Salmeterol administration by metered-dose inhaler alone vs metered-dose inhaler plus valved holding chamber

Study objective: To determine whether a spacer device designed as a valved holding chamber with a flow signal increases the efficacy of the long-acting beta(2)-agonist, salmeterol, in patients who use incorrect technique with metered-dose inhaler (MDI) alone. Design: Double-blind, randomized, placebo-controlled study. Setting: University hospital outpatient rooms. Patients: Twenty adult outpatients with stable persistent asthma, receiving a daily anti-inflammatory drug. Interventions: Patients were randomized to either salmeterol MDI (incorrect use: 1 s after actuating MDI, inhale rapidly) and placebo plus spacer (correct use: inhale slowly as MDI is actuated, continue to inhale slowly and deeply) or placebo MDI (incorrect use) and salmeterol plus spacer (correct use). The following week, patients received the opposite treatment. The dose was two puffs from each device on each treatment day; each puff was separated by 1 min. Measurements and results: After baseline peak expiratory flow (PEF), salmeterol was administered and serial PEF determined (0.5, 1, 2, 3, 4, 6, 8, 10, and 12 h). Administration of salmeterol MDI plus spacer resulted in significantly greater increases in PEF from baseline vs MDI at 4 h (44 L/min ra 10 L/min; p < 0.01) and 6 h (49 L/min vs 24 L/min; p < 0.05). Both methods of administration were equally well tolerated. Conclusion: We conclude that patients who have poor timing and rapid inhalation with salmeterol MDI alone will have greater increases in PEF at 4 h and 8 h and no additional side effects if the dose is administered with a valved holding chamber that is used correctly. Further study is needed regarding other errors in MDI technique with salmeterol.