Comparison of mannitol and methacholine to predict exercise-induced bronchoconstriction and a clinical diagnosis of asthma

Diagnostic Testing in Exercise-Induced Bronchoconstriction

Exercise-induced bronchoconstriction (EIB), a reversible airflow obstruction triggered by exercise, should be considered in patients presenting with symptoms of dyspnea, cough, wheeze, and chest tightness during or after vigorous exercise. Over the past several years, various diagnostic modalities have been developed and evaluated for the diagnosis of EIB, giving the clinician multiple options for diagnostic testing. Here, the authors present a review of the various testing options that can be used in the diagnosis of EIB, with a discussion of testing protocols and considerations for choosing the appropriate diagnostic test.

Biomarkers in asthma, potential for therapeutic intervention

Asthma is a heterogeneous disease characterized by multiple phenotypes with varying risk factors and therapeutic responses. This Commentary describes research on biomarkers for T2-"high" and T2-"low" inflammation, a hallmark of the disease. Patients with asthma who exhibit an increase in airway T2 inflammation are classified as having T2-high asthma. In this endotype, Type 2 cytokines interleukins (IL)-4, IL-5, and IL-13, plus other inflammatory mediators, lead to increased eosinophilic inflammation and elevated fractional exhaled nitric oxide (FeNO). In contrast, T2-low asthma has no clear definition. Biomarkers are considered valuable tools as they can help identify various phenotypes and endotypes, as well as treatment response to standard treatment or potential therapeutic targets, particularly for biologics. As our knowledge of phenotypes and endotypes expands, biologics are increasingly integrated into treatment strategies for severe asthma. These treatments block specific inflammatory pathways or single mediators. While single or composite biomarkers may help to identify subsets of patients who might benefit from these treatments, only a few inflammatory biomarkers have been validated for clinical application. One example is sputum eosinophilia, a particularly useful biomarker, as it may suggest corticosteroid responsiveness or reflect non-compliance to inhaled corticosteroids. As knowledge develops, a meaningful goal would be to provide individualized care to patients with asthma.

Inhaled alkaline hypertonic divalent salts reduce refractory chronic cough frequency

Background

Treatment of chronic cough remains a challenge. We hypothesised that inhaled alkaline hypertonic divalent salts (alkaline HDS) might provide relief for refractory chronic cough by laryngeal and tracheal hydration.

Methods

We conducted an exploratory, single-blinded, nasal saline-controlled study in 12 refractory chronic cough patients to examine cough suppression efficacy of an alkaline HDS composition (SC001) at pH 8 or pH 9 administered by nasal inhalation. As control, we used nasal saline with the same hand-held pump spray aerosol device. Each subject was monitored continuously using a digital cough monitor watch for 1 week of baseline, 1 week of control treatment and 1 week of active treatment.

Results

Baseline daily cough rates ranged from 4 to 34 coughs·h-1 with mean visual analogue score 65±17 pre- and post-baseline testing. Control-adjusted efficacy of cough rate reduction ranged from 15% (p=0.015) (from Day 1) to 23% (p=0.002) (from Day 3). Control-adjusted efficacy was highest with SC001 pH 9 (n=5), ranging from 25% (p=0.03) (from Day 1) to 35% (p=0.02) (from Day 3), and lowest for SC001 pH 8 (n=7), ranging from 9% (p=0.08) (from Day 1) to 16% (p=0.02) (from Day 3). Hourly cough counts and visual analogue score correlated for baseline (r=0.254, p=0.02) and control (r=0.299, p=0.007) monitoring weeks. Treatment improved this correlation (r=0.434, p=0.00006). No adverse events were reported.

Conclusions

Alkaline (pH 9) HDS aerosol is a promising treatment for refractory chronic cough and should be further evaluated.

Hypertonic Aerosols Hydrate Airways Longer and Reduce Acidification Risk with Nonpermeating Cation and Permeating Anion Salts

Background: Hyperosmolar aerosols appear to promote or suppress upper airway dysfunction caused by dehydration in a composition-dependent manner. We sought to explore this composition dependence experimentally, in an interventional human clinical study, and theoretically, by numerical analysis of upper airway ion and water transport. Methods: In a double-blinded, placebo-controlled clinical study, phonation threshold pressure (PTP) was measured prenasal and postnasal inhalation of hypertonic aerosols of NaCl, KCl, CaCl2, and MgCl2 in seven human subjects. Numerical analysis of water and solute exchanges in the upper airways following deposition of these same aerosols was performed using a mathematical model previously described in the literature. Results: PTP decreased by 9%-22% relative to baseline (p < 0.05) for all salts within the first 30 minutes postadministration, indicating effective laryngeal hydration. Only MgCl2 reduced PTP beyond 90 minutes (21% below baseline at 2 hours postadministration). By numerical analysis, we determined that, while airway water volume up to 15 minutes postdeposition is dictated by osmolarity, after 30 minutes, divalent cation salts, such as MgCl2, better retain airway surface liquid (ASL) volume by slow paracellular clearance of the divalent cation. Fall of CFTR chloride flux with rise in ASL height, a promoter of airway acidification, appears to be a signature of permeating cation (NaCl) and nonpermeating anion (mannitol) aerosol deposition. For hypertonic aerosols that lack permeating cation and include permeating anion (CaCl2 and MgCl2), this acid-trigger signature does not exist. Conclusions: Nonpermeating cation and permeating anion hypertonic aerosols appear to hydrate upper airways longer and, rather than provoke, may reduce laryngeal dysfunction such as cough and bronchoconstriction.

Mucus Transpiration as the Basis for Chronic Cough and Cough Hypersensitivity

Chronic cough is characterized by a state of cough hypersensitivity. We analyze the process of transpiration, by which water appears to evaporate from laryngeal and tracheal mucus as from the surface of a leaf, as a potential cause of cough hypersensitivity. In this process, osmotic pressure differences form across mucus, pulling water toward the air, and preventing mucus dehydration. Recent research suggests that these osmotic differences grow on encounter with dry and dirty air, amplifying pressure on upper airway epithelia and initiating a cascade of biophysical events that potentially elevate levels of ATP, promote inflammation and acidity, threaten water condensation, and diminish mucus water permeability. Among consequences of this inflammatory cascade is tendency to cough. Studies of isotonic, hypotonic, and hypertonic aerosols targeted to the upper airways give insights to the nature of mucus transpiration and its relationship to a water layer that forms by condensation in the upper airways on exhalation. They also suggest that, while hypertonic NaCl and mannitol may provoke cough and bronchoconstriction, hypertonic salts with permeating anions and non-permeating cations may relieve these same upper respiratory dysfunctions. Understanding of mucus transpiration and its role in cough hypersensitivity can lead to new treatment modalities for chronic cough and other airway dysfunctions promoted by the breathing of dry and dirty air.

Mannitol Challenge to Assess Therapy Response in Asthmatic Children: An Interventional Cohort Study

Bronchial provocation tests, such as the mannitol challenge, can be performed to identify and quantify the severity of bronchial hyperresponsiveness in asthmatic patients. Studies of the mannitol challenge as a monitoring tool in asthmatic children are limited. Our primary aim was to compare the bronchial hyperresponsiveness to mannitol in treatment-naive asthmatic children between baseline and three months after receiving the indicated asthma prophylaxis. Twenty-three asthmatic patients aged 4-16 years were analyzed in this prospective cohort study. All subjects underwent the mannitol challenge at baseline and after three months of treatment with budesonide ± formoterol. The difference in the provocative dose of mannitol to induce a 15% drop in FEV₁ (PD₁₅) between baseline and follow-up, as well as its association with the presence of exercise-induced or nocturnal asthma symptoms, were evaluated. The PD₁₅ value increased significantly post-treatment (228.5 mg [4.50-458.15]; p = 0.04). Independently of the evaluation time point, the PD₁₅ values were significantly lower in the presence of nocturnal asthma symptoms (490 mg [122-635] vs. 635 mg [635-635]; p = 0.03), whereas there was no association between the PD₁₅ value and the presence of exercise-induced asthma (p = 0.73). These results suggest that bronchial hyperresponsiveness to mannitol may be a potential monitoring tool in the pediatric asthmatic population, reflecting therapy response in children receiving prophylactic treatment.

