Bronchial reactions to carbachol inhalation in patients with a suspected diagnosis of cough due to asthma

: In 50 patients with persistent cough suspected to be of asthmatic origin and in 16 healthy subjects, the bronchoconstrictor response to carbachol inhalation was determined by the method of Orehek. Data analysis yielded the following results: on average, the bronchial reactivity of patients was significantly higher than that of normal subjects (p less than 0.005), in healthy subjects, the spectrum of airway responsiveness showed a log-normal distribution, the patients' bronchial reactivities also showed a log-normal distribution, but with larger variance than in healthy subjects, both distributions overlapped to a considerable extent. These distribution patterns, and the difficulties in estimating the probability of errors, call for a cautious interpretation of the results of provocation testing in patients with chronic cough. Increased airway reactivity is an additional sign, rather than proof, of the asthmatic origin of chronic cough.