Among diagnostic procedures for detection of bronchial asthma, bronchial provocation tests using bronchoconstrictor substances have long been employed to evaluate bronchial sensitivity and reactivity. The sensitivity, or threshold value, is identified by the threshold-dose at which the bronchial tree starts to respond to a drug with a significant variation of functional parameters. The reactivity, on the contrary, expresses the intensity and the type of response of the bronchial tree to over-threshold doses of the 'challenger' drug. Both sensitivity and reactivity are pointed out by studying the relationship between a certain dose of the drug and the relative response of the bronchial tree, i.e. construction dose-response curves. The authors, based on the literature, analyse the methodology of construction of the dose-response curves, reporting synthetically the features of the employed substances and their respective threshold values. Among such sustances, histamine and methacholine seems to be preferred in a standardization of the procedures. Furthermore, the various factors able to influence in some measure the results of a bronchial provocation test, i.e. body position, age, smoking habits, occupation, are taken into account. In the study of bronchial reactivity, carbachol and methacholine seem to be the most useful substances. The bronchial reactivity may be expressed either as the dose of the drug necessary to cause a bronchoconstrictor effect of double the threshold dose, or by the mathematical study of the dose-response curve in its part referring to over-threshold doses (by the over-threshold doses in the dose-response curve), or by the measure of the effect produced by a dose double the threshold one. The slope of the dose-response curve seems, however, the best one to distinguish the asthmatics from the normal subjects.
|Number of pages||15|
|Journal||Folia Allergologica et Immunologica Clinica|
|Publication status||Published - 1979|
ASJC Scopus subject areas
- Immunology and Allergy