Exercise-induced Bronchoconstriction In Children Research Articles

Exercise-Induced Bronchoconstriction in Children: State of the Art from Diagnosis to Treatment.

Exercise-induced bronchoconstriction (EIB) is a common clinical entity in people with asthma. EIB is characterized by postexercise airway obstruction that results in symptoms such as coughing, dyspnea, wheezing, chest tightness, and increased fatigue. The underlying mechanism of EIB is not completely understood. "Osmotic theory" and "thermal or vascular theory" have been proposed. Initial assessment must include a specific work-up to exclude alternative diagnoses like exercise-induced laryngeal obstruction (EILO), cardiac disease, or physical deconditioning. Detailed medical history and clinical examination must be followed by basal spirometry and exercise challenge test. The standardized treadmill running (TR) test, a controlled and standardized method to assess bronchial response to exercise, is the most adopted exercise challenge test for children aged at least 8 years. In the TR test, the goal is to reach the target heart rate in a short period and maintain it for at least 6 min. The test is then followed by spirometry at specific time points (5, 10, 15, and 30 min after exercise). In addition, bronchoprovocation tests like dry air hyperpnea (exercise and eucapnic voluntary hyperpnea) or osmotic aerosols (inhaled mannitol) can be considered when the diagnosis is uncertain. Treatment options include both pharmacological and behavioral approaches. Considering medications, the use of short-acting beta-agonists (SABA) just before exercise is the commonest option strategy, but daily inhaled corticosteroids (ICS) can also be considered, especially when EIB is not controlled with SABA only or when the patients practice physical activity very often. Among the behavioral approaches, warm-up before exercise, breathing through the nose or face mask, and avoiding polluted environments are all recommended strategies to reduce EIB risk. This review summarizes the latest evidence published over the last 10 years on the pathogenesis, diagnosis using spirometry and indirect bronchoprovocation tests, and treatment strategies, including SABA and ICS, of EIB. A specific focus has been placed on EIB management in young athletes, since this condition can not only prevent them from practicing regular physical activity but also competitive sports.

Association of temperature and absolute humidity with incidence of exercise-induced bronchoconstriction in children.

Exercise test outdoors is widely used to diagnose asthma in children, but it is unclear how much outdoor air factors affect the results. We analysed 321 outdoor exercise challenge tests with spirometry in children 6-16 years conducted due to suspicion of asthma or for assessing the effect of medication on asthma. We studied the association of FEV1 decrease and incidence of exercise-induced bronchoconstriction (EIB) with temperature, relative humidity (RH) and absolute humidity (AH). Asthma was diagnosed in 57% of the subjects. AH ≥5 g/m3, but not RH or temperature, was associated with the EIB incidence (p = 0.035). In multivariable logistic regression, AH ≥5 g/m3 was negatively associated (OR = 0.51, 95% CI [0.28─0.92], p = 0.026) while obstruction before exercise (OR = 2.11, 95% CI [1.16─3.86], p = 0.015) and IgE-mediated sensitisation were positively associated with EIB (OR = 2.24, 95% CI [1.11─4.51], p = 0.025). AH (r = -0.12, p = 0.028) and temperature (r = -0.13, p = 0.023) correlated with decrease in FEV1. In multivariable linear regression, only AH was associated with FEV1 decrease (coefficient = -0.044, 95% CI [-0.085 to -0.004], p = 0.033). AH of outdoor air associates with occurrence and severity of EIB in outdoor exercise tests in children. Care should be taken when interpreting negative outdoor exercise test results if AH of air is high.

Exercise-Induced Bronchoconstriction in Children: A Comparison between Athletes and Non-Athletes.

