Methods for assessing bronchial reactivity.

Tests of bronchial reactivity in man may help in understanding the nature of bronchial hyperreactivity which is characteristic of asthmatic subjects. Comparison of published studies is, at present, limited because diverse methods have been used to study and to report the results of bronchial provocation tests. The factors which affect the response include the type of provoking agent used, the method of delivery, the lung function test used, the method of expressing the result and "subject" factors. The effect of each of these factors is reviewed. Histamine and methacholine are the most useful substances for distinguishing normal from asthmatic subjects, the technique of provocation appears to have only a small effect on the results and, the FEV1 appear to be the best test for distinguishing asthmatic from normal subjects. It is recommended that, whenever possible, the whole dose response curve is reported with the percent change in FEV1 plotted against the dose delivered on a log scale.