[Carbachol inhalation provocation test using a reservoir method. 4-step test for the assessment of bronchial hyperreactivity]

Abstract

Inhalative bronchial provocation tests with pharmacodynamic substances, such as histamine, methacholine or carbachol are performed to confirm or exclude bronchial hyperreactivity. The provocation schemas employed so far are often very tedious, with 8 or 9 inhalation steps, or include the danger of severe or hazardous obstructions in case of 1-step or 2-step tests. A provocation test is presented that can be conducted in about 30 minutes' time comprising only 4 inhalation steps. In a separate group of 44 clinically defined healthy subjects and patients suffering from asthma bronchiale, we determined the minimal concentration and cumulative total dose of carbachol to find a non-hazardous initial concentration on the one hand and to arrive at a best possible separation of healthy subjects and asthmatics on the other. Subsequently, 20 patients suspected of bronchial hyperreactivity were provoked by inhalation, using a commercial reservoir method 1. We used carbachol provocative solutions of 0.1 and 0.5% (0.1% 5 1, 0.1% 5 1, 0.5% 5 1, 0.5% 5 1, 0.5% 10 1). At the beginning and at the end of the study, whole body plethysmography was performed (Raw, FEV1, ITGV). A peak flow meter was employed for the intermediate steps. 13 of the 20 patients showed bronchial hyperreactivity. 11 of these 13 patients were provoked according to the schema mentioned above; an intermediate step was introduced in 2 patients. The peak flow dropped on the average by 28% and the FEV1 on the average by 33%. The airway resistance increased by 300% on the average compared with the initial value. There were no severe obstructions that required parenteral treatment.(ABSTRACT TRUNCATED AT 250 WORDS)