Evaluation of the Diagnostic Accuracy of Non-Specific Bronchial Provocation Tests in the Diagnosis of Asthma: A Randomized Cross-Over Study

INTRODUCTION

The role of bronchial provocation tests in the diagnosis of asthma remains to be fully explored. We aimed to evaluate methacholine and mannitol challenge testing, and explore the factors associated with this broncoprovocation response.

METHODS

Observational, cross-over, randomized trial evaluating adult cases with suspected asthma, naïve to treatment, with normal pre-bronchodilator spirometry, and negative bronchodilator test. Patients were randomized to start with methacholine or mannitol. The diagnosis of bronchial asthma was confirmed if there was a good functional and clinical response to one month with twice daily formoterol/budesonide 9/320. The diagnostic profile and the concordance were calculated. Factors associated with a positive provocation test were entered into a multivariate binomial logistic regression analysis, and classification trees were created for both tests.

RESULTS

The study included 108 cases (50.0% diagnosed with asthma and 51.9% cases starting with methacholine). The percentage of cases positive to methacholine and mannitol were 30.6% and 25.0% respectively. Kappa values were 0.40 (p<0.001). The diagnostic profile for methacholine was sensitivity 59.3% and specificity 98.1%, while for mannitol it was sensitivity 48.1% and specificity 98.1%. Variables associated with a positive methacholine response included sex, atopy, FEV₁, FEV₁/FVC and FENO, whereas they were FEV₁/FVC and FENO for mannitol. A FENO value>26ppb, FEV1≤103.3% and female sex correctly classified 78.7% of methacholine responders. FENO value>26ppb was enough to correctly classify 81.5% of mannitol responders.

CONCLUSIONS

Our study confirms the diagnostic profile of methacholine and mannitol challenge tests and describes the variable associated to their positivity with new proposed cutoff values.

Reduced Diffusing Capacity in Humidifier Disinfectant-Associated Asthma Versus Typical Asthma: A Retrospective Case Control Study

BACKGROUND

Humidifier disinfectant-related lung injury (HDLI) is a severe form of toxic inhalational pulmonary parenchymal damage found in residents of South Korea previously exposed to specific guanidine-based compounds present in humidifier disinfectants (HD). HD-associated asthma (HDA), which is similar to irritant-induced asthma, has been recognized in victims with asthma-like symptoms and is probably caused by airway injury. In this study, diffusing capacity of the lung for carbon monoxide (DL_CO) in individuals with HDA was compared to that in individuals with pre-existing asthma without HD exposure.

METHODS

We retrospectively compared data, including DL_CO values, of 70 patients with HDA with that of 79 patients having pre-existing asthma without any known exposure to HD (controls). Multiple linear regression analysis and logistic regression analysis were performed to confirm the association between HD exposure and DL_CO after controlling for confounding factors. The correlation between DL_CO and several indicators related to HD exposure was evaluated in patients with HDA.

RESULT

The mean DL_CO was significantly lower in the HDA group than in the control group (81.9% vs. 88.6%; P = 0.021). The mean DL_CO of asthma patients with definite HD exposure was significantly lower than that of asthma patients with lesser exposure (P for trend = 0.002). In multivariable regression models, DL_CO in the HDA group decreased by 5.8%, and patients with HDA were 2.1-fold more likely to have a lower DL_CO than the controls. Pathway analysis showed that exposure to HD directly affected DL_CO values and indirectly affected its measurement through a decrease in the forced vital capacity (FVC). Correlation analysis indicated a significant inverse correlation between DL_CO% and cumulative HD exposure time.

CONCLUSION

DL_CO was lower in patients with HDA than in asthma patients without HD exposure, and decreased FVC partially mediated this effect. Therefore, monitoring the DL_CO may be useful for early diagnosis of HDA in patients with asthma symptoms and history of HD exposure.

Exercise-induced bronchoconstriction in university field hockey athletes: Prevalence, sex differences, and associations with dyspnea symptoms

Introduction

Exercise-induced bronchoconstriction (EIB) is a prevalent condition in athletes. EIB screening studies identify many athletes with undiagnosed EIB. Moreover, there is a poor relationship between EIB and dyspnea symptoms recalled from memory.

Purpose

This study investigated: (I) the prevalence of EIB in British university field hockey athletes; (II) the effect of sex and diagnostic criteria on EIB prevalence; and (III) the association between EIB and contemporaneous dyspnea symptoms.

Methods

52 field hockey athletes (age: 20 ± 2 years; height: 173 ± 9 cm; body mass: 72 ± 10 kg; male = 31; female = 22) completed a eucapnic voluntary hyperpnea (EVH) test with multi-dimensional dyspnea scores measured 3–10 mins post-EVH. A test was deemed positive (EIB⁺) if a fall index (FI) ≥10% in FEV₁ occurred at two consecutive time points post-test (FI_ATS). Two further criteria were used to assess the effect of diagnostic criteria on prevalence: FI_≥10%, determined by a pre-to-post-EVH fall in FEV₁ of ≥10% at any single time-point; and FI_{≥10%−NORM} calculated as FI_≥10% but with the fall in FEV₁ normalized to the mean ventilation achieved during EVH.

Results

EIB prevalence was 19% and greater in males (30%) than females (5%). In EIB⁺ athletes, 66% did not have a previous diagnosis of EIB or asthma and were untreated. Prevalence was significantly influenced by diagnostic criteria (P = 0.002) ranging from 19% (FI_ATS) to 38% (FI_{≥10%−NORM}). Dyspnea symptoms were higher in EIB⁺ athletes (P ≤ 0.031), produced significant area under the curve for receive operator characteristics (AUC ≥ 0.778, P ≤ 0.011) and had high negative prediction values (≥96%).

Conclusion

Overall, 19% of university field hockey athletes had EIB, and most were previously undiagnosed and untreated. EVH test diagnostic criteria significantly influences prevalence rates, thus future studies should adopt the ATS criteria (FI_ATS). Contemporaneous dyspnea symptoms were associated with bronchoconstriction and had high negative prediction values. Therefore, contemporaneous dyspnea scores may provide a useful tool in excluding a diagnosis of EIB.

Practical approaches to the diagnosis of asthma in school-age children

INTRODUCTION

Asthma is a chronic airways disease characterized by episodes of wheeze, chest tightness, and evidence of reversible airflow obstruction. Symptoms are frequently triggered by exercise, exposure to aeroallergens, and respiratory viruses. It is the commonest non-communicable respiratory condition in children, affecting over 5.5 million children in the European Union alone. Both over- and under- diagnosis of asthma are common for several reasons.

AREAS COVERED

The diagnosis is frequently based on parental or patient reported non-specific symptoms alone. All major asthma guidelines now recommend the use of objective tests, including spirometry, bronchodilator reversibility testing, fraction of exhaled nitric oxide measurements and challenge testing to confirm the diagnosis. Recently, the European Respiratory Society published the first evidence-based international guidelines for diagnosing asthma in school-age children using objective measures. Major barriers to implementation in primary care and less well-resourced healthcare settings are access to relevant objective tests for children and quality assurance to obtain reliable results.

EXPERT OPINION

We highlight the importance of diagnosing asthma in school-age children using objective tests and outline a practical approach for the use of widely available tests. We also review challenges and barriers to implementation of objective testing in children managed outside specialist settings.

European Respiratory Society guidelines for the diagnosis of asthma in adults

Although asthma is very common, affecting 5-10% of the population, the diagnosis of asthma in adults remains a challenge in the real world, which results in both over- and under-diagnosis. A taskforce was set up by the European Respiratory Society to systematically review the literature on the diagnostic accuracy of tests used to diagnose asthma in adult patients and provide recommendations for clinical practice.The taskforce defined eight Population, Index, Comparator and Outcome questions that were assessed using the Grading of Recommendations, Assessment, Development and Evaluation approach. The taskforce utilised the outcomes to develop an evidence-based diagnostic algorithm, with recommendations for a pragmatic guideline for everyday practice that was directed by real-life patient experiences.The taskforce supports the initial use of spirometry followed by bronchodilator reversibility testing (if airway obstruction is present). If initial spirometry fails to show obstruction, further tests should be performed in the following order: exhaled nitric oxide fraction, peak expiratory flow variability, or, in secondary care, bronchial challenge. We present the thresholds for each test that are compatible with a diagnosis of asthma in the presence of current symptoms.The taskforce reinforces spirometry as a priority and recognises the value of measuring blood eosinophils and serum immunoglobulin E to phenotype the patient. Measuring gas trapping by body plethysmography in patients with preserved forced expiratory volume in 1 s/forced vital capacity ratio deserves further attention. The taskforce draws attention to the difficulty of making a correct diagnosis in patients already receiving inhaled corticosteroids; the comorbidities that may obscure diagnosis; the importance of phenotyping; and the necessity of considering the patient experience in the diagnostic process.

