Pediatric exercise-induced bronchoconstriction: contemporary developments in epidemiology, pathogenesis, presentation, diagnosis, and therapy

Exercise-induced bronchoconstriction, allergy and sports in children

Exercise-induced bronchoconstriction (EIB) is characterized by the narrowing of airways during or after physical activity, leading to symptoms such as wheezing, coughing, and shortness of breath. Distinguishing between EIB and exercise-induced asthma (EIA) is essential, given their divergent therapeutic and prognostic considerations. EIB has been increasingly recognized as a significant concern in pediatric athletes. Moreover, studies indicate a noteworthy prevalence of EIB in children with atopic predispositions, unveiling a potential link between allergic sensitivities and exercise-induced respiratory symptoms, underpinned by an inflammatory reaction caused by mechanical, environmental, and genetic factors. Holistic management of EIB in children necessitates a correct diagnosis and a combination of pharmacological and non-pharmacological interventions. This review delves into the latest evidence concerning EIB in the pediatric population, exploring its associations with atopy and sports, and emphasizing the appropriate diagnostic and therapeutic approaches by highlighting various clinical scenarios.

An Overview on the Primary Factors That Contribute to Non-Allergic Asthma in Children

The prevalence of non-allergic asthma in childhood is low, peaking in late adulthood. It is triggered by factors other than allergens, like cold and dry air, respiratory infections, hormonal changes, smoke and air pollution. In the literature, there are few studies that describe non-allergic asthma in pediatric age. Even though it is a less common disorder in kids, it is crucial to identify the causes in order to keep asthma under control, particularly in patients not responding to conventional treatments. In this review, we discuss non-IgE-mediated forms of asthma, collecting the latest research on etiopathogenesis and treatment.

Physical activity, lung function, and sleep outcomes in urban children with asthma

OBJECTIVES

To examine (1) whether daily declines in physical activity (PA) level and/or in lung function (FEV1) predict an asthma exacerbation in a sample of urban children with asthma, and (2) the association between number of sleep awakenings and decline in daytime PA in this group.

METHODS

In this sample of urban children aged 7-9 years with persistent asthma (N = 147), objective methods assessing lung function via a handheld spirometer and moderate-to-vigorous physical activity (MVPA) via accelerometry were measured over a 4-week period during the fall and early winter of each year as part of a larger 5-year study.

RESULTS

In the entire sample, a significant association between PA and lung function was noted such that a greater decline in daily MVPA was associated with lower odds of exacerbation. Ethnic group differences showed that this association was also significant only among Latino children (odds ratio [OR] = 0.98; 95% confidence interval [CI]:0.97-0.99). A greater number of sleep awakenings were associated with greater declines in daily MVPA among Latinos only (p = .05).

CONCLUSIONS

Results suggest that declining MVPA may contribute to lower risk for an exacerbation. Reasons for declining MVPA need to be further explored in this group. Children with asthma may avoid or be fearful of engaging in PA or may face early symptoms which influence patterns of PA, and this may minimize risk for an exacerbation. Results also suggest reasons for night-time disruptions may need to be targeted in further research or interventions as they can contribute to PA avoidance in this high-risk group.

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.

Management/Comorbidities of School-Aged Children with Asthma

Asthma is a complex heterogeneous disease characterized by reversible airflow obstruction. After appropriate diagnosis, the management in school-aged children centers on 3 broad domains: pharmacologic treatment, treatment of underlying comorbidities, and education of the patient and caregivers. It is important to understand that the phenotypic differences that exist in the school-aged child with asthma may impact underlying comorbid conditions as well as pharmacologic treatment choices. Following initiation of therapy, asthma control must be continually evaluated in order to optimize management.

Exhaled TGF-β1 levels before and after an exercise challenge in asthmatic and healthy children, and during exacerbation

BACKGROUND

There is conflicting data regarding the role of transforming growth factor-β1 (TGF-β1) in the pathogenesis of airway hyper-reactivity and asthma exacerbation.

