Effects of Salmeterol on Sleeping Oxygen Saturation in Chronic Obstructive Pulmonary Disease

Abstract

Background: Sleep is associated with important adverse effects in patients with chronic obstructive pulmonary disease (COPD), such as disturbed sleep quality and gas exchange, including hypoxemia and hypercapnia. The effects of inhaled long-acting β₂-agonist therapy (LABA) on these disturbances are unclear. Objectives: The aim of the study was to assess the effect of inhaled salmeterol on nocturnal sleeping arterial oxygen saturation (SaO₂) and sleep quality. Methods: In a randomized, double-blind, placebo-controlled, crossover study of moderate/severe stable COPD patients, we compared the effects of 4 weeks of treatment with salmeterol 50 µg b.d. and matching placebo on sleeping SaO₂ and sleep quality. Overnight polysomnography (PSG) was performed at baseline, and after 4 and 8 weeks in addition to detailed pulmonary function testing. Of 15 patients included, 12 completed the trial (median age 69 years, forced expiratory volume in 1 s, FEV₁: 39%). Results: Both mean SaO₂ [salmeterol vs. placebo: 92.9% (91.2, 94.7) vs. 91.0% (88.9, 94.8); p = 0.016] and the percentage of sleep spent below 90% of SaO₂ [1.8% (0.0, 10.8) vs. 25.6% (0.5, 53.5); p = 0.005] improved significantly with salmeterol. Sleep quality was similar with both salmeterol and placebo on PSG. Static lung volumes, particularly trapped gas volume, tended to improve with salmeterol. Conclusion: We conclude that inhaled LABA therapy improves sleeping SaO₂ without significant change in sleep quality.