Cold air inhalation and exercise-induced bronchoconstriction in relationship to metacholine bronchial responsiveness: different patterns in asthmatic children and children with other chronic lung diseases

Cold waves and fine particulate matter in high-altitude Chinese cities: assessing their interactive impact on outpatient visits for respiratory disease

BACKGROUND

Extreme weather events like heatwaves and fine particulate matter (PM2.5) have a synergistic effect on mortality, but research on the synergistic effect of cold waves and PM2.5 on outpatient visits for respiratory disease, especially at high altitudes in climate change-sensitive areas, is lacking.

METHODS

we collected time-series data on meteorological, air pollution, and outpatient visits for respiratory disease in Xining. We examined the associations between cold waves, PM2.5, and outpatient visits for respiratory disease using a time-stratified case-crossover approach and distributional lag nonlinear modeling. Our analysis also calculated the relative excess odds due to interaction (REOI), proportion attributable to interaction (AP), and synergy index (S). We additionally analyzed cold waves over time to verify climate change.

RESULTS

Under different definitions of cold waves, the odds ratio for the correlation between cold waves and outpatient visits for respiratory disease ranged from 0.95 (95% CI: 0.86, 1.05) to 1.58 (1.47, 1.70). Exposure to PM2.5 was significantly associated with an increase in outpatient visits for respiratory disease. We found that cold waves can synergize with PM2.5 to increase outpatient visits for respiratory disease (REOI > 0, AP > 0, S > 1), decreasing with stricter definitions of cold waves and longer durations. Cold waves' independent effect decreased over time, but their interaction effect persisted. From 8.1 to 21.8% of outpatient visits were due to cold waves and high-level PM2.5. People aged 0-14 and ≥ 65 were more susceptible to cold waves and PM2.5, with a significant interaction for those aged 15-64 and ≥ 65.

CONCLUSION

Our study fills the gap on how extreme weather and PM2.5 synergistically affect respiratory disease outpatient visits in high-altitude regions. The synergy of cold waves and PM2.5 increases outpatient visits for respiratory disease, especially in the elderly. Cold wave warnings and PM2.5 reduction have major public health benefits.

Evaluating Children and Adolescents with Suspected Exercise Induced Asthma: Real Life Data

OBJECTIVE

Exercise-induced bronchoconstriction (EIB) occurs frequently in children and adolescents and may be a sign of insufficient asthma control. EIB is often evaluated by respiratory symptoms, spirometry, eNO measurement and methacholine testing (MCT) instead of time consuming exercise test. Aim of this study was to analyse the amount of patients for which an exercise challenge in a cold chamber (ECC) was needed for a clear EIB diagnosis, to characterize EIB phenotypes and the incidence of exercise induced laryngeal obstruction (EILO) in a large cohort of patients with EIB.

METHODS

A retrospective analysis was performed in 595 children and adolescents (mean age 12.1 years) with suspected EIB from January 2014 to December 2018. Complete data sets of skin prick test, spirometry, eNO and MCT were available from 336 patients.

RESULTS

An ECC to confirm the EIB diagnosis was performed in 125 (37.2%) of patients. Three EIB phenotypes were detected: group 1: EIB without allergic sensitization (n=159); group 2: EIB with other than house dust mite (HDM) sensitization (n=87) and group 3: EIB with HDM sensitization (n=90). MCT and eNO showed significant differences between the subgroups: An eNO>46 ppb and/or a MCT<0.1 mg was found in 23.9% vs. 50.6% vs. 57.8% in group 1-3, respectively. Significantly more patients suffered from EILO in group 1 compared to group 2 and 3 (n=13 vs. n=1).

CONCLUSION

EIB without sensitization is as often as EIB with sensitization. In patients without sensitization, EILO has to be considered as a possible cause of symptoms during exercise.

Recommendations for 24-Hour Movement Behaviours in Adults with Asthma: A Review of Current Guidelines

Background: Many countries have clinical practice guidelines (CPG) for asthma that serve as an important resource for healthcare professionals and inform the development of policies and practices relevant to asthma care. The purpose of this scoping review was to search for CPGs related to asthma to determine what recommendations related to the 24-h movement behaviours are provided. Methods: We searched for the most recent CPGs published by a national authoritative body from 195 countries. Guidelines were reviewed for all movement behaviours; that is, physical activity, sedentary behaviour, and sleep. Results: In total, 82 documents were searched for eligibility and 19 were included in our review. Of these, only 10 CPGs provided information on physical activity; none provided recommendations consistent with the FITT principle, while seven recommended activity levels similar to the general population. None of the guidelines included information on sedentary behaviour. Nine guidelines included information on sleep: recommendations mostly focused on changes to medication to reduce disruptions in sleep. Conclusions: It is recommended that future work be conducted to create comprehensive movement behaviour guidelines accompanied with relevant precautions and strategies to ensure that adults with asthma are able to safely and effectively engage in movement behaviours throughout the day.

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).

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.

Tools in Asthma Evaluation and Management: When and How to Use Them?

The goals of asthma management are accurate diagnosis, prompt initiation of treatment and monitoring of disease progression to limit potential morbidity and mortality. While the diagnosis and management is largely based on history taking and clinical examination, there are an increasing number of tools available that could be used to aid diagnosis, define phenotypes, monitor progress and assess response to treatment. Tools such as the Asthma Predictive Index could help in making predictions about the possibility of asthma in childhood based on certain clinical parameters in pre-schoolers. Lung function measurements such as peak expiratory flow, spirometry, bronchodilator responsiveness, and bronchial provocation tests help establish airway obstruction and variability over time. Tools such as asthma questionnaires, lung function measurements and markers of airway inflammation could be used in combination with clinical assessments to assess ongoing asthma control. Recent advances in digital technology, which open up new frontiers in asthma management, need to be evaluated and embraced if proven to be of value. This review summarises the role of currently available tools in asthma diagnosis and management. While many of the tools are readily available in resource rich settings, it becomes more challenging when working in resource poor settings. A rational approach to the use of these tools is recommended.

