THE INFLUENCE OF AGE, DIAGNOSIS, AND GENDER ON PROPER USE OF METERED-DOSE INHALERS

Metered dose inhalers (MDIs) are widely used in clinical practice for administering pharmaceuticals targeted to the lung. It is well known t hat the inhalation technique used with MDIs can substantially influenc e the clinical response to inhaled medications. To determine the accep tability of MDI maneuvers, we studied 59 subjects (26 females and 33 m ales; age, 20 to 81 yr; mean age, 38 yr) to determine whether the MDI technique used by these individuals complied with published recommenda tions for acceptable inhalation technique. Measurements were made with an MDI adapter that contained an unobtrusive, lightweight, miniature sensing system. Inspiratory flow at the moment of MDI actuation (Va), the volume (integrated from airflow) at actuation as a fraction of tot al inspiratory volume (Va/VI), breath-holding time (tBH), and inspirat ory volume as a fraction of FVC (VI/FVC) were determined from 59 uncoa ched inhalations. We defined an acceptable maneuver, based on publishe d data, by four components: (1) inspiratory flow at actuation (Va) bet ween 25 and 90 L/min; (2) actuation during early inspiration (0 < Va/V I less than or equal to 0.20); (3) adequate breath-holding time (tBH > 4 s), and (4) a deep inhalation (VI/FVC > 0.50). For all subjects, on ly 25% of inhalation maneuvers met all four criteria for acceptability . We found that a significantly higher proportion of male than female subjects performed an acceptable MDI maneuver (43% versus 4%, p < 0.00 1). There were no significant differences in technique between younger and older subjects or between patients with a diagnosis of asthma or chronic obstructive pulmonary disease (COPD). We conclude that most pa tients use their MDIs incorrectly; females of all ages are much more l ikely to have improper MDI technique than are males.