Mechanisms for Dyspnea on Exertion in Children With Obesity and Asthma: Distinct Physiological Phenotypes

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.
• •History of oral steroid medications for 4 weeks prior to enrollment
• •History of being admitted to an intensive care unit or being intubated because of their asthma in the past five years
• •History of allergy or hypersensitivity to albuterol
• •On long acting muscarinic antagonists (LAMA)
• •History of vocal cord dysfunction
• •History of obesity hypoventilation syndrome
• •History of untreated sleep apnea
• •History of heart disease, metabolic disease, or renal disease that, in the opinion of the PI (or co-I's), would increase the risks of exercise testing or alter the physiological responses to exercise
• •History of significant mental illness that in the opinion of the PI (or co-I's) would interfere with study participation or increase risks to the participant
• •History of musculoskeletal abnormality that would preclude cycling exercise
• •Pregnant or become pregnant during their participation in the study
• •History of other significant illnesses that, in the opinion of the PI (or co-I's), either increase risks of participation or alter the physiological responses to exercise
• •Inability to successfully complete pulmonary function or exercise testing measurements or difficulty with following instructions during testing
• •Inability to tolerate testing procedures or complications related to testing
• •If a participant develops hypoxemia or meets indications for terminating exercise, the exercise test will be terminated, and the participant will be referred for further evaluation In general, all participants will be encouraged to follow up with their asthma care provider or pediatrician for any health concerns that are discovered during their participation.