The role of small airways in monitoring the response to asthma treatment: what is beyond FEV1?

Small airway inflammation in atypical asthma

Background

Less attention has been paid to the pathophysiological changes in atypical asthma such as cough variant asthma (CVA) and chest tightness variant asthma (CTVA). The obstruction of large and small airways is the important component in the development of asthma. We investigated whether small airway inflammation (SAI) induced small airway dysfunction (SAD) in these atypical asthmatics.

Methods

Six hundred and eighty-six patients were enrolled and analyzed in the study. The partitioned airway inflammation was assessed by fractional exhaled nitric oxide (FeNO), such as FnNO, FeNO50, FeNO200, and calculated alveolar fraction of exhaled NO (CaNOdual). Correlations between exhaled NOs and SAD-related variables were assessed, whereas cell classification was evaluated by Spearman's rank tests. Classic asthma, CVA, and CTVA about potential risk were conducted using binary logistic regression models.

Results

The whole airway inflammation increased in classic and atypical asthma than controls, whereas the central and peripheral airway inflammation in the CVA and CTVA groups increased compared with the classic asthma group. Smoking exposure was found to increase the central and peripheral airway inflammation in patients with asthma. The exhaled NO of FeNO50 and FeNO200 was associated with SAD in classic asthma, but not in CVA and CTVA. FeNO200 was the main risk (adjusted odds ratio [OR], 1.591; 95 % CI, 1.121-2.259; P = .009) in classic asthma and (adjusted OR, 1.456; 95 % CI, 1.247-1.700; P = .000) in CVA. The blood eosinophil levels were correlated with FeNO50 and FeNO200 in classic asthma and atypical asthma.

Conclusion

More severe inflammatory process was present in central and peripheral airways in CVA and CTVA, which might reflect a pre-asthmatic state. SAI was the predominant risk factor in the development of asthma before SAD.

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.

Static lung volumes and diffusion capacity in adults 30 years after being diagnosed with asthma

Background

Long-term follow-up studies of adults with well-characterized asthma are sparse. We aimed to explore static lung volumes and diffusion capacity after 30 + years with asthma.

Methods

A total of 125 adults with an objectively verified diagnosis of asthma between 1974–1990 at a Danish respiratory outpatient clinic completed a follow-up visit 2017–19. All participants (age range 44–88 years) completed a comprehensive workup and were, based on these assessments, classified as having either active asthma or being in complete remission. The examination program included measurements of static lung volumes and diffusion capacity.

Results

Participants with active asthma were hyperinflated (residual volume/total lung capacity ratio 0.43, 95% CI 0.41—0.45) (RV/TLC ratio) compared with those in remission (RV/TLC ratio 0.38, 95% CI 0.36—0.41) (p < 0.03). A tendency towards higher diffusion capacity per liter lung volume was seen in participants with active asthma (KCO 100% predicted, 95% CI 97—104) compared with those in remission (KCO 94% pred., 95% CI 89—99) (P = 0.10). Longer asthma duration was associated with a higher KCO 0.47% pred./year (95% CI 0.14—0.80), adjusted for age and smoking. Patients on GINA step 4 and 5 treatment were more hyperinflated (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\Delta$$\end{document}Δ RV 14% pred., 95% CI 3—27) and had higher airway resistance (mean 53% pred., 95% CI 9—97) than participants on lower GINA steps. Patients with uncontrolled disease had substantially higher airway resistance (72% pred. 95% CI 20—124) than well-controlled patients.

Conclusion

Thirty years after a confirmed diagnosis of asthma, those continuing to have active asthma and those having severe asthma, have higher diffusion capacity and more hyperinflation than patients in remission.

Forced Vital Capacity and Low Frequency Reactance Area Measurements Are Associated with Asthma Control and Exacerbations

Introduction

Forced vital capacity (FVC) is often preserved in severe asthma unless there is evidence of either airway remodelling or air trapping. Area under the reactance curve (AX) can be used to assess small airways dysfunction related lung stiffness and is related to disease control in severe asthma.

Methods

We explore if there may be a potential synergistic interaction between FVC and AX in terms of impaired asthma control as ACQ and exacerbations requiring oral corticosteroids (OCS). We pragmatically defined < 100% and ≥ 1.0 kPa/L/s as impaired FVC or AX, respectively.

Results

Patients with combined impairment of FVC and AX had significantly worse asthma control as higher ACQ, more severe exacerbations requiring OCS and worse spirometry (FEV₁ and FEF_25–75) than those with impaired FVC but preserved AX.

Conclusion

This in turn supports using both spirometry and oscillometry to characterise airway physiology more comprehensively in patients with more severe asthma.

FEF25-75% Is a More Sensitive Measure Reflecting Airway Dysfunction in Patients with Asthma: A Comparison Study Using FEF25-75% and FEV1

BACKGROUND

Reduced forced expiratory flow between 25% and 75% of vital capacity percent predicted (FEF_25-75%) representing small airway dysfunction (SAD) was associated with asthma development and progression.

OBJECTIVE

To investigate whether FEF_25-75% was superior to forced expiratory volume in 1 second in predicted (FEV₁%) in reflecting asthma features in adult patients.