Exercise-induced bronchoconstriction (EIB) is a dysfunction of the respiratory tract consisting of transient airflow obstruction. This study is a retrospective analysis of two prospective studies concerning EIB symptoms in two adolescent populations. Our study group included 400 non-athletes and 101 athletes. Due to the similarity of indoor exercise conditions, an analysis was performed on the basis of where training took place. The study aims to assess the EIB prevalence in the following groups of adolescent children: non-athletes and athletes. In "indoor" athletes, the EIB prevalence was 22.4%. Among non-athletes, EIB was diagnosed in 10.2% (p = 0.007). A history of asthma was found in 6.5% of non-athletes and 29.3% of indoor athletes (p < 0.001). The incidence of EIB without asthma was higher in indoor athletes (14.6%) than in non-athletes (9.9%). Athletes achieved higher mean values in forced expiratory volume in one second (FEV1), forced vital capacity (FVC), peak expiratory flow (PEF), and maximum expiratory flow rate at 25% (MEF25) parameters. In the group of non-athletes, higher results were observed in forced expiratory volume in one second % of vital capacity (FEV1%VC), MEF50, and MEF75. The findings of the study present the complexity of the EIB diagnosis among children training in an indoor environment.

Exercise-induced bronchoconstriction is associated with air humidity and particulate matter concentration in preschool children.

Long-term exposure to air pollution is connected to asthma morbidity in children. Exercise-induced bronchoconstriction (EIB) is common in asthma, and the free running test outdoors is an important method for diagnosing asthma in children. It is not known whether momentary air pollution exposure affects the results of outdoor exercise tests in children. We analyzed all reliable exercise challenge tests with impulse oscillometry in children (n = 868) performed between January 2012 and April 2015 at Tampere University Hospital. Pollutant concentrations (PM2.5 , NO2 , and O3 ) at the time of the exercise test were collected from public registers. We compared the pollutant concentrations with the proportion and severity of EIB and adjusted the analyses for air humidity and pollen counts. Pollution levels were rarely high (median PM2.5 6.0 µg/m3 , NO2 12.0 µg/m3 , and O3 47.0 µg/m3 ). The relative change in resistance at 5 Hz after exercise did not correlate with O3 , NO2 or PM2.5 concentrations (p values 0.065-0.884). In multivariate logistic regression, we compared the effects of PM2.5 over 10 µg/m³, absolute humidity (AH) over 10 g/m³ and alder or birch pollen concentration over 10 grains/m³. High (over 10 g/m3 ) AH was associated with decreased incidence (OR 0.31, p value 0.004), and PM2.5 over 10 µg/m³ was associated with increased incidence (OR 1.69, p value 0.036) of EIB. Even low PM2.5 levels may have an effect on EIB in children. Of the other properties of air, only AH was associated with the incidence of EIB.

Impulse oscillometry (IOS) for detection of exercise induced bronchoconstriction in children with asthma ages 6–15 years

Objectives To determine the discriminatory value of various impulse oscillometry (IOS) parameters, and to find the cutoff value of the appropriate parameter for identifying exercise-induced bronchoconstriction (EIB) in children with asthma. Methods This cross-sectional study was conducted in India from October 2016 to March 2018 in children with asthma who were 6–15 years of age. One hundred and five children were enrolled and subjected to pre-exercise IOS and spirometry followed by free running treadmill test as an exercise challenge. All children could achieve minute ventilation >17.5–21 times of FEV1 during the exercise challenge test. Then, IOS and spirometry were performed at 10 ± 2, 20 ± 2, and 30 ± 2 min post-exercise challenge. EIB was defined as reduction of FEV1 ≥10% within 30 min of exercise. For purposes of analysis, the children were grouped into two categories: “EIB Present” or “EIB Absent”. Results The prevalence of EIB in our study was 20.95% (n = 22). ΔR5max percentage within 30 min post-exercise (AUC 0.74; 95% CI: 0.64, 0.84) had the best discriminating capacity among all IOS parameters for identifying EIB. A cutoff value of 14.1% increase in R5 within 30 min post-exercise was obtained for detection of EIB (sensitivity—95.45%, specificity—50.6%, PPV—33.87% and NPV—97.67%). Conclusions A percentage change in R5 with a cutoff value of 14.1% increase post-exercise had the best discriminatory capacity among all IOS parameters for detection of EIB in children with asthma. However, low positive predictive value (PPV) with high negative predictive value (NPV) made this cutoff value more apt to rule out EIB.