Difficult vs. Severe Asthma: Definition and Limits of Asthma Control in the Pediatric Population

Evaluating the degree of disease control is pivotal when assessing a patient with asthma. Asthma control is defined as the degree to which manifestations of the disease are reduced or removed by therapy. Two domains of asthma control are identified in the guidelines: symptom control and future risk of poor asthma outcomes, including asthma attacks, accelerated decline in lung function, or treatment-related side effects. Over the past decade, the definition and the tools of asthma control have been substantially implemented so that the majority of children with asthma have their disease well controlled with standard therapies. However, a small subset of asthmatic children still requires maximal therapy to achieve or maintain symptom control and experience considerable morbidity. Childhood uncontrolled asthma is a heterogeneous group and represents a clinical and therapeutic challenge requiring a multidisciplinary systematic assessment. The identification of the factors that may contribute to the gain or loss of control in asthma is essential in differentiating children with difficult-to-treat asthma from those with severe asthma that is resistant to traditional therapies. The aim of this review is to focus on current concept of asthma control, describing monitoring tools currently used to assess asthma control in clinical practice and research, and evaluating comorbidities and modifiable and non-modifiable factors associated with uncontrolled asthma in children, with particular reference to severe asthma.

Bronchial hyper-responsiveness after preterm birth

Being born preterm often adversely affects later lung function. Airway obstruction and bronchial hyperresponsiveness (BHR) are common findings. Respiratory symptoms in asthma and in lung disease after preterm birth might appear similar, but clinical experience and studies indicate that symptoms secondary to preterm birth reflect a separate disease entity. BHR is a defining feature of asthma, but can also be found in other lung disorders and in subjects without respiratory symptoms. We review different methods to assess BHR, and findings reported from studies that have investigated BHR after preterm birth. The area appeared understudied with relatively few and heterogeneous articles identified, and lack of a pervasive understanding. BHR seemed related to low gestational age at delivery and a neonatal history of bronchopulmonary dysplasia. No studies reported associations between BHR after preterm birth and the markers of eosinophilic inflammatory airway responses typically found in asthma. This should be borne in mind when treating preterm born individuals with BHR and airway symptoms.

Compact Eucapnic Voluntary Hyperpnoea Apparatus for Exercise-Induced Respiratory Disease Detection

Eucapnic voluntary hyperpnoea (EVH) challenge provides objective criteria for exercise-induced asthma (EIA) or exercise-induced bronchoconstriction (EIB), and it was recommended to justify the use of inhaled β₂-agonists by athletes for the Olympics. This paper presents the development of a compact and easy-to-use EVH apparatus for assessing EIB in human subjects. The compact apparatus has been validated on human subjects and the results have been compared to the conventional EVH system. Twenty-two swimmers, including eleven healthy subjects and eleven subjects who had been physician-diagnosed with asthma, were recruited from sport and recreation centers throughout Auckland, New Zealand. Each subject performed two EVH challenge tests using the proposed breathing apparatus and the conventional Phillips EVH apparatus on separate days, respectively. Forced expiratory volume in one second (FEV₁) was measured before and after the challenges. A reduction in FEV₁ of 10% or more was considered positive. Of the eleven subjects who were previously diagnosed with asthma, EIB was present in all subjects (100%) in the compact EVH group, while it was presented in ten subjects (90.91%) in the conventional EVH challenge group. Of the eleven healthy subjects, EIB was present in one subject (4.55%) in the compact EVH group, while it was not present in the conventional EVH group. Experimental results showed that the compact EVH system has potential to become an alternative tool for EIB detection.

Bronchial hyperresponsiveness in childhood: A narrative review

Bronchial hyperresponsiveness (BHR) is an important but not asthma-specific characteristic and can be assessed by direct and indirect methods, based on the stimulus causing airway obstruction. BHR has been proposed as a prognostic marker of asthma severity and persistence, and may also be used to control pharmacological management of asthma. The most recent data on the prevalence and development of BHR in childhood and its predictive value for subsequent asthma development in late adolescence and adulthood is discussed in this review. According to the BHR-related scientific articles written in the English language and indexed in the publicly searchable PubMed database, the prevalence of BHR varies based upon the methods used to assess it and the population examined. In general, however, BHR prevalence is reduced as children grow older, in both healthy and asthmatic populations. While asthma can be predicted by BHR, the predictive value is limited. Reduced lung function, allergic sensitization, female sex, and early respiratory illness have been identified as risk factors for BHR. The collective studies further indicate that BHR is a dynamic feature related to asthma, but asymptomatic BHR is also common. Ultimately, the prevalence of BHR varies depending on the population, the environment, and the evaluation methods used. While both the methacholine challenge and the exercise test may predict asthma in adolescence or early adulthood, the predictive value is higher for the methacholine challenge compared to the exercise test. The collective data presented in the present study demonstrate how BHR develops through childhood and its relation to bronchial asthma.

Monitoring asthma in childhood: lung function, bronchial responsiveness and inflammation

This review focuses on the methods available for measuring reversible airways obstruction, bronchial hyperresponsiveness (BHR) and inflammation as hallmarks of asthma, and their role in monitoring children with asthma. Persistent bronchial obstruction may occur in asymptomatic children and is considered a risk factor for severe asthma episodes and is associated with poor asthma outcome. Annual measurement of forced expiratory volume in 1 s using office based spirometry is considered useful. Other lung function measurements including the assessment of BHR may be reserved for children with possible exercise limitations, poor symptom perception and those not responding to their current treatment or with atypical asthma symptoms, and performed on a higher specialty level. To date, for most methods of measuring lung function there are no proper randomised controlled or large longitudinal studies available to establish their role in asthma management in children. Noninvasive biomarkers for monitoring inflammation in children are available, for example the measurement of exhaled nitric oxide fraction, and the assessment of induced sputum cytology or inflammatory mediators in the exhaled breath condensate. However, their role and usefulness in routine clinical practice to monitor and guide therapy remains unclear, and therefore, their use should be reserved for selected cases.

Assessment of exercise-induced bronchoconstriction in adolescents and young children

Recent research shows important differences in exercise-induced bronchoconstriction (EIB) between children and adults, suggesting a different pathophysiology of EIB in children. Although exercise can trigger classic symptoms of asthma, in children symptoms can be subtle and nonspecific; parents, children, and clinicians often do not recognize EIB. With an age-adjusted protocol, an exercise challenge test can be performed in children as young as 3 years of age. However, an alternative challenge test is sometimes necessary to assess potential for EIB in children. This review summarizes age-related features of EIB and recommendations for assessing EIB in young children and adolescents.