METHODS

A retrospective spirometry dataset comprising 1801 adult patients with confirmed asthma and a subgroup of 332 patients having detailed clinical data were used to explore the association of FEF_25-75% and/or FEV₁% with clinical features of asthma.

RESULTS

Of the 1801 subjects, FEV₁% and FEF_25-75% ranged from 136.8% to 10.2% and 127.3% to 3.1%, respectively. FEF_25-75% < 65% was present in 1,478 (82.07%) of patients. FEF_25-75% was strongly correlated with matched FEV₁% (r = 0.900, P < .001). FEF_25-75% and FEV₁% were both correlated with airway hyperresponsiveness (r = 0.436, P < .001; r = 0.367, P < .001), asthma control test score (r = 0.329, P < .001; r = 0.335, P < .001), and sputum eosinophil count (r = -0.306, P < .001; r = -0.307, P < .001). Receiver-operating characteristic curves showed that FEF_25-75% had greater value in predicting severe asthma (area under the curve: 0.84 vs 0.81, P = .018), airflow obstruction (0.97 vs 0.89, P < .001), and severe bronchial hyperresponsiveness (0.74 vs 0.69, P = .012) as compared with FEV₁%. Patients with SAD (FEF_25-75% < 65%) in the presence of normal FEV₁% exhibited higher sputum eosinophil counts and had an increased dosage of daily inhaled corticosteroids (P < .001 and P = .010) than patients with normal lung function and their FEF_25-75% values correlated with sputum eosinophil count (r = -0.419, P = .015), but not FEV₁%.

CONCLUSION

FEF_25-75% represented small airway function and was more sensitive at reflecting airway hyperresponsiveness, inflammation, and disease severity as compared with FEV₁% in patients with asthma. Our data suggest further assessment of FEF_25-75% in asthma management, particularly for those with SAD who present normal FEV₁%.

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.

Minimal clinically important difference for asthma endpoints: an expert consensus report

Minimal clinically important difference (MCID) can be defined as the smallest change or difference in an outcome measure that is perceived as beneficial and would lead to a change in the patient's medical management.

The aim of the current expert consensus report is to provide a “state-of-the-art” review of the currently available literature evidence about MCID for end-points to monitor asthma control, in order to facilitate optimal disease management and identify unmet needs in the field to guide future research.

A series of MCID cut-offs are currently available in literature and validated among populations of asthmatic patients, with most of the evidence focusing on outcomes as patient reported outcomes, lung function and exercise tolerance. On the contrary, only scant and partial data are available for inflammatory biomarkers. These clearly represent the most interesting target for future development in diagnosis and clinical management of asthma, particularly in view of the several biologic drugs in the pipeline, for which regulatory agencies will soon require personalised proof of efficacy and treatment response predictors.

Minimal clinically important difference (MCID) cut-offs in asthma are validated for patient reported outcomes and lung function, but not for inflammatory biomarkers. MCID represents a key target for future development in asthma management. http://bit.ly/33hcWIe

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.

Children with Asthma Have Fixed Airway Obstruction through Childhood Unaffected by Exacerbations

BACKGROUND

Children with asthma may have a disease course with or without exacerbations, but the relationship between exacerbations and lung function development is poorly understood.

OBJECTIVE

To compare lung function trajectories from birth till adolescence in asthmatic children with and without exacerbations.

METHODS

Children with asthma from the Copenhagen Prospective Studies on Asthma in Childhood₂₀₀₀ (COPSAC₂₀₀₀) birth cohort had lung function and bronchial reactivity assessed repeatedly from 1 month to 13 years. Exacerbations were diagnosed at the COPSAC clinic defined as symptoms requiring hospitalization, oral or high-dose inhaled corticosteroid treatment. Mixed models were applied to analyze lung function trajectories.

RESULTS

Children with asthma with exacerbations (N = 50) had a trajectory of increased, fixed airway obstruction compared with children without exacerbations (N = 47): z-score difference in airway resistance (sRaw_z) (95% confidence interval [CI]): +0.34 (+0.03; +0.66), P = .03, and maximal mid-expiratory flow (MMEF_z): -0.41 (-0.69; -0.13), P = .004, but no differences in forced expiratory volume (FEV_z): -0.14 (-0.41; +0.13), P = .29, or bronchial reactivity to methacholine (PD_z): +0.08 (-0.26; +0.42), P = .65. This did not change comparing lung function trajectories before and after exacerbations: z-score difference (95% CI) sRaw_z: -0.04 (-0.35; 0.27), P = .80; MMEF_z: 0.01 (-0.02; 0.04), P = .55; FEV_z: 0.02 (-0.02; 0.05), P = .42; and PD_z: -0.01 (-0.06; 0.05), P = .88.

CONCLUSION

Children with asthma with exacerbations compared with children with asthma without exacerbations are characterized by increased airway obstruction since infancy through childhood. The airway obstruction is a fixed trajectory without progression due to exacerbations, suggesting that exacerbations are a consequence rather than a cause of diminished airway caliber in childhood.

