A comparison of three methods of measuring broncholability in asthmatics, bronchitic cigarette smokers and normal...

Bronchial lability was measured in 10 normal subjects, 33 typical asthmatics, and 23 smokers with ventilatory defect, by three different methods in the course of a week. There was little difference between exercise/bronchodilator lability index, spontaneous diurnal variation, and histamine challenge in detecting bronchial lability. It was possible that histamine challenge was more sensitive and more specific to asthma. It is recommended that this test is used first in studies to detect bronchial lability but those apparently normal should also be tested by the other methods. There was no correlation between the numerical value of these indices of broncholability in abnormal subjects. The asthmatic and bronchitic subjects were not separated by any of the three methods.