokers (30.2% vs. 35.8%, p < 0.001), had greater airway resistance and worse lung function, indicated by a larger R5-R20 (0.15 ± 0.08 vs. 0.03 ± 0.02 kPa/L/s, p < 0.001) and smaller forced expiratory volume in 1 s to forced vital capacity after bronchodilation (60.2 ± 14.4% vs. 72.6 ± 10.0%, p < 0.001); on CT, the IOS-SAD group had higher prevalences of emphysema and gas trapping. Risk factors for SAD were older age, high BMI, smoking, childhood cough, and asthma.

CONCLUSION

Subjects with IOS-SAD had increased airway resistance and visible CT changes. Individuals with smoking exposure, advanced age, high BMI, childhood cough, and asthma were more prone to SAD.

CLINICAL TRIAL REGISTRATION

ChiCTR1900024643.

Determining Response to Treatment for Drug-Induced Bronchocentric Granulomatosis by the Forced Oscillation Technique

Anti-tumor necrosis factor alpha (TNFα) therapy is widely used to treat various inflammatory conditions. Paradoxically, there are several case reports describing the development of bronchocentric granulomatosis treated with TNFα inhibitors, and it is difficult to determine the effect of treatment using conventional spirometry because the lesions are located in small airways. However, it has been reported that the forced oscillation technique (FOT) is useful in the evaluation of small airway disease in bronchial asthma or chronic obstructive pulmonary disease. We performed the FOT to determine the effect of treatment on bronchocentric granulomatosis and found it to be useful. We report the case of a 55-year-old female with ulcerative colitis who was treated with golimumab and who developed bronchocentric granulomatosis as a sarcoid-like reaction to golimumab. She was successfully treated with prednisone, and the treatment efficacy was confirmed by the FOT. The FOT may be useful in the evaluation of small airway disease in bronchocentric granulomatosis. This case may help inform clinicians of the usefulness of the FOT to assess small airway disease in various diseases.

Improving the risk-to-benefit ratio of inhaled corticosteroids through delivery and dose: current progress and future directions

INTRODUCTION

Inhaled corticosteroids (ICS) are known to increase the risk of systemic and local adverse effects, especially with high doses and long-term use. Hence, considerable resources are invested to improve pharmacokinetic/pharmacodynamic (PK/PD) properties of ICS, effective delivery systems and novel combination therapies to enhance the risk-to-benefit ratio of ICS.

AREAS COVERED

There is an unmet need for new solutions to achieve optimal clinical outcomes with minimal dose of ICS. This paper gives an overview of novel treatment strategies regarding the safety of ICS therapy on the basis of the three most recent molecules introduced to our everyday clinical practice - ciclesonide, mometasone furoate, and fluticasone furoate. Advances in aerosol devices and new areas of inhalation therapy are also discussed.

EXPERT OPINION

Current progress in improving the risk-to-benefit ratio of ICS through dose and delivery probably established pathways for further developments. This applies both to the improvement of the PK/PD properties of ICS molecules but also includes technical aspects that lead to simplified applicability of the device with simultaneous optimal drug deposition in the lungs. Indubitably, the future of medicine lies not only in the development of new molecules but also in technology and digital revolution.

Small Airways Response to Bronchodilators in Adults with Asthma or COPD: A Systematic Review

BACKGROUND

Bronchodilator responsiveness (BDR) is commonly used in the diagnosis of lung disease. Although small airways dysfunction is a feature of asthma and COPD, physiological tests of small airways are not included in guidelines for BDR testing. This systematic review assessed the current evidence of BDR using small airways function in asthma and COPD.

METHODS

The systematic review used standard methodology with the protocol prospectively registered on PROSPERO (CRD42020164140). Electronic medical databases (EMBASE and Medline) were searched using related keywords. Abstracts and full texts were screened independently by two reviewers. Studies that reported the change of physiological small airways function and FEV₁ were included in the review. The revised Cochrane risk of bias tool for RCT and NIH quality assessment tool for cohort and cross-sectional studies were used to evaluate the studies.

