Sunovion Brovana Versus Serevent Inspiratory Capacity High Resolution Computed Tomography

Inclusion Criteria: * Age \>=40 years * History of smoking \>=20 pack-years of cigarettes * Be using medically acceptable birth-control measures if a female of child-bearing potential * Be willing to withhold any existing short or long-acting bronchodilators for the appropriate time period prior to each test day. Use of inhaled corticosteroids is not exclusionary, but will be maintained at a constant level throughout the study. * Must be willing and able to perform spirometry, slow vital capacity, plethysmography, DLCO, and 6 minute walk after appropriate instruction. * Informed consent * At the screening visit: * Post-albuterol FEV1/FVC \<LLN (Hankinson) * Post-albuterol FEV1 \<70%% and \>=30 % predicted (Hankinson) * An increase in FEV1 after 4 puffs albuterol sulfate HFA of at least 5% and 50ml Exclusion Criteria: * Presence of other clinically significant illnesses or condition that might interfere with the study, including but not limited to uncontrolled hypertension, cardiovascular disease, cardiac arrhythmia, diabetes, hyperthyroidism, seizure disorder or any history of pheochromocytoma * History of asthma (in the opinion of the investigator) * A COPD exacerbations within the past 2 months requiring oral corticosteroids or hospitalization. * Continuous oxygen therapy greater than 12 hours per day * Subjects with a body mass index less than 15 or greater than 38 * Known allergy or contradiction to albuterol, arformoterol, salmeterol, tiotropium or prior significant adverse reactions to other beta agonists or ipratropium. * Hypersensitivity to milk protein. Bloating or gas from lactose is not an exclusion. * Inability to withhold other adrenergic drugs (salmeterol, arformoterol, formoterol, albuterol etc.) for an appropriate duration before each visit. * Ongoing need for drugs which might potentiate hypokalemia (xanthine derivatives (theophylline), steroids, non-potassium sparing diuretics (unless in fixed combination with potassium sparing diuretic) * Ongoing need for drugs which might cause QTc prolongation (MAO inhibitors, tricyclic antidepressants, cardiac anti-arrhythmics Class Ia (e.g., disopyramide, procainamide, quinidine), or class III (e.g., amiodarone, dofetilide, ibutilide, sotalol), terfenadine, astemizole, mizolastin and any other drug with potential to significantly prolong the QT interval.) * Ongoing need for beta-blockers (selective or non-selective) * Use of phenothizines (thioridizine), or other drugs that may interact with arformoterol, salmeterol or albuterol for the duration of the study. Washout of greater than seven half-lives of the drug prior to the study. * History of angle closure glaucoma, symptomatic prostatic hypertrophy or bladder neck obstruction. * Investigational drugs within 30 days * Affiliation with the Division of Pulmonary and Critical Care Medicine, David Geffen School of Medicine * Pregnancy, breastfeeding, planning to become pregnant during study, or woman of childbearing potential unwilling to use adequate contraception