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Bronchodilatory Effect of Deep Inspiration Is Absent in Subjects With Mild COPD^*

^* From the Istituto di Medicina Generale e Pneumologia, Cattedra di Malattie dell’Apparato Respiratorio, University of Palermo, Palermo, Italy; and the Division of Allergy and Clinical Immunology, and Division of Respiratory and Critical Care Medicine, Department of Medicine, Johns Hopkins University, School of Medicine, Baltimore, MD.

Correspondence to: Nicola Scichilone, MD, Istituto di Medicina Generale e Pneumologia, Cattedra di Malattie dell’Apparato Respiratorio, University of Palermo, via Trabucco 180, 90146 Palermo, Italy; e-mail: n.scichilone{at}libero.it

Study objectives: 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 FEV₁ or FEV₁/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.

Key Words: aging • bronchial obstruction • bronchoconstriction • bronchodilation • COPD • deep inspiration • methacholine

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				N. Scichilone, S. Permutt, V. Bellia, and A. Togias Inhaled Corticosteroids and the Beneficial Effect of Deep Inspiration in Asthma Am. J. Respir. Crit. Care Med., September 15, 2005; 172(6): 693 - 699. [Abstract] [Full Text] [PDF]