%0 Journal Article
%T Comparison of Airway Hyperreactivity in Chronic Obstructive Pulmonary Disease and Asthma
%A Shieh-Ching Yang
%A Bon-Yuan Lin
%J Chang Gung Medical Journal
%D 2010
%I 
%X Background: Airway hyperreactivity (AHR) has been described in patients with chronicobstructive pulmonary disease (COPD). However, the nature and characteristicsof AHR in this disease have not been fully investigated.Methods: AHR was examined in a sample of 33 patients with COPD and 25 with asthmaand compared during continuous inhalation of stepwise increased concentrationsof methacholine. Respiratory resistance (Rrs) was measured bythe forced oscillation technique and the dose-response curves were recorded.Results: The mean values for both forced vital capacity (FVC) and forced expiratoryvolume in 1s (FEV1) were well-preserved in subjects with asthma. In contrast,there was an obstructive ventilatory defect in patients with COPD, asevidenced by the FEV1/FVC ratio, which fell below 70%. Upon methacholinechallenge, only 54.5% (18/33) of the patients with COPD had AHR,compared with 100% (25/25) of those with asthma. Analysis of the doseresponsecurves revealed that the patients with COPD had a significantlyhigher baseline Rrs, and thus lower baseline respiratory conductance (Grs),than those with asthma. The cumulative dose of methacholine capable ofprovoking a positive reaction was significantly higher in patients withCOPD. The slope of the Grs was also less steep in responders with COPD.There was good correlation between the severity of AHR and the initial levelof airway narrowing in patients with COPD (r = 0.623, p < 0.01), but not inthose with asthma.Conclusion: AHR is not uncommon in COPD, and it has different characteristics fromthat occurring in asthma.
%K airway hyperreactivity
%K methacholine challenge
%K respiratory resistance
%K chronic obstructive pulmonary disease
%U http://memo.cgu.edu.tw/cgmj/3305/330505.pdf