Abstract

BACKGROUND: Lung mucociliary clearance rates are reduced during sleep in patients with asthma. Methylxanthines and beta 2 agonists have been shown to enhance rates of lung mucociliary clearance. This study examined whether oral slow release bronchodilators may also have an effect on this clearance mechanism during sleep in patients with asthma. METHODS: Nine patients with asthma with a mean(SE) age of 65(5) years and percentage predicted forced expiratory volume in one second (FEV1 of 61(9)% participated in a double blind, placebo controlled, within subject crossover study to assess the effect of two weeks of treatment with salbutamol (Volmax; 8 mg twice daily) or theophylline (Phyllocontin; 350 mg twice daily) on lung mucociliary clearance during sleep. Lung mucociliary clearance rates were measured by a radioaerosol technique. RESULTS: The observation period for radioaerosol clearance was approximately 0.3 hours before sleep, 6.0 hours during sleep and 0.6 hours after sleep. Mean mucociliary clearance rates for theophylline, placebo and salbutamol before sleep were: 39, 39, and 32%/hour respectively; during sleep: 11, 10, and 9%/hour respectively; and after sleep: 39, 32, and 35%/hour respectively. CONCLUSION: During sleep lung mucociliary clearance in stable asthma was reduced, which is in agreement with the group's previous findings. Treatment with controlled/slow release oral bronchodilators had no effect on this reduced rate of clearance associated with sleep.