RESULTS

A total of 934 articles were identified, with 12 meeting the inclusion criteria. Ten studies included asthma patients, 1 study included COPD patients and 1 study included both asthma and COPD. A total of 1104 participants were included, of whom 941 were asthmatic, 64 had COPD and 109 were healthy controls. Studies were heterogeneous in design including the device, dose and time intervals for BDR assessment. A small airway BDR was seen for most tests in asthma and COPD, including oscillometry (R5-20, reactance (X5), area of reactance (AX) and resonant frequency (Fres)) and Maximal Mid Expiratory Flow.

CONCLUSION

There is a measurable BDR in the small airways. However, with no consensus on how to assess BDR, studies were heterogeneous. Further research is needed to inform how BDR should be assessed, its clinical impact and place in routine clinical practice.

Small airways targeted treatment with smart nebulizer technology could improve severe asthma in children: a retrospective analysis

OBJECTIVE

Conventional inhaler devices have a low efficacy in targeting small airways. Smart nebulizers can be used to increase deposition to small airways by adjusting the flow and depth of each inhalation based on patients 'individual inspiratory capacity. We investigated whether targeting of high dose inhaled corticosteroids (ICS) to small airways with a smart nebulizer could reduce exacerbation rate in children with severe asthma (SA).

METHODS

We conducted a retrospective study in children with SA using a smart nebulizer (Akita® Jet nebulizer) for the administration of high dose ICS in our outpatient clinic at the Erasmus MC - Sophia Children's Hospital. Clinical data before and after start of treatment were collected. The primary outcome was exacerbation rate, defined as: number of asthma exacerbations for which oral corticosteroid courses (OCS) were prescribed. The exacerbation rate 1 year before treatment was compared with the exacerbation rate 1 year after start of treatment. Secondary outcomes were changes in spirometry parameters, hospital admissions and medication use.

RESULTS

Data on OCS use was available for 28/31 patients. Median number of asthma exacerbations requiring OCS courses 1 year before decreased from 2 (interquartile range(IQR) 2) to 0.5 (IQR 3) 1 year after treatment (p = 0.021). Hospital admission decreased from 1 (IQR 3) to 0 (IQR 1)(p = 0.028). FEV1, FEF_25-75 and FEF₇₅ were not significantly improved after one year of treatment with the smart nebulizer (p = 0.191; p = 0.248; p = 0.572).

CONCLUSION

Targeting small airways with high dose ICS using a smart nebulizer resulted in a significant reduction in exacerbations requiring OCS after one year of treatment.

Impact of long-acting muscarinic antagonists on small airways in asthma and COPD: A systematic review

Small airway disease is recognized as a cardinal pathological process of chronic obstructive pulmonary disease (COPD), and recently small airways have been recognized as a major site of airflow obstruction also in asthmatic patients. The transversal involvement of small airways in COPD and asthma has warranted research efforts to identify therapeutic strategies able to unlock the small airway compartment. The mainstay of COPD treatment is represented by long-acting β₂-adrenoceptor agonists (LABAs) and long-acting muscarinic antagonists (LAMAs). In asthma, the efficacy of LAMAs administered add-on to inhaled corticosteroids (ICSs) or ICS/LABA combinations has been investigated only in recent years. The aim of this systematic review was to examine the current literature concerning the impact of LAMAs on small airways and their lung deposition in both COPD and asthma. LAMAs administered either alone or in combination induced an effective bronchorelaxant effect of small airways, however the effectiveness of respiratory medications not only relies on the selected drug, but also on the employed inhalation device and patient's adherence. Tiotropium delivered via Respimat® SMI achieved a superior drug deposition in the peripheral lung compared to HandiHaler® dry powder inhaler and metered-dose inhalers (MDIs). The use of co-suspension™ delivery technology for MDIs and the introduction of the eFlow® nebulizer to deliver glycopyrronium improved aerosol drug delivery to the peripheral lung, by achieving uniform distribution of drug particles. This systematic review provides a synthesis of current literature concerning the impact of LAMAs on small airways and an insight on LAMAs distribution within the lung.

