Abstract

BACKGROUND The metered dose inhaler is difficult to use correctly, synchronising actuation with inhalation being the most important problem. A breath actuated pressurised inhaler, designed to help patients with poor inhaler technique, was compared with a conventional metered dose inhaler in terms of aerosol deposition and bronchodilator response. METHODS Radioaerosol deposition and bronchodilator response to 100 micrograms salbutamol were measured in 18 asthmatic patients, who inhaled from a conventional metered dose inhaler by their own chosen metered dose inhaler technique, from a conventional metered dose inhaler by a taught metered dose inhaler technique, and from a breath actuated pressured inhaler (Autohaler). RESULTS In the 10 patients who could coordinate actuation and inhalation of the inhaler on their own deposition of aerosol in the lungs and bronchodilator response were equivalent on the three study days. By contrast, in the eight patients who could not coordinate the mean (SEM) percentage of the dose deposited in the lungs with their own inhaler technique (7.2% (3.4%] was substantial lower than those attained by the taught metered dose inhaler technique (22.8% (2.5%] and by Autohaler (20.8% (1.7%]. CONCLUSION Although of little additional benefit to asthmatic patients with good coordination, the Autohaler is potentially a valuable aid to those with poor coordination, and should be considered in preference to a conventional metered dose inhaler in any patient whose inhaler technique is not known to be satisfactory.