Asthma in Children, Dyspnea; Asthmatic, Obesity, Childhood
Conditions
Keywords
Pediatric, Breathlessness, Ventilatory Constraints, Exercise
Brief summary
The overall objective of this study is to better understand the respiratory mechanisms provoking dyspnea on exertion in obese asthmatic children.
Detailed description
Obesity and asthma are the most common diseases of childhood, causing activity limitation and impaired quality of life. Most obese asthmatic children report dyspnea on exertion (DOE) as their primary asthma symptom. Fear of dyspnea promotes sedentariness and reduces exercise capacity and quality of life. DOE in asthmatic children is typically attributed to bronchoconstriction but it is also possible that obesity is an equal or even major contributor to dyspnea. Excess chest and abdominal weight in obese children results in low lung volumes, which increases the risk of mechanical ventilatory constraints such as expiratory flow limitation, dynamic hyperinflation, and airway closure, all of which can provoke DOE. Unnecessary use of corticosteroids and other asthmatic medication in obese asthmatic children cannot treat obesity-specific mechanical ventilatory constraints and could have unintended deleterious effects. Therefore, there is an urgent need to better understand the mechanisms involved in DOE to provide evidence-based symptom management for obese asthmatic children that will promote regular physical activity and lessen DOE. The overall objective of this study is to better understand the respiratory mechanisms provoking DOE in obese asthmatic children. The investigators hypothesize that low lung volume breathing in obesity leads to mechanical ventilatory constraints in the presence or absence of bronchoconstriction during exercise. Whereas DOE attributable to bronchoconstriction should respond to bronchodilators, DOE attributable to obesity-specific mechanical ventilatory constraints will not respond to bronchodilators. A comprehensive physiological pulmonary function and exercise-testing based approach will be used to identify 9-17-year-old obese asthmatic children who do and do not bronchoconstrict during exercise. The presence/absence of bronchoconstriction will be determined by a comprehensive measure of exercise-induced central and peripheral airway reactivity using spirometry and impulse oscillometry (i.e., greater than or equal to 10% reduction in forced expiratory volume in 1s, FEV1, or greater than or equal to 40% increase in peripheral airway resistance, R5-20, will be indicative of bronchoconstriction). The investigators will also determine the mechanisms by which bronchodilators like albuterol affect bronchoconstriction amd mechanical ventilatory constraints in asthmatic children with obesity.
Interventions
OTHERControl
In this condition, the participants will not receive any medications or drugs before exercise
DRUGAlbuterol
180 mcg of Albuterol will be administered before exercise
Sponsors
Nationwide Children's Hospital
Ohio State University
Study design
Allocation
NA
Intervention model
SINGLE_GROUP
Primary purpose
BASIC_SCIENCE
Masking
NONE
Intervention model description
2 repeated measures (within factor): Control and Albuterol
Eligibility
Sex/Gender
ALL
Age
9 Years to 17 Years
Healthy volunteers
No
Inclusion criteria
General inclusion criteria: * Age range: 9-17 years of age * Participants with physician diagnosed asthma will be recruited for this study. * Objectively Confirmed Asthma Diagnosis: Asthma diagnosis will be confirmed objectively using spirometry (FEV1 \< 80% predicted or FEV1/FVC \< lower limit of normal), bronchodilator reversibility testing (post-bronchodilator improvement of ≥ 12% and 200mL in FEV1 or FVC; or a decrease in lung hyperinflation of at least 150 mL; ATS guidelines on lung function test interpretation). Patients in whom asthma cannot be confirmed objectively will be excluded from the study. * Experience dyspnea on exertion as assessed by answering yes to one of the following two questions on the screening questionnaire: 1) Do you get short of breath with exertion? 2) Do you feel that your asthma is limiting you from participating in exercise? * Ability to communicate in English Body mass index criteria (BMI): We will study asthmatic children with obesity based on their BMI percentile: • Obese: BMI ≥95th percentile and less than 170% of the 95th BMI percentile based on norms from the CDC
Exclusion criteria
Criteria for pulmonary function: We will exclude asthmatic children with: * Severe asthma: Forced expiratory volume in 1s (FEV1) \< 50% predicted * Restrictive pulmonary disease: Forced vital capacity (FVC) and total lung capacity (TLC) \< 80% predicted * Diffusion limitation: Diffusing capacity relative to alveolar volume (DLCO/VA) \< 80% predicted Daily activity levels: Children participating in regular vigorous conditioning exercise such as running, jogging, aerobics, cycling, or swimming for ≥60min/session and ≥five times per week will be excluded to ensure similarity in physical activity levels between subjects and to avoid enrolling a potential high-fit, extremely active child. Children who participate in daily, unorganized physical activity (i.e., majority of children), will not be excluded. Children who are sedentary or only participate in school physical education classes will not be excluded. The following
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Expiratory flow limitation | up to 2 hours during the intervention (exercise) | Units: % of tidal volume, measured as overlap between exercise tidal flow volume loop and maximal expiratory flow volume loop |
| Dynamic hyperinflation | up to 2 hours during the intervention (exercise) | Units: % of total lung capacity, measured as change in end-expiratory lung volume from rest to exercise |
| Forced expiratory volume in 1 s | Pre to 30 min post exercise | Units: Litres, measured with spirometry |
| Peripheral airway reactivity (R5-R20) | Pre to 30 min post exercise | Units: % change from pre to post exercise, measured with impulse oscillometry |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Rating of perceived breathlessness | up to 2 hours during the intervention (exercise) | Borg 0 - 10 scale |
Countries
United States
Outcome results
None listed