Positive exercise test and obstructive spirometry in young male conscripts associated with persistent asthma 20 years later

BACKGROUND

Asthma often begins in childhood or early adulthood and is a common disease among conscripts. The identification of long-term predictive factors for persistent asthma may lead to improved treatment opportunities and better disease control.

OBJECTIVE

Our aim was to study the prognostic factors of the severity of asthma among 40-year-old male conscripts whose asthma began in youth.

METHODS

We studied 119 conscripts who were referred to the Central Military Hospital during 1987-1990 due to asthma and who attended a follow-up visit approximately 20 years later. Asthma severity was evaluated during military service according to the medical records, and 20 years later during a follow-up visit using Global Initiative for Asthma guidelines. We used the results of lung function and allergy tests at baseline as predictors of current persistent asthma.

RESULTS

Compared with baseline, asthma was less severe at follow-up: 11.8% of subjects were in remission, 42.0% had intermittent asthma, 10.9% had mild persistent asthma, and 35.3% had moderate/severe persistent asthma (p < .001). In multivariate models, a positive exercise test at baseline yielded an odds ratio (OR) of 3.2 (95% CI 1.0-9.8, p = .046), a decreased FEV1/FVC % predicted an OR of 4.0 (95% CI 1.7-9.3, p = .002), and a decreased FEF50% % predicted an OR of 2.8 (95% CI 1.3-6.4, p = .012) for current persistent asthma.

CONCLUSIONS

About half of the men had persistent asthma at the 20-year follow-up. Positive exercise tests and obstructive spirometry results were related to the persistence of asthma and may be useful long-term prognostic factors for asthma severity.

Does bronchial hyperresponsiveness in childhood predict active asthma in adolescence?

RATIONALE

Bronchial hyperresponsiveness (BHR) is an important, but not specific, asthma characteristic.

OBJECTIVES

We aimed to assess the predictive value of BHR tested by methacholine and exercise challenge at age 10 years for active asthma 6 years later.

METHODS

From a Norwegian birth cohort, 530 children underwent methacholine challenge and exercise-induced bronchoconstriction (EIB) test (n = 478) at 10 years and structured interview and clinical examination at age 16 years. The methacholine dose causing 20% reduction in FEV(1) (PD(20)) and the reduction in FEV(1) (%) after a standardized treadmill test were used for BHR assessment. Active asthma was defined with at least two criteria positive: doctor's diagnosis of asthma, symptoms of asthma, and/or treatment for asthma in the last year.

MEASUREMENTS AND MAIN RESULTS

PD(20) and EIB at 10 years of age increased the risk of asthma (β = 0.94 [95% confidence interval (CI), 0.92-0.96] per μmol methacholine and β = 1.10 [95% CI, 1.06-1.15] per %, respectively). Separately the tests explained 10 and 7%, respectively, and together 14% of the variation in active asthma 6 years later. The predicted probability for active asthma at the age of 16 years increased with decreasing PD(20) and increasing EIB. The area under the curve (receiver operating characteristic curves) was larger for PD(20) (0.69; 95% CI, 0.62-0.75) than for EIB (0.60; 95% CI, 0.53-0.67).

CONCLUSIONS

BHR at 10 years was a significant but modest predictor of active asthma 6 years later, with methacholine challenge being superior to exercise test.

Current concepts in the diagnosis and management of exercise-induced bronchospasm

Exercise-induced bronchospasm (EIB) is a common occurrence in individuals with asthma, though it can also affect individuals without asthma. It occurs frequently in athletes. Common symptoms include coughing, dyspnea, chest tightness, and wheezing; however, there can be a variety of more subtle symptoms. The differential diagnosis of EIB is broad and includes several pulmonary and cardiac disorders. During the initial evaluation, a complete history, physical examination, and spirometry should be performed. In most patients with EIB, the baseline spirometry is normal; therefore, bronchoprovocation testing is strongly recommended. Both pharmacologic and nonpharmacologic approaches are important in the treatment of EIB. Management of EIB on the sideline of athletic events requires preparation and immediate access to rescue inhalers.

Childhood asthma and environmental exposures at swimming pools: state of the science and research recommendations

OBJECTIVES

Recent studies have explored the potential for swimming pool disinfection by-products (DBPs), which are respiratory irritants, to cause asthma in young children. Here we describe the state of the science on methods for understanding children's exposure to DBPs and biologics at swimming pools and associations with new-onset childhood asthma and recommend a research agenda to improve our understanding of this issue.

DATA SOURCES

A workshop was held in Leuven, Belgium, 21-23 August 2007, to evaluate the literature and to develop a research agenda to better understand children's exposures in the swimming pool environment and their potential associations with new-onset asthma. Participants, including clinicians, epidemiologists, exposure scientists, pool operations experts, and chemists, reviewed the literature, prepared background summaries, and held extensive discussions on the relevant published studies, knowledge of asthma characterization and exposures at swimming pools, and epidemiologic study designs.

SYNTHESIS

Childhood swimming and new-onset childhood asthma have clear implications for public health. If attendance at indoor pools increases risk of childhood asthma, then concerns are warranted and action is necessary. If there is no such relationship, these concerns could unnecessarily deter children from indoor swimming and/or compromise water disinfection.

CONCLUSIONS

Current evidence of an association between childhood swimming and new-onset asthma is suggestive but not conclusive. Important data gaps need to be filled, particularly in exposure assessment and characterization of asthma in the very young. Participants recommended that additional evaluations using a multidisciplinary approach are needed to determine whether a clear association exists.

