Hyperpolarized (3)He MRI previously revealed spatially persistent ventilation defects in healthy, older compared with healthy, younger never-smokers. To understand better the physiological consequences and potential relevance of (3)He MRI ventilation defects, we evaluated (3)He-MRI ventilation-defect percent (VDP) and the effect of deep inspiration (DI) and salbutamol on VDP in older never-smokers. To identify the potential determinants of ventilation defects in these subjects, we evaluated dyspnea, pulmonary function, and cardiopulmonary exercise test (CPET) measurements, as well as occupational and second-hand smoke exposure. Fifty-two never-smokers (71 ± 6 yr) with no history of chronic respiratory disease were evaluated. During a single visit, pulmonary function tests, CPET, and (3)He MRI were performed and the Burden of Obstructive Lung Disease questionnaire administered. For eight of 52 subjects, there was spirometry evidence of airflow limitation (Global Initiative for Chronic Obstructive Lung Disease-Unclassified, I, and II), and occupational exposure was reported in 13 of 52 subjects. In 13 of 52 (25%) subjects, there were no ventilation defects and in 39 of 52 (75%) subjects, ventilation defects were observed. For those subjects with ventilation defects, six of 39 showed a VDP response to DI/salbutamol. Ventilation heterogeneity and VDP were significantly greater, and forced expiratory volume in 1 s (FEV1)/forced vital capacity was significantly lower (P < 0.05) for subjects with ventilation defects with a response to DI/salbutamol than subjects with ventilation defects without a response to DI/salbutamol and subjects without ventilation defects. In a step-wise, forward multivariate model, FEV1, inspiratory capacity, and airway resistance significantly predicted VDP (R(2) = 0.45, P < 0.001). In conclusion, most never-smokers had normal spirometry and peripheral ventilation defects not reversed by DI/salbutamol; such ventilation defects were likely related to irreversible airway narrowing/collapse but not to dyspnea and decreased exercise capacity.
Keywords: 3He MRI; bronchodilation; cardiopulmonary exercise testing; deep inspiration; pulmonary aging.
Copyright © 2014 the American Physiological Society.