Bronchodilatory effect of deep inspiration is absent in subjects with mild COPD.
OBJECTIVE
To investigate whether the bronchodilatory effect of deep inspiration is impaired in subjects with COPD.


METHODS
We measured deep inspiration-induced bronchodilation in 19 patients with COPD and 17 healthy subjects (mean age, 67.8 +/- 7.1 years vs 62.5 +/- 9.3 years, respectively [+/- SEM]). Each subject underwent a series of single-dose methacholine provocations to induce at least a 15% reduction in inspiratory vital capacity (IVC). When this was achieved, subjects were asked to perform four consecutive deep inspirations, after which the IVC measurement was repeated and the percentage of bronchodilation by deep inspiration was calculated.


RESULTS
The percentage of reduction in IVC from baseline prior to the deep inspirations did not differ between the two groups (COPD, 20.1 +/- 1.6%; healthy, 22.7 +/- 2.4%; p = 0.38); median single methacholine doses employed were 20 mg/mL (range, 0.025 to 75 mg/mL) and 25 mg/mL (range, 10 to 75 mg/mL), respectively (p = 0.19). Deep inspirations were not able to reverse bronchoconstriction in patients with COPD (bronchodilation, 3.9 +/- 2.6%; p = 0.15 by one-sample t test). Bronchodilation by deep inspiration was present in healthy subjects (13.7 +/- 3.0%, p = 0.0003), and was significantly higher than that of patient with COPD (p = 0.02). In patients with COPD, deep inspiration-induced bronchodilation correlated with the percentage of predicted transfer factor of the lung for carbon monoxide (r = 0.53, p = 0.05), but not with airway obstruction, as assessed by FEV(1) or FEV(1)/FVC.


CONCLUSIONS
The bronchodilatory ability of deep inspiration is lost in mild COPD. We speculate that the absence of deep inspiration-induced bronchodilation contributes to the development and severity of chronic respiratory symptoms in patients with COPD.
Scichilone
Nicola
N
Istituto di Medicina Generale e Pneumologia, Cattedra di Malattie dell'Apparato Respiratorio, University of Palermo, Palermo, Italy. n.scichilone@libero.it
Marchese
Roberto
R
Catalano
Filippo
F
Vignola
Antonio Maurizio
AM
Togias
Alkis
A
Bellia
Vincenzo
V
D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D001985:Bronchial Provocation Tests / Q000379:methods; D016022:Case-Control Studies; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D001239:Inhalation / Q000502:physiology*; D008176:Lung Volume Measurements; D008297:Male; D016210:Methacholine Chloride; D008875:Middle Aged; D011336:Probability; D011379:Prognosis; D029424:Pulmonary Disease, Chronic Obstructive / Q000175:diagnosis* / Q000503:physiopathology; D011659:Pulmonary Gas Exchange; D012016:Reference Values; D015656:Respiratory Mechanics; D012680:Sensitivity and Specificity; D013147:Spirometry; D018709:Statistics, Nonparametric; D014797:Vital Capacity
D016210:Methacholine Chloride