The Effect Of Mouth Breathing On Exercise Induced Bronchoconstriction In Children

BACKGROUND: Exercise induced bronchoconstriction (EIB) is a common finding in the pediatric population. Nose breathing is considered to decreases hyper-responsiveness of the airways. Therefore, nose clip (NC) is used during exercise challenge test (ECT) in adults to increase test sensitivity. Data on the need for NC during ECT in children is scarce. Our aim was to evaluate the effect of breathing with and without NC on EIB in children. METHODS: A prospective study evaluating two ECT’s with/without NC within a month period. Demographic, clinical data, Total Nasal Symptoms Score (TNSS) and Asthma Control Test (ACT) were recorded. RESULTS: Fifty-four children (mean age 16.7 ± 1.2 y/o, 39% Female) were evaluated. Forty-four returned to visit 2. At Visit 1 (with NC) baseline FEV1 was 92.8 ± 11.0%pred and 27/44 (61%) had positive ECT (decline≥12% in FEV1) with mean FEV1 drop of 14.7 ± 11.3%pred. At visit 2 ,8.7 ± 7.7 days post visit 1 (without NC), baseline FEV1 was 88.9 ± 11.3%pred (p < 0.001), mean FEV1 drop was 9.0 ± 10.1%pred (p < 0.0001) and only 14/44 (32%) had positive ECT (p < 0.0001). A total of 14/44 (32%) of children with a positive ECT with a NC turned negative without a NC. CONCLUSIONS: Use of NC during ECT increases the rate of positive tests thus possibly improving the yield of EIB diagnosis in children. Optional physiologic mechanisms could be humidification and warming of the inhaled air through the nose cavity. The findings strengthen the recommendation of nasal blockage during ECT. Larger randomized studies are needed to unfold the full effect of nose breathing during exercise.

Exercise-Induced Bronchoconstriction in Children.

Exercise-induced bronchoconstriction (EIB) is a transient airflow obstruction, typically 5–15 min after physical activity. The pathophysiology of EIB is related to the thermal and osmotic changes of the bronchial mucosa, which cause the release of mediators and the development of bronchoconstriction in the airways. EIB in children often causes an important limitation to physical activities and sports. However, by taking appropriate precautions and through adequate pharmacological control of the condition, routine exercise is extremely safe in children. This review aims to raise awareness of EIB by proposing an update, based on the latest studies, on pathological mechanisms, diagnosis, and therapeutic approaches in children.

The Role of Physical Aerobic Activity in Controlling Exercise-Induced Bronchoconstriction in Children and Adolescents with Asthma

Asthma, one of the major widespread chronic disorders among children and adolescents, has become more prevalent recently. The common manifestations of this disorder are caused by inflammatory airways that lead to airway restriction and lung hypersensitivity causing dry coughing, wheezing, and shortness of breath, all of which are combined with sleep disturbance, impaired physical activity, and reduced quality of life. The main goal of this brief review was to identify the associated variables that affect the management of asthma disease in children and young adolescents and to identify the role of physical aerobic exercise in the treatment of asthmatic children. The current review was based on prior research published in English databases such as Google Scholar, PubMed, and Embase in scientific articles published between January 2010 and October 2021 with the keywords "asthma," "children," "adolescents," "breathing episodes," "physical activity," and "physical exercise." Regular physical aerobic exercise training with moderate intensity has been shown to improve pulmonary functions, life quality, psychological conditions, and reduce asthma symptoms and EIB in children and adolescents with bronchial asthma.