OBJECTIVE

To investigate the role of exhaled-TGF-β1 in exercise-induced bronchospasm (EIB) in asthmatic and nonasthmatic healthy children, and in asthma exacerbation and asthma control.

METHODS

The exhaled-TGF-β1 levels of 56 stable asthmatic children and 15 nonasthmatic healthy children were evaluated before and 30 min after an exercise challenge. The exhaled-TGF-β1 levels of 20 additional children with asthma exacerbation were evaluated.

RESULTS

While no significant difference in the exhaled-TGF-β1 levels was found at the baseline, exhaled-TGF-β1 levels after the exercise challenge were significantly higher in the non-EIB (n = 31) asthmatics when compared to the asthmatic children with EIB (n = 25) (p = 0.04). Although there was a statistically significant increase in the concentration of the exhaled-TGF-β1 after the exercise challenge in the non-EIB asthmatics (p = 0.008), the concentration of the TGF-β1 was not increased after the exercise challenge in EIB + asthmatics. The exhaled-TGF-β1 was significantly correlated with the ACT score (p = 0.01, r = 0.49) and the baseline FEV₁ level (p = 0.02, r = 0.35). The exhaled-TGF-β1 levels were significantly higher in the stable asthmatic children when compared to the nonasthmatic children (p < 0.0001). There was no significant difference in exhaled-TGF-β1 levels after the exercise challenge in the nonasthmatics. The exhaled-TGF-β1 levels were significantly lower in those children with asthma exacerbation when compared to the stable asthmatic children (p = 0.0003).

CONCLUSION

Our results suggest that TGF-β1 may play a role in suppressing airway reactivity and its deficiency is associated with asthma exacerbation.

Can Pediatricians Assess Exercise-Induced Bronchoconstriction From Post-exercise Videos?

Objective: Exercise-induced bronchoconstriction (EIB) is a highly prevalent morbidity of childhood asthma and defined by a transient narrowing of the airways during or after physical exercise. An exercise challenge test (ECT) is the reference standard for the diagnosis of EIB. Video evaluation of EIB symptoms could be a practical alternative for the assessment of EIB. We studied the ability of pediatricians to assess EIB from post-exercise videos. Methods: A clinical assessment was performed in 20 asthmatic children (mean age 11.6 years) and EIB was measured with a standardized ECT performed in cold, dry air. EIB was defined as a fall in forced expiratory volume in 1 s (FEV₁) of ≥10% post-exercise. Children were filmed before and after exercise in frontal position and bare chested. The clinical assessment results and videos were shown to 20 pediatricians (mean experience 14.4 years). Each assessed EIB severity in 5 random children providing 100 assessments, scored on a continuous rating scale (0-10) and in severity classifications (no, mild, moderate, severe) using a scoring list including physical asthma symptoms. Correlations between predicted scores and objective scores were calculated with Spearman's rho and Cohen's Kappa. A generalized linear model was used to assess the relationship between physical symptoms and fall in FEV₁. Results: Median fall in FEV₁ after exercise was 15.1% (IQR 1.2-65.1). Pediatricians detected EIB with a sensitivity of 78% (95% CI 66-87%) and a specificity of 40% (95% CI 27-55%). The positive predictive value for a pediatricians' diagnosis of EIB was 61% (95% CI 50-72%). The negative predictive value was 60% (95% CI 42-76%). The agreement between predicted EIB severity classifications and the validated classifications based on the ECT's, was fair [Kappa = 0.36 (95% CI 0.23-0.48)]. The correlation between predicted EIB severity scored on a continuous rating scale and fall in FEV₁ after exercise was weak (r_s = 0.39, p < 0.001). Independent predictive variables for fall in FEV₁ were wheezing (-11%), supraclavicular retractions (-8.4%) and a prolonged expiratory phase (-8.8%). Conclusion: The ability of pediatricians to assess EIB from post-exercise videos is fair at best, implicating that standardized ECT's are still vital in the assessment of EIB.

