PATTERNS OF RESPONSE TO BRONCHODILATOR IN YOUNG PATIENTS WITH ASTHMA

Use of a special inhaler attachment in asthmatic children

Asthmatics often find difficulties in using an aerosol inhaler correctly as they are unable to co-ordinate the release of a bolus of drug to coincide with an inspiratory effort. This is especially the case with children. The addition of a special attachment to an ordinary inhaler overcame this problem. Twelve asthmatic children produced significantly better PEFR measurements when 0.25 mg terbutaline sulphate was administered via an inhaler with the attachment than when an ordinary inhaler was used alone.

Clinical assessment of bronchodilator drugs delivered by aerosol

A method is described for the early clinical evaluation of bronchodilator aerosols. It is simple to perform, and an accurate estimate of potency can be obtained in a small number of patients. Using this method, three new sympathomimetic drugs, Th 1165a, salmefamol, and rimiterol, have been tested. All proved to be active bronchodilators and were equipotent with isoprenaline or salbutamol.

Time factor in the measurement of response to bronchodilators

The measurement of response to bronchodilators by recording the change in forced expiratory volume in 1 second (F.E.V._1·0) can underestimate response unless the correct time for postbronchodilator tests is chosen. In 18 patients given isoprenaline, the time of peak response varied, but a 30-minute testing time gave the closest approximation to peak response. In order to test whether repeated doses would increase the response, inhalations of isoprenaline were given at 30-minute intervals, the F.E.V._1·0 being measured after each dose. There was a further response after successive doses until a plateau was reached, usually after the third dose. The maximum response obtained was often considerably greater than the response after the first administration of isoprenaline, the average increase in F.E.V._1·0 being 600 ml. after the first dose and 840 ml. after repeated doses. A similar response was obtained in four patients using orciprenaline spray administered with a metered aerosol, the dose being repeated at hourly intervals. Four patients were given repeated inhalations of isoprenaline until the response reached a plateau, and then 250 mg. of aminophylline was injected intravenously. None of these patients showed any further improvement with aminophylline. The significance of these findings is discussed.