Bronchial smooth muscle cell in asthma: where does it fit?

Asthma is a frequent respiratory condition whose pathophysiology relies on altered interactions between bronchial epithelium, smooth muscle cells (SMC) and immune responses. Those leads to classical hallmarks of asthma: airway hyper-responsiveness, bronchial remodelling and chronic inflammation. Airway smooth muscle biology and pathophysiological implication in asthma are now better understood. Precise deciphering of intracellular signalling pathways regulating smooth muscle contraction highlighted the critical roles played by small GTPases of Rho superfamily. Beyond contractile considerations, active involvement of airway smooth muscle in bronchial remodelling mechanisms is now established. Not only cytokines and growth factors, such as fibroblats growth factor or transforming growth factor-β, but also extracellular matrix composition have been demonstrated as potent phenotype modifiers for airway SMC. Although basic science knowledge has grown significantly, little of it has translated into improvement in asthma clinical practice. Evaluation of airway smooth muscle function is still limited to its contractile activity. Moreover, it relies on tools, such as spirometry, that give only an overall assessment and not a specific one. Interesting technics such as forced oscillometry or specific imagery (CT and MRI) give new perspectives to evaluate other aspects of airway muscle such as bronchial remodelling. Finally, except for the refinement of conventional bronchodilators, no new drug therapy directly targeting airway smooth muscle proved its efficacy. Bronchial thermoplasty is an innovative and efficient therapeutic strategy but is only restricted to a small proportion of severe asthmatic patients. New diagnostic and therapeutic strategies specifically oriented toward airway smooth muscle are needed to improve global asthma care.

Daily Inhaled Corticosteroids Treatment Abolishes Airway Hyperresponsiveness to Mannitol in Defence and Police Recruits

Background

Airway hyperresponsiveness (AHR) is a key pathophysiological feature of asthma and causes exercise-induced bronchoconstriction (EIB). Indirect bronchial provocation tests (BPTs) (e.g., exercise, mannitol) aid to diagnose asthma and identify EIB. Daily inhaled corticosteroids (ICS) can abolish AHR caused by indirect stimuli. Where strenuous physical exertion is integral to an occupation, identification of those at risk of EIB is important and documentation of inhibition of AHR with ICS is required before recruitment.

Methods/Objectives

A retrospective analysis was performed on 155 potential recruits with AHR to mannitol who underwent follow-up assessment after daily ICS treatment to determine the proportion that can abolish AHR using ICS and to determine any predictors of the persistence of AHR.

Results

Airway hyperresponsiveness was abolished in the majority (84%, n = 130) over the treatment period (mean ± SD 143 ± 72days), and it was defined as the provoking dose of mannitol to cause a 15% fall in FEV1 (cumulative inhaled dose of mannitol to cause 15% fall in FEV₁, PD₁₅) improved from (GeoMean) 183 to 521 mg. Compared with recruits in whom AHR was abolished with daily ICS (i.e., no 15% fall in FEV₁ to the maximum cumulative dose of mannitol of 635 mg), in those where AHR remained (16%, n = 25), baseline AHR was more severe (PD15: 85 mg vs. 213 mg, P < 0.001), baseline FEV₁% was lower (89 vs. 96%; 95%CI:2–12, P=0.004), and they had a longer follow-up duration (180 vs. 136 days; 13–74, P = 0.006). Baseline FEV₁% (adjusted odds ratio 0.85; 95%CI:0.77–0.93), FEV₁/FVC (0.78; 0.67–0.90), FEF_25−75% (1.15; 1.06–1.25), and airway reactivity to mannitol (%Fall/cumulative dose of mannitol multiplied by 100) (1.07; 1.03–1.11) predicted AHR remaining after daily ICS.

Conclusion

Airway hyperresponsiveness to mannitol can be abolished after 20 weeks of daily treatment with ICS. Inhibition of AHR is likely due to attenuation of airway inflammation in response to ICS treatment. Increased airway reactivity and lower spirometry variables predicted the persistence of AHR. Thus, those with a slower response to daily ICS on AHR can potentially be identified at the commencement of monitoring ICS using inhaled mannitol.

An Algorithm for Strategic Continuation or Restriction of Asthma Medication Prior to Exercise Challenge Testing in Childhood Exercise Induced Bronchoconstriction

Exercise induced bronchial (EIB) constriction is a common and highly specific feature of pediatric asthma and should be diagnosed with an exercise challenge test (ECT). The impact of EIB in asthmatic children's daily lives is immense, considering the effects on both physical and psychosocial development. Monitoring childhood asthma by ECT's can provide insight into daily life disease burden and the control of asthma. Current guidelines for bronchoprovocation tests restrict both the use of reliever and maintenance asthma medication before an exercise challenge to prevent false-negative testing, as both have significant acute bronchoprotective properties. However, restricting maintenance medication before an ECT may be less appropiate to evaluate EIB symptoms in daily life when a diagnosis of asthma is well established. Rigorous of maintenance medication before an ECT according to guidelines may lead to overestimation of the real, daily life asthma burden and lead to an inappropiate step-up in therapy. The protection against EIB offered by the combined acute and chronic bronchoprotective effects of maintenance medication can be properly assessed whilst maintaining them. This may aid in achieving the goal of unrestricted participation of children in daily play and sports activities with their peers without escalation of therapy. When considering a step down in medication, a strategic wash-out of maintenance medication before an ECT aids in providing objective support of potential discontinuation of maintenance medication.

Current Status of Studies Investigating Asthma-Chronic Obstructive Pulmonary Disease Overlap in Korea: A Review

There is a considerable number of individuals who exhibit features of both asthma and chronic obstructive pulmonary disease (COPD), defined as asthma-COPD overlap (ACO). Many studies have reported that these patients have a greater burden of symptoms, including cough and dyspnea, and experience more exacerbations and hospitalizations than those with non-ACO COPD or asthma. Although diagnostic criteria for ACO have not yet been clearly established, their clinical significance remains to be determined. As interest in ACO grows, related studies have been conducted in South Korea as well. The present review summarizes ACO-related studies in South Korea to better understand Korean ACO patients and guide further research. Several cohort studies of asthma and COPD and population-based studies for ACO were reviewed and the key results from demographics, clinical features, lung function, biomarkers, treatment, and prognosis were summarized.

Incremental shuttle walk test: is it able to detect exercise-induced bronchospasm in young adult asthmatics?

OBJECTIVE

To determine the accuracy of incremental Shuttle Walking Test (ISWT) in detecting exercise-induced bronchospasm (EIB) in adults with asthma and to verify whether there is an association of the drop in FEV₁ between ISWT and cardiopulmonary exercise testing with constant-load CPET-CL.

METHODS

In this cross-sectional study 32 individuals with asthma performed two ISWTs, an incremental cardiopulmonary exercise test (CPET-I) and a constant-load cardiopulmonary exercise test (CPET-CL) with na interval of 48 h between tests. Spirometric measurements were obtained 5, 10, 15, 20 and 30 min after exercise; an FEV1 decline > 10% was considered EIB.

RESULTS

Fifteen individuals had EIB in both tests [χ2 = 9.41; κ = 0.46 p < 0.002 (95% CI: 0.201-0.708)], with moderate agreement. There was a significant correlation between the greatest variation in the drop in FEV₁ between the ISWT and the CPET-CL (r = 0.48; p < 0.01). There was a significant difference for ventilation maintenance time above 40% of Maximum Voluntary Ventilation between the groups of positive EIB (p = 0.001) and negative EIB (p = 0.001) and for ventilatory demand (positive EIB group) (p = 0.008) between ISWT vs CPET-CL. Moreover, assuming CPET-CL as the criterion test, ISWT presented a sensitivity of 62.5% and specificity was 100%.

