title: Is ventilation heterogeneity related to asthma control?
abstract: In asthma patients, magnetic resonance imaging (MRI) and the lung clearance index (LCI) have revealed persistent ventilation heterogeneity, although its relationship to asthma control is not well understood. Therefore, our goal was to explore the relationship of MRI ventilation defects and the LCI with asthma control and quality of life in patients with severe, poorly controlled asthma.18 patients with severe, poorly controlled asthma (mean±sd 46±12 years, six males/12 females) provided written informed consent to an ethics board approved protocol, and underwent spirometry, LCI and (3)He MRI during a single 2-h visit. Asthma control and quality of life were evaluated using the Asthma Control Questionnaire (ACQ) and Asthma Quality of Life Questionnaire (AQLQ). Ventilation heterogeneity was quantified using the LCI and (3)He MRI ventilation defect percent (VDP).All participants reported poorly controlled disease (mean±sd ACQ score=2.3±0.9) and highly heterogeneous ventilation (mean±sd VDP=12±11% and LCI=10.5±3.0). While VDP and LCI were strongly correlated (r=0.86, p<0.0001), in a multivariate model that included forced expiratory volume in 1 s, VDP and LCI, VDP was the only independent predictor of asthma control (R(2)=0.38, p=0.01). There was also a significantly worse VDP, but not LCI in asthma patients with an ACQ score >2 (p=0.04) and AQLQ score <5 (p=0.04), and a trend towards worse VDP (p=0.053), but not LCI in asthma patients reporting ≥1 exacerbation in the past 6 months.In patients with poorly controlled, severe asthma MRI ventilation, but not LCI was significantly worse in those with worse ACQ and AQLQ.
authors.affiliation: Robarts Research Institute, The University of Western Ontario, London, ON, Canada.
authors.forename: Sarah
authors.initials: S
authors.lastname: Svenningsen
authors.affiliation: Division of Respirology, Dept of Medicine, McMaster University, Hamilton, ON, Canada.
authors.forename: Parameswaran
authors.initials: P
authors.lastname: Nair
authors.affiliation: Robarts Research Institute, The University of Western Ontario, London, ON, Canada Graduate Program in Biomedical Engineering, The University of Western Ontario, London, ON, Canada.
authors.forename: Fumin
authors.initials: F
authors.lastname: Guo
authors.affiliation: Division of Respirology, Dept of Medicine, The University of Western Ontario, London, ON, Canada.
authors.forename: David G
authors.initials: DG
authors.lastname: McCormack
authors.affiliation: Robarts Research Institute, The University of Western Ontario, London, ON, Canada Graduate Program in Biomedical Engineering, The University of Western Ontario, London, ON, Canada gparraga@robarts.ca.
authors.forename: Grace
authors.initials: G
authors.lastname: Parraga
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001249:Asthma / Q000503:physiopathology*; D001980:Bronchi / Q000473:pathology; D018450:Disease Progression; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D008168:Lung / Q000000981:diagnostic imaging*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D011788:Quality of Life; D012119:Respiration; D013147:Spirometry; D011795:Surveys and Questionnaires; D055815:Young Adult