The effect of bronchodilators on lung ventilation in chronic obstructive pulmonary disease

INTERVENTION: Washout period is one week between interventions. Single dose of 18µg tiotropium bromide and 200µg salbutamol. Both drugs are inhaled CONDITION: Chronic Obstructive Pulmonary Disease PRIMARY OUTCOME: Primary Outcome 1: Ventilation perfusion before and after treatment SECONDARY OUTCOME: Secondary Outcome 1: Ventilation heterogeneity measured using multiple breath nitrogen washout technique INCLUSION CRITERIA: Subjects must have a doctor diagnosis of COPD, greater than 15pack year smoking history and obstructed lung function that cannot be normalised with bronchodilator. Subjects must all be over the age of 50 with no history of asthma or allergic disease. Minimum age: 50 years for females and 40 years for males