CONCLUSION

ISWT showed moderate accuracy in detecting EIB in adults with asthma and was able to show similar metabolic and ventilatory demand presented in CPET-CL.

Bronchodilator response and lung function decline: Associations with exhaled nitric oxide with regard to sex and smoking status

Background

Fractional exhaled nitric oxide (FeNO) is a marker of type-2 inflammation used both to support diagnosis of asthma and follow up asthma patients. The associations of FeNO with lung function decline and bronchodilator (BD) response have been studied only scarcely in large populations.

Objectives

To study the association between FeNO and a) retrospective lung function decline over 20 years, and b) lung function response to BD among asthmatic subjects compared with non-asthmatic subjects and with regards to current smoking and sex.

Methods

Longitudinal analyses of previous lung function decline and FeNO level at follow-up and cross-sectional analyses of BD response and FeNO levels in 4257 participants (651 asthmatics) from the European Community Respiratory Health Survey.

Results

Among asthmatic subjects, higher percentage declines of FEV₁ and FEV₁/FVC were associated with higher FeNO levels (p = 0.001 for both) at follow-up. These correlations were found mainly among non-smoking individuals (p = 0.001) and females (p = 0.001) in stratified analyses.

Percentage increase in FEV₁ after BD was positively associated with FeNO levels in non-asthmatic subjects. Further, after stratified for sex and smoking separately, a positive association was seen between FEV₁ and FeNO levels in non-smokers and women, regardless of asthma status.

Conclusions

We found a relationship between elevated FeNO and larger FEV₁ decline over 20 years among subjects with asthma who were non-smokers or women. The association between elevated FeNO levels and larger BD response was found in both non-asthmatic and asthmatic subjects, mainly in women and non-smoking subjects.

Bronchial Provocation Testing for the Identification of Exercise-Induced Bronchoconstriction

Exercise-induced bronchoconstriction (EIB) occurs in patients with asthma, children, and otherwise healthy athletes. Poor diagnostic accuracy of respiratory symptoms during exercise requires objective assessment of EIB. The standardized tests currently available are based on the assumption that the provoking stimulus to EIB is dehydration of the airway surface fluid due to conditioning large volumes of inhaled air. "Indirect" bronchial provocation tests that use stimuli to cause endogenous release of bronchoconstricting mediators from airway inflammatory cells include dry air hyperpnea (eg, exercise and eucapnic voluntary hyperpnea) and osmotic aerosols (eg, inhaled mannitol). The airway response to different indirect tests is generally similar in patients with asthma and healthy athletes with EIB. Furthermore, the airway sensitivity to these tests is modified by the same pharmacotherapy used to treat asthma. In contrast, pharmacological agents such as methacholine, given by inhalation, act directly on smooth muscle to cause contraction. These "direct" tests have been used traditionally to identify airway hyperresponsiveness in clinical asthma but are less useful to diagnose EIB. The mechanistic differences between indirect and direct tests have helped to elucidate the events leading to airway narrowing in patients with asthma and elite athletes, while improving the clinical utility of these tests to diagnose and manage EIB.

European Respiratory Society clinical practice guidelines for the diagnosis of asthma in children aged 5-16 years

Diagnosing asthma in children represents an important clinical challenge. There is no single gold standard test to confirm the diagnosis. Consequently, both over-, and under-diagnosis of asthma are frequent in children.A Task Force (TF) supported by the European Respiratory Society has developed these evidence-based clinical practice guidelines for the diagnosis of asthma in children aged 5-16 years using nine PICO (Population, Intervention, Comparator and Outcome) questions. The TF conducted systematic literature searches for all PICO questions and screened the outputs from these, including relevant full text articles. All TF members approved the final decision for inclusion of research papers. The TF assessed the quality of the evidence using the GRADE (Grading of Recommendations, Assessment, Development and Evaluation) approach.The TF then developed a diagnostic algorithm based on the critical appraisal of the PICO questions, preferences expressed by lay members and test availability. Proposed cut-offs were determined based on the best available evidence. The TF formulated recommendations using the GRADE Evidence to Decision framework.Based on the critical appraisal of the evidence and the Evidence to Decision Framework the TF recommends spirometry, bronchodilator reversibility testing and FeNO as first line diagnostic tests in children under investigation for asthma. The TF recommends against diagnosing asthma in children based on clinical history alone or following a single abnormal objective test. Finally, this guideline also proposes a set of research priorities to improve asthma diagnosis in children in the future.

Work Group Report: Perspectives in Diagnosis and Management of Exercise-Induced Bronchoconstriction in Athletes

Exercise-induced bronchoconstriction, otherwise known as exercise-induced bronchoconstriction with asthma or without asthma, is an acute airway narrowing that occurs as a result of exercise and can occur in patients with asthma. A panel of members from the American Academy of Allergy, Asthma & Immunology Sports, Exercise, & Fitness Committee reviewed the diagnosis and management of exercise-induced bronchoconstriction in athletes of all skill levels including recreational athletes, high school and college athletes, and professional athletes. A special emphasis was placed on the recommendations and regulations set forth by professional athletic organizations after a detailed review of their collective bargaining agreements, substance abuse policies, antidoping program manuals, and the World Anti-Doping Agency antidoping code. The recommendations in this review are based on currently available evidence in addition to providing guidance for athletes of all skill levels as well as their treating physicians to better understand which pharmaceutical and nonpharmaceutical management options are appropriate as well as which medications are permitted or prohibited, and the proper documentation required to remain compliant.

Performance Characteristics of Spirometry With Negative Bronchodilator Response and Methacholine Challenge Testing and Implications for Asthma Diagnosis

BACKGROUND

In patients with a history suggestive of asthma, diagnosis is usually confirmed by spirometry with bronchodilator response (BDR) or confirmatory methacholine challenge testing (MCT).

RESEARCH QUESTION

We examined the proportion of participants with negative BDR testing who had a positive MCT (and its predictors) result and characteristics of MCT, including effects of controller medication tapering and temporal variability (and predictors of MCT result change), and concordance between MCT and pulmonologist asthma diagnosis.

STUDY DESIGN AND METHODS

Adults with self-reported physician-diagnosed asthma were recruited by random-digit dialing across Canada. Subjects performed spirometry with BDR testing and returned for MCT if testing was nondiagnostic for asthma. Subjects on controllers underwent medication tapering with serial MCTs over 3 to 6 weeks. Subjects with a negative MCT (the provocative concentration of methacholine that results in a 20% drop in FEV₁ [PC₂₀] > 8 mg/mL) off medications were examined by a pulmonologist and had serial MCTs after 6 and 12 months.

RESULTS

Of 500 subjects (50.5 ± 16.6 years old, 68.0% female) with a negative BDR test for asthma, 215 (43.0%) had a positive MCT. Subjects with prebronchodilator airflow limitation were more likely to have a positive MCT (OR, 1.90; 95% CI, 1.17-3.04). MCT converted from negative to positive, with medication tapering in 18 of 94 (19.1%) participants, and spontaneously over time in 25 of 165 (15.2%) participants. Of 231 subjects with negative MCT, 28 (12.1%) subsequently received an asthma diagnosis from a pulmonologist.

INTERPRETATION

In subjects with a self-reported physician diagnosis of asthma, absence of bronchodilator reversibility had a negative predictive value of only 57% to exclude asthma. A finding of spirometric airflow limitation significantly increased chances of asthma. MCT results varied with medication taper and over time, and pulmonologists were sometimes prepared to give a clinical diagnosis of asthma despite negative MCT. Correspondingly, in patients for whom a high clinical suspicion of asthma exists, repeat testing appears to be warranted.

