Evaluation of severity of bronchial asthma through an exercise bronchial challenge

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.

Exercise-induced bronchoconstriction in children with asthma: An observational cohort study

BACKGROUND/PURPOSE

The diagnosis of exercise-induced bronchoconstriction (EIB) was established by changes in lung function after exercise challenge. The prevalence of EIB and factors related to EIB were not fully described in children with asthma. The aim of this study was to investigate the prevalence and predictors of EIB in children with asthma.

METHODS

A total of 149 children with physician-diagnosed asthma above 5 years of age underwent standardized treadmill exercise challenge for EIB and methacholine challenge for airway hyper-responsiveness from October 2015 to December 2016.

RESULTS

EIB presented in 52.5% of children with asthma. Compared with children without EIB, there were more patients with atopic dermatitis in children with EIB (p = 0.038). Allergic to Dermatohagoides pteronyssinus and Dermatophagoides farinae were also found more in children with EIB (p = 0.045 and 0.048 respectively). Maximal decrease in forced expiratory volume in 1 s (FEV₁) were highest in patients who were most sensitive to methacholine provocation (provocation concentration causing 20% fall in FEV1 [PC₂₀] ≤ 1 mg/mL). Patients, who were more sensitive to methacholine challenge (with lower PC₂₀ levels), develop EIB with more decline in FEV₁ after exercise challenge (p = 0.038). Among patients with EIB, airflow limitation development in patient with methacholine-induced airway hyper-responsiveness was more abrupt and severe compared with patients without airway hyper-responsiveness (p = 0.045 and 0.033 respectively).

CONCLUSION

EIB presented in 52.5% of children with asthma. The more severe methacholine-induced hyper-responsiveness, the higher prevalence of EIB as well as the severity.

Correlation between nitrites in induced sputum and asthma symptoms in asthmatic schoolchildren

OBJECTIVE

To determine if nitrites (nitric oxide metabolites) measured in induced sputum decrease and correlate with improvement of clinical asthma symptoms after treatment, we performed a prospective longitudinal study in a tertiary care hospital in Arequipa, Peru.

METHODS

In 95 schoolchildren with mild and moderate persistent asthma we determined nitrites in induced sputum samples (measured using the Griess assay). Clinical parameters and exercise bronchial challenge (EBC) test were performed twice, at baseline and after 3 months of beclomethasone-dipropionate treatment (median doses: 300 mcg/day, IQR: 300-450).

RESULTS

Sixty out of 95 children completed the study (median age of 9-year [IQR: 7-13]). A significant change in sputum nitrites levels between admission and the end of the study was observed (34.4 nmol/ml [IQR:18.2-58.4] and 11.2 nmol/ml [6-20.1], respectively, P = < 0.0001). Also a significant correlation between decrease of sputum nitrites levels and improvement of clinical parameters (acute exacerbations [r = 0.361, P = 0.005]; use of salbutamol [r = 0.322, P = 0.013]; emergency visits [r = 0.275, P = 0.033]; and school absence [r = 0.41, P = 0.001]) from admission to the end of the study was found. However, sputum nitrites levels did not correlated with peripherical blood eosinophils or serum IgE levels or with EBC test at any point of the study. The decrease of sputum nitrites levels after the treatment was significant in each asthma group (mild and moderate), but not between groups.

CONCLUSION

This study showed that measured nitrite in induced sputum (a simple and cheap non-invasive method) is a good alternative for monitoring asthmatic treatment in schoolchildren.

What makes a difference in exercise-induced bronchoconstriction: an 8 year retrospective analysis

Background

Exercise-induced bronchoconstriction (EIB) was recently classified into EIB alone and EIB with asthma, based on the presence of concurrent asthma.

Objective

Differences between EIB alone and EIB with asthma have not been fully described.

Methods

We retrospectively reviewed who visited an allergy clinic for respiratory symptoms after exercise and underwent exercise bronchial provocation testing. More than a 15% decrease of forced expiratory volume in 1 second (FEV1) from baseline to the end of a 6 min free-running challenge test was interpreted as positive EIB.

