Abstract

Background and aim The standard treatment of patients with COPD comprises β2-agonists and anticholinergics. Both drugs exert similar effects in terms of bronchodilation but in the clinical use we observed that some patients reported a stable degree or even an increase of dyspnea after the administration of β2-agonists compared to anticholinergics. We hypothesized that β2-agonists might favor an additional change in breathing pattern leading to increased minute volume and respiratory rate, and thereby a smaller reduction of dyspnea compared to anticholinergics. Methods Nineteen patients with moderate to severe COPD were evaluated in a placebo-controlled, randomized, double-blinded, triple-crossover design comprising four visits. We evaluated changes in respiratory rate, tidal volume, lung function and dyspnea before and after administration of fenoterol, oxitropium and placebo. Results The changes in respiratory patterns were not statistically significant and showed large variability. Despite this there were overall tendencies. Respiratory rate increased after fenoterol and decreased after oxitropium and placebo, while tidal volume increased after fenoterol and decreased after oxitropium and placebo. Overall, the perceived reduction of dyspnea, however, was similar after fenoterol and oxitropium. Conclusion The data did not indicate a homogeneous and stable pattern over all patients. Although the observed changes were not statistically significant, they pointed towards the hypothesis underlying this study. It may be that in single patients with COPD indeed the beneficial effect of β2-agonists is partially counteracted by an adverse change in breathing pattern. We believe that this possibility is worth of clinical attention.

Authors and Affiliations