Asthma Mimickers: Approach to Differential Diagnosis

The airway of a child can be easily obstructed because of its small size and there are myriad conditions that may obstruct it. Though asthma is the most common condition causing reversible obstruction of the airway; there are a large number of conditions which can obstruct the airway both reversibly and irreversibly. These asthma mimics can present as clinical problems from the neonatal period through adolescence. This article presents an overview of the clinical situations that must be kept in mind when the child presents with subtly unusual clinical features or a deviant course. This is followed by a brief description of the common mimickers along with clinical clues to their diagnosis. Clinicians will need a high index of suspicion for diagnosing these conditions. Prompt recognition and optimal case management and referral will ensure the best outcomes in these children.

Interventions for autumn exacerbations of asthma in children

BACKGROUND

Asthma exacerbations in school-aged children peak in autumn, shortly after children return to school following the summer holiday. This might reflect a combination of risk factors, including poor treatment adherence, increased allergen and viral exposure, and altered immune tolerance. Since this peak is predictable, interventions targeting modifiable risk factors might reduce exacerbation-associated morbidity and strain upon health resources. The peak occurs in September in the Northern Hemisphere and in February in the Southern Hemisphere.

OBJECTIVES

To assess the effects of pharmacotherapy and behavioural interventions enacted in anticipation of school return during autumn that are designed to reduce asthma exacerbations in children during this period.

SEARCH METHODS

We searched the Cochrane Airways Group Trials Register, ClinicalTrials.gov, the World Health Organization International Clinical Trials Registry Platform, reference lists of primary studies and existing reviews, and manufacturers' trial registries (Merck, Novartis and Ono Parmaceuticals). We searched databases from their inception to 1 December 2017, and imposed no restriction on language of publication.

SELECTION CRITERIA

We included all randomised controlled trials comparing interventions aimed specifically at reducing autumn exacerbations with usual care, (no systematic change in management in preparation for school return). We included studies providing data on children aged 18 years or younger.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane. Two review authors independently screened records identified by the search and then extracted data and assessed bias for trials meeting the inclusion criteria. A third review author checked for accuracy and mediated consensus on disagreements. The primary outcome was proportion of children experiencing one or more asthma exacerbations requiring hospitalisation or oral corticosteroids during the autumn period.

MAIN RESULTS

Our searches returned 546 trials, of which five met our inclusion criteria. These studies randomised 14,252 children to receive either an intervention or usual care. All studies were conducted in the Northern Hemisphere. Three interventions used a leukotriene receptor antagonist, one used omalizumab or a boost of inhaled corticosteroids, and the largest study, (12,179 children), used a medication reminder letter. Whilst the risk of bias within individual studies was generally low, we downgraded the evidence quality due to imprecision associated with low participant numbers, poor consistency between studies, and indirect outcome ascertainment.A US study of 513 children with mild/severe asthma and allergic sensitisation was the only study to provide data for our primary outcome. In this study, the proportion of participants experiencing an exacerbation requiring oral corticosteroids or hospital admission in the 90 days after school return was significantly reduced to 11.3% in those receiving omalizumab compared to 21.0% in those receiving placebo (odds ratio 0.48, 95% confidence interval 0.25 to 0.92, moderate-quality evidence). The remaining studies used alternative exacerbation definitions. When data from two leukotriene receptor antagonist studies with comparable outcomes were combined in a random-effects model, there was no evidence of an effect upon exacerbations. There was no evidence that a seasonal medication reminder letter decreased unscheduled contacts for a respiratory diagnosis between September and December.Four studies recorded adverse events. There was no evidence that the proportion of participants experiencing at least one adverse event differed between intervention and usual care groups. Lack of data prevented planned subgroup and sensitivity analyses.