Diagnostic value of bronchoprovocation challenge with adenosine monophosphate versus exercise testing in early diagnosis of asthma

Background

Airway hyperresponsiveness (AHR) is a characteristic feature of bronchial asthma and is diagnosed using direct and indirect bronchoprovocation tests. The diagnosis of AHR is a challenge in symptomatic patients with a normal baseline prebronchodilator spirometry and postbronchodilator spirometry. Exercise-induced asthma or exercise-induced bronchoconstriction (EIB) is a distinct form of AHR. There is no single test that is sufficient to exclude AHR in symptomatic military personnel with normal spirometry. This study was conducted to compare the diagnostic value of indirect bronchoprovocation test using inhaled adenosine monophosphate (AMP) and exercise challenge test (ECT) in the diagnosis of EIB.

Methods

A crossover study was conducted with consecutive sampling of patients presenting with symptoms suggestive of asthma and with normal spirometry results who were subjected to both ECT and bronchoprovocation test using inhaled AMP on separate days.

Results

Forty participants were recruited (the mean age: 25 yrs, 100% male). The commonest presentation was breathlessness on exercise (55%). With exercise alone, 40% tested positive for AHR, while with AMP alone, the positivity increased to 53%, and the difference was statistically significant (p= 0.03). Exercise alone failed to detect 8 cases that tested positive for AHR by inhaled AMP challenge.

Conclusion

Indirect bronchoprovocation test using inhaled AMP may be used to diagnose AHR in conditions in which exercise challenge testing is not available or the patient is unable to complete ECT.

Comparison of methacholine and mannitol challenges: importance of method of methacholine inhalation

Background

Direct inhalation challenges (e.g. methacholine) are stated to be more sensitive and less specific for a diagnosis of asthma than are indirect challenges (e.g. exercise, non-isotonic aerosols, mannitol, etc.). However, data surrounding comparative sensitivity and specificity for methacholine compared to mannitol challenges are conflicting. When methacholine is inhaled by deep total lung capacity (TLC) inhalations, deep inhalation inhibition of bronchoconstriction leads to a marked loss of diagnostic sensitivity when compared to tidal breathing (TB) inhalation methods. We hypothesized that deep inhalation methacholine methods with resulting bronchoprotection may be the explanation for conflicting sensitivity/specificity data.

Methods

We reviewed 27 studies in which methacholine and mannitol challenges were performed in largely the same individuals. Methacholine was inhaled by dosimeter TLC methods in 13 studies and by tidal breathing in 14 studies. We compared the rates of positive methacholine (stratified by inhalation method) and mannitol challenges in both asthmatics and non-asthmatics.

Results

When methacholine was inhaled by TLC inhalations the prevalence of positive tests in asthmatics, 60.2% (548/910), was similar to mannitol, 58.9% (537/912). By contrast, when methacholine was inhaled by tidal breathing the prevalence of positive tests in asthmatics 83.1% (343/413) was more than double that of mannitol, 41.5% (146/351). In non-asthmatics, the two methacholine methods resulted in positive tests in 18.8% (142/756) and 16.2% (27/166) by TLC and TB inhalations respectively. This compares to an overall 8.3% (n = 76) positive rate for mannitol in 913 non-asthmatics.

Conclusion

These data support the hypothesis that the conflicting data comparing methacholine and mannitol sensitivity and specificity are due to the method of methacholine inhalation. Tidal breathing methacholine methods have a substantially greater sensitivity for a diagnosis of asthma than either TLC dosimeter methacholine challenge methods or mannitol challenge. Methacholine challenges should be performed by tidal breathing as per recent guideline recommendations. Methacholine (more sensitive) and mannitol (more specific) will thus have complementary diagnostic features.

Diagnosis of asthma in children: the contribution of a detailed history and test results

INTRODUCTION

There are few data on the usefulness of different tests to diagnose asthma in children.

AIM

We assessed the contribution of a detailed history and a variety of diagnostic tests for diagnosing asthma in children.

METHODS

We studied children aged 6-16 years referred consecutively for evaluation of suspected asthma to two pulmonary outpatient clinics. Symptoms were assessed by parental questionnaire. The clinical evaluation included skin-prick tests, measurement of exhaled nitric oxide fraction (F _eNO), spirometry, bronchodilator reversibility and bronchial provocation tests (BPT) by exercise, methacholine and mannitol. Asthma was diagnosed by the physicians at the end of the visit. We assessed diagnostic accuracy of symptoms and tests by calculating sensitivity, specificity, positive and negative predictive values and area under the curve (AUC).

RESULTS

Of the 111 participants, 80 (72%) were diagnosed with asthma. The combined sensitivity and specificity was highest for reported frequent wheeze (more than three attacks per year) (sensitivity 0.44, specificity 0.90), awakening due to wheeze (0.41, 0.90) and wheeze triggered by pollen (0.46, 0.83) or by pets (0.29, 0.99). Of the diagnostic tests, the AUC was highest for F _eNO measurement (0.80) and BPT by methacholine (0.81) or exercise (0.74), and lowest for forced expiratory volume in 1 s (FEV₁) (0.62) and FEV₁/forced vital capacity ratio (0.66), assessed by spirometry.

CONCLUSION

This study suggests that specific questions about triggers and severity of wheeze, measurement of F _eNO and BPT by methacholine or exercise contribute more to the diagnosis of asthma in school-aged children than spirometry, bronchodilator reversibility and skin-prick tests.

Utility and efficiency of methacholine challenge testing in evaluating pediatric asthma: unraveling the diagnostic conundrum

OBJECTIVE

Interpretation of methacholine challenge testing (MCT) results depends on the patient's pretest probability of asthma as well as the provocative concentration (PC₂₀); however, ordering providers rarely understand the complexity associated with its interpretation. This study investigated the clinical utility and efficiency of MCT at a tertiary center in evaluating pediatric asthma.

METHODS

Retrospective chart review was done for all MCT done at a tertiary center over a six year period (2011-2017). Demographics, referring provider, referral diagnosis, current symptoms with and without exercise, and baseline spirometry were collected. Pretest probability of asthma was assigned by author (RB) who was blinded to MCT results and PC₂₀. Post-test probability of asthma was assigned based on pretest probability, MCT result (+/-), and PC₂₀. Three assigned asthma probability categories were "unlikely" "likely", and "very likely".

RESULTS

Of 172 subjects (91 Females, age range 5-21 years), 64.9% of MCT results (n = 111)) were negative and 35.1% (n = 60)) were positive. One was inconclusive. Those who tested positive were shorter, lighter, younger and had lower forced expiratory volume in one second/forced vital capacity (FEV₁/FVC) ratio than those who tested negative (p < 0.05). Subjects with exercise symptoms only were less likely to test positive (OR 0.2, CI 0.1-0.5). In a majority of subjects (91.8%; 157/171), MCT increased the certainty of presence or absence of asthma.

CONCLUSIONS

In our subject population, MCT could be useful in evaluating pediatric asthma if subject's pretest probability of asthma and PC₂₀ was taken into account. It was not as useful for subjects with exercise symptoms only.

Predictors and reproducibility of exercise-induced bronchoconstriction in cold air

Background

Physical activity is an important part of life, and hence exercise-induced bronchoconstriction (EIB) can reduce the quality of life. A standardized test is needed to diagnose EIB. The American Thoracic Society (ATS) guidelines recommend an exercise challenge in combination with dry air. We investigated the feasibility of a new, ATS guidelines conform exercise challenge in a cold chamber (ECC) to detect EIB. The aim of this study was to investigate the surrogate marker reaction to methacholine, ECC and exercise challenge in ambient temperature for the prediction of a positive reaction and to re-evaluate the reproducibility of the response to an ECC.

Methods

Seventy-eight subjects aged 6 to 40 years with suspected EIB were recruited for the study. The subjects performed one methacholine challenge, two ECCs, and one exercise challenge at an ambient temperature. To define the sensitivity and specificity of the predictor, a receiver-operating characteristic curve was plotted. The repeatability was evaluated using the method described by Bland and Altman (95% Limits of agreement).