Spirometry parameters used to define small airways obstruction in population-based studies: systematic review protocol

INTRODUCTION

In recent years, there has been increasing interest in the use of spirometry for the assessment of small airways obstruction (SAO) driven by the idea that these changes occur prior to development of established obstructive lung disease. Maximal mid-expiratory and distal flow rates have been widely used despite a lack of agreement regarding parameter selection or definition of an abnormal result. We aim to provide evidence from population-based studies, describing the different parameters, definitions of normal range and the resulting impact on prevalence estimates for SAO. Summarising this evidence is important to inform development of future studies in this area.

METHODS AND ANALYSIS

A systematic review of population-based studies will be conducted. MEDLINE, Web of Science and Google Scholar will be searched from database inception to May 2021. Primary outcomes will include the spirometry parameter used to define SAO, and the definition of an abnormal result. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines will be followed for study selection. Study methods will be assessed using the Newcastle-Ottawa scale and the Grading of Recommendations Assessment, Development and Evaluation working group methodology. Narrative synthesis will be conducted for all included studies. Meta-analysis will also be conducted for prevalence estimates and associated risk factors where data quality and availability allow. Random effects models will be used to conduct the meta-analysis and I² statistics will be used to assess heterogeneity across studies. Where appropriate subgroup analysis will be conducted to explore heterogeneity.

ETHICS AND DISSEMINATION

There is no requirement for ethical approval for this project. Findings will be disseminated via peer-reviewed publications and other formats, for example, conferences, congresses or symposia.

PROSPERO REGISTRATION NUMBER

CRD42021250206.

Small-Airway Dysfunction is Involved in the Pathogenesis of Asthma: Evidence from Two Mouse Models

Background

There has been growing evidence of small-airway dysfunction in patients with asthma. Few studies have evaluated the mechanism of small-airway dysfunction in mouse models of asthma.

Purpose

We explored the correlation between small-airway spirometric variables and large-airway function or inflammation in different endotypes of asthma.

Methods

Ovalbumin (OVA) sensitization/challenge was used to produce a type 2 (T2)-high asthma model, and OVA combined with ozone exposure (OVA + ozone) was used for the T2-low asthma model with increased neutrophils. Spirometry, airway responsiveness, cytokine levels in bronchoalveolar lavage fluid (BALF), and pathological analyses of lung slices stained with hematoxylin-eosin, periodic acid–Schiff, and Masson’s trichrome stain were all determined. Muc5ac expression in lung tissue was evaluated by the reverse transcription-polymerase chain reaction (RT-PCR), and alpha-smooth muscle actin was measured by immunohistochemistry.

Results

Inflammatory cells infiltrated the lung tissue and inflammatory cytokines were increased in the BALF of both the OVA and OVA + ozone groups, compared with the control group. Peribronchial hypersecretion and collagen deposition were evident in the models. The OVA + ozone group showed greater neutrophilic infiltration and peribronchial smooth muscle proliferation than the OVA group. Large-airway obstruction, small-airway dysfunction, and airway hyperresponsiveness were confirmed in both models. Small-airway functional variables, such as MMEF (mean midexpiratory flow, average flow from 25 to 75% forced vital capacity [FVC]) and FEF50 (forced expiratory flow at 50% of FVC), were positively correlated with large-airway function and had a stronger negative correlation with airway inflammation, mucus secretion, and responsiveness than large-airway function.

Conclusion

Small-airway dysfunction was evident in the two endotypes of asthma and was correlated with severe airway inflammation, mucus hypersecretion, and airway hyperresponsiveness. The small airways may be an important target in asthma treatment, and further research in the role of small-airway variables in the pathogenesis of asthma is warranted.

Long-acting muscarinic antagonists and small airways in asthma: Which link?