Severe T2-high asthma in the biologics era: European experts' opinion

The European Respiratory Biologics Forum gathered participants from 21 countries in Madrid, Spain, to discuss the management and treatment of severe asthma in the era of biologics. The current insights on the pathophysiology of severe asthma were discussed, as well as the role of respiratory biologics in clinical practice and strategies for eliminating chronic use of oral corticosteroids. The participants also highlighted the key challenges in identifying patients with severe asthma based on phenotypes, biomarkers and treatable traits, and the existing problems in patient referral to specialist care. The monitoring of treatment was debated and the need for a change towards precision medicine and personalised care was emphasised throughout the meeting. This review provides a summary of the discussions and highlights important concerns identified by the participants regarding the current management of severe asthma.

Asthma and obesity

The problem of modern medicine is to optimize the treatment of patients with comorbidity, whose number has been growing steadily in recent years. The concurrence of asthma and obesity determines the severity of disease, low-level control, and resistance to basic therapy in conjunction with more frequent use of β-agonists for relief of symptoms, and frequent hospitalizations for a disease exacerbation. Currently, there are only a few known pathogenetic components that are responsible for the negative impact of visceral obesity on the course of asthma.

Does airway hyperresponsiveness monitoring lead to improved asthma control?

The current guidelines recommend an approach to asthma management based on asthma control, rather than asthma severity. Although several specific questionnaires have been developed and control criteria have been established based on clinical guidelines, the evaluation of asthma control is still not optimal. In general, these indicators provide adequate assessment of current control, but they are more limited when estimating future risk. There is much evidence demonstrating the persistence of airway inflammation and airway hyperresponsiveness (AHR) in patients with total control. Therefore, the objective of this review was to analyse the possible role of AHR monitoring as an instrument for assessing asthma control. We will evaluate its capacity as an indicator for future risk, both for estimating the possibility of clinical deterioration and loss of lung function or exacerbations. Furthermore, its relationship with inhaled corticosteroid treatment will be analysed, while emphasizing its capacity for predicting response and adjusting dosage, as well as information about the capability of AHR for monitoring treatment. Last of all, we will discuss the main limitations and emerging opportunities of AHR as an assessment instrument for asthma control.

Small airway dysfunction and bronchial asthma control : the state of the art

According to national and international guidelines, achieving and maintaining asthma control is a major goal of disease management. In closely controlled clinical trials, good asthma control can be achieved , with the medical treatments currently available, in the majority of patients , but large population-based studies suggest that a significant proportion of patients in real-life setting experience suboptimal levels of asthma control and report lifestyle limitations with a considerable burden on quality of life. Poor treatment adherence and persistence, failure to use inhalers correctly, heterogeneity of asthma phenotypes and associated co-morbidities are the main contributing factors to poor disease control. Now, it is widely accepted that peripheral airway dysfunction , already present in patients with mild asthma, is a key contributor of worse control. The aim of this paper is to investigate the association between small-airways dysfunction and asthma symptoms/control. We therefore performed a PubMed search using keywords : small airways; asthma (limits applied: Humans, English language) and selected papers with a study population of asthmatic patients, reporting measurement of small-airways parameters and clinical symptoms/control.

What long-term changes in lung function can tell us about asthma control

Asthma severity is typically classified according to lung function, but asthma control in relation to lung function is often harder to define. In this paper, we will review how lung function measured at rest, as well as over time, relates to asthma control. We will explore not only conventional lung function as measured by spirometry, such as peak expiratory flow and forced expiratory volume in 1 s, but also more sophisticated measurements of peripheral airway function related to respiratory system impedance and ventilation heterogeneity. In particular, we will review the emerging area of assessing the fluctuation of lung function over time and how it may correlate to both past and future asthma control.

Development of a tool to recognize small airways dysfunction in asthma (SADT)

Background

Small airways dysfunction (SAD) contributes to the clinical expression of asthma. The identification of patients who suffer from SAD is important from a clinical perspective, as targeted therapy may improve patients’ well-being and treatment efficacy.

Aims

We aimed to realize the first step in the development of a simple small airways dysfunction tool (SADT) that may help to identify asthma patients having SAD.

Methods

Asthma patients with and without SAD were interviewed. Patients were selected to participate in this study based on FEF_50% and R5-R20 values from spirometry and impulse oscillometry respectively.

Results

Ten in depth interviews and two focus groups revealed that patients with and without SAD perceived differences in symptoms and signs, habits and health related issues. For example, patients with SAD reported to wheeze easily, were unable to breathe in deeply, mentioned more symptoms related to bronchial hyperresponsiveness, experienced more pronounced exercise-induced symptoms and more frequently had allergic respiratory symptoms after exposure to cats and birds. Based on these differences, 63 items were retained to be further explored for the SADT.

Conclusions

The first step of the development of the SADT tool shows that there are relevant differences in signs and respiratory symptoms between asthma patients with and without SAD. The next step is to test and validate all items in order to retain the most relevant items to create a short and simple tool, which should be useful to identify asthma patients with SAD in clinical practice.