The Effects of Climate Therapy on Cardiorespiratory Fitness and Exercise-Induced Bronchoconstriction in Children with Asthma

We investigated whether a 1-week stay in the mountains may have a positive impact on Exercise-Induced Bronchoconstriction (EIB) and cardiorespiratory endurance in asthmatic children from an urban area. Spirometry was performed before and 10 min after a 20 m shuttle run test (20mSRT) on the first and seventh day of a summer asthma camp in the Italian Alps at 900 m of altitude. Spirometry z-scores were derived from the Global Lung Initiative 2012 prediction equations, and percentiles of the 20mSRT performance were assigned according to De Miguel-Etayo’s and Tomkinson’s predictive equations. A FEV1 decrease ≥10% after the exercise was defined as EIB. Particulate matter pollution was monitored during the camp and in the urban area of provenience. Twenty-four subjects (age range 7–16 years) were included. Frequency of EIB decreased from 58% (14/24) at day-1 to 33% (8/24) at the end of the camp (p = 0.08). Most subjects with a 20mSRT in the lowest quartile at day 1 had EIB (9/11). The proportion of children with a 20mSRT &lt;25° percentile decreased from 45% (11/24) at day-1 to 16% (4/24) at day-7 (p = 0.02). Conclusion: One-week climate therapy in the mountains improved both bronchial hyperreactivity and cardiorespiratory endurance in our cohort of asthmatic children.

Diagnostic performance of the physical activity-related question of the GINA questionnaire to detect exercise-induced bronchoconstriction in asthma

IntroductionThe aim of the study was to evaluate the diagnostic performance of the item concerning physical activity of the Global Initiative for Asthma (GINA) asthma control questionnaire for detection of exercise-induced bronchoconstriction (EIB) in children and adolescents. Material and methodsWe divided participants (aged 6–18 years) with a diagnosis of asthma into two groups according to the GINA severity classification: mild/moderate asthma (MMA) and severe therapy-resistant asthma (STRA). We collected anthropometric, clinical and functional data (spirometry) and performed an EIB test. We used item 4 of the GINA questionnaire regarding exercise-induced symptoms to assess the diagnostic power of this instrument. ResultsWe included 40 patients (17 with MMA and 23 with STRA) with a mean age of 11.3 years and a mean FEV1z-score of –0.33, of who 13 (32.5%) were classified as having uncontrolled asthma. Of the patients with uncontrolled asthma, 7 (53.8%) exhibited a decrease in the FEV1 after the EIB test. We found a higher frequency of EIB in participants with FEV1 z-score values of less than –1.0 compared to those with a z-score of –1.0 or greater (P = .05). There were no significant differences in the frequency of EIB based on disease severity and control. We also found no association of item 4 (GINA) with EIB. The area under the ROC curve demonstrated that the discriminative power of the GINA questionnaire for the detection of EIB is inadequate (P = .41), with sensitivity of 42.1% and specificity of 57.1%. ConclusionsThe item concerning physical activity in the GINA questionnaire has insufficient diagnostic power to detect EIB in children and adolescents with asthma.

Effect of age on exercise-induced bronchoconstriction in children and adolescents with asthma

Objective The relationship between exercise-induced bronchoconstriction (EIB) and exertional dyspnea in children and adolescents is yet to be fully established. This study examined whether indicators of fractional exhaled nitric oxide (FeNO), forced expiratory volume in 1 s (FEV1) percent predicted at baseline, and dyspnea are useful for predicting children and adolescents with EIB. Methods We enrolled 184 children and adolescents diagnosed with asthma (mean age 11.2 years); participants were divided into two groups according to age (12 years) and were subjected to a 6-min exercise challenge test. Lung function tests and modified Borg scale scores were used to examine perceptions of dyspnea at 0, 5 and 15 min after exercise. Results Among children, the maximum percentage drop in FEV1 after exercise correlated significantly with FeNO (adjusted β = 2.3, P < 0.001) and with the perception of dyspnea at 5 min after exercise (adjusted β = 1.9, P < 0.001). Among adolescents, the maximum percentage drop in FEV1 correlated with FeNO (adjusted β = 2.7, P = 0.007) and with lung function (FEV1, percent predicted; adjusted β = −0.28, P = 0.006). Children with EIB had significantly stronger dyspnea after exercise than did children without EIB. Adolescents even without EIB may experience more exertional dyspnea than children without EIB. Conclusions Overall, our findings indicated that EIB was associated with FeNO and exertional dyspnea in asthmatic children. By contrast, EIB was associated with FEV1 percent predicted at baseline and FeNO but not with exertional dyspnea in asthmatic adolescents.

