Manifesto on small airway involvement and management in asthma and chronic obstructive pulmonary disease: an Interasma (Global Asthma Association - GAA) and World Allergy Organization (WAO) document endorsed by Allergic Rhinitis and its Impact on Asthma (ARIA) and Global Allergy and Asthma European Network (GA2LEN)

Detailed characterization and impact of small airway dysfunction in school-age asthma

BACKGROUND

Small airway dysfunction (SAD) is increasingly recognized as an important feature of pediatric asthma yet typically relies on spirometry-derived FEF25-75 to detect its presence. Multiple breath washout (MBW) and oscillometry potentially offer improved sensitivity for SAD detection, but their utility in comparison to FEF25-75, and correlations with clinical outcomes remains unclear for school-age asthma. We investigated SAD occurrence using these techniques, between-test correlation and links to clinical outcomes in 57 asthmatic children aged 8-18 years.

METHODS

MBW and spirometry abnormality were defined as z-scores above/below ± 1.96, generating MBW reference equations from contemporaneous controls (n = 69). Abnormal oscillometry was defined as > 97.5th percentile, also from contemporaneous controls (n = 146). Individuals with abnormal FEF25-75, MBW, or oscillometry were considered to have SAD.

RESULTS

Using these limits of normal, SAD was present on oscillometry in 63% (resistance at 5-20 Hz; R5-R20; >97.5th percentile), on MBW in 54% (Scond; z-scores> +1.96) and in spirometry FEF25-75 in 44% of participants (z-scores< -1.96). SAD, defined by oscillometry and/or MBW abnormality, occurred in 77%. Among those with abnormal R5-R20, Scond was abnormal in 71%. Correlations indicated both R5-R20 and Scond were linked to asthma medication burden, baseline FEV1 and reversibility. Additionally, Scond correlated with FENO and magnitude of bronchial hyper-responsiveness. SAD, detected by oscillometry and/or MBW, occurred in almost 80% of school-aged asthmatic children, surpassing FEF25-75 detection rates.

CONCLUSIONS

Discordant oscillometry and MBW abnormality suggests they reflect different aspects of SAD, serving as complementary tools. Key asthma clinical features, like reversibility, had stronger correlation with MBW-derived Scond than oscillometry-derived R5-R20.

Impact of biologics on lung hyperinflation in patients with severe asthma

BACKGROUND

In asthma, inflammation affects both the proximal and distal airways and can cause significant hyperinflation, which is thought to be a major cause of dyspnea.

METHODS

This is a retrospective observational study evaluating the effect of three months of treatment with different biologic drugs (benralizumab, dupilumab and omalizumab) on pulmonary hyperinflation in a cohort of patients with severe asthma already receiving regular triple inhaled therapy. Changes in RV, RV/TLC ratio, FRC and FRC/TLC ratio were the primary efficacy measures. Secondary outcomes included FEV1, FVC, FEV1/FVC ratio, IC, IC/TLC ratio, asthma control test, the percentage of eosinophils in the blood and fractional FENO.

RESULTS

Benralizumab led to significant changes (p < 0.001) in RV, RV/TLC, FRC, and FRC/TLC. Dupilumab demonstrated a notable reduction in RV (p = 0.017) and RV/TLC (p = 0.002), but the decreases in FRC and FRC/TLC were merely numerical and not as pronounced as those induced by benralizumab. Omalizumab's positive impact on RV (p = 0.057) and RV/TLC (p = 0.085), as well as FRC (p = 0.202) and FRC/TLC (p = 0.096), was also predominantly numerical, with a tendency towards efficacy, albeit excluding the effect on FRC. Treatment with biologics resulted in improvements in all other lung function parameters assessed and a decrease in FENO levels.

CONCLUSION

This study, although limited by small sample size, lack of a placebo control, and unbalanced group sizes, suggests that biological agents are effective in reducing lung hyperinflation even after a relatively short treatment.

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.

Might It Be Appropriate to Anticipate the Use of Long-Acting Muscarinic Antagonists in Asthma?

A growing number of clinical trials are documenting that adding a long-acting muscarinic antagonist (LAMA) to established asthma treatment with an inhaled corticosteroid (ICS) and a long-acting β₂-agonist (LABA) is a treatment option that improves the health of patients with uncontrolled severe asthma even when therapy is optimized. These favorable results are the reason why the leading guidelines recommend triple therapy with ICS + LABA + LAMA in patients with asthma uncontrolled by medium- to high-dose ICS-LABA. However, we suggest adding LAMAs to ICS-LABAs at an earlier clinical stage. Such action could positively influence airflow limitation, exacerbations, and eosinophilic inflammation, conditions that are associated with acetylcholine (ACh) activity. It could also interrupt the vicious cycle related to a continuous release of ACh leading to the progressive expansion of neuronal plasticity resulting in small airway dysfunction. The utility of an earlier use of triple therapy in asthma should, in any case, be confirmed by statistically powered trials.

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.

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.

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.

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.

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

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

Shirazi thyme (Zataria multiflora) extract can alleviate allergic rhinitis: a randomized clinical trial

Introduction

Atopic diseases are global concerns in the today's industrialized world. Allergic rhinitis is the most common allergic condition affecting 20% of individuals. This disorder is associated with remarkable morbidity and rising healthcare expenditure.

Aim

Considering the anti-inflammatory properties of a plant Zataria multiflora (ZM) with the common name of Shirazi thyme, a randomized clinical trial was designed to evaluate the alleviation of the symptoms of allergic rhinitis.