Electronic supplementary material

The online version of this article (doi:10.1186/s12955-014-0155-7) contains supplementary material, which is available to authorized users.

Budesonide/formoterol maintenance and reliever therapy in asthma control: acute, dose-related effects and real-life effectiveness

BACKGROUND AND OBJECTIVE

The efficacy of budesonide/formoterol maintenance and reliever therapy (BFMRT) in asthma control is well documented in large randomized controlled trials. However, the acute reliever effects and real-life effectiveness are seldom reported.

METHODS

This multicenter trial enrolled steroid-naïve, symptomatic asthmatics with baseline exhaled nitric oxide (eNO) of ≥ 40 ppb. There were 120 eligible patients who were randomized and received a dose of inhaled budesonide/formoterol 320/9 μg (lower dose budesonide/formoterol), 640/18 μg (higher dose budesonide/formoterol (HDBF)), or terbutaline (TERB) 1 mg. Inflammatory cells and mediators in induced sputum, eNO and lung function were measured at baseline and 6 h (acute phase). Subsequently, all patients used BFMRT as real-life practice for 24 weeks (maintenance phase).

RESULTS

In the acute phase, the degree of post-treatment reduction in total eosinophil counts, interleukin-8 and matrix metalloproteinase-9 in induced sputum were significantly greater in group HDBF (vs TERB, P < 0.05). The increase in forced expiratory volume in first second (FEV1 ) in group HDBF was significantly higher (vs LDBF and TERB, P < 0.05) 3 h after dosing. In the maintenance phase, significant improvement of asthma control (presented by eNO, FEV1 and a five-item asthma control questionnaire) in real-life settings was observed at 4 weeks and sustained to the end of study. The rate of patients who followed scheduled visits declined over time (87% at week 4 and 42% at week 24).

CONCLUSIONS

Budesonide/formoterol as reliever exerts acute, dose-related anti-inflammatory effects and FEV1 improvement in symptomatic asthmatics. BFMRT is effective in asthma control. However, the decrease in long-term follow-up rate remains an issue to overcome in real-life settings.

Predictors of asthma control and lung function responsiveness to step 3 therapy in children with uncontrolled asthma

BACKGROUND

Predictors of improvement in asthma control and lung function to step 3 therapy in children with persistent asthma have not been identified despite reported heterogeneity in responsiveness.

OBJECTIVE

We sought to evaluate potential predictors of asthma control and lung function responsiveness to step 3 therapy.

METHODS

A post hoc analysis from the Best Add-On Giving Effective Response (BADGER) study tested the association between baseline biological, asthma control, pulmonary function, and demographic markers and responsiveness to step-up to a higher dose of inhaled corticosteroid (ICS step-up therapy) or addition of leukotriene receptor antagonist (LTRA step-up therapy) or long-acting β₂-agonist (LABA step-up therapy).

RESULTS

In multivariate analyses higher impulse oscillometry reactance area was associated (P = .048) with a differential FEV₁ response favoring LABA over ICS step-up therapy, whereas higher urinary leukotriene E₄ levels were marginally (P = .053) related to a differential FEV₁ response favoring LTRA over LABA step-up therapy. Predictors of differential responses comparing ICS with LTRA step-up therapy were not apparent, probably because of suppression of allergic markers with low-dose ICS treatment. Minimal overlap was seen across FEV₁ and asthma control day predictors, suggesting distinct mechanisms related to lung function and asthma control day responses.

CONCLUSION

Levels of impulse oscillometry reactance area indicating peripheral airway obstruction and urinary leukotriene E₄ levels indicating cysteinyl leukotriene inflammation can differentiate LABA step-up responses from responses to LTRA or ICS step-up therapy. Further studies with physiologic, genetic, and biological markers related to these phenotypes will be needed to predict individual responses to LABA step-up therapy.

Measurements of fractional exhaled nitric oxide in pediatric asthma

Exhaled nitric oxide (NO) has been extensively investigated as a noninvasive marker of airway inflammation in asthma. The increased NO expression induced by inflammatory mediators in airways can be monitored easily in exhaled air from asthmatic children. Based on the relationship between the increased NO expression and eosinophilic airway inflammation, fractional exhaled nitric oxide (FeNO) measurements become an important adjunct for the evaluation of asthma. In addition, the availability of portable devices makes it possible to measure FeNO more easily and frequently in the routine pediatric practice. Despite various confounding factors affecting its levels, FeNO can be applicable in diagnosing asthma, monitoring treatment response, evaluating asthma control, and predicting asthma exacerbations. Thus, although pulmonary function tests are the standard tools for objective measurements of asthmatic control, FeNO can broaden the way of asthma monitoring and supplement standard clinical asthma care guidelines.