AUTHORS' CONCLUSIONS

Seasonal omalizumab treatment from four to six weeks before school return might reduce autumn asthma exacerbations. We found no evidence that this strategy is associated with increased adverse effects other than injection site pain, but it is costly. There were no data upon which to judge the effect of this or other seasonal interventions on asthma control, quality of life, or asthma-related death. In future studies definitions of exacerbations should be provided, and standardised where possible. To investigate possible differential effects according to subgroup, participants in future trials should be well characterised with respect to baseline asthma severity and exacerbation history in addition to age and gender.

Inducible Laryngeal Obstruction in the Paediatric Population – Review of the Literature and Current Understanding

Inducible laryngeal obstruction (ILO) is a complex entity and its exact mechanisms are still unclear. It is characterised by transient and reversible narrowing of the larynx in response to external triggers, resulting in symptoms such as cough, dyspnoea and noisy breathing. The prevalence of this condition in adult or paediatric populations is uncertain. Management of ILO starts by establishing an accurate diagnosis, and treatment includes control of trigger factors, breathing and relaxation techniques, and speech and respiratory therapy. The aim of this article is to summarise current understanding and provide a review of the literature of ILO in the paediatric population.

Differentiating vocal cord dysfunction from asthma

Vocal cord dysfunction (VCD)-associated symptoms are not rare in pediatric patients. Dyspnea, wheezing, stridor, chest pain or tightness and throat discomfort are the most commonly encountered symptoms. They may occur either at rest or more commonly during exercise in patients with VCD, as well as in asthmatic subjects. The phase of respiration (inspiration rather than expiration), the location of the wheezing origin, the rapid resolution of symptoms, and the timing occurring in relation to exercise, when VCD is exercise induced, raise the suspicion of VCD in patients who may have been characterized as merely asthmatics and, most importantly, had not responded to the appropriate treatment. The gold standard method for the diagnosis of VCD is fiberoptic laryngoscopy, which may also identify concomitant laryngeal abnormalities other than VCD. However, as VCD is an intermittent phenomenon, the procedure should be performed while the patient is symptomatic. For this reason, challenges that induce VCD symptoms should be performed, such as exercise tests. Recently, for the evaluation of patients with exercise-induced VCD, continuous laryngoscopy during exercise (such as treadmill, bicycle ergometer, swimming) was used. A definite diagnosis of VCD is of importance, especially for those patients who have been erroneously characterized as asthmatics, without adequate response to treatment. In these cases, another therapeutic approach is necessary, which will depend on whether they suffer solely from VCD or from both conditions.

Associations of self-reported allergic diseases and musculoskeletal problems in children: A US population-based study

BACKGROUND

Previous studies have found increased rates of musculoskeletal problems in adults with allergic disease, but whether this association holds true for children is unknown.

OBJECTIVE

To investigate the association of bone, joint, and muscle problems in children with a history of allergic disease.

METHODS

Data were obtained from the 2007 Child and Adolescent Health Measurement Initiative. Univariable and multivariable logistic regression models accounting for the sampling design were used to evaluate associations of bone, joint, and muscle problems with allergic diseases, such as asthma, hay fever, food allergies, and eczema. Associations were summarized with odds ratios (ORs) and 95% confidence intervals (CIs).

RESULTS

The survey included 91,642 individuals aged 0 to 17 years. Multivariable modeling found statistically significant associations between the number of allergic diseases and bone, joint, and muscle problems (1 allergic disease: adjusted OR, 1.28; 95% CI, 1.04-1.56; P = .02; 2 allergic diseases: adjusted OR, 2.55; 95% CI, 1.92-3.39; P < .001; 3 allergic diseases: adjusted OR, 2.70; 95% CI, 1.88-3.86; P < .001; and 4 allergic diseases: adjusted OR, 4.35; 95% CI, 2.46-7.69; P < .001). Severe eczema (but not mild eczema) was associated with bone, joint, and muscle problems (adjusted OR, 2.81; 95% CI, 1.64-4.81; P < .001) and with bone problems (adjusted OR, 6.08; 95% CI, 1.94-19.12; P = .002).