Mechanisms of asthma in Olympic athletes--practical implications

Athletes' symptoms may only occur in extreme conditions, which are far from normal. Exercise may increase ventilation up to 200 l/min for short periods in speed and power athletes, and for longer periods in endurance athletes such as swimmers and cross-country skiers. Increasing proportions of young athletes are atopic, i.e. they show signs of IgE-mediated allergy which is, along with the sport event (endurance sport), a major risk factor for asthma and respiratory symptoms. Mechanisms in the etiology and clinical phenotypes vary between disciplines and individuals, and it may be an oversimplification to discuss athlete's asthma as a distinct and unambiguous disease. Nevertheless, the experience on Finnish Olympic athletes suggests at least two different clinical phenotypes, which may reflect different underlying mechanisms. The pattern of 'classical asthma' is characterized by early onset childhood asthma, methacholine responsiveness, atopy and signs of eosinophilic airway inflammation, reflected by increased exhaled nitric oxide levels. Another distinct phenotype includes late onset symptoms (during sports career), bronchial responsiveness to eucapnic hyperventilation test, but not necessarily to inhaled methacholine, and a variable association with atopic markers and nitric oxide. A mixed type of eosinophilic and neutrophilic airway inflammation seems to affect especially swimmers, ice-hockey players, and cross-country skiers. The inflammation may represent a multifactorial trauma, in which both allergic and irritant mechanisms play a role. There is a significant problem of both under- and overdiagnosing asthma in athletes and the need for objective testing is emphasized. Follow-up studies are needed to assess the temporal relationship between asthma and competitive sporting, taking better into account individual disposition, environmental factors (exposure), intensity of training and potential confounders.

Exercise-induced changes in respiratory impedance in young wheezy children and nonatopic controls

Exercise-induced bronchoconstriction (EIB) is a specific sign of active asthma, but its assessment in young children may be difficult with lung function techniques requiring active cooperation. The aim of the study was to assess the normal pattern of exercise-induced responses of respiratory impedance by using impulse oscillometry (IOS), and to investigate how these responses discriminate wheezy children from control subjects. IOS measurements were performed in a consecutive sample of wheezy children aged 3-7 years (n = 130) and in an aged matched control group of nonatopic children without respiratory symptoms (n = 79) before and after a free running test. After exercise, wheezy children showed significantly larger responses in respiratory resistance (Rrs5), reactance (Xrs5), and the resonance frequency (Fr) than the control subjects. In the control group, the upper 95% confidence limit of the maximal change was 32.5% for Rrs5, 85.7% for Xrs5, and 53.1% for Fr. By using analysis of receiver operating characteristics, the change in Rrs5 distinguished the wheezy children from the control subjects more effectively than change in Xrs5 or Fr. In wheezy children, the response was significantly effected by the outdoor temperature and exercise intensity in terms of maximum heart rate. In conclusion, an increase of 35% in Rrs5 after a free running test can be regarded as an abnormal response. Wheezy children show an enhanced airway response, which is clearly distinguishable from the control subjects. IOS is a feasible method to detect EIB in young children.

Exercise-induced asthma, respiratory and allergic disorders in elite athletes: epidemiology, mechanisms and diagnosis: part I of the report from the Joint Task Force of the European Respiratory Society (ERS) and the European Academy of Allergy and Clinical Immunology (EAACI) in cooperation with GA2LEN

AIMS

To analyze the changes in the prevalence of asthma, bronchial hyperresponsiveness (BHR) and allergies in elite athletes over the past years, to review the specific pathogenetic features of these conditions and to make recommendations for their diagnosis.

METHODS

The Task Force reviewed present literature by searching Medline up to November 2006 for relevant papers by the search words: asthma, bronchial responsiveness, EIB, athletes and sports. Sign criteria were used to assess level of evidence and grades of recommendation.

RESULTS

The problems of sports-related asthma and allergy are outlined. Epidemiological evidence for an increased prevalence of asthma and BHR among competitive athletes, especially in endurance sports, is provided. The mechanisms for development of asthma and bronchial hyperresponsiveness in athletes are outlined. Criteria are given for the diagnosis of asthma and exercise induced asthma in the athlete.

CONCLUSIONS

The prevalence of asthma and bronchial hyperresponsiveness is markedly increased in athletes, especially within endurance sports. Environmental factors often contribute. Recommendations for the diagnosis of asthma in athletes are outlined.

Exercise capacity and exercise-induced bronchoconstriction (EIB) in a cold environment

INTRODUCTION

Exercise in a cold environment has been reported to increase exercise-induced bronchoconstriction (EIB). However, the effect of a cold environment upon exercise capacity in subjects with EIB has, to our knowledge, not been previously reported.

PURPOSE

Primary: To examine the influence of changing environmental temperature upon exercise capacity measured by peak oxygen uptake (VO(2 peak)), peak ventilation (VE(peak)) and peak running speed in subjects with diagnosed EIB. Secondary: To assess the influence of changing environmental temperature upon EIB.

METHODS

Twenty subjects (10-45 years old, male/female: 13/7) with EIB underwent exercise testing by running on a treadmill in a climate chamber under standardised, regular conditions, 20.2 degrees C (+/-1.1) and 40.0% (+/-3.3) relative humidity [mean(+/-SD)], and in a standardised cold environment, -18.0 degrees C (+/-1.4) and 39.2% (+/-3.8) relative humidity in random order on separate days. Oxygen uptake (VO(2)), minute ventilation (V E), respiratory exchange ratio (RER), heart rate (HR) and running speed were measured during exercise. Lung function (flow volume loops) was measured before and 1, 3, 6, 10 and 15 min after exercise and 15 min after inhalation of salbutamol.

RESULTS

VO(2 peak) decreased 6.5%, from 47.9 (45.0, 50.8) to 44.8 ml kg(-1)min(-1) (41.2, 48.4) [mean (95% confidence intervals)] (p=0.004) in the cold environment. Also running speed was significantly lower in the cold environment (p=0.02). No differences were found for VE(peak), RER(peak) or HR(peak). The post-exercise reduction in forced expiratory volume in 1s (FEV(1)) (DeltaFEV(1)) increased significantly from 24% (19,29) to 31% (24,38), respectively (p=0.04) after exercise in the cold environment. No correlation was found between reduction in VO(2 peak) and the increased maximum fall in FEV(1) in the cold environment.

CONCLUSION

Exercise capacity (VO(2 peak) and peak running speed) was markedly reduced during exercise in a cold environment whereas EIB increased in subjects suffering from EIB.

