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Relationship between the baseline alveolar volume‐to‐total lung capacity ratio and airway responsiveness
Author(s) -
Kaminsky David A.,
Daud Anees,
Chapman David G.
Publication year - 2014
Publication title -
respirology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 85
eISSN - 1440-1843
pISSN - 1323-7799
DOI - 10.1111/resp.12347
Subject(s) - medicine , spirometry , lung volumes , airway , methacholine , vital capacity , anesthesia , diffusing capacity , cardiology , lung , lung function , asthma , respiratory disease
Background and objective Ventilation heterogeneity ( VH ) has been linked to airway responsiveness ( AR ) based on various measures of VH involving inert gas washout, forced oscillation and lung imaging. We explore whether VH at baseline, as measured by the simple ratio of single breath alveolar volume to plethysmographically determined total lung capacity ( VA / TLC ), would correlate with AR as measured by methacholine challenge testing. Methods We analysed data from spirometry, lung volumes, diffusing capacity and methacholine challenge to derive the VA / TLC and the dose–response slope ( DRS ) of forced expiratory volume in 1 s ( DRS ‐ FEV 1) during methacholine challenge from 136 patients. We separated out airway closure versus narrowing by examining the DRS for forced vital capacity ( DRS‐FVC ) and the DRS for FEV 1/ FVC ( DRS ‐ FEV 1/ FVC ), respectively. Similarly, we calculated the DRS for s G aw ( DRS ‐s G aw) as another measure of airway narrowing. We performed statistical analysis using Spearman rank correlation and multifactor linear regression using a backward stepwise modelling procedure. Results We found that the DRS ‐ FEV 1 correlated with baseline VA / TLC (rho = −0.26, P < 0.01), and VA / TLC and FEV 1 were independently associated with DRS ‐ FEV 1 (R 2 = 0.14, P = 0.01). In addition, VA / TLC was associated with both airway narrowing and closure in response to methacholine. Conclusions These results confirm that baseline VA / TLC is associated with AR , and reflects both airway closure and airway narrowing following methacholine challenge.