CONCLUSION

Self-reported allergic diseases in children were associated with bone, joint, and muscle problems, and associations strengthened with allergic disease severity and number of allergic diseases. Severe eczema may be associated with bone problems in children. Bone, joint, and muscle problems must be considered in children with severe allergic disease, and prospective studies are necessary to define this association.

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.

Respiratory muscle strength and pulmonary function in children with rhinitis and asthma after a six-minute walk test

OBJECTIVE

Rhinitis and asthma decrease quality of life. Few studies have assessed the performance of children with asthma or rhinitis under submaximal exercise. We evaluated maximal respiratory pressures, spirometric parameters, and ability to sustain submaximal exercise in these children before and after the 6-minute walk test (6MWT), compared to healthy children.

METHODS

This cross-sectional, analytical study included 89 children aged 6-12 years in outpatient follow-up: 27 healthy (H), 31 with rhinitis (R), and 31 with mild asthma under control (A). Pulmonary function parameters and maximal respiratory pressures were measured before and 5, 10, and 30 minutes after the 6MWT. Wilcoxon test was used to compare numerical numerical variables between two groups and analysis of variance or Kruskal-Wallis test for comparison among three groups.

RESULTS

Total distance traveled in the 6MWT was similar among the three groups. Compared to pre-test values, VEF1 (Forced Expiratory Volume in 1 second), VEF0.75 (Forced Expiratory Volume in 0.75 second), and FEF25-75 (Forced Expiratory Flow 25-75% of the Forced Vital Capacity - CVF - curve) decreased significantly after the 6MWT in group A, and VEF0.75, FEF25-75, and VEF1/CVF decreased significantly in group R. Groups A and R had lower Maximum Inspiratory Pressure values than group H before and after the 6MWT at all time points assessed.

CONCLUSIONS

The findings suggest that children with rhinitis and mild asthma present with alterations in respiratory muscle strength and pulmonary function not associated with clinical complaints, reinforcing the concept of the united airways.

Exercise-induced inspiratory symptoms in school children

BACKGROUND AND AIMS

Exercise-induced inspiratory symptoms (EIIS) have multiple causes, one of which is exercise-induced laryngeal obstruction (EILO). There is limited knowledge regarding EIIS in children, both in primary care practices and in pediatric asthma clinics. The aim of this study was to describe the feasibility of a diagnostic methodology and its results in a cohort of children with EIIS referred to our tertiary pediatric pulmonary center.

METHODS

This study analyzed consecutively collected data in children from East Denmark and Greater Copenhagen referred during a 3½ years period. The continuous laryngoscopy exercise (CLE) test directly visualizes the larynx using a flexible laryngoscope during a maximal exercise test. A post-test questionnaire evaluated the subjective impact of the examination.

RESULTS

The study included 60 children (37 girls/23 boys) with a mean age of 14 years (range 9-18). The feasibility of the CLE test was 98%; 18 children (35%) had EILO, while 33 children (61%) showed no abnormalities. Other laryngeal abnormalities were observed in three children before the exercise test. Asthma medication was successfully discontinued in 13 (72%) children with EILO. A significantly greater proportion of children shown to have EILO in the CLE test reported coping better with their EIIS than children with negative test (85% vs. 45%; P = 0.03).

CONCLUSIONS

Continuous laryngoscopy during exercise is feasible and useful for identifying children with EILO. A correct diagnosis of EILO can help relieve patient anxiety, improve their coping with symptoms, and prevent unnecessary long-term and potentially harmful asthma treatments involving high-dose inhaled steroids. Pediatr Pulmonol. 2016;51:1200-1205. © 2016 Wiley Periodicals, Inc.