Bronchial hyperresponsiveness, atopy, and bronchoalveolar lavage eosinophils in persistent middle lobe syndrome

Most cases of middle lobe syndrome (MLS) in children are considered to be due to asthma and may recover spontaneously; however, in persistent MLS, repeated episodes of infection often institute a vicious cycle that may lead to persistent symptoms and bronchial hyperresponsiveness (BHR). The present study was undertaken to investigate whether asthma, as an underlying diagnosis, is predictive of a favorable outcome of children with persistent MLS. We evaluated 53 children with MLS who underwent an aggressive management protocol that included fiberoptic bronchoscopy (FOB) and bronchoalveolar lavage (BAL). These patients were compared to two other groups: one consisting of children with current asthma but no evidence of MLS (N = 40) and another of non-asthmatic controls (N = 42), matched for age and sex. Prevalence of sensitization (>or=1 aeroallergen) did not differ between patients with MLS and "non-asthmatics" but was significantly lower than that of "current asthmatics." A positive response to methacholine bronchial challenge was observed with increased frequency among children with MLS when compared to "current asthmatic" and non-asthmatic children. Multivariate logistic regression analysis revealed a positive correlation between an increased number of eosinophils in the BAL fluid (BALF) and a favorable outcome, whereas no correlation was detected between sensitization or BHR and BAL cellular components. In conclusion, children with MLS have an increased prevalence of BHR, even when compared to asthmatics, but exhibit prevalence of atopy similar to that of non-asthmatics. An increased eosinophilic BALF count is predictive of symptomatic but not radiographic improvement of MLS patients after aggressive anti-asthma management.

Clinical Stress Testing in the Pediatric Age Group

This statement is an updated report of the American Heart Association’s previous publications on exercise in children. In this statement, exercise laboratory requirements for environment, equipment, staffing, and procedures are presented. Indications and contraindications to stress testing are discussed, as are types of testing protocols and the use of pharmacological stress protocols. Current stress laboratory practices are reviewed on the basis of a survey of pediatric cardiology training programs.

Humidity influences exercise capacity in subjects with exercise-induced bronchoconstriction (EIB)

RATIONALE

Exercise-induced bronchoconstriction (EIB) increases in cold and dry air and decreases in humid air in subjects with asthma. Few reports have reported on the effect of humid environment upon exercise capacity in subjects with EIB.

OBJECTIVE

The primary aim of the present study was to examine the effect of changing the humidity of the environmental air upon exercise capacity measured by peak oxygen uptake (V O2 peak), peak ventilation (V Epeak) and peak running speed (V peak) and secondarily to assess the influence of environmental humidity upon EIB in subjects suffering from EIB.

METHODS

Twenty subjects (10-45 years old, male/female:13/7) with diagnosed EIB performed exercise testing under standardised, regular environmental conditions, 20.2 degrees C (+/- 1.1) and 40% (+/- 3.3) relative humidity [mean (+/- SD)], and under standardised humid environmental conditions; 19.9 degrees C (+/- 1.0) and 95% (+/- 1.7) relative humidity in random order on separate days. Lung function was measured before and 1, 3, 6, 10 and 15 min after exercise. Heart rate (HR), oxygen uptake (V O2), respiratory gas exchange ratio (RER), breathing frequency (BF) and minute ventilation (V E) were measured during exercise.

RESULTS

V O2 peak and V peak increased significantly from 40% to 95% relative humidity of the environmental air, 4.5% and 5.9%, respectively (P = 0.001). HRpeak increased significantly in the humid environment, while BF(peak) decreased significantly. RERpeak and V Epeak did not change significantly. Post-exercise reduction in FEV1 (DeltaFEV1) and FEF50 (forced expiratory flow at 50% of FVC) (DeltaFEF50) significantly decreased after exercise in a humid environment as compared to regular conditions, DeltaFEV1: 12% (7,17) vs. 24% (19,29) [mean (95% confidence intervals)], respectively, DeltaFEF50: 20% (12,29) vs. 38% (30,46), respectively (P < 0.001).

CONCLUSION

Exercise capacity (V O2 peak and V peak) markedly improved during exercise in humid air in subjects with EIB, whereas EIB was reduced to the half.

Exercise-induced bronchospasm among healthy elite cross country skiers and non-athletic students

Regular exercise in cold, dry air is believed to be a predisposing factor for exercise-induced bronchospasm (EIB). The aim of this study was to compare the occurrence of EIB among previously healthy elite cross country skiers and their non-athletic control subjects. Twenty healthy elite cross country skiers and 18 non-asthmatic controls were challenged by a standardized free exercise test. Thereafter, subjects' respiratory function was followed by flow-volume spirometry up to 30 min. EIB was defined in the post-exercise spirometry as at least one of the following: a >or=10% decrease in forced expiratory volume in 1 s (FEV1), a >or=20% decrease in mean maximal expiratory flow (MMEF) or a >or=25% decrease in peak expiratory flow rate (PEF). EIB was found in two skiers and one control according to FEV1, for seven skiers and two controls according to MMEF. Two skiers and one control had exercise-induced asthma (EIA) according to both parameters. The largest decrease in PEF was 13%, that did not result in additional diagnoses. All nine of the subjects with a positive test result reported asthma-like symptoms (dyspnea, cough or increased mucus excretion) after the exercise challenge. Accordingly, seven previously healthy skiers (35%) and two controls (11%) were diagnosed as having EIB. In addition, three skiers of the original cohort were excluded because of an earlier asthma diagnosis, making the total asthma prevalence 10/23 (42%) among the elite skiers. It was concluded that EIB is more common in elite cross country skiers than in non-athletic controls. The bronchoconstriction induced by exercise is usually mild or moderate, and flow-volume spirometry with sensitive flow parameters is needed for it to be diagnosed. Even a mild asthma decreases minute ventilation and maximal performance of winter sport athletes. Therefore, skiers with long-term respiratory symptoms or decreased performance should be studied for EIA and treated adequately.

Health, place and childhood asthma in southwest Alaska

Social science theories of health and place posit that individuals perceive a relationship between characteristics of the geographic location in which they reside and their health, well-being, and self-identity. A number of ethnographies of health and place have studied how urban and suburban populations impacted by industrial pollution or waste have come to perceive a link between rates of cancer and their unhealthy environment. There has been little study of the applicability of the health and place framework to community perceptions of long-term chronic illness. This paper examines the asthma perceptions of Yup'ik parents of asthmatic children using data from semi-structured ethnographic interviews conducted in five villages and one town of the Yukon-Kuskokwim delta of southwest Alaska. Informants cited local climatic features, large-scale changes of the last 30 years to the village built landscape, and ongoing conditions of substandard housing and sanitation as etiological factors associated with childhood asthma. Our study suggests the need for further research concerning lay perceptions of one aspect of the epidemilogic transition-the association between chronic illness and place, especially in rural communities undergoing dramatic developmental change.

