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Abstract

Despite the rise in vaping, its effect on the lungs is not well characterized. Therefore, we aimed to investigate the effects of vaping on lung structure and vasculature, pulmonary function, and patient-reported respiratory symptom burden in young persons with minimal combustible cigarette or cannabis exposure. In this cross-sectional study, young and otherwise healthy adults who reported current vaping with minimal combustible tobacco/cannabis exposure and age-matched never-vaping/smoking controls were recruited from the community. The vaping group was stratified into low (≤10 inhalations/day) and moderate/high (>10 inhalations/day) groups. Participants completed pulmonary function tests (PFTs), respiratory questionnaires, ¹²⁹Xe magnetic resonance imaging (¹²⁹Xe MRI) and chest computed tomography (CT). ¹²⁹Xe MRI measured airway function using ventilation defect percent (VDP) and ventilation low percent, and gas exchange using membrane-to-gas ratio (Mem/Gas), red blood cell-to-gas ratio (RBC/Gas) and RBC/Mem. Quantitative CT measured lung density, total pulmonary vascular volume (TPVV) normalized by the CT-measured total lung volume (TLV), and the volume of blood vessels with cross-sectional areas <5mm² (BV₅), 5-10mm² (BV5-10) and >10mm² (BV₁₀) normalized to TPVV. We evaluated 20 vaping (median[IQR], 25[22-31] years, 14-female) and 20 age-matched never-vaping/smoking participants (28[24-30] years, 15-female). Vaping substances included nicotine only (n=12), tetrahydrocannabinol/cannabidiol only (n=5) or both (n=3). Vaping frequency ranged from 1-250 inhalations per day (median=7) and vaping duration ranged from 1-13 years (median=3). While PFTs were not different between groups (p>0.1), vaping participants reported greater St. George’s Respiratory Questionnaire and Chronic Obstructive Pulmonary Disease Assessment Test scores (p<0.05). ¹²⁹Xe MRI gas-exchange measures were not different between groups (p>0.1). Increased vaping exposure was associated with increased VDP (p=0.027), decreased CT lung density (p<0.001) as well as decreased TPVV/TLV and BV₁₀/TPVV (p<0.05) and an increased BV₅/TPVV (p<0.001). Young persons who reported vaping exhibited increased respiratory symptoms with increased MRI ventilation abnormalities, decreased CT lung density and altered pulmonary vasculature, suggesting small airways dysfunction and early emphysema. This work is imperative in understanding early abnormalities before decades of exposure to help better inform policy and public risk perception.