The Visual Analog Scale detects exercise-induced bronchoconstriction in children with asthma

Objective: Exercise-induced bronchoconstriction (EIB) is a specific morbidity of childhood asthma and an important sign of uncontrolled asthma. The occurrence of EIB is insufficiently identified by the Childhood Asthma Control Test (C-ACT) and Asthma Control Test (ACT). This study aimed to (1) evaluate the Visual Analog Scale (VAS) for dyspnea as a tool to detect EIB in asthmatic children and (2) assess the value of combining (C-)ACT outcomes with VAS scores. Methods: We measured EIB in 75 asthmatic children (mean age 10.8 years) with a standardized exercise challenge test (ECT) performed in cold and dry air. Children and parents reported VAS dyspnea scores before and after the ECT. Asthma control was assessed by the (C-)ACT. Results: Changes in VAS scores (ΔVAS) of children and parents correlated moderately with fall in forced expiratory volume in 1 second (FEV1), respectively rs=0.57 (p < .001) and rs=0.58 (p < .001). At a ΔVAS cutoff value of ≥3 in children, sensitivity and specificity for EIB were 80% and 79% (AUC 0.82). Out of 38 children diagnosed with EIB, 37 had a (C-)ACT score of ≤19 and/or a ΔVAS of ≥3, corresponding with a sensitivity of 97% and a negative predictive value of 96%. Conclusion: This study shows that the VAS could be an effective additional tool for diagnosing EIB in children. A reported difference in VAS scores of ≥3 after a standardized ECT combined with low (C-)ACT scores was highly effective in detecting and excluding EIB.

Assessing Exercise-Induced Bronchoconstriction in Children; The Need for Testing.

Objective: Exercise-induced bronchoconstriction (EIB) is a specific morbidity of childhood asthma and a sign of insufficient disease control. EIB is diagnosed and monitored based on lung function changes after a standardized exercise challenge test (ECT). In daily practice however, EIB is often evaluated with self-reported respiratory symptoms and spirometry. We aimed to study the capacity of pediatricians to predict EIB based on information routinely available during an outpatient clinic visit.Methods: A clinical assessment was performed in 20 asthmatic children (mean age 11.6 years) from the outpatient clinic of the MST hospital from May 2015 to July 2015. During this assessment, video images were made. EIB was measured with a standardized ECT performed in cold, dry air. Twenty pediatricians (mean years of experience 14.4 years) each evaluated five children, providing 100 evaluations, and predicted EIB severity based on their medical history, physical examination, and video images. EIB severity was predicted again after additionally providing baseline spirometry results.Results: Nine children showed no EIB, four showed mild EIB, two showed moderate, and five showed severe EIB. Based on clinical information and spirometry results, pediatricians detected EIB with a sensitivity of 84% (95% CI 72–91%) and a specificity of 24% (95% CI 14–39%).The agreement between predicted EIB severity classifications and the validated classifications after the ECT was slight [Kappa = 0.05 (95% CI 0.00–0.17)]. This agreement still remained slight when baseline spirometry results were provided [Kappa = 0.19 (95% CI 0.06–0.32)].Conclusion: Pediatricians' prediction of EIB occurrence was sensitive, but poorly specific. The prediction of EIB severity was poor. Pediatricians should be aware of this in order to prevent misjudgement of EIB severity and disease control.

Ventilatory Demand During Stepping and Running: Implications for Exercise-Induced Bronchoconstriction in Children.

