[Dependence of bronchial hyperreactivity on the initial value of airway resistance]

In 403 patients, the influence of the initial value of the airway resistance on the incidence and extent of a positive reaction after an unspecific inhalative provocation with methacholine was investigated. The higher the original airway resistance was, the greater was the probability of obtaining a positive reaction. At an original resistance of more than 4 cm H2O/l/sec. all patients responded with an increase in airway resistance to more than 6 cm H2O/l/sec. In 91 per cent of these patients, the Rt figure increased more than 100 per cent. The extent of the increase in airway resistance following a positive response was independent of the initial value; the effect of subsequent spasmolysis following a positive test result, showed no dependence on the airway resistance prior to provocation.