Study Design and Methods Rationale~The expected FEV1 response to a bronchodilator is uncertain as multiple factors influence this measure, including severity of disease, day to day variability, varying reversibility in COPD patients, the delivery of the drug to a patient and the effectiveness of the medication delivered. Thus, the measurement of an acute bronchodilator response after delivering a long acting bronchodilator may not identify whether a medication has been effectively delivered to a patient.~However, if a long acting bronchodilator has not been effectively delivered to the lung, then subsequent delivery of a short acting bronchodilator should produce a significant additional bronchodilator response. On the other hand, if a long acting bronchodilator has been effectively delivered to the lung, then subsequent delivery of a short acting bronchodilator should not produce any further significant bronchodilation.~Based on this rationale, comparison of the acute bronchodilator response to a short acting bronchodilator after receiving a long acting should identify whether drug delivery is ineffective in a selected patient population, irrespective of baseline FEV1 and of any partial response to the long acting bronchodilator. Comparison of the short acting bronchodilator measurement between patient groups with differing PIF thresholds should identify whether PIF has an impact of drug delivery of a long acting bronchodilator via a DPI.~Open label design comparing the acute bronchodilator response after delivery of a long acting bronchodilator via Ellipta DPI in patients with normal, suboptimal and minimal PIF.
The purpose of the study is to determine whether PIF is clinically important when using the Ellipta DPI device. In addition, the study will validate the best/most clinically appropriate way to perform a PIF maneuver, to determine the testing capabilities of the preferred PIF maneuver and to relate this PIF measurement to meaningful clinical outcomes in COPD patients