Small airway impairment in moderate to severe asthmatics without significant proximal airway obstruction

Asthma is a disease characterized by inflammation which affects both proximal and distal airways. We evaluated the prevalence of small airway obstruction (SAO) in a group of clinically stable asthmatics with both normal forced expiratory volume in the first second (FEV1) and normal FEV1/forced vital capacity (FVC) and treated with an association of inhaled corticosteroids (ICSs) and long acting β2-agonists (LABAs). Clinical evaluation included the measurement of dyspnea, asthma control test and drug compliance. The prevalence of SAO was estimated by spirometry and plethysmography and defined by the presence of one or more of the following criteria: functional residual capacity (FRC) > 120% predicted (pred), residual volume (RV) > pred + 1.64 residual standard deviation (RSD), RV/total lung capacity (TLC) > pred + 1.64 RSD, forced expiratory flow (FEF)25-75% < pred - 1.64 RSD, FEF50% < pred - 1.64 RSD, slow vital capacity (SVC) - FVC > 10%. Among the 441 patients who were included, 222 had normal FEV1 and FEV1/FVC. At least one criteria of SAO was found in 115 (52%) mainly lung hyperinflation (39% based on high FRC, RV or RV/TLC) and more rarely distal airflow limitation (15% based on FEF25-75% or FEF50%) or expiratory trapping (10% based on increased SVC - FVC). In the patients with only SAO (no PAO), there was no relationship between SAO, asthma history and the scores of dyspnea, asthma control or drug compliance. These results suggest that in asthmatics with normal FEV1 and FEV1/FVC, treated with ICSs and LABAs, SAO is found in more than half of the patients indicating that the routinely used lung function tests can underestimate dysfunctions occurring in the small airways.

Leukotriene receptor antagonists for small-airway abnormalities in asthmatics: a systematic review and meta-analysis

BACKGROUND

Airway inflammation that occurs in asthma is mainly distributed in the small airways. Leukotriene receptor antagonists (LTRAs) are systemically active drugs that may act on the small airways.

OBJECTIVES

The aim of our study was to assess the efficacy of LTRAs for small-airway abnormalities in asthmatics.

METHODS

We searched the databases of Cochrane Central, MEDLINE, and EMBASE from the time of the establishment of the databases to December 2012. The data were extracted using a pooled mean difference (MD) or standardized mean difference (SMD) with a 95% confidence interval (CI).

RESULTS

Eight studies were included. The outcomes were the conventional parameters for the detection of small-airway abnormalities. Eight studies were included. The outcomes were the conventional parameters for the detection of small-airway abnormalities. LTRAs compared to placebo improved small-airway abnormalities, as indicated by a number of radiological and physiological parameters, such as lung attenuation (MD, 61.00; 95% CI, 26.32 to 95.68) and residual volume (SMD, -0.85; 95% CI, -1.29 to -0.42). Conventional inhaled corticosteroids (ICSs) compared to LTRAs improved small-airway abnormalities, as indicated by the reactance area (p = 0.028). Compared with conventional treatment alone, a combination of LTRAs and conventional treatment improved small-airway abnormalities, as indicated by a number of radiological and physiological parameters, such as airway wall thickness (p < 0.05), alveolar nitric oxide concentration (p = 0.04), a decrease in resistance from 5 to 20 hertz (p = 0.032), reactance area (p = 0.014), eosinophil cationic protein levels (p = 0.045) and number of eosinophils (p = 0.035) in the late-phase induced sputum. However, there was no significant improvement in forced expiratory flow between 25% and 75% of forced vital capacity in any of the comparisons.

CONCLUSIONS

LTRAs may improve most of the conventional parameters for the detection of small-airway abnormalities in asthmatics. However, there is no evidence of the superiority of LTRAs over ICSs in improving functional parameters related to the small airways.

Real life clinical study design supporting the effectiveness of extra-fine inhaled beclomethasone/formoterol at the level of small airways of asthmatics

BACKGROUND

In an attempt to establish how treatment with inhaled extra-fine beclomethasone/formoterol (I-EF-BDP/F) formulation differs from other combinations of inhaled corticosteroid (ICS) and long acting beta-agonist (LABA), we studied lung function and markers of airway inflammation upon switching to the extra-fine formulation and after 8 weeks of treatment with it.

METHODS

We carried out a real-life clinical observation of undercontrolled asthmatic patients switched over from dry powder inhalers of fluticasone/salmeterol and budesonide/formoterol to I-EF-BDP/F (Foster(®), Chiesi Farmaceutici S.p.A., Italy). The effects of 8-weeks of treatment were documented by means of visual analog scale (VAS), quality of life by Asthma Quality of Life Questionnaire (AQLQ), spirometry and markers of airway or systemic inflammation: exhaled breath temperature (EBT), blood eosinophils (Eos), and high sensitivity C-reactive protein (CRP). Before/after treatment differences between forced vital capacity percent of predicted (%FVC), a simple indicator of small airways involvement, were calculated and subjects were ranked accordingly to reflect the magnitude of the therapeutic response. Subjects above the 75th percentile (n = 15), "top responders", were then compared with those below the 25th percentile (n = 15) "poor responders".