Results

The following cut-off values showed the best combination of sensitivity and specificity: the provocation dose causing a 20% decrease in the forced expiratory volume in 1 s (PD₂₀FEV₁) of methacholine: 1.36 mg (AUC 0.69, p < 0.05), the maximal decrease in FEV₁ during the ECC: 8.5% (AUC 0.78, p < 0.001) and exercise challenges at ambient temperatures: FEV₁ 5.2% (AUC 0.64, p = 0.13). The median decline in FEV₁ was 14.5% (0.0–64.2) during the first ECC and 10.7% (0.0–52.5) during the second ECC. In the comparison of both ECCs, the Spearman rank correlation of the FEV₁ decrease was r = 0.58 (p < 0.001). The 95% limits of agreement (95% LOAs) for the FEV₁ decrease were − 17.7 to 26.4%.

Conclusions

The surrogate markers PD₂₀FEV₁ of methacholine and maximal decrease in FEV₁ during ECC can predict a positive reaction in another ECC, whereas the maximal FEV₁ decrease in an exercise challenge at an ambient temperature was not predictive. Compared with previous studies, we can achieve a similar reproducibility with an ECC.

Clinical trial registration

NCT02026492 (retrospectively registered 03/Jan/2014).

Usefulness of mannitol challenge testing for diagnosing asthma in everyday clinical practice

Background: The mannitol test is widely used for assessment of airway responsiveness in patients with possible asthma, but our knowledge of the value in everyday clinical practice is limited.Objective: To investigate the diagnostic value of the mannitol test in a clinical setting.Methods: All patients having a mannitol challenge test as part of their diagnostic work-up for asthma at the respiratory outpatient clinic, Hvidovre Hospital, over a 5-year period were included in the present analysis. Case history, including previous diagnoses, spirometry, exhaled nitric oxide (F_ENO) was obtained. The mannitol challenge was performed according to guidelines, i.e. increasing doses of mannitol (from 5 to 635 mg) until maximum dose or a 15% decline in FEV₁ (PD₁₅) was achieved (positive test defined as a PD₁₅ < 635 mg).Results: Our cohort comprised 566 patients (210 men). Post-challenge, 247 patients were diagnosed with asthma by a specialist in respiratory medicine, of whom 138 (56%) had a positive mannitol test. A diagnosis of asthma was ruled out by the specialist in 319 individuals, of whom 18 (6%) had a positive mannitol test and 77 (24%) previous doctor-diagnosed asthma (but with no evidence of a confirmatory test). The specificity and sensitivity of the test was 94% and 56%, respectively. Female gender (p = 0.005), increasing BMI (p < 0.001), exercise-induced cough (p = 0.002), night-time respiratory symptoms (p = 0.002), low FEV₁/FVC ratio (p = 0.008) and high F_ENO (p < 0.001) were determinants for a positive mannitol test.Conclusion: In everyday clinical work-up of patients with possible asthma, the sensitivity and specificity of the mannitol challenge test is comparable to previous controlled trials.

Bronchoprovocation Testing in Asthma: An Update

Bronchial hyperresponsiveness (BHR) is defined as a heightened bronchoconstrictive response to airway stimuli. It complements the cardinal features in asthma, such as variable or reversible airflow limitation and airway inflammation. Although BHR is considered a pathophysiologic hallmark of asthma, it should be acknowledged that this property of the airway is dynamic, because its severity and even presence can vary over time with disease activity, triggers or specific exposure, and with treatment. In addition, it is important to recognize that there is a component that is not reflective of a specific disease entity.

Testing for Exercise-Induced Bronchoconstriction

Exercise-induced bronchoconstriction (EIB) is a form of airway hyperresponsiveness that occurs with or without current symptoms of asthma. EIB is an indicator of active and treatable pathophysiology in persons with asthma. The objective documentation of EIB permits the identification of an individual who may be at risk during a recreational sporting activity or when exercising as an occupational duty. EIB can be identified with laboratory exercise testing or surrogate tests for EIB. These include eucapnic voluntary hyperpnea and osmotic stimuli (eg, inhaled mannitol) and offer improved diagnostic sensitivity to identify EIB and improved standardization when compared with laboratory exercise.

Asthma: Diagnosis and Treatment

Asthma is an obstructive lung disease affecting >230 million people worldwide and a significant cause of morbidity in patients of all ages. It is a heterogeneous disease with a complex pathophysiology and phenotype. Diagnosis is made with thorough history-taking and physical examination, and the condition is characterised by variable airflow obstruction and airway hyper-responsiveness. Understanding the severity of the disease is important, and treatment is aimed at symptom control and the prevention of future exacerbations. Pharmacologic treatment with beta-agonists for intermittent asthma and inhaled corticosteroids and a combination of inhaled corticosteroids and long-acting beta-2 agonists for persistent asthma are recommended. Additional and alternative treatments with leukotriene modifiers, anticholinergics, biologics, and bronchial thermoplasty are also available. However, understanding an individual’s disease phenotype, endotype, and comorbidities is necessary for asthma treatment, with appropriate consultation with asthma specialists required for those with severe asthma.

ERS technical standard on bronchial challenge testing: pathophysiology and methodology of indirect airway challenge testing

Recently, this international task force reported the general considerations for bronchial challenge testing and the performance of the methacholine challenge test, a "direct" airway challenge test. Here, the task force provides an updated description of the pathophysiology and the methods to conduct indirect challenge tests. Because indirect challenge tests trigger airway narrowing through the activation of endogenous pathways that are involved in asthma, indirect challenge tests tend to be specific for asthma and reveal much about the biology of asthma, but may be less sensitive than direct tests for the detection of airway hyperresponsiveness. We provide recommendations for the conduct and interpretation of hyperpnoea challenge tests such as dry air exercise challenge and eucapnic voluntary hyperpnoea that provide a single strong stimulus for airway narrowing. This technical standard expands the recommendations to additional indirect tests such as hypertonic saline, mannitol and adenosine challenge that are incremental tests, but still retain characteristics of other indirect challenges. Assessment of airway hyperresponsiveness, with direct and indirect tests, are valuable tools to understand and to monitor airway function and to characterise the underlying asthma phenotype to guide therapy. The tests should be interpreted within the context of the clinical features of asthma.

[Guidelines for methacholine provocation testing]

Bronchial challenge with the direct bronchoconstrictor agent methacholine is commonly used for the diagnosis of asthma. The "Lung Function" thematic group of the French Pulmonology Society (SPLF) elaborated a series of guidelines for the performance and the interpretation of methacholine challenge testing, based on French clinical guideline methodology. Specifically, guidelines are provided with regard to the choice of judgment criteria, the management of deep inspirations, and the role of methacholine bronchial challenge in the care of asthma, exercise-induced asthma, and professional asthma.

Exhaled nitric oxide and mannitol test to predict exercise-induced bronchoconstriction

BACKGROUND

Exercise-induced bronchoconstriction (EIB) is diagnosed via exercise challenge on a treadmill, but such testing requires complex equipment and sufficient health-care resources. The fraction of exhaled nitric oxide (FeNO) test and mannitol bronchial provocation test (BPT) may serve as a surrogate for exercise testing.

METHODS

We compared the diagnostic utilities of the FeNO test and mannitol BPT in predicting EIB in asthmatic children. We retrospectively analyzed data from 60 asthmatic children aged 6-16 years. We compared the exercise BPT results, FeNO levels, and mannitol BPT data.

RESULTS

All subjects were divided into exercise-positive (n = 41) or -negative (n = 19) BPT groups. Of the 41 exercise-positive patients, 32 were mannitol BPT positive and nine were mannitol BPT negative. Of the 19 exercise-negative patients, nine and 10, respectively, were mannitol BPT positive and BPT negative. The maximum % forced expiratory volume in 1 s (FEV₁ ) decrease after exercise was positively correlated with FeNO (r = 0.556, P < 0.001), and with mannitol response-dose ratio (RDR; r = 0.416, P = 0.001). The receiver operating characteristic (ROC) curve for FeNO to discriminate between asthmatic subjects with and without EIB had an area under the curve (AUC) of 0.771 (95%CI: 0.643-0.870). The discriminatory ROC curve for mannitol RDR had an AUC of 0.763 (95%CI: 0.633-0.864). The AUC of FeNO and mannitol RDR did not differ significantly.

CONCLUSIONS

EIB significantly correlated with both FeNO and mannitol BPT data. Given that both methods similarly predicted EIB in asthmatic children, the simpler and safer FeNO test alone may be a clinically useful diagnostic tool.