Results

EIB was observed in 66.9% of the study subjects (89/133). EIB-positive subjects showed higher positivity to methacholine provocation testing (61.4% vs. 18.9%, p<0.001) compared with EIB-negative subjects. In addition, sputum eosinophilia was more frequently observed in EIB-positive subjects than in EIB-negative subjects (56% vs. 23.5%, p = 0.037). The temperature and relative humidity on exercise test day were significantly related with the EIB-positive rate. Positive EIB status was correlated with both temperature (p = 0.001) and relative humidity (p = 0.038) in the methacholine-negative EIB group while such a correlation was not observed in the methacholine-positive EIB group. In the methacholine-positive EIB group the time to reach a 15% decrease in FEV1 during exercise was significantly shorter than that in the methacholine-negative EIB group (3.2±0.7 min vs. 8.6±1.6 min, p = 0.004).

Conclusions

EIB alone may be a distinct clinical entity from EIB with asthma. Conditions such as temperature and humidity should be considered when performing exercise tests, especially in subjects with EIB alone.

Asthma outcomes: pulmonary physiology

BACKGROUND

Outcomes of pulmonary physiology have a central place in asthma clinical research.

OBJECTIVE

At the request of National Institutes of Health (NIH) institutes and other federal agencies, an expert group was convened to provide recommendations on the use of pulmonary function measures as asthma outcomes that should be assessed in a standardized fashion in future asthma clinical trials and studies to allow for cross-study comparisons.

METHODS

Our subcommittee conducted a comprehensive search of PubMed to identify studies that focused on the validation of various airway response tests used in asthma clinical research. The subcommittee classified the instruments as core (to be required in future studies), supplemental (to be used according to study aims and in a standardized fashion), or emerging (requiring validation and standardization). This work was discussed at an NIH-organized workshop in March 2010 and finalized in September 2011.

RESULTS

A list of pulmonary physiology outcomes that applies to both adults and children older than 6 years was created. These outcomes were then categorized into core, supplemental, and emerging. Spirometric outcomes (FEV(1), forced vital capacity, and FEV(1)/forced vital capacity ratio) are proposed as core outcomes for study population characterization, for observational studies, and for prospective clinical trials. Bronchodilator reversibility and prebronchodilator and postbronchodilator FEV(1) also are core outcomes for study population characterization and observational studies.

CONCLUSIONS

The subcommittee considers pulmonary physiology outcomes of central importance in asthma and proposes spirometric outcomes as core outcomes for all future NIH-initiated asthma clinical research.

Seasonal factors influencing exercise-induced asthma

Purpose

Exercise-induced bronchoconstriction (EIB) in patients with asthma occurs more frequently in winter than in summer. The concentration of house dust mite (HDM) allergens in beds also shows seasonal variation. This study examined the relationship between seasonal differences in the prevalence of EIB and sensitization to HDMs in patients with asthma.

Methods

The medical records of 74 young adult male patients with asthma-like symptoms who underwent bronchial challenge with methacholine, 4.5% saline and exercise, and allergen skin prick tests, were reviewed. The subjects were divided into summer (n=27), spring/fall (n=26) and winter (n=21) groups according to the season during which they underwent testing.

Results

The positive responses to exercise differed according to season (48.1% in summer, 73.1% in spring/fall, and 90.5% in winter; P<0.01). In addition, the prevalence of positive responses to HDM (70.4%, 88.5%, and 95.2%, respectively; P<0.05) and pollen skin tests (37.0%, 19.2%, and 0%, respectively; P<0.01) also showed significant seasonal differences. Severe responses to 4.5% saline showed a similar trend, although it was not statistically significant (44.4%, 50.0%, and 71.4%, respectively; P=0.07). Skin test reactivity to HDMs was significantly related to maximal fall in forced expiratory volume in one second (FEV1) following exercise (r=0.302, P<0.01) and the index of airway hyperresponsiveness (AHR) to 4.5% saline (r=-0.232, P<0.05), but not methacholine (r=-0.125, P>0.05).

Conclusions

Positive skin test reactions to HDMs and EIB occurred in winter, spring/fall, and summer in decreasing order of frequency. Seasonal variation in the prevalence of EIB may be related to seasonal variation in sensitization to HDMs, accompanied by differences in indirect, but not direct, AHR.

The Peru Urban versus Rural Asthma (PURA) Study: methods and baseline quality control data from a cross-sectional investigation into the prevalence, severity, genetics, immunology and environmental factors affecting asthma in adolescence in Peru

OBJECTIVES

According to a large-scale international survey, Peru has one of the highest prevalences of asthma worldwide; however, data from this survey were limited to participants from urban Lima. The authors sought to characterise the epidemiology of asthma in Peru in two regions with disparate degrees of urbanisation. In this manuscript, the authors summarise the study design and implementation.