RESULTS

On average, the 59 patients completing the study (mean age ± SD 51 ± 12 years, 38 women) had significant improvement in VAS and QLQ scores at the end of the treatment period (49.1 ± 2.4 vs. 73.1 ± 2.05 and 146.1 ± 2.7 vs. 176.7.1 ± 3.4 respectively, P < 0.001), but not in the inflammatory indicators (EBT, CRP and Eos). However, when comparing the "top responders" with the "poor responders", significant improvement in these inflammatory indicators was observed: EBT significantly decreased from 34.04/mean/± 0.30/s.e.m./[°C] to 33.57 ± 0.33, P = 0.003, Eos in blood fell from 381.7 ± 91.2 [cells/μL] to 244.2 ± 43.2, P = 0.02. Before/after treatment differences in hsCRP decreased significantly in the top responders compared with the poor responders (Mann-Whitney test, P = 0.04).

CONCLUSION

Asthmatic subjects who had the most improvement in FVC after transition to I-EF-BDP/F from other combined ICS/LABA preparations also demonstrated a significant decrease in some indicators of airway/systemic inflammation. These results support the notion that I-EF-BDP/F exerts an effect also at the level of the small airways through a reduction of the level of air trapping. Patients in whom inflammation of the small airways plays an important clinical role are the ones to derive most benefit from this small airways tailored treatment. However, improved compliance due to the "promise of a new drug" effect should also be considered as contributing to the treatment results.

New insight into the assessment of asthma using xenon ventilation computed tomography

BACKGROUND

Image analyses include computed tomography (CT), magnetic resonance imaging, and xenon ventilation CT, which is new modality to evaluate pulmonary functional imaging.

OBJECTIVE

To examine the usefulness of dual-energy xenon ventilation CT in asthmatic patients.

METHODS

A total of 43 patients 18 years or older who were nonsmokers were included in the study. Xenon CT images in wash-in and wash-out phases were obtained at baseline and after inhalation of methacholine and salbutamol. The degrees of ventilation defects and xenon trappings were evaluated through visual analysis.

RESULTS

Ventilation defects and xenon trapping were significantly increased and decreased after methacholine challenge and salbutamol inhalation, respectively (P < .005). The ventilation abnormalities were not significantly related to the percentage of forced expiratory volume in 1 second (FEV1) or the ratio of FEV1 to forced vital capacity. Xenon trappings after salbutamol inhalation were negatively related to the scores of the asthma control test, wheezing, or night symptoms, with statistical significance (P < .05), whereas, FEV1 showed no significant correlation with symptom scores. Baseline FEV1 was significantly lower and dyspnea and wheezing were more severe in the non-full reversal group than in the full reversal group after salbutamol inhalation in xenon CT (P < .05). The degree of ventilation defects were positively correlated with FEV1 improvement after 3 months of treatment (P = .02).

CONCLUSION

The results of this study suggest that xenon ventilation CT can be used as a new method to assess ventilation abnormalities in asthma, and these ventilation abnormalities can be used as novel parameters that reflect the status of asthma control and symptom severity.

Alveolar nitric oxide and asthma control in mild untreated asthma

BACKGROUND

The role of the peripheral airways in asthma is increasingly being recognized as a potential target for the achievement of optimal control of the disease. We postulated that the inflammatory changes of the small airways are implicated in the lack of asthma control in mild asthma.

OBJECTIVE

To test this hypothesis, we measured the alveolar fraction of exhaled NO (CalvNO) in patients with mild asthma with different levels of control of symptoms.

METHODS

Seventy-eight patients with asthma (35 men, age, 37 ± 15 years; FEV1 percentage of predicted, 100% ± 9%) were studied. Asthma control was assessed by using the Asthma Control Test (ACT). Measurements of exhaled NO at multiple constant flows were performed.

RESULTS

Bronchial NO concentrations were 27.1 ± 20 nL/min, [corrected] and CalvNO levels were 5.7 ± 3.4 ppb. The ACT score was 20 ± 4.2. The level of asthma control was not associated with bronchial NO concentrations (rs = 0.16, P = .15). However, a significant correlation was found between the ACT score and CalvNO (rs = 0.25, P = .03). Moreover, CalvNO was significantly higher in patients with uncontrolled asthma than in patients with controlled/partially controlled asthma (6.7 ± 2.6 ppb vs 4.9 ± 2.6 nL/min, [corrected] respectively, P = .02). In the subgroup of patients with asthma who underwent extrafine inhaled corticosteroid treatment, the magnitude of the inhaled corticosteroid-induced improvement in asthma control positively correlated with baseline CalvNO at 1 month (rs = 0.39, P = .003) and at 3 months (rs = 0.49, P < .0001).

CONCLUSIONS

The alveolar component of exhaled NO is associated with the lack of asthma control in patients with mild, untreated asthma. This observation supports the notion that abnormalities of the peripheral airways are implicated in the mildest forms of asthma.

Do small airway abnormalities characterize asthma phenotypes? In search of proof

The role of small airway abnormalities in asthma pathogenesis has been extensively studied and debated for several decades. However, whether or not small airway abnormalities play a relevant role in specific phenotypes of asthmatic patients and contribute to clinical presentation is largely unknown. In the present review, we evaluated available data on the role of small airways in severe asthma, with a further focus on asthma in smokers and asthma in the elderly. These phenotypes are characterized by a poor response to treatment and they can represent a model of greater small airway impairment. In severe asthmatics, small airway involvement has been shown through evidence of both distal inflammation and of increased air trapping. The few available data on asthmatics who smoke, and elderly asthmatics, similarly suggests that small airway abnormalities contribute to the pathogenesis of the disease. In this perspective, there could be a rationale for specifically assessing small airway impairment in these patients and for clinical studies evaluating whether pharmacological approaches targeting the more peripheral airways result in clinical benefits beyond conventional therapy.