Exercise-Induced Asthma: An Update

Exercise-induced asthma (E.I.A) affects 12–16% of the general population and most of the patients affected by extrinsic or intrinsic asthma. Surprisingly, also a high percentage of professional and Olympic athletes are affected, showing that E.I.A. does not impair physical activity, whereas endurance sports bear a higher risk than the others. The mast cell role, late asthmatic responses, diagnosis, therapy, theories and data about immunological parameters in sports are taken into consideration in this review.

Does living in a cold climate or recreational skiing increase the risk for obstructive respiratory diseases or symptoms?

OBJECTIVES

Respiratory symptoms and obstructive pulmonary diseases experienced during exercise and in cold weather were analysed in a large postal questionnaire study of a general adult population living in a cold climate. The aim of this study was to assess the prevalence of shortness of breath (SOB) during exercise, or in cold weather, and to find out if the risks (odds ratio=OR) for asthma, chronic bronchitis, or SOB during exercise, or in cold weather, were affected by recreational cross-country skiing, or by outdoor work in a cold climate.

RESULTS

Of the 7937 invited persons, 84% responded; 876 of them were outdoor workers and 1497 were recreational cross-country skiers. Of the non-smoking responders, asthmatic subjects had the highest prevalence of SOB during exercise in cold weather (78%-82%), but allergic and bronchitic persons also had significantly higher prevalence rates (22%-38% and 27%-59%, respectively) than healthy persons (10%-19%). In all categories, the prevalence of SOB was significantly higher among current smokers than among ex- or non-smokers. Risk factor analysis revealed increased risks for respiratory conditions among those who had a family history of obstructive airway disease, or allergy. Skiers did not have a significantly increased risk for asthma, or respiratory symptoms. Among outdoor workers the risk for SOB during exercise in cold weather, OR 1.23 (CI 1.03-1.47), and for chronic bronchitis, OR 1.77 (CI 1.21-2.60), was higher than among indoor workers.

CONCLUSIONS

In conclusion, the risk for chronic bronchitis and bronchitic symptoms was elevated among outdoor workers, but not among regular recreational cross-country skiers, and the risk for asthma was not significantly elevated by regular exercising, or by working in a cold climate.

Methods for "indirect" challenge tests including exercise, eucapnic voluntary hyperpnea, and hypertonic aerosols

Bronchial provocation tests that use stimuli that act indirectly to cause airway narrowing have a high specificity for identifying people with active asthma who have the potential to respond to treatment with antiinflammatory drugs. The first test to be developed was exercise and it was used to assess the efficacy of drugs such as sodium cromoglycate. Eucapnic voluntary hyperpnea was developed later, as a surrogate test for exercise. Hypertonic aerosols were introduced to mimic the dehydrating effects of evaporative water loss that occurs during hyperpnea. A wet aerosol of 4.5% saline or a dry powder formulation of mannitol is used. At present the indirect challenge tests are becoming increasingly recognised as appropriate for monitoring treatment with inhaled steroids. Indirect tests identify those with potential for exercise-induced bronchoconstriction, an important problem for some occupations, such as the defence forces, fire fighters and the police force and for some athletic activities. The advantage in using an indirect challenges, over a direct challenge with a single pharmacological agonist, is that a positive response indicates that inflammatory cells and their mediators (prostaglandins, leukotrienes and histamine) are present in the airways in sufficient numbers and concentration to indicate that asthma is active at the time of testing. The corollary to this is that a negative test in a known asthmatic indicates good control or mild disease. Another advantage is that healthy subjects do not have significant airway narrowing to indirect challenge tests. The protocols used for challenge with indirectly acting stimuli are presented in detail.

Exercise-induced bronchoconstriction in children: montelukast attenuates the immediate-phase and late-phase responses

BACKGROUND

Montelukast, a leukotriene receptor antagonist, attenuates exercise-induced bronchoconstriction. We and others have shown that there is a late-phase response 3 to 8 hours after exercise in a subset of asthmatic patients.

OBJECTIVE

We sought to evaluate the protective effect of montelukast on immediate-phase and late-phase responses after exercise challenges.

METHODS

Twenty-two atopic asthmatic children aged 7 to 16 years with reproducible exercise-induced bronchoconstriction (minimum of 15% decrease of FEV(1) from baseline) were enrolled in this placebo-controlled crossover study. Exercise challenges were performed while breathing cold dry air, and FEV(1) measurements were taken up to 480 minutes after exercise. Patients underwent exercise challenges on a screening day and 1 week after placebo treatment. Subsequently, after a week with no treatment, pulmonary function was assessed after breathing dry cold air (control day). Finally, an exercise challenge was carried out after a week of treatment with montelukast.

RESULTS

Reproducible late-phase reactions occurred in 5 of 22 patients, which correlated with the extent of the immediate response (P <.05). After 1 week of treatment with montelukast, a significant decrease of immediate responses was observed. Montelukast treatment compared with placebo was associated with a lower mean maximum decrease of FEV(1) (mean +/- SEM: 17.3% +/- 2.4% and 35.1% +/- 2.6%, respectively), decrease of the area above the curve (267.8% +/- 42.7%/min and 868.0% +/- 103.8%/min, respectively), and shorter time for recovery (6.9 +/- 1.1 minutes and 30.9 +/- 4.0 minutes, respectively; P <.05). Treatment with montelukast also abolished late-phase responses.

CONCLUSION

Once daily treatment with oral montelukast attenuated the immediate-phase response and abolished the late-phase response induced by means of exercise challenge in asthmatic children.

In search of childhood asthma: questionnaire, tests of bronchial hyperresponsiveness, and clinical evaluation

BACKGROUND

The definition or diagnosis of asthma is a challenge for both clinicians and epidemiologists. Symptom history is usually supplemented with tests of bronchial hyperresponsiveness (BHR) in spite of their uncertainty in improving diagnostic accuracy.

METHODS

To assess the interrelationship between respiratory symptoms, BHR, and clinical diagnosis of asthma, the respiratory symptoms of 1633 schoolchildren were screened using a questionnaire (response rate 81.2%) and a clinical study was conducted in a subsample of 247 children. Data from a free running test and a methacholine inhalation challenge test were available in 218 children. The diagnosis of asthma was confirmed by a paediatric allergist.