Single-step tests have been proposed as simple and inexpensive challenges to diagnose exercise-induced bronchoconstriction (EIB) in the pediatric population. Work performed and the resulting ventilation, however, might be substantially lower in stepping than running. This might decrease the diagnostic yield of step-based challenges. In a cross-sectional study, 53 children with asthma with exercise-related symptoms (34 boys, age 6-18 y) underwent an incremental stepping test, a 6-min constant stepping test, and a treadmill running test on different days. Constant and incremental stepping tests presented with lower metabolic demands (V̇O2 1.42 ± 0.48 and 1.34 ± 0.55 L/min, respectively), ventilatory demands (V̇O2 45 ± 14 and 43 ± 16 L/min, respectively), and cardiovascular demands (160 ± 20 and 161 ± 19 beats/min, respectively) than the treadmill running test (1.65 ± 0.60 L/min, 54 ± 17 L/min, and 172 ± 7 beats/min, respectively) (P < .05). Between-test agreement in diagnosing EIB was poor (kappa 0.217-0.361). Although EIB prevalence was higher after the treadmill running test (60%) compared to constant (53%) and incremental (47%) stepping tests, 7 subjects developed EIB only in stepping. Clinical and resting functional characteristics did not differ in discordant subjects (ie, EIB negative in a given test but positive in another) versus concordant subjects (ie, EIB negative or positive in both tests). EIB was not related to individual test ability in eliciting high to very-high ventilation (≥ 40% or ≥ 60% maximum voluntary ventilation, respectively). Moreover, a negative stepping test but a positive treadmill test (and vice versa) was not associated with greater ventilatory demands. Lower prevalence of EIB in stepping compared to treadmill running is not related to less ventilation demand in the former modality. Although stepping might be useful as a screening EIB test due its portability and low cost, a negative test should be confirmed with a running-based test in symptomatic children.

FeNO and Exercise Testing in Children at Risk of Asthma

Exercise testing is the gold standard for diagnosing exercise-induced bronchoconstriction in children, but requires considerable cooperation and medical resources. Therefore, fraction of exhaled nitric oxide (FeNO) has been proposed as a tool to predict the need for exercise testing. The objective of this study was to investigate the relationship between FeNO, exercise test results, and a history of respiratory symptoms during exercise in children at risk of asthma. FeNO measurement, exercise testing, and interview about respiratory symptoms during exercise were completed in 224 seven-year-old children from the at-risk Copenhagen Prospective Studies on Asthma in Childhood2000 birth cohort. The associations between FeNO, exercise test results, and reported respiratory symptoms during exercise were analyzed adjusting for gender, respiratory infections, and inhaled corticosteroid treatment. The associations were also analyzed stratified by asthma and atopic status. Of the 224 children, 28 (13%) had an established asthma diagnosis and 58 (26%) had a positive exercise test (≥15% drop in forced expiratory volume in 1 second [FEV1] from baseline). FeNO and bronchial obstruction after exercise were linearly associated with a doubling of FeNO corresponding to a 2.4% drop in FEV1 (95% confidence interval, 0.8-4.1; P<.01). However, a receiver operating characteristic curve analysis showed that the best cutoff of FeNO for predicting exercise test outcome among children who reported respiratory symptoms during exercise was 17 ppb, which only had 74% negative predictive value. There was no association between FeNO and reported respiratory symptoms during exercise (odds ratio= 1.3 [0.8-1.9]; P= .29) or reported symptoms during exercise and exercise test results (odds ratio= 1.0 [1.0-1.1]; P= .12). A history of respiratory symptoms during exercise was not associated with either elevated FeNO or a positive exercise test in children at risk of asthma. FeNO and exercise test results were linearly associated traits, but FeNO could not reliably be used dichotomized to predict the need of exercise testing.