Assessing and accessing the small airways; implications for asthma management

Despite the wealth of experience in the management of asthma, the disease remains inadequately controlled in some patients, who face long-term respiratory impairment and disability. The disease has been characterised as an inflammatory condition affecting first the larger airways and eventually the smaller airways, but there is evidence that peripheral airway involvement defines a particular and more severe phenotype of asthma. For this reason, assessing functional and biological parameters reflective of small airways involvement is important prognostically. No assessment method is universally and directly representative of peripheral airway function, but the traditional spirometric tests, including vital capacity, residual volume and forced vital capacity, are somewhat correlated with this function; useful methods for further assessment include the single-breath nitrogen wash-out test, impulse oscillometry, nitrous oxide and exhaled breath concentrate measurements, as well as computed tomography to reflect air trapping and response to treatment. Formulation advancements have made for easier treatment access to the smaller airways, with the new extrafine formulations resulting in better asthma control compared with non-extrafine formulations.

Fractional exhaled nitric oxide and forced expiratory flow between 25% and 75% of vital capacity in children with controlled asthma

Purpose

Fractional exhaled nitric oxide (FeNO) and forced expiratory flow between 25% and 75% of vital capacity (FEF_25-75) are not included in routine monitoring of asthma control. We observed changes in FeNO level and FEF_25-75 after FeNO-based treatment with inhaled corticosteroid (ICS) in children with controlled asthma (CA).

Methods

We recruited 148 children with asthma (age, 8 to 16 years) who had maintained asthma control and normal forced expiratory volume in the first second (FEV₁) without control medication for ≥3 months. Patients with FeNO levels >25 ppb were allocated to the ICS-treated (FeNO-based management) or untreated group (guideline-based management). Changes in spirometric values and FeNO levels from baseline were evaluated after 6 weeks.

Results

Ninety-three patients had FeNO levels >25 ppb. These patients had lower FEF_25-75% predicted values than those with FeNO levels ≤25 ppb (P<0.01). After 6 weeks, the geometric mean (GM) FeNO level in the ICS-treated group was 45% lower than the baseline value, and the mean percent increase in FEF_25-75 was 18.% which was greater than that in other spirometric values. There was a negative correlation between percent changes in FEF_25-75 and FeNO (r=-0.368, P=0.001). In contrast, the GM FeNO and spirometric values were not significantly different from the baseline values in the untreated group.

Conclusion

The anti-inflammatory treatment simultaneously improved the FeNO levels and FEF_25-75 in CA patients when their FeNO levels were >25 ppb.

Assessing and treating small airways disease in asthma and chronic obstructive pulmonary disease

Asthma and chronic obstructive pulmonary disease (COPD) are chronic inflammatory disorders of the respiratory tract that are characterized by airflow limitation. They are distinct conditions with different causes, structural changes, and immunopathology. The pathophysiology in asthma and COPD involves not only the proximal large airways, but also the distal small airways, and thus the small airways are an important therapeutic target in the treatment of both diseases. The assessment of diseased distal small airways is challenging. Extensive disease can be present in the small airways with little abnormality in conventional pulmonary function tests. Recent advances in imaging technologies have led to better spatial resolution to assess small airways morphology non-invasively. New physiological tests have been developed to detect disease and response to therapy in regional airways. Improving the efficiency of existing aerosolized therapy to direct drug to the appropriate lung regions may improve clinical efficacy. Approaches to target distal lung regions include developing new drug formulations with smaller aerosol particle size or using inhaler devices that emit aerosolized drug at slow inhalation flows. Large studies are needed to determine whether better distal lung deposition leads to improvements in small airways function that are translated into clinically significant patient outcomes.

Monitoring asthma status

PURPOSE

Asthma is a chronic disorder of the airways involving inflammation and airway hyper-reactivity. Clinical diagnosis and monitoring of asthma must incorporate the immunological, biochemical, and histological changes of a chronic disorder, while recognizing acute phenotypic changes in order to optimally tailor therapeutics to each individual.

RECENT FINDINGS

Articles published within the previous 18 months are summarized in this article in order to present an up to date review of the latest findings regarding the monitoring of asthma. The articles encompass a wide array of specialties from basic research and histology to clinical medicine as well as community medicine and nursing.

SUMMARY

Exciting new advancements in the monitoring of asthma continue to unfold. Potentially new diagnostic and monitoring tools are highlighted in this study. Continued investigations may enable a select few methodologies to reach clinical utility in the ongoing monitoring and treatment of patients with asthma.

Targeting small airways in asthma: improvement in clinical benefit?

BACKGROUND AND AIM

Disease control is not achieved in a substantial proportion of patients with asthma. Recent advances in aerosol formulations and delivery devices may offer more effective therapy. This review will focus on the importance and potential clinical benefit of targeting the lung periphery in adult asthma by means of ultra-fine aerosols.