Repurposing excipients as active inhalation agents: The mannitol story

The story of how we came to use inhaled mannitol to diagnose asthma and to treat cystic fibrosis began when we were looking for a surrogate for exercise as a stimulus to identify asthma. We had proposed that exercise-induced asthma was caused by an increase in osmolarity of the periciliary fluid. We found hypertonic saline to be a surrogate for exercise but an ultrasonic nebuliser was required. We produced a dry powder of sodium chloride but it proved unstable. We developed a spray dried preparation of mannitol and found that bronchial responsiveness to inhaling mannitol identified people with currently active asthma. We reasoned that mannitol had potential to replace the 'osmotic' benefits of exercise and could be used as a treatment to enhance mucociliary clearance in patients with cystic fibrosis. These discoveries were the start of a journey to develop several registered products that are in clinical use globally today.

Evaluating the Athlete with Suspected Exercise-Induced Asthma or Bronchospasm

Exercise-induced asthma (EIA) and exercise-induced bronchospasm (EIB)/bronchoconstriction (EIC) describes two clinical entities by which exercise triggers bronchial hyperresponsiveness. Exercise is a common trigger of bronchospasm in the asthmatic (EIA), as well as athletes without the underlying inflammation associated with asthma (EIC/EIB). Approximately 10% to 20% of the general population have EIA or EIB (). The approach to the diagnosis and subsequent management relies on the clinician's ability to recognize clinical signs and symptoms, then selecting the correct diagnostic test. A baseline spirometry/pulmonary function test is recommended for all athletes to evaluate for underlying asthma. Subsequent direct or indirect bronchial provocation testing is recommended to correctly diagnose EIA or EIB (). Athletes should not be treated empirically with bronchodilators based on symptoms alone without confirmatory spirometry and provocative testing.

Asthma and exercise-induced respiratory symptoms in the athlete: new insights

PURPOSE OF REVIEW

Asthma and exercise-induced bronchoconstriction (EIB) are common in the athlete and can interfere with sport performances. In this review, we report recent findings on the prevalence, diagnosis and evaluation of these conditions, in addition to specific issues regarding their treatment and antidoping regulations.

RECENT FINDINGS

Recent studies confirmed the high prevalence of exercise-induced respiratory symptoms, asthma and EIB, in athletes and showed that these conditions are still underdiagnosed and undertreated. Recent studies highlight the suboptimal use of asthma medication in asthmatic and allergic athletes. Regarding the diagnosis and treatment, questions about the role and criteria for positivity of eucapnic voluntary hyperpnea test were raised. It was confirmed that there is a subgroup of athletes with poor response to asthma medication. Finally, regarding antidoping regulations, new methods and changes in criteria for urinary bronchodilator thresholds were suggested.

SUMMARY

Recent publications confirm that exercise-induced respiratory symptoms, asthma and EIB are common in athletes but often unrecognized and not optimally or successfully treated. It was suggested that current criteria for diagnostic bronchoprovocation test responses could be reassessed, as well as antidoping criteria for β2-agonists urinary levels. There is a need for more research on prevention of airways dysfunction in athletes, identification of different asthma phenotypes and the benefits of standard asthma medication in this population.

Realising the potential of various inhaled airway challenge agents through improved delivery to the lungs

Inhaled airway challenges provoke bronchoconstriction in susceptible subjects and are a pivotal tool in the diagnosis and monitoring of obstructive lung diseases, both in the clinic and in the development of new respiratory medicines. This article reviews the main challenge agents that are in use today (methacholine, mannitol, adenosine, allergens, endotoxin) and emphasises the importance of controlling how these agents are administered. There is a danger that the optimal value of these challenge agents may not be realised due to suboptimal inhaled delivery; thus considerations for effective and reproducible challenge delivery are provided. This article seeks to increase awareness of the importance of precise delivery of inhaled agents used to challenge the airways for diagnosis and research, and is intended as a stepping stone towards much-needed standardisation and harmonisation in the administration of inhaled airway challenge agents.

The efficacy and safety of mannitol challenge in a workplace setting for assessing asthma prevalence

OBJECTIVE

There is no standard definition of asthma for epidemiological purposes; most surveys use symptoms and bronchial hyperresponsiveness. Few studies tested mannitol challenge test (MCT) in occupational settings. We sought to determine efficacy and safety of MCT in detecting subjects with asthma symptoms in the workplace.

METHODS

In this cross-sectional study we recruited 908 workers in 2 universities; they underwent a respiratory questionnaire, spirometry, skin prick tests, and MCT.

RESULTS

Eight hundred and eleven subjects completed the study; 11.1% had a positive MCT; 8.14% had asthma. MCT had low sensitivity (35.4-61.9%) but high specificity (90.2-94.9%) to detect symptomatic individuals. The most prevalent symptom was wheezing in the last 12 months. Twenty-four of those with a positive MCT (26.7%) had no positive replies to the questions on asthma symptoms. Among subjects with a positive MCT, 71.9% achieved 95% of baseline FEV₁ after 15 minutes of salbutamol recovery treatment. Nine subjects (1.1%) had adverse events that prevented the test from being completed.

CONCLUSIONS

MCT has high specificity but low sensitivity to detect symptomatic subjects in the workplace. It may detect subjects with hyperresponsiveness but no symptoms, who could be at risk of developing airway diseases. The test is safe and well tolerated.

Noninvasive ventilation and respiratory physical therapy reduce exercise-induced bronchospasm and pulmonary inflammation in children with asthma: randomized clinical trial

BACKGROUND

Asthma is characterized by hyperresponsiveness of the airways, and exercise-induced bronchospasm (EIB) is a symptom that limits a large proportion of asthmatic patients, especially children. Continuous positive airway pressure (CPAP) leads to a reduction in the reactivity of the airways. The aim of this study was to evaluate the effect of outpatient treatment with CPAP and bilevel pressure combined with respiratory physical therapy for children and adolescents with asthma following bronchial hyperresponsiveness caused by an exercise bronchoprovocation test.

METHODS

A randomized, controlled, blind, clinical trial was conducted involving 68 asthmatic children and adolescents aged 4 to 16 years divided into three groups: G1, treated with bilevel pressure (inspiratory positive airway pressure: 12 cm H2O; expiratory positive airway pressure: 8 cm H2O), G2, treated with CPAP (8 cm H2O) and G3, treated with respiratory muscle training (RMT), considered as the control group. All groups were treated at an outpatient clinic and submitted to 10 1-hour sessions, each of which also included respiratory exercises. Evaluations were performed before and after treatment and involved spirometry, an exercise bronchoprovocation test, respiratory pressures, fraction of nitric oxide (FeNO), the Asthma Control Questionnaire (ACQ6) and anthropometric variables. This study received approval from the local ethics committee (certificate number: 1487225/2016) and is registered with ClinicalTrials [ ClinicalTrials.gov identifier: NCT02939625].

RESULTS

A total of 64 patients concluded the protocol; the mean age of the patients was 10 years. All were in the ideal weight range and had adequate height ( z score: -2 to +2). The three groups demonstrated improved asthma control after the treatments, going from partial to complete control. A significant increase in maximal inspiratory pressure occurred in the three groups, with the greatest increase in the RMT group. A reduction in FeNO in the order of 17.4 parts per billion (effect size: 2.43) and a reduction in bronchial responsiveness on the exercise bronchoprovocation test occurred in the bilevel group. An improvement in FeNO on the order of 15.7 parts per billion (effect size: 2.46) and a reduction in bronchial responsiveness occurred in the CPAP group. No changes in lung function or responsiveness occurred in the RMT group.

CONCLUSION

Positive pressure and respiratory exercises were effective in reducing pulmonary inflammation, exercise-innduced bronchoespasm (EIB), and increased the clinical control of asthma, as well as RMT, which also resulted in improved clinical control.