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

The diagnosis of exercise-induced bronchoconstriction (EIB) was established by changes in lung function after exercise challenge. The prevalence of EIB and factors related to EIB were not fully described in children with asthma. The aim of this study was to investigate the prevalence and predictors of EIB in children with asthma. A total of 149 children with physician-diagnosed asthma above 5 years of age underwent standardized treadmill exercise challenge for EIB and methacholine challenge for airway hyper-responsiveness from October 2015 to December 2016. EIB presented in 52.5% of children with asthma. Compared with children without EIB, there were more patients with atopic dermatitis in children with EIB (p=0.038). Allergic to Dermatohagoides pteronyssinus and Dermatophagoides farinae were also found more in children with EIB (p=0.045 and 0.048 respectively). Maximal decrease in forced expiratory volume in 1s (FEV1) were highest in patients who were most sensitive to methacholine provocation (provocation concentration causing 20% fall in FEV1 [PC20]≤1mg/mL). Patients, who were more sensitive to methacholine challenge (with lower PC20 levels), develop EIB with more decline in FEV1 after exercise challenge (p=0.038). Among patients with EIB, airflow limitation development in patient with methacholine-induced airway hyper-responsiveness was more abrupt and severe compared with patients without airway hyper-responsiveness (p=0.045 and 0.033 respectively). EIB presented in 52.5% of children with asthma. The more severe methacholine-induced hyper-responsiveness, the higher prevalence of EIB as well as the severity.

BMI predicts exercise induced bronchoconstriction in asthmatic boys.

Exercise induced bronchoconstriction (EIB) is a frustrating morbidity of asthma in children. Obesity has been associated with asthma and with more severe EIB in asthmatic children. To quantify the effect of BMI on the risk of the occurrence of EIB in children with asthma. Data were collected from six studies in which exercise challenge tests were performed according to international guidelines. We included 212 Children aged 7-18 years, with a pediatrician-diagnosed mild-to-moderate asthma. A total of 103 of 212 children (49%) had a positive exercise challenge (fall of FEV1 ≥ 13%). The severity of EIB, as measured by the maximum fall in FEV1 , was significantly greater in overweight and obese children compared to normal weight children (respectively 23.9% vs 17.9%; P = 0.045). Asthmatic children with a BMI z-score around +1 had a 2.9-fold higher risk of the prevalence of EIB compared to children with a BMI z-score around the mean (OR 2.9; 95%CI: 1.3-6.1; P < 0.01). An increase in BMI z-score of 0.1 in boys led to a 1.4-fold increased risk of EIB (OR 1.4; 95%CI: 1.0-1.9; P = 0.03). A reduction in pre-exercise FEV1 was associated with a higher risk of EIB (last quartile six times higher risk compared to highest quartile (OR 6.1 [95%CI 2.5-14.5]). The severity of EIB is significantly greater in children with overweight and obesity compared to non-overweight asthmatic children. Furthermore, this study shows that the BMI-z-score, even with a normal weight, is strongly associated with the incidence of EIB in asthmatic boys.

Exercise intolerance and exercise-induced bronchoconstriction in children.

Respiratory symptoms at rest or during exercise may restrain the physical capabilities required for normal motor and psychosocial development in children. The most frequent cause of exercise intolerance, apart from poor physical fitness, is exercise-induced bronchoconstriction (EIB), which may occur in some healthy children and in children with asthma. It is proposed that hyperventilation during exercise is associated with drying and cooling of airways, which can trigger a proinflammatory response. Several tests are used to confirm EIB, and the exercise-challenge test is the most common. Some nonpharmacologic therapies may induce airway refractoriness; warm-up exercise can result in the attenuation of EIB in more than half of the people with EIB. Prophylactic intermittent treatment with short-acting bronchodilators is the most commonly used treatment, but the conventional pharmacologic therapy for patients with uncontrolled asthma is the regular use of inhaled corticosteroids, with or without long-acting beta-agonists and montelukast. Therapy should result in optimal control of exercise-induced symptoms during habitual physical activity and also allow participation in sports activity in athletes.

Serum tryptase level and inflammatory markers in exhaled breath condensate of children with exercise-induced symptoms.

