Background: Poor coordination of canister actuation and inspiration often prevents adequate metered-dose inhaler (MDI) usage by patients, perhaps especially so among the elderly. Breath-actuated inhalers (BAI) have been developed to prevent this problem.
Methods: We compared the adequacy of inhaler technique and patient preferences between MDI and BAI in a group of elderly subjects (mean age, 70.8 +/- 5.4 years). Half of the subjects were regular MDI users; half had never before used one. Two trained observers assessed the adequacy of MDI and BAI usage subjectively while performance was monitored objectively using a light source and infrared system to detect canister actuation and a spirometer to measure the inspiratory volume. If canister actuation was not followed by at least a 50 percent vital capacity, inhaler use was deemed unsuccessful. A brief teaching session preceded inhaler usage.
Results: By subjective assessment, BAI was used successfully more often than MDI (79 vs 60 percent, p < 0.05). By objective assessment, BAI was used successfully more often than MDI (64 vs 36 percent, p < 0.0005), although the percentage of inhalations scored adequate was lower than when assessment was subjective. Neither device was used correctly as often by those unfamiliar with MDIs as by those who were regular users. A significantly higher percentage of patients preferred BAI to MDI (71 vs 19 percent, p < 0.005), similar preferences being reported by MDI familiar and MDI unfamiliar groups.
Conclusions: We conclude that (1) elderly subjects frequently handle inhalers poorly, (2) mishandling is better detected by objective than subjective monitoring, and (3) BAI is used correctly and preferred by patients more often than conventional MDIs.