Forced expiratory volume before and after isoprenaline.

Improvement in the results of tests of ventilatory function in response to a bronchodilator drug, given by inhalation or by injection, is now widely used to indicate the presence of reversible " bronchospasm" (Rossier, 1949; Gilson and Hugh-Jones, 1955; Kennedy and Thursby-Pelham, 1956). Frequent repetition of some of these tests in a small series of patients has revealed an interesting relationship between the initial values for the tests and the changes observed after the inhalation ofisoprenaline.