[Clinical and epidemiological application of carbachol for the testing of bronchial hyperreactivity in school-age]

Abstract

Airway reactivity was investigated by inhalation of the cholinergic agent carbachol. A standardized Carbachol challenge test (CCT) was carried out in a cumulative manner in 59 school-aged children as well as 10 not asthmatic individuals. The carbachol aerosol was delivered by jet nebulization. It was administered by inhalation of stepwise twofold increasing cumulative doses from a balloon taking tidal breaths. The inhalation was finished at the dose step eliciting a 100% increase in R(aw). Bronchial reactivity was derived by linear regression from the dose-response function. Bronchial sensitivity was registered by the threshold dose. Calculated on the bronchial reactivity of 57 asthmatics the asthma-related sensitivity of the CCT was 83%. The specificity was 90%. In 7 children the week-to-week reproducibility was tested: 6 children showed discrepancies of the threshold dose of less than two steps, in one case a shift of two steps was observed. In none of the probands a severe systemic side effect occurred. The carbachol challenge test is an appropriate method to distinguish asthmatic children from the normal population. The validity and good reproducibility as well as the feasibility in children makes the procedure valuable for pediatric investigations of bronchial hyperreactivity as a common feature in asthma.