Grant: Master's Award: Canada Graduate Scholarships

E-cigarette use is widely used in Canada, with a prevalence of 15%. E-cigarette users are more likely to develop respiratory symptoms and are at higher risk for respiratory diseases. Recent imaging and physiological studies suggest subclinical lung function abnormalities in young, healthy e-cigarette users with normal spirometry. Several studies in smokers with mild airflow obstruction have demonstrated abnormal ventilatory responses to exercise, including expiratory flow limitation, dynamic ventilatory constraint, and pulmonary gas exchange abnormalities. Understanding if similar pathophysiological issues occur in e-cigarette users is important. The proposed study will characterize the pulmonary function of young adult e-cigarette users by comparing detailed physiological and perceptual parameters at rest and during exercise compared to healthy individuals with no prior smoking or e-cigarette use. We hypothesize that e-cigarette users will have evidence of small airway dysfunction, which will be associated with abnormal ventilatory responses and heightened dyspnea during exercise compared with non-users. The proposed case-controlled cross-sectional study will include 20 e-cigarette users and 20 never-users. Over two visits, participants will undergo pulmonary function tests, cardiopulmonary exercise tests (CPET), and measurements of respiratory neuromechanics. CPET involves progressive exercise intensity on a cycle ergometer while assessing expired gas, breathing patterns, esophageal and gastric pressures, and diaphragm electromyography. Participants will rate dyspnea and leg discomfort using the modified Borg scale. Data analysis will include unpaired t-tests and linear mixed models to explore group differences and exercise intensity interactions.