Document Detail

Lung function changes following methacholine inhalation in COPD.
MedLine Citation:
PMID:  19081234     Owner:  NLM     Status:  MEDLINE    
BACKGROUND: The non-specific bronchial hyper-responsiveness reported in mild to moderate COPD is usually attributed to reduced airway calibre accentuating the effect of airway smooth muscle shortening. We hypothesized that in more severe COPD the fall in forced expiratory volume in 1 second (FEV(1)) seen during methacholine challenge would result from an increase in residual volume and decrease in vital capacity rather than an increase in airways resistance. METHODS: Twenty-five subjects with moderate to severe COPD and 10 asthmatic subjects had spirometry and oscillatory mechanics measured before methacholine challenge and at a 20% fall from baseline post challenge (PC(20)FEV(1)). RESULTS: In the COPD subjects median PC(20) was 0.35mg/mL. Comparing baseline to PC(20) there were significant falls in forced vital capacity (FVC) (2.91 vs. 2.2L; p<0.001), slow vital capacity (3.22 vs. 2.58L; p<0.001) and IC (2.21 vs. 1.75L; p<0.001) without change in FEV(1)/FVC ratio (0.52 vs. 0.52; not significant) or in total lung capacity where this was measured. Total respiratory system resistance (R(5)) was unchanged (0.66 vs. 0.68; not significant) but total respiratory system reactance decreased significantly (-0.33 vs. -0.44; p<0.001). In contrast, the asthmatics became more obstructed and showed a proportionally smaller fall in lung volume with increase in R(5) (0.43 vs. 0.64; p<0.01). CONCLUSIONS: In moderate to severe COPD the fall in FEV(1) with methacholine is mainly due to increases in residual volume, which may represent airway closure and new-onset expiratory flow limitation.
Paul P Walker; Justine Hadcroft; Richard W Costello; Peter M A Calverley
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Publication Detail:
Type:  Comparative Study; Journal Article     Date:  2008-12-10
Journal Detail:
Title:  Respiratory medicine     Volume:  103     ISSN:  1532-3064     ISO Abbreviation:  Respir Med     Publication Date:  2009 Apr 
Date Detail:
Created Date:  2009-03-02     Completed Date:  2010-02-22     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8908438     Medline TA:  Respir Med     Country:  England    
Other Details:
Languages:  eng     Pagination:  535-41     Citation Subset:  IM    
Division of Infection and Immunity, School of Clinical Sciences, University of Liverpool, University Hospital Aintree, Liverpool, UK.
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MeSH Terms
Asthma / physiopathology*
Bronchoconstrictor Agents / diagnostic use*
Forced Expiratory Volume / drug effects
Methacholine Chloride / diagnostic use*
Middle Aged
Pulmonary Disease, Chronic Obstructive / physiopathology*
Residual Volume / drug effects
Vital Capacity / drug effects
Reg. No./Substance:
0/Bronchoconstrictor Agents; 62-51-1/Methacholine Chloride

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