RESULTS

Ultra-fine formulations of inhaled corticosteroids (ICS) have improved lung deposition up to at least 50%, primarily in the peripheral airways. Ultra-fine formulations of ICS provide equivalent asthma control to non-ultra-fine ICS at approximately half the daily dose, with no increased risk of systemic effects. Clinical studies of adults with asthma have shown a greater effect of ultra-fine ICS, compared with non-ultra-fine ICS, on quality of life, small airway patency, and markers of pulmonary and systemic inflammation, but no difference with regard to conventional clinical indices of lung function and asthma control.

CONCLUSIONS

Asthma patients treated with ultra-fine ICS, compared with non-ultra-fine ICS, have at least similar chance of achieving asthma control at a lower daily dose. Further clinical studies are needed to explore whether treatment with ultra-fine formulations of ICS will change the natural history of asthma and prevent airway remodelling in both the large and small airways.

Potential roles of pentosidine in age-related and disease-related impairment of pulmonary functions in patients with asthma

BACKGROUND

Pentosidine is well established as an intermolecular cross-linking type of advanced glycation end products, and it accumulates with aging in various connective tissues.

OBJECTIVE

To determine whether pentosidine contributes to age-related and disease-related impairment of pulmonary functions in patients with asthma.

METHODS

We measured pentosidine levels in induced sputum from young to elderly patients with asthma and assessed the slope of the nitrogen (N(2)) alveolar plateau (delta N(2)), closing volume (CV), and closing capacity (CC) from a nitrogen washout curve in a single breath.

RESULTS

Pentosidine levels in induced sputum were significantly higher in patients with asthma than in normal controls (patients with asthma: median, 20.1, interquartile range, 16.7-26.5 ng/mL; normal controls: median, 3.0, interquartile range, 0.7-7.5 ng/mL; P < .001). The levels were closely correlated with age in both normal controls and patients with asthma. However, the slope of age-related increase in pentosidine levels was markedly steeper in patients with asthma than in normal controls. CV/vital capacity, CC/total lung capacity, and delta N(2) increased with aging in both normal controls and patients with asthma. Moreover, in each range of age (21-40, 41-60, 61-80 years), CV/vital capacity, CC/total lung capacity, and delta N(2) were significantly higher in patients with asthma than in normal controls. In addition, pentosidine levels in patients with asthma were closely correlated with each of these variables.

CONCLUSION

Our results demonstrated the association between sputum levels of pentosidine and age-related small airways function in both normal controls and patients with asthma. Moreover, the age-related increase in pentosidine levels was more pronounced in patients with asthma. These findings will herald new era in the pathophysiology of elderly asthma.

The bronchodilator response of in vivo specific airway compliance in adults with asthma

A new technique has been developed to determine in vivo airway compliance in humans that is specific to airway size and transpulmonary pressure, and can be represented as a three-dimensional surface. As yet, the ability of this technique to detect changes in specific airway compliance with disease status has not been demonstrated. The aim of this study was to assess whether this technique could determine changes in airway compliance which are thought to occur with altered smooth muscle tone in adults with asthma. Airway compliance was measured and displayed as a surface in adults with asthma before and after a reduction in smooth muscle tone by bronchodilator administration. Compliance, with respect to airway size, was calculated at three specific lung volumes; functional residual capacity (FRC), total lung capacity (TLC), and midway between FRC and TLC (MID). After bronchodilator, airway compliance increased at FRC and MID in the smaller airways (<3 mm). Furthermore, airway compliance under both conditions was greater in the smaller airways compared to the larger airways. In conclusion, our method may have future utility in assessing changes in airway compliance in respiratory diseases such as asthma.

Peripheral lung mechanics in asthma: exploring the outer limits

Asthma is a disease characterized by airways hyperresponsiveness (AHR), which is traditionally thought to involve the large, central airways. However, there is increasing evidence of the importance of peripheral airway involvement in asthma as well. Our group has developed particular expertise in measuring peripheral lung mechanics in both humans and mice. This presentation will review data on lung mechanics in subjects with asthma obtained by both classical means and uniquely through the wedged bronchoscope, as well as relevant experiments in mice. Our findings reveal that the lung periphery is hyperresponsive to stimuli in asthmatic subjects, with evidence of airway closure. We also show that the overall impedance of the lung is determined by a combination of peripheral airway narrowing and central airway shunting that occurs in both normal and asthmatic subjects. Experiments in mice have revealed the importance of airway closure in contributing to the phenomenon of AHR. Based on the effects of fibrin on lung mechanics, fibrin may contribute to airway closure via inactivation of surfactant. Another mechanism contributing to AHR is the heterogeneity of airway narrowing. We have explored this in humans by combining the forced oscillation technique with computerized tomography imaging of the lung, and demonstrated that heterogeneity is common to both normal and asthmatic subjects. Further experiments are ongoing and planned in both mice and humans to elucidate the role of fibrin, surfactant and heterogeneous airway narrowing and closure in contributing to AHR in asthma.