The Effect of Isoproterenol Sulfate Aerosol on the Small Airways in Asymptomatic Asthmatic Patients

In 19 asymptomatic asthmatic patients the effect of isoproterenol sulfate aerosol on small airways was assessed. All patients were symptom-free for at least three days before the investigation. On the day of examination, before inhalation of isoproterenol, the total lung resistance (RL) was normal, while the frequency dependence of lung compliance (Cdyn) was increased, indicating an obstruction of airways with an inner diameter of less than 2 to 3 mm. After inhalation of 400 micrograms of isoproterenol, no statistically significant change in Cdyn occurred up to one hour. From our results we assume that in the early stage of recovery from an acute asthmatic attack, isoproterenol aerosol has no effect on the obstruction of peripheral airways.