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-actin g beta(2)-agonist, salmeterol, in patients who use incorrect technique with metered-dose inhaler (MDI) alone. Design: Double-blind, randomized, placebo-controlled study. Setting: Univer sity 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 (cor rect use: inhale slowly as MDI is actuated, continue to inhale slowly and d eeply) or placebo MDI (incorrect use) and salmeterol plus spacer (correct u se). The following week, patients received the opposite treatment. The dose was two puffs from each device on each treatment day; each puff was separa ted by 1 min. Measurements and results: After baseline peak expiratory flow (PEF), salmet erol 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 signif icantly greater increases in PEF from baseline vs MDI at 4 h (44 L/min ra 1 0 L/min; p < 0.01) and 6 h (49 L/min vs 24 L/min; p < 0.05). Both methods o f administration were equally well tolerated. Conclusion: We conclude that patients who have poor timing and rapid inhala tion with salmeterol MDI alone will have greater increases in PEF at 4 h an d 8 h and no additional side effects if the dose is administered with a val ved holding chamber that is used correctly. Further study is needed regardi ng other errors in MDI technique with salmeterol.