The pathogenesis of exercise-induced bronchoconstriction (EIB) is poorly understood. To evaluate the biomarkers concentration in exhaled breath condensate (EBC) in schoolchildren with postexercise symptoms. We also evaluated changes in fractional exhaled nitric oxide (FeNO) value and the serum tryptase level after exercise. One hundred children with postexercise symptoms were included. Methacholine challenge testing (MCT) was performed at visit 2, and exercise challenge testing (ECT) was performed at visit 3. Before and after ECT serum tryptase levels and FeNO values were measured. EBC was collected after ECT from 10 randomly selected children from each group. The children were assigned to the following groups: ECT(+) MCT(+), ECT(+) MCT(-), ECT(-) MCT(+), ECT(-) MC(-). We measured the following molecules: eotaxin, interleukin (IL) 8, IL-1ra, IL-1 beta, IL-6, IL-1 alpha, IL-12(p40), IL-5, granulocyte-macrophage colony-stimulating factor, IL-7, IL-15, IL-4, IL-2, IL-10, tumor necrosis factor alpha, interferon gamma, IL-13, tumor necrosis factor beta, monocyte chemoattractant protein-1, IL-17A, macrophage inflammatory proteins-1 alpha, macrophage inflammatory proteins-1 beta, IL-12(p70), and regulated on activation, normal T-cell expressed and secreted by using a multiplex immunoassay. Prostaglandin E2 (PGE2), leukotriene B4, and cysteinyl leukotriene were analyzed by using separate enzyme-linked immunosorbent assay kits. In the MCT(+) group, a detectable level of IL4 in EBC and detectible levels of eicosanoids were seen in the ECT(+) group. We observed the opposite direction of ECT-induced changes in FeNO and serum tryptase concentrations in patients with detectable compared with patients without detectable levels of cytokines in EBC. We showed ECT-induced reduction in the tryptase level in patients with a nondetectable PGE2 level in EBC and an increase in tryptase levels in patients who had detectable levels of PGE2 in EBC. EBC was a useful method to estimate inflammation but only in children with symptoms and with EIB shown by a positive ECT. Children with a positive ECT had detectable levels of eicosanoids in EBC; the opposite direction of ECT-induced changes in FeNO and serum tryptase concentrations was observed. The results of above study confirm the role of mast cells and eicosanoids in the pathogenesis of EIB in children.

The association of forced expiratory volume in one second and forced expiratory flow at 50% of the vital capacity, peak expiratory flow parameters, and blood eosinophil counts in exercise-induced bronchospasm in children with mild asthma.

BackgroundExercise-induced bronchoconstriction (EIB), which describes acute airway narrowing that occurs as a result of exercise, is associated with eosinophilic airway inflammation, bronchial hyperresponsiveness. The forced expiratory volume in one second (FEV1) is the most commonly used spirometric test in the diagnosis of EIB in exercise challenge in asthma. Other parameters such as forced expiratory flow at 50% of the vital capacity (FEF50%) and peak expiratory flow (PEF) are used less often in the diagnosis of EIB.ObjectiveThe purpose of this study is to evaluate the association of FEV1 and FEF50%, PEF parameters, blood eosinophil counts in EIB in children with mild asthma.MethodsSixty-seven children (male: 39, female: 28) with mild asthma were included in this study. Pulmonary functions were assessed before and at 1, 5, 10, 15, and 20 minutes after exercise. The values of spirometric FEV1, FEF50%, PEF, and blood eosinophil counts were evaluated in EIB in children with mild asthma.ResultsThere was a positive correlation between FEV1 with FEF50% and PEF values (p<0.05; FEF50%, r=0.68; PEF, r=0.65). Also, a positive correlation was found between blood eosinophil counts and the values of spirometric FEV1, FEF50%, and PEF (p<0.05; FEV1, r=0.54; FEF50%, r=0.42; PEF, r=0.26). In addition to these correlations, in the exercise negative group for FEV1, the FEF50% and PEF values decreased more than the cutoff values in 3, and 2 patients, respectively.ConclusionAccording to the presented study, eosinophil may play a major role in the severity of EIB in mild asthma. FEF50% and PEF values can decrease in response to exercise without changes in FEV1 in mild asthmatic patients.