Exercise-Induced Bronchospasm and Allergy

Sport is an essential part of childhood, with precious and acknowledged positive health effects but the impact of exercise-induced bronchoconstriction (EIB) significantly reduces participation in physical activity. It is important to recognize EIB, differentiating EIB with or without asthma if the transient narrowing of the airways after exercise is associated with asthmatic symptoms or not, in the way to select the most appropriate treatment among the many treatment options available today. Therapy is prescribed based on symptoms severity but diagnosis of EIB is established by changes in lung function provoked by exercise evaluating by direct and indirect tests. Sometimes, in younger children it is difficult to obtain the registration of difference between the preexercise forced expiratory volume in the first second (FEV1) value and the lowest FEV1 value recorded within 30 min after exercise, defined as the gold standard, but interrupter resistance, in association with spirometry, has been showed to be a valid alternative in preschool age. Atopy is the main risk factor, as demonstrated by epidemiologic data showing that among the estimated pediatric population with EIB up to 40% of them have allergic rhinitis and 30% of these patients may develop adult asthma, according with atopic march. Adopting the right treatment and prevention, selecting sports with no marked hyperventilation and excessive cooling of the airways, children with EIB can be able to take part in physical activity like all others.

Usefulness of Biomarkers in Work-Related Airway Disease

Determination of biomarkers may be useful in the surveillance of occupational exposure and workers' health. The possibility of predicting development/clinical course of specific disorders or current disease, diagnosing in early steps, and health condition monitoring is a real necessity. Various agents present in the workplace environment (or their metabolites) can be measured in samples possessed from human body (blood and urine, saliva, etc.). On the other hand, inhalant exposure may induce specific or non-specific, local or systemic, acute or chronic biological response expressed by synthesis or releasing specific or non-specific substances/mediators that also can be determined in blood, nasal and bronchial lavage or sputum, tear fluid, exhaled breath, etc. The least is known about genetic markers which may predict individual susceptibility to develop some work-related disorders under the influence of occupational exposure. Due to common exposure to inhalant agents at workplace, researches on biomarkers that allow to inspect the impact of exposure to humans' health are still needed. The authors of this article summarize the utility of biomarkers' determination in work-related airway diseases in a recent clinical approach.

Role of bronchoprovocation tests in identifying exercise-induced bronchoconstriction in a non-athletic population: a pilot study

BACKGROUND

Studies on diagnostic tests for exercise-induced bronchoconstriction (EIB) have centered around the asthmatic and elite athletic population. Traditionally, the exercise challenge test (ET) was recommended to assess EIB. We aimed to compare the performance of surrogate testing, mainly the hypertonic saline (HS) test, and methacholine challenge test (MCT) versus ET in identifying EIB among non-athletic subjects.

METHODS

We prospectively recruited subjects who did not have confirmed active asthma, but who reported exercise-induced dyspnoea. The participants underwent HS and ET on separate days within two weeks. MCT performed within one year were obtained retrospectively from medical records. The sensitivity, specificity, and accuracy of each diagnostic test were calculated using ET as the gold standard.

RESULTS

We recruited 27 participants (mean age 20.6±2.5 years; 92.6% male). Five (18.5%) had a history of self-reported asthma prior to recruitment. Eleven participants (40.7%) had a positive ET test. The sensitivity, specificity and accuracy of HS in diagnosing EIB was 90.9%, 62.5% and 74.1%; while that of MCT was 88.9%, 83.3% and 85.7% respectively. Six subjects were positive to HS but had negative ET test.

CONCLUSIONS

Both HS and MCT were found to be suitable alternatives to ET in screening for EIB in the non-athletic population in this pilot study. Further large scale studies are required to confirm this finding. These tests have the potential to replace ET for the diagnosis of EIB in centres without ET equipment or facilities.

Perceived exercise limitation in asthma: The role of disease severity, overweight, and physical activity in children

BACKGROUND

Children with asthma may be less physically active than their healthy peers. We aimed to investigate whether perceived exercise limitation (EL) was associated with lung function or bronchial hyper-responsiveness (BHR), socioeconomic factors, prenatal smoking, overweight, allergic disease, asthma severity, or physical activity (PA).

METHODS

The 302 children with asthma from the 10-year examination of the Environment and Childhood Asthma birth cohort study underwent a clinical examination including perceived EL (structured interview of child and parent(s)), measure of overweight (body mass index by sex and age passing through 25 kg/m² or above at 18 years), exercise-induced bronchoconstriction (forced expiratory volume in one-second (FEV₁ ) pre- and post-exercise), methacholine bronchial challenge (severe BHR; provocative dose causing ≥20% decrease in FEV₁ ≤ 1 μmol), and asthma severity score (dose of controller medication and exacerbations last 12 months). Multivariate logistic regression analyses were conducted to assess associations with perceived EL.

RESULTS

In the final model explaining 30.1%, asthma severity score (OR: 1.49, (1.32, 1.67)) and overweight (OR: 2.35 (1.14, 4.82)) only were significantly associated with perceived EL. Excluding asthma severity and allergic disease, severe BHR (OR: 2.82 (1.38, 5.76)) or maximal reduction in FEV₁ post-exercise (OR: 1.48 (1.10, 1.98)) and overweight (OR: 2.15 (1.13, 4.08) and 2.53 (1.27, 5.03)) explained 9.7% and 8.4% of perceived EL, respectively.

CONCLUSIONS

Perceived EL in children with asthma was independently associated with asthma severity and overweight, the latter doubling the probability of perceived EL irrespectively of asthma severity, allergy status, socioeconomic factors, prenatal smoking, or PA.

Mannitol challenge testing for asthma in a community cohort of young adults

BACKGROUND AND OBJECTIVE

Mannitol challenge testing is an established tool for clinical asthma diagnosis, and can be performed outside of specialized respiratory laboratories. Despite applicability in both clinical and non-clinical populations, with different pre-test asthma probabilities, differences in diagnostic properties have not been well explored. This study aimed to quantify the diagnostic utility of mannitol challenge testing for asthma in a community cohort and a symptomatic wheezing subset of this cohort.

METHODS

During the 22-year follow-up of the Western Australian Pregnancy (Raine) Cohort, 772 participants (384 males) completed mannitol challenge and skin prick testing and respiratory health questionnaires, of whom 148 reporting wheeze in the past 12 months were included in a wheezing subset.

RESULTS

Responsiveness to mannitol had low sensitivity (19%) and high specificity (97%) to identify current asthma in the complete cohort, with positive and negative predictive values (PPV and NPV) of 45% and 92%, respectively. Within the wheezing subset, sensitivity (19%) and specificity (94%) remained similar, but PPV increased to 79%, and NPV decreased to 52%.

CONCLUSION

Our findings support previously reported high specificity and good PPV for mannitol challenge testing in symptomatic wheezing populations, and highlight the need for caution when interpreting mannitol test results in non-clinical populations.

Comparison of diagnostic validity of mannitol and methacholine challenges and relationship to clinical status and airway inflammation in steroid-naïve asthmatic patients

OBJECTIVES

The purpose of this study was to demonstrate and compare the diagnostic validity of two bronchial challenges and to investigate their correlation with patient clinical status, atopy and inflammation markers.

METHODS

Eighty-eight patients, 47 women and 41 men, mean age 38.56 ± 16.73 years who presented with asthma related symptoms and were not on any anti-asthma medication, were challenged with mannitol and methacholine on separate days. Medical history regarding asthmatic symptoms, physical examination, skin prick tests and FeNO levels were also assessed. The clinical diagnosis of asthma was based on bronchodilator reversibility test.

RESULTS

Sixty-seven patients were diagnosed with asthma and 21 without asthma. Both methacholine (P < 0.014) and mannitol (P < 0.000) challenges were significant in diagnosing asthma. The positive/negative predictive value was 93.33%/41.86% for methacholine, 97.72%/45.45% for mannitol and 97.05%/45.45%. for both methods assessed together. Worthy of note that 22% of asthmatics had both tests negative. There was a negative correlation between PC20 of methacholine and the FeNO level P < 0.001, and positive with the PD15 of mannitol P < 0.001 and the pre-test FEV₁% pred P < 0.005, whereas PD15 of mannitol was negatively correlated with the FeNO level P < 0.001. Furthermore, dyspnea was the only asthmatic symptom associated with FeNO level P < 0.035 and the positivity of mannitol P < 0.014 and methacholine P < 0.04.

CONCLUSIONS

Both challenge tests were equivalent in diagnosing asthma. Nevertheless, specificity appeared to be slightly higher in mannitol challenge.