Involvement of small airways, those of <2 mm in internal diameter, is present in all stages of asthma and contributes substantially to its pathophysiologic expression. Therefore, small airways are a potential target to achieve optimal asthma control. Airway tone, which is increased in asthma, is mainly controlled by the vagus nerve that releases acetylcholine (ACh) and activates muscarinic ACh receptors (mAChRs) post-synaptically on airway smooth muscle (ASM). In small airways, M₃ mAChRs are expressed, but there is no vagal innervation. Non-neuronal ACh released from the epithelial cells that may express choline acetyltransferase in response to inflammatory stimuli, as well as from other structural cells in the airways, including fibroblasts and mast cells, can activate mAChRs. By antagonizing M₃ mAChR, the contraction of the ASM is prevented and, potentially, local inflammation can be reduced and the progression of remodeling may be averted. In fact, ACh also contributes to inflammation and remodeling of the airways and regulates the growth of ASM. Several experimental studies have demonstrated the potential benefit derived from the use of mAChR antagonists, mainly long-acting mAChR antagonists (LAMAs), on small airways in asthma. However, there are several confounding factors that may cause a wrong estimation of the relationship between LAMAs and small airways in asthma. Further studies are needed to differentiate broncholytic and anti-inflammatory effects of LAMAs and to better understand the interaction between LAMAs and corticosteroids, also in the context of a triple therapy that includes a β₂ -AR agonist, at different levels of the bronchial tree.

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

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

Ceiling effect of beclomethasone/formoterol/glycopyrronium triple fixed-dose combination in COPD: A translational bench-to-bedside study

BACKGROUND

Currently, data on the possible synergy of adding a LAMA to ICS/LABA combination are missing and no studies assessed whether triple therapy may induce ceiling bronchodilator effect. A translational study was performed to investigate the interaction between glycopyrronium bromide (GB) and beclomethasone dipropionate (BDP)/formoterol fumarate (FF) combination in human isolated airways and the effect on FEV₁ and small airway resistance of BDP/FF/GB in COPD.

METHODS

The interaction of adding GB to BDP/FF combination was tested in vitro in medium and small airways via Bliss, Loewe, and Highest Single Agent models. The peak and trough effect on FEV₁ and R5-R19 of salbutamol on top of BDP/FF/GB 100/6/12.5 μg FDC via extrafine formulation was investigated in severe COPD patients after two weeks of treatment.

RESULTS

GB plus BDP/FF elicited significant synergistic bronchorelaxation in medium and small isolated airways (overall maximal effect: +32% vs. additive effect). No significant (P > 0.05) improvement in R5-R19 was detected when salbutamol was administered on top of BDP/FF/GB 100/6/12.5 μg FDC (peak -0.12 ± 0.22 cmH₂O/L/s, trough -0.23 ± 0.25 cmH₂O/L/s). Salbutamol significantly (P < 0.01) increased FEV₁ when administered on top of triple FDC (peak +145 ± 119 ml, trough +221 ± 111 ml).

CONCLUSION

The synergistic interaction detected in vitro when adding GB to BDP/FF combination may lead to ceiling bronchorelaxation of small airways in vivo, an effect that may improve hyperinflation in subjects with small airway disease and, thus, explain the substantial clinical benefits of triple combination therapy administered via extrafine formulation in severe COPD patients.

STUDY REGISTRATION

ISRCTN94089001.

Small airway dysfunction and poor asthma control: a dangerous liaison

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

Specificities of small airways dysfunction development in patients with mild asthma

The study goal was to identify specificities of small airways dysfunction development (SAD) in patients with mild asthma. Material and Methods — The study involved 114 patients with mild asthma. Depending on the condition of their small airways, the patients were split among two groups: Group 1 of 94 patients with asthma without SAD (82.5%); Group 2 of 20 patients with asthma and SAD (17.5%). The control group consisted of 25 volunteers. SAD was diagnosed by the presence of air trapping and hyperinflation. Results — SAD was diagnosed in 17.5% of patients with mild asthma. The development of SAD was observed in 80% of asthma patients with ailment duration of over 5 years and family history of asthma. Obesity was diagnosed 1.7 times more often in patients with SAD compared with those without it. Food allergy, allergic rhinitis, allergic conjunctivitis, urticaria and bronchial obstruction were identified two or more times more often in patients with SAD compared with those without it. Among all patients with mild asthma and SAD, bronchial obstruction was detected in 55% of cases. Conclusion — The development of SAD in the presence of mild asthma is characteristic for patients with ailment duration over 5 years, family history of asthma, obesity, predominant sensitization to food allergens, and concomitant non-pulmonary allergic diseases. Bronchial obstruction is not the obligatory feature of SAD development in presence of mild asthma.