Material and methods

A total of 30 allergic rhinitis patients were randomly and equally assigned to experimental and control groups. Afterwards, the case group was treated with an extract of ZM and the control group with placebo for 2 months. Finally, the clinical signs and symptoms before and after the treatment according to the SNOT22 questionnaire were analysed.

Results

Comparing the symptoms of allergic rhinitis and an average score of SNOT22 questionnaire between the two groups before the intervention provided some difference, which was significantly greater after the treatment. Based on this questionnaire, our patients in the ZM syrup group had lower grades than before the treatment and experienced amelioration.

Conclusions

Regarding the significant effect of the ZM syrup in reducing symptoms of allergic rhinitis, its use is highly recommended. Since allergic rhinitis is a multifactorial condition, the use of herbal antioxidants along with conventional treatment would result in a more effective improvement of the disease.

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.

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.

Small-airway dysfunction in paediatric asthma

PURPOSE OF REVIEW

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

RECENT FINDINGS

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

SUMMARY

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

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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

BACKGROUND

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Small airway inflammation and extrafine inhaled corticosteroids plus long-acting beta2-agonists formulations in chronic obstructive pulmonary disease

OBJECTIVES

To summarize the evidence of small airways involvement in chronic obstructive pulmonary disease (COPD) pathophysiology, and to evaluate the efficacy of extrafine formulations of inhaled corticosteroids (ICS) in combination with long-acting beta₂-agonists (LABAs) in the treatment of COPD.

DATA SOURCE

A search of the PubMed database was conducted using the keywords "COPD", "small airways", "inflammation" and "extrafine formulation." The search was limited to entries published in English before August 2016. Only studies conducted in humans were considered.

STUDY SELECTION

Publications were included on the basis of relevance.

RESULTS

COPD is a common preventable and treatable disease, characterized by persistent and progressive airflow limitation. With improved understanding of COPD pathophysiology, small airways (internal diameter <2 mm), a well-known major site of COPD-associated inflammation and remodeling, have emerged as a potential target for COPD pharmacologic therapies. The ability of extrafine formulations of ICS in combination with LABAs to achieve central and peripheral lung deposition, and the implications of the enhanced efficacy that this may bring, are discussed by examining findings from the development trials plan of the extrafine formulation of beclometasone dipropionate/formoterol fumarate (Foster^®, Chiesi Farmaceutici, Italy) in patients with COPD.

CONCLUSION

There is an urgent need for improved and reliable techniques for small airways assessment in order to detect early damage, disease progression and response to treatment. Evidence from randomized clinical trials supports the benefits of extrafine ICS/LABA formulations in COPD, real world studies are necessary to confirm this.

Oral Administration of Zataria multiflora Extract Decreases IL-17 Expression in Perennial Allergic Rhinitis

BACKGROUND

Rhinitis, which occurs most commonly as allergic rhinitis and affects 20% of the world's population, is a major health care burden causing significant morbidity. Considering the high prevalence of allergic rhinitis and anti-inflammatory effects of thyme, a favorite condiment, we performed a randomized clinical trial to determine whether thyme can relieve allergic rhinitis symptoms and affect the expression of TH17- and T-regulatory cell- (Treg) related cytokines IL-17, TGF-β, FOXP3, and IL-10.

METHODS

Thirty patients with allergic rhinitis symptoms and positive skin prick test for common aero allergens were randomly assigned to experimental or control groups. The experimental group received thyme or Zataria multiflora (ZM) extracts and the control group received placebo for two months. Expression of IL-17, TGF-β, FOXP3, and IL-10 was evaluated in all subjects by real-time PCR before and after intervention.

RESULTS

After treatment IL-17 expression was significantly less in the ZM group than in controls (p<0.05), while TGF-β, FOXP3, and IL-10, expression were not significantly changed.

CONCLUSION

Given the significant effect of thyme in reducing symptoms of allergic rhinitis and decrease IL-17 gene expression and because allergic rhinitis is a multifactorial disease, the administration of thyme extract along with conventional treatments may benefit allergic rhinitis sufferers.

Utility of single versus multiple breath washout in adult asthma

Nitrogen multiple breath washout (N2 MBW) is a sensitive method to identify peripheral airway involvement in asthma, but is a time-consuming test. The N2 vital capacity single breath (VC SBW) test offers greater time efficiency, but concordance with N2 MBW is poorly understood. The prevalence of peripheral airway abnormality was determined by N2 MBW and N2 SBW tests in 194 asthmatic subjects aged 18-1 years. N2 MBW data were related to findings in 400 healthy controls, aged 17-71 years, while N2 SBW data were compared to findings in 224 healthy controls, aged 15-65 years, to derive equipment-specific reference values. Amongst asthmatic subjects, relationships between N2 SBW and N2 MBW outcomes were studied. N2 SBW relationship with clinical history, spirometry, blood eosinophils and fraction exhaled nitric oxide (FENO) data was also explored. The prevalence of peripheral airway involvement (i.e. abnormal ventilation distribution) determined by N2 SBW-derived phase III slope (N2 SIII ) was 24·7%, compared to 44% determined by N2 MBW-derived lung clearance index (LCI) (P<0·001). Predictors of abnormal N2 SIII were older age, smoking history and lower FEV1. N2 SBW offers lower sensitivity than N2 MBW to detect small airway dysfunction in adult asthma, but may be a marker of more severe disease.