title: Ventilation heterogeneity is associated with airway responsiveness in asthma but not COPD.
abstract: Airway hyperresponsiveness (AHR) occurs in both asthma and COPD. In older people with asthma, AHR is associated with increased acinar ventilation heterogeneity, but it is unknown if this association exists in COPD. Thirty one COPD and 19 age-matched asthmatic subjects had measures of spirometry, lung volumes, exhaled nitric oxide, ventilation heterogeneity, and methacholine challenge. Indices of acinar (Sacin) and conducting (Scond) airway ventilation heterogeneity were calculated from the multiple breath nitrogen washout. Predictors of AHR were then determined. In COPD, AHR was predicted by lower Sacin and lower FVC (model r(2)=0.35, p=0.001). In asthma, AHR was predicted by higher Sacin and higher residual volume (model r(2)=0.62, p<0.001). These findings suggest that airway responsiveness in COPD and asthma is determined by underlying disease-specific processes, rather than a common pattern of physiological abnormality.
authors.affiliation: Woolcock Institute of Medical Research, PO Box M77, Missenden Rd, Glebe NSW 2050, Australia; University of Sydney, Darlington, Australia; Cooperative Research Centre for Asthma and Airways, Glebe, Australia. Electronic address: kate.hardaker@sydney.edu.au.
authors.forename: Kate M
authors.initials: KM
authors.lastname: Hardaker
authors.forename: Sue R
authors.initials: SR
authors.lastname: Downie
authors.forename: Jessica A
authors.initials: JA
authors.lastname: Kermode
authors.forename: Norbert
authors.initials: N
authors.lastname: Berend
authors.forename: Gregory G
authors.initials: GG
authors.lastname: King
authors.forename: Cheryl M
authors.initials: CM
authors.lastname: Salome
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001249:Asthma / Q000503:physiopathology*; D001944:Breath Tests; D016535:Bronchial Hyperreactivity / Q000503:physiopathology*; D001985:Bronchial Provocation Tests; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008176:Lung Volume Measurements; D008297:Male; D008875:Middle Aged; D010991:Plethysmography; D029424:Pulmonary Disease, Chronic Obstructive / Q000503:physiopathology*; D012123:Pulmonary Ventilation / Q000502:physiology*; D013147:Spirometry
keywords: Aging; Airway hyperresponsiveness; Chronic obstructive pulmonary disease; Physiology; Pulmonary mechanics