RESULTS

Despite their high specificity (>0.97), BHR tests did not significantly improve the diagnostic accuracy after the symptom history: area under the receiver operator characteristic (ROC) curve was 0.90 for a logistic regression model with four symptoms and 0.94 for the symptoms with free running test and methacholine inhalation challenge results. On the other hand, BHR tests had low sensitivity (0.35-0.47), whereas several symptoms had both high specificity (>0.97) and sensitivity (>0.7) in relation to clinical asthma, which makes them a better tool for asthma epidemiology than BHR.

CONCLUSIONS

Symptom history still forms the basis for defining asthma in both clinical and epidemiological settings. BHR tests only marginally increased the diagnostic accuracy after symptom history had been taken into account. The diagnosis of childhood asthma should not therefore be overlooked in symptomatic cases with no objective evidence of BHR. Moreover, BHR should not be required for defining asthma in epidemiological studies.

Protection against cold air and exercise-induced bronchoconstriction while on regular treatment with Oxis

This study aimed to compare the duration of protection against exercise-induced bronchoconstriction (EIB) after inhalation of formoterol (Oxis) Turbuhaler with that of terbutaline Turbuhaler and placebo Turbuhaler in asthmatic patients treated regularly with formoterol Turbuhaler 9 microg b.i.d. and inhaled steroids. The study. performed at three centres (Göteborg and Lund, Sweden, and Trondheim, Norway), consisted of an open-label part with formoterol Turbuhaler 9 microg b.i.d. and a randomized, double-blind, cross-over part with a single dose (on top of the regular treatment) of either formoterol Turbuhaler 9 microg, terbutaline Turbuhaler 0.5 mg or placebo Turbuhaler. The patients attended the clinic six times: twice for screening visits, three times for randomized treatment and once for a follow-up visit. Patients received regular b.i.d. treatment with formoterol 9 microg for a mean period of 16 days. Formoterol gave a post-exercise fall of 12, 10, 15 and 17% in forced expiratory volume in 1 sec (FEV1) 15 min, 4, 8 and 12 h after inhalation. The differences compared with placebo (falls of 26, 22, 23 and 22%) and terbutaline (falls of 17, 18, 22 and 22%) were all statistically significant (P<0.05 for all comparisons). Patients on regular treatment with formoterol Turbuhaler 9 microg b.i.d. have a significant protection against EIB up to 12 h after inhalation of formoterol 9 microg. The protection was also significantly better than that of terbutaline Turbuhaler 0.5 mg.

Laboratory protocol for exercise asthma to evaluate salbutamol given by two devices

PURPOSE

As new delivery devices and formulations are being introduced for drugs given by inhalation, there is a need to evaluate their equivalence with old preparations. One way to do this is to investigate their equivalence in protecting from exercise-induced asthma (EIA).

METHODS

We used a protocol for EIA to compare the protective effect of salbutamol delivered by the pressurised metered dose inhaler (pMDI) and the new Diskus dry powder device. Twenty-seven asthmatic subjects with moderately severe EIA completed an exercise test on four separate days at two study centers. Exercise was performed by cycling for 8 min while inhaling dry air (0% RH, 20-24 degrees C). The target workload in W was predicted as (53.76 x predicted FEV1) - 11.07 and 95% of this target was achieved at 4 min of exercise. This target was chosen in order to achieve ventilation between 50 and 60% of predicted maximum in the last 4 min.

RESULTS

There was no significant difference in the workload, ventilation, or heart rate achieved on the study days. The severity of EIA was measured as the % fall in FEV1. EIA severity was similar on the placebo and control day and the coefficient of variation was 19.4%. The mean +/- SD % fall on the control, placebo, salbutamol by Diskus, and pMDI were 42.0% +/- 15, 39.4% +/-17.6, 13.4% +/- 13.2, and 8.5% +/- 13.8, respectively. Salbutamol significantly inhibited the % fall in FEV1 after exercise, and there was no difference between the preparations.

CONCLUSION

The protocol described here is suitable for evaluating equivalence of salbutamol preparations in protecting against EIA and could be used to evaluate the protective effect of other medications.

Histamine challenges discriminate between symptomatic and asymptomatic children. MAS-Study Group. Multicentre Allergy Study

The aims of this study were to investigate a threshold value for bronchial responsiveness in children aged 7 yrs, which discriminates between symptomatic and asymptomatic children, and to identify determinants of this responsiveness. Titrated bronchial histamine challenges using the reservoir method were performed in 645 children aged 7 yrs, from the birth cohort Multicentre Allergy Study (MAS). When defining a reference population of healthy children within the MAS cohort, the 95th percentile of the provocative concentration causing a 20% fall in forced expired volume in one second PC20 among these asymptomatic study subjects amounted to 0.60 mg x mL(-1). This resulted in a specificity of 93.0% and a sensitivity of 45.9%, for discriminating between "current wheezers" and "non-current wheezers". Determinants of airway responsiveness at this age were pulmonary function, sensitization to indoor allergens, total immunoglobulin E and current wheeze. The results indicate that a very low cut-off provocative concentration causing a 20% fall in forced expired volume in one second (<1.0 mg x mL(-1)) defines airway hyperresponsiveness in children aged 7 yrs using the reservoir method. Provocation protocols for histamine challenges in this age group should therefore start with concentrations markedly below 1.0 mg x mL(-1).

Exercise-induced asthma: is it the right diagnosis in elite athletes?

Exercise-induced asthma, as recognized in asthmatic subjects, is an exaggerated airway response to airway dehydration in the presence of inflammatory cells and their mediators. The airway narrowing is primarily caused by contraction of bronchial smooth muscle. The milder airway narrowing documented in response to exercise in elite athletes and otherwise healthy subjects may simply be the result of the physiologic responses and pathologic changes in airway cells arising from dehydration injury. These changes, which include excessive mucus production and airway edema, would serve both to cause cough and to amplify the narrowing effects of normal bronchial smooth muscle contraction, resulting in symptoms. These changes are more likely to occur in healthy subjects who exercise intensely for long periods of time breathing cold air, dry air, or both. Under these conditions, the ability to humidify inspired air may be overwhelmed, causing significant dehydration of the airway mucosa and an increase in osmolarity, even in small airways. In addition to dehydration injury, airway narrowing to pharmacologic and physical agents may occur as a result of injury caused by large volumes of air containing irritant gases, particulate matter, or allergens being inspired during exercise. As a result, the airways may become inflamed, and the airway smooth muscle may become more sensitive. These events could result in the same exaggerated airway response to dehydration, as documented in asthmatic subjects.

