Indacaterol Versus Tiotropium on Dynamic Hyperinflation in COPD

Exercise intolerance is a major complain of patients with chronic obstructive pulmonary disease (COPD). Dynamic hyperinflation has been recognized as an important limiting factor responsible for the appearance of intolerable dyspnea during exercise. Regular treatment with long-acting bronchodilators promotes a more sustained reduction of hyperinflation and consequent symptom relief and increase in the patient's ability to overcome physical demands of daily life. Tiotropium bromide (TIO) is a new generation, long-acting anticholinergic bronchodilator that significantly improves lung function, reduces symptoms and improves exercise tolerance in patients with advanced COPD. Indacaterol is a new ultra-long duration (\>24 h) β2-agonist, which promotes sustained dilation of the bronchi with a once-daily administration. Compared to tiotropium, indacaterol provides evidence that is as effective as tiotropium for bronchodilation, as well as other clinical outcomes such as dyspnea and state of health. However, comparative effects of indacaterol versus tiotropium with regard to outcomes in tolerance, dyspnea and dynamic lung hyperinflation during exercise is scarce. We hypothesized that indacaterol and TIO are not different in terms of exercise tolerance and its determinants (dynamic hyperinflation and dyspnea).