Perforomist Versus Foradil Evaluated by Inspiratory Capacity and High Resolution Computed Tomography (HRCT)

Inclusion Criteria: * Symptomatic subjects with moderate to severe COPD * Age greater than/equal to 40 years * History of smoking greater than/equal to 20 pack-years of cigarettes * No history of asthma (in the opinion of the investigator) * No COPD exacerbations within the past 2 months requiring oral corticosteroids or hospitalization. * No continuous oxygen therapy * Subjects with a body mass index less than 15 or greater than 38 * Patients must be without 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 * Be using medically acceptable birth-control measures if a female of child-bearing potential * Not be pregnant or breastfeeding * Be willing to withhold any existing short or long-acting bronchodilators for the appropriate time period prior to each test day (see below). 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. * No known allergy or contradiction to albuterol or formoterol or prior significant adverse reactions to other beta agonists. * No hypersensitivity to milk protein. Bloating or gas from lactose is not an exclusion. * No use of beta-blockers (selective or non-selective), phenothiazines (thioridazine), or other drugs that may interact with formoterol or albuterol for the duration of the study. Washout of greater than seven half-lives of the drug prior to the study. * No use of cardiac anti-arrhythmics Class Ia (e.g., disopyramide, procainamide, quinidine), or class III (e.g., amiodarone, dofetilide, ibutilide, sotalol), terfenadine, astemizole, mizolastine and any other drug with potential to significantly prolong the QT interval. * No use of non-potassium sparing diuretics unless in fixed combination with potassium sparing diuretic. * No investigational drugs within 30 days * No subjects affiliated with the Division of Pulmonary, Critical Care Medicine and Hospitalists, David Geffen School of Medicine * Informed consent Exclusion Criteria: * Post-albuterol FEV1/FVC less than lower limit of normal (Hankinson) * Post-albuterol FEV1 between 30% and 60% predicted (Hankinson) * An increase in FEV1 after albuterol sulfate HFA of at least 5% and 50 ml