Standardized allergen provocation test. Variation in bronchial response.
Standardized bronchial allergen provocation with the same individual allergen dose was performed 3-9 times in 20 symptomless adult asthmatic patients at intervals of 1 week or more during 1/2-22 months in order to study variations in bronchial response. The immediate type reaction was recorded by monitoring FEV1, FVC, PEFR and MEF50% for 30-40 min after provocation. FEV1 was highly significantly correlated to the other variables. The coefficient of variation corresponding to maximum decrease in FEV1 was 23%. All provocations were followed by a bronchial reaction within clinically acceptable limits. There was no indication of hypo- or hypersensitization. It is concluded that although many different factors influence the bronchial response, careful standardization of the provocation procedure leads to a moderate variation in bronchial response, making the allergen provocation test suitable for pathophysiological studies and clinical evaluation of anti-asthmatic drugs.