Response to bronchodilator drug administration by a new reservoir aerosol delivery system and a review of other auxiliary delivery systems.

Response to bronchodilator aerosols delivered by metered dose inhalers (MDI) depends in part upon the amount of drug depositing on the airways. Ideally, the MDI should be actuated during a slow deep inhalation followed by a breathholding pause, an impossible maneuver for many patients. We developed a new reservoir aerosol delivery system (RADS) consisting of a 700-ml collapsible bag in which aerosol could be injected. The mouthpiece-canister was filtered with a reed that vibrated at inspiratory flows greater than 0.3 L/s to produce a noise. Patients were instructed to keep inhalation silent while breathing from RADS. One puff of metaproterenol (650 microgram) administered via RADS (with one breath rebreathed) was compared with one puff of metaproterenol (650 micrograms) from usual MDI using serial measurements of body plethysmography and spirometry. Respiratory inductive plethysmography measured the point of MDI actuation, volume of inhalation, inspiratory flow, and breathholding pause. Ten patients with chronic airflow limitation caused by asthma or chronic bronchitis were given typed instructions on MDI usage and trained shortly before the study. Metaproterenol via RADS produced significantly greater maximal increase in SGaw (195 +/- 52% SE) compared with metaproterenol via conventional MDI (101 +/- 24%, p less than 0.003). Bronchodilator response in 4 patients unable to coordinate actuation of the MDI with inspiration was significantly less than in 6 patients with good MDI technique (p less than 0.005). The mean flow rates were 0.54 +/- 0.16 L/s during inhalation of metaproterenol compared with 0.19 +/- 0.02 L/s and 0.24 +/- 0.03 L/s during the first and second inhalations, respectively, using RADS. This reservoir aerosol delivery system, which was well accepted by the patients, promotes more effective bronchodilation than the conventional metered dose inhaler.