Exercise-induced bronchoconstriction update-2016

The first practice parameter on exercise-induced bronchoconstriction (EIB) was published in 2010. This updated practice parameter was prepared 5 years later. In the ensuing years, there has been increased understanding of the pathogenesis of EIB and improved diagnosis of this disorder by using objective testing. At the time of this publication, observations included the following: dry powder mannitol for inhalation as a bronchial provocation test is FDA approved however not currently available in the United States; if baseline pulmonary function test results are normal to near normal (before and after bronchodilator) in a person with suspected EIB, then further testing should be performed by using standardized exercise challenge or eucapnic voluntary hyperpnea (EVH); and the efficacy of nonpharmaceutical interventions (omega-3 fatty acids) has been challenged. The workgroup preparing this practice parameter updated contemporary practice guidelines based on a current systematic literature review. The group obtained supplementary literature and consensus expert opinions when the published literature was insufficient. A search of the medical literature on PubMed was conducted, and search terms included pathogenesis, diagnosis, differential diagnosis, and therapy (both pharmaceutical and nonpharmaceutical) of exercise-induced bronchoconstriction or exercise-induced asthma (which is no longer a preferred term); asthma; and exercise and asthma. References assessed as relevant to the topic were evaluated to search for additional relevant references. Published clinical studies were appraised by category of evidence and used to document the strength of the recommendation. The parameter was then evaluated by Joint Task Force reviewers and then by reviewers assigned by the parent organizations, as well as the general membership. Based on this process, the parameter can be characterized as an evidence- and consensus-based document.

Associations of Physical Activity and Sedentary Behavior with Atopic Disease in United States Children

OBJECTIVES

To determine if eczema, asthma, and hay fever are associated with vigorous physical activity, television/video game usage, and sports participation and if sleep disturbance modifies such associations.

STUDY DESIGN

Data were analyzed from 2 cross-sectional studies including 133 107 children age 6-17 years enrolled in the 2003-2004 and 2007-2008 National Survey of Children's Health. Bivariate and multivariate survey logistic regression models were created to calculate the odds of atopic disease and atopic disease severity on vigorous physical activity, television/video game use, and sports participation.

RESULTS

In multivariate logistic regression models controlling for sociodemographic factors, lifetime history of asthma was associated with decreased odds of ≥1 days of vigorous physical activity (aOR, 0.87; 95% CI, 0.77-0.99) and decreased odds of sports participation (0.91; 95% CI, 0.84-0.99). Atopic disease accompanied by sleep disturbance had significantly higher odds of screen time and lower odds of sports participation compared with children with either atopic disease or sleep disturbance alone. Severe eczema (aOR, 0.39; 95% CI, 0.19-0.78), asthma (aOR, 0.29; 95% CI, 0.14-0.61), and hay fever (aOR, 0.48; 95% CI, 0.24-0.97) were all associated with decreased odds of ≥1 days of vigorous physical activity. Moderate (aOR, 0.76; 95% CI, 0.57-0.99) and severe eczema (aOR, 0.45; 95% CI, 0.28-0.73), severe asthma (aOR, 0.47; 95% CI, 0.25-0.89), and hay fever (aOR, 0.53; 95% CI, 0.36-0.61) were associated with decreased odds of sports participation in the past year.

CONCLUSIONS

Children with severe atopic disease, accompanied by sleep disturbance, have higher risk of sedentary behaviors.

Obesity, Asthma, and Exercise in Child and Adolescent Health

Obesity increases the risk of asthma throughout life but the underlying mechanisms linking these all too common threats to child health are poorly understood. Acute bouts of exercise, aerobic fitness, and levels of physical activity clearly play a role in the pathogenesis and/or management of both childhood obesity and asthma. Moreover, both obesity and physical inactivity are associated with asthma symptomatology and response to therapy (a particularly challenging feature of obesity-related asthma). In this article, we review current understandings of the link between physical activity, aerobic fitness and the asthma-obesity link in children and adolescents (e.g., the impact of chronic low-grade inflammation, lung mechanics, and direct effects of metabolic health on the lung). Gaps in our knowledge regarding the physiological mechanisms linking asthma, obesity and exercise are often compounded by imprecise estimations of adiposity and challenges of assessing aerobic fitness in children. Addressing these gaps could lead to practical interventions and clinical approaches that could mitigate the profound health care crisis of the increasing comorbidity of asthma, physical inactivity, and obesity in children.

