Study objective: To investigate the short-term effects of inhaled salmeterol on the perception of dyspnea and lung function in patients with COPD.
Design: Double-blind, crossover, randomized trial comparing inhaled salmeterol and inhaled placebo over 4 h.
Setting: Pulmonary function laboratory at university medical center.
Patients: Sixteen patients with symptomatic COPD and at least 200-mL increase in FEV1 after inhalation of two puffs (180 microg) of albuterol.
Interventions: Visit 1 was used for familiarization. At visits 2 and 3 (2 to 3 days apart), patients inhaled either two puffs of salmeterol (42 microg) or placebo.
Measurements and results: Lung function and dyspnea were measured at 0.5, 2, and 4 h after inhalation of the study medication. Dyspnea was measured by the -5 to +5 category scale at rest and by the 0 to 10 category-ratio scale while breathing through inspiratory resistances of 5, 15, and 30 cm H20/L/s. Age was 66+/-8 years (mean+/-SD). FEV1 was 0.97+/-0.331 (51+/-13% predicted). There were significantly higher values for FEV1 and FVC (at all time periods) and lower values for functional residual capacity (at all time periods) and residual volume (at 4 h) with salmeterol than with placebo. There were significantly lower dyspnea ratings on the -5 to +5 category scale (p=0.03 at 2 h and p=0.02 at 4 h) and for the mean dyspnea scores during resistive breathing with salmeterol compared with placebo (p=0.002).
Conclusions: Inhaled salmeterol reduced dyspnea, increased airflow, and reduced hyperinflation over 4 h in patients with symptomatic COPD.