Exercise-induced bronchoconstriction depends on exercise load

Exercise-induced bronchoconstriction (EIB) is often used as a measure of bronchial hyperresponsiveness and employed in epidemiological studies. Different tests are used, including free running tests with poor standardization of exercise load. The present study aimed to assess the role of exercise load in relationship to level of EIB.

METHODS

20 asthmatic children, 9-17 years old with a history of EIB, underwent two treadmill test with 85% and 95% exercise load. The children ran with increasing speed for the first 2 min until reaching a heart rate of 85% or 95% of calculated maximum (220-age) and maintained this speed for the last 4 min. Lung function was measured before running, and 0, 3, 6, 10 and 15 min after the run. Borg scale for perceived exertion was employed for children's self-evaluation of exercise load.

RESULTS

Peak heart rate, mean Borg score during 85% exercise load was 178.7/13.6 and during 95% was 194.3/18.2 (P<0.001). Maximum fall in FEV1 after 85% exercise load was 8.84% vs. 25.11% after 95% (P<0.001). Nine subjects (40%) fell > or = 10% in FEV1 after 85% exercise load vs. 20 subjects (100%) after 95% exercise load. EIB from the 95% exercise load test had markedly higher correlation with serum ECP (r=0.77, P<0.001).

CONCLUSION

Exercise load is essential for the interpretation of EIB, and strict standardization of exercise tests should be undertaken. The EIB from the high exercise load tests seemed better correlated to inflammatory activity than the low exercise load test.

Formoterol via Turbuhaler gave better protection than terbutaline against repeated exercise challenge for up to 12 hours in children and adolescents

We aimed to compare the protective effect of single doses of 4.5 and 9 microg of formoterol fumarate (F), 0.5 mg terbutaline sulphate (T) and placebo (P), all via Turbuhaler, against exercise-induced bronchoconstriction (EIB) in children. Twenty-seven asthmatic children, showing a fall of > or =20% in FEV1 after a standardized exercise challenge test (ECT) combined with cold air (-10 degrees C) inhalation, were randomized in this cross-over, double-blind study. They had a mean age of 12.6 years (range 8-17 years), mean baseline FEV1 90% (73.9-105.6%) of predicted normal value. Seventeen children used inhaled glucocorticosteroids (120-750 microg day(-1)). ECTs were performed 15 min and 4, 8, and 12 h after drug administration. F significantly reduced the fall in FEV1 after ECT to 5.4% (15 min), 5.2% (4 h), 8.2% (8 h) and 9.3% (12 h) after 4.5 microg, and 2.5%, 3.0%, 5.0% and 5.4% after 9 microg, compared with a fall of 18.4%, 15.7%, 15.6% and 16.5% in FEV1 after P. The fall after T was 3.3%, 11.6%, 14.4% and 19.1% after 15 min, 4, 8 and 12 h respectively. The difference between F and T was statistically significant from 4 h and onward (P-value for all comparisons < 0.05). Children using a single dose of either formoterol Turbuhaler 4.5 or 9 microg had significantly better bronchoprotection against repeated exercise challenge up to 12 h compared with placebo and from 4 h onward compared with terbutaline Turbuhaler 0.5 mg.

Asthma and allergy among schoolchildren in a mountainous, dry, non-polluted area in Norway

The aim of this study was to assess prevalence of asthma and allergy in the non-polluted mountain area of Upper Hallingdal, Norway. All schoolchildren (7-16 years) who in a previous questionnaire survey (n = 1177) reported 'sometime' asthma were enrolled in group I (n = 80), the 59 who reported asthma-like symptoms in the past 12 months formed group II, and 77 of the healthy controls were randomly selected as group III. All 216 children underwent clinical examination, skin prick test, spirometry, bronchial provocation (PD20 metacholine) and treadmill exercise test. Subsequently they were reclassified as (1) healthy, never had asthma or symptoms, (2) symptoms not confirmed as asthma, (3) previous asthma, now healthy, (4) current asthma. Lifetime asthma prevalence was 10.2%. Based upon clinical examination, the specificity and sensitivity of the questionnaire for asthma diagnosis were 88 and 74%, respectively. Forced vital capacity was significantly higher among the asthmatics (group 4 versus 1), whereas forced expiratory volume in one second (FEV1) and forced expiratory flow at 50% of vital capacity were similar in all groups. More than 10% reduction in FEV1 following treadmill-run was found in 20% of children. Children with current asthma compared to controls had significantly; lower mean values of PD20 (9.1 versus 16.5 micromol), higher eosinophil cationic protein (13.4 versus 7.7 micromol) and more frequent sensitization to animal dander (56% versus 10%). In conclusion, despite a favorable climate, little mite sensitization and low outdoor pollution, asthma prevalence was surprisingly high in Upper Hallingdal. Sensitization to animal dander was the most important contributing factor for current asthma.

Prevalence and characteristics of exercise-induced asthma in children

We have evaluated the prevalence and the characteristics of exercise-induced asthma (EIA) in a group of 71 patients with a prior history of mild, moderate or severe asthma (42 males and 29 females), aged 6-16 years-old. Measurements of the forced expiratory volume in 1 second (FEV1) were obtained before and at regular intervals up to 8 hours following exercise. As a control, the same patients were evaluated at similar time intervals on another day when they had not been submitted to an exercise challenge. Using pre-exercise FEV1 values as the reference, 32 patients (45.1%) had a positive exercise challenge, defined as a fall in FEV1 value equal to or greater than 15% from baseline following exercise. Among the patients with a positive exercise challenge, the majority (23/32, 71.8%) had an immediate response alone, with no significant changes in FEV1 within the 8-hour follow-up. However, a subgroup of patients (9/32, 28.1%) had both an immediate and a late-phase response to exercise. During the control day, no significant fall in FEV1 were observed. In keeping with previous investigations, no correlation was found between a history of EIA and a positive exercise challenge in the present study. Positive exercise challenges were found more frequently among patients with moderate and severe asthma than patients with mild asthma.