Breathing-related changes of respiratory resistance in vocal cord dysfunction

Vocal cord dysfunction induced by exercise in children with uncontrolled asthma was identified by laryngoscopy. The paradoxical adduction of the vocal cords was also indicated by the breathing-related changes of the forced oscillation respiratory resistance showing prominent increase during inspiration and a large positive difference between inspiration and expiration. The breathing-related changes of respiratory resistance offer thus a useful first-line technique to diagnose vocal cord dysfunction.

Asthma Control Test and Bronchial Challenge with Exercise in Pediatric Asthma

BACKGROUND

Poor asthma control can lead to exercise-induced bronchoconstriction (EIB), but the relationship between subjective disease control and EIB is unclear. No studies have compared asthma control test (ACT) scores of children with those of their parents regarding EIB. We assessed whether ACT scores predict the occurrence of EIB in two age groups. We also evaluated ACT scores and objective measures as explanatory variables for airway response to exercise.

METHODS

Patients (71, aged <12 years; 93, aged ≥12 years) and their parents completed an ACT questionnaire separately. Current therapy, skin prick testing, and spirometry at baseline and after exercise were assessed. EIB was defined as a fall in forced expiratory volume in 1 s (FEV1) of at least 12% from baseline. Sensitivity and specificity for cut-off values of ACT scores predictive of EIB were plotted, and the area under curve (AUC) was described.

RESULTS

Atopy and current therapy were similarly frequent. EIB was observed in 23.9% of children aged <12 years and in 33.3% of children aged ≥12 years. EIB occurrence in subjects previously scored as having full control (25), partial control (20-24), and no control (<20) varied according to the age group and responders. Percentages of EIB cases increased as ACT scores decreased in children aged ≥12 years alone (child ACT scores, 25: 21.9%, 20-24: 31.1%, <20: 62.5%, p = 0.017). Plots for ACT scores as predictors of EIB yielded low non-significant AUC values in children aged <12 years; in contrast, moderate AUC values emerged in children aged ≥12 years (child: 0.67, p = 0.007; parent: 0.69, p = 0.002). Sensitivity of ACT scores below 20 as a predictor of EIB was low in older children (child: 32.3%, parent: 22.6%), whereas specificity was high (child: 90.3%, parent: 93.5%). Multiple regression analysis with percent fall in FEV1 as dependent variable included FEV1/FVC%, ACT child score, and gender in the prediction model (r = 0.42, p = 0.000).

CONCLUSION

ACT scores are a more effective means of excluding than confirming EIB in asthmatic patients aged ≥12 years; their predictive value decreases in younger patients. ACT scores together with lung function may help to predict airway response to exercise. New tools for pediatric asthma assessment may optimize this association.

Protective effect of a low single dose inhaled steroid against exercise induced bronchoconstriction

OBJECTIVE

Daily use of inhaled corticosteroids (ICS) reduces exercise induced bronchoconstriction (EIB) in asthmatic children. A high single dose of ICS also provided acute protection against EIB. Objective of this study is to investigate whether a low single dose of ICS offers protection against EIB in asthmatic children.

METHODS

31 Mild asthmatic children not currently treated with inhaled corticosteroids, 5-16 years, with EIB (fall in FEV0.5/1 ≥ 13%) were included in a prospective intervention study. They performed two ECT's within 2 weeks. Four hours before the second test children inhaled 200 μg beclomethasone-dipropionate (BDP) with a breath-actuated inhaler (BAI).

RESULTS

The median fall in FEV0.5/1 after 200 μg BDP was significantly reduced from 30.9% at baseline to 16.0% (P < 0.001). Twenty children (64.5%) showed a good response to 200 μg BDP (≥ 50% decrease in fall of FEV0.5/1), while 8 children showed a moderate response (25-50%), and three children showed no response at all (< 25%).

CONCLUSION

A low single dose ICS offers acute protection against EIB in the majority of asthmatic children not currently treated with inhaled corticosteroids.