DESIGN

A cross-sectional study.

PARTICIPANTS

Using census data of 13-15-year-old adolescents from two communities in Peru, the authors invited a random sample of participants in Lima (n=725) and all adolescents in Tumbes (n=716) to participate in our study.

PRIMARY AND SECONDARY OUTCOME MEASURES

The authors asked participants to complete a questionnaire on asthma symptoms, environmental exposures and socio-demographics and to undergo spirometry before and after bronchodilator, skin allergy testing and exhaled nitric oxide testing. The authors obtained blood samples for haematocrit, total IgE levels, vitamin D levels and DNA in all participants and measured indoor particulate matter concentrations for 48 h in a random subset of 70-100 households at each site.

RESULTS

Of 1851 eligible participants, 1441 (78%) were enrolled and 1159 (80% of enrolled) completed all physical tests. 1283 (89%) performed spirometry according to standard guidelines, of which 86% of prebronchodilator tests and 92% of postbronchodilator tests were acceptable and reproducible. 92% of allergy skin tests had an adequate negative control. The authors collected blood from 1146 participants (79%) and saliva samples from 148 participants (9%). Overall amounts of DNA obtained from blood or saliva were 25.8 μg, with a 260/280 ratio of 1.86.

CONCLUSIONS

This study will contribute to the characterisation of a variety of risk factors for asthma, including urbanisation, total IgE levels, vitamin D levels and candidate genes, in a resource-poor setting. The authors present data to support high quality of survey, allergic, spirometric and genetic data collected in our study.

Exercise challenge test in 3- to 6-year-old asthmatic children

RATIONALE

The exercise challenge test (ECT) is a common tool to assess exercise-induced asthma (EIA) in school-aged children. EIA has not been explored in the early childhood setting.

OBJECTIVE

To assess the existence of EIA in children in this age group.

MEASUREMENTS AND MAIN RESULTS

A 6-min, controlled, free-run test was performed in 55 children (age range, 3 to 6 years old) who were classified into the following groups: 30 children in whom asthma had been previously diagnosed (group A); and 25 children with prolonged coughing (group B). Spirometry measurements were obtained before the run, and at 1, 2, 3, 5, 10, and 20 min after the run. A positive finding of EIA was defined as a 13% decrease from baseline FEV(1) or baseline forced expiratory volume in the first 0.5 s (FEV(0.5)). The actual duration of each run was age-related (mean [+/- SD] duration, 4.8 +/- 0.8 min). The nadir in indexes occurred after a mean time of 2.98 +/- 1.31 min. A positive EIA finding determined by FEV(1) was present in 15 children, and by FEV(0.5) in 34 children. Twenty-six children were from group A, but only 8 children were from group B. Wheezing and/or prolonged expiration were associated with a positive test result in 31 of 34 children. Coughing was frequent in children with both negative and positive ECT findings.

CONCLUSION

The present study documents for the first time the presence of EIA in response to a free-run test in early childhood. Our findings suggest that a free-run test for the presence of EIA is suitable, but that the running duration is limited by age. The duration of airflow limitation after exercise is significantly earlier and shorter in young children with asthma compared with older children. FEV(0.5) is a better index than the traditional FEV(1) for describing positive ECT results in young children. The association of wheezing and/or prolonged expiration may help in defining EIA in early childhood in the absence of a spirometer.

[Exercise test for asthmatic children. For whom? What indications?]

Asthma in children is not the most important indication for an exercise test. However, one might recommend a cardiopulmonary exercise test systematically in the follow-up of patients with severe asthma when there is persistent bronchial obstruction, when an asthmatic child complains of dyspnoea on exertion, or when the child's physical activity is limited. This test could be used to assess exercise tolerance, ventilatory adaptations, and the need for exercise training. Follow-up and evaluation of this training could be through a field exercise test (shuttle test or walk test). Moreover, the diagnosis of childhood asthma is frequently based only on symptoms suggestive of exercise-induced asthma. When the clinical features or a bronchodilatator test are not diagnostic, analysis of symptoms occurring during an exercise test can establish the diagnosis. The exercise test is thus a method that provides the time and intensity necessary to trigger exercise-induced bronchospasm.