Small airways in asthma: from bench-to-bedside

INTRODUCTION

Historically, asthma was considered a disease predominantly of the large airways, but gradually small airways have been recognized as the major site of airflow obstruction. Small airway dysfunction (SAD) significantly contributes to the pathophysiology of asthma and it is present across all asthma severities. Promising pre-clinical findings documented enhanced beneficial effects of combination therapies on small airways compared to monocomponents, thus it was questioned whether this could translate into further clinical implications from bench-to-bedside. The aim of this review was to systematically assess the state of the art of small airway involvement in asthma, especially in response to different pharmacological treatments acting on the respiratory system.

EVIDENCE ACQUISITION

A comprehensive literature search was performed in MEDLINE for randomized controlled trials (RCTs) characterizing the impact on small airways of different pharmacological treatments acting on the respiratory system. The results were extracted and reported via qualitative synthesis.

EVIDENCE SYNTHESIS

Overall, 63 studies were identified from the literature search, whereas 23 RCTs met the inclusion criteria. Evidence confirms that both drug particle size and the type of inhalation devices represent two of the most important variables for an effective peripheral lung distribution.

CONCLUSIONS

Despite the numerous methodological tools to detect SAD, there is still no gold standard diagnostic method to assess small airways, especially in severe asthma. Further research should be directed to improve primary and secondary prevention strategies by supporting the combined approach of different non-invasive techniques for an early detection of peripheral abnormalities and optimization of asthma therapy.

Structure and function of small airways in asthma patients revisited

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

Delivery and adherence with inhaled therapy in asthma

The benefits of inhaled medication for the treatment of respiratory diseases are immense. Inhalers are unquestionably the most important medical devices for the treatment of asthma and in Europe today there are more than 230 different device and drug combinations of inhaled therapies many of which are available for the treatment of asthma. They are designed to alleviate the symptoms of asthma by controlling inflammation and minimising exacerbations and are intended to be simple enough to operate by all patients regardless of their age and education. However, it is still a huge challenge for patients to use their inhaler correctly and consistently and achieving asthma control continues to be an elusive goal for most patients worldwide. The reality is that despite advances in the diagnosis of asthma, the availability of comprehensive asthma management guidelines and potent asthma medications combined with efficient delivery systems, uncontrolled disease is still linked to substantial morbidity and mortality. Despite the enormous benefits of delivering topically acting medication directly to the site of disease in the lungs adherence to treatment still remains one of the biggest challenges in asthma control. This current review looks at why patients have difficulty in using their inhalers and why adherence is so poor and how this may be improved through the use of innovation in inhaler design.

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

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

Small Airways, Big Problem: Extrafine beclomethasone/formoterol in asthma and chronic obstructive pulmonary disease

Asthma and chronic obstructive pulmonary disease (COPD) are common chronic respiratory diseases characterized by an inflammatory process that extends from the central to peripheral airways. Conventional pressurized metered-dose inhalers and most dry-powder inhalers emit drug particles too large to target the small airways effectively. Advancements in drug formulation have given rise to a new generation of inhalers that can generate aerosols with extrafine drug particles that leads to more effective aerosol penetration into the lung periphery. An extrafine formulation of inhaled beclomethasone/formoterol (BDP-FF) with enhanced lung deposition is now available. This document reviews the various real-world and controlled studies that have evaluated the efficacy of extrafine BDP-FF in asthma and COPD.