DIE DURCHFÜHRUNG INHALATIVER ANTIGEN-PROVOKATIONSPROBEN MIT HILFE DER GANZKÖRPERPLETHYSMOGRAPHIE

Isocyanate-induced asthma: results of inhalation tests with TDI, MDI and methacholine

We performed diisocyanate inhalation tests (maximal concentration, 20 ppb; exposure time, 1-2 h) using toluene diisocyanate (TDI, n = 15) and diphenylmethane diisocyanate (MDI, n = 7) as well as methacholine challenges in 19 workers who had a clinical history of TDI/MDI-induced asthma. Additionally we tested volunteers who had no previous contact with diisocyanates: 10 healthy individuals with a negative methacholine test and 14 patients with asthma and a positive methacholine test were exposed to TDI. In all, 1 of the normal volunteers and 3 of the patients with asthma unrelated to diisocyanates showed a positive airway reaction to TDI, and 13 of the 19 diisocyanate workers displayed a positive result in the TDI/MDI inhalation test; however, only 6 of these 13 individuals reacted to methacholine. Furthermore, 3 of the 6 patients with a negative TDI/MDI challenge test demonstrated a significant response to methacholine. We conclude that bronchial hyperreactivity as evaluated by the methacholine challenge test is not closely related to isocyanate-induced bronchoconstriction and, therefore, the metacholine challenge is only of limited diagnostic value in patients with suspected isocyanate-induced asthma.

[Allergy diagnosis in patients with bronchial asthma (bronchial provocation test, skin test and RAST) (author's transl)]

87 patients with bronchial asthma underwent skin test, RAST and measurment of airway resistance before and after inhalation of control solution as well as at least 10 times after each of one to four bronchial provocations (making up a total of 171 tests) with extracts of house dust, house dust mite, animal dander, mould spores and pollen in increasing concentrations. An actual clinical significance of the skin test reactions was found in 60% of all cases and of the RAST results in 66% of all cases. The overall agreement between skin test results and RAST results was 61%. The correlations between the different tests depended on the degree of hypersensitivity, on the tested allergen and on whether the results of skin test and RAST, respectively, were positive or negative. There existed a good correlation between the results of all three test methods and case history only for pollen allergens and animal dander. Noticeably often negative RAST results with house dust and mould spores, as well as positive skin tests with house dust mite and mould spores could not be confirmed by the provocation test. Important indications for a bronchial provocation test in asthmatics are doubtful case history, doubtful skin test or RAST results with the problem-allergens house dust, house dust mite and mould spores; the bronchial provocation test is especially commendable when drastic or cumbersome therapeutic measures (immunotherapy, change of home, change of job) are to follow or if late asthmatic reactions are expected.