[Experimental determination of equivalent percentage changes in measurement parameters of dose-response relations...

For the experimental determination of equivalent changes of the measurement parameters in the non-specific inhalative provocation test with metacholine, 26 persons with exogenous allergic asthma bronchiale were examined during the symptom-free interval. The inhalative provocation test was performed as dose-response relationship. Linear regressions were calculated with the data obtained. The percentage change of the measurement parameters that occurred with a quantity of 400 micrograms of aerosolised methacholine was calculated on the basis of the regression equation. These changes correspond to equivalent changes of the individual measurement parameters compared with each other. Generally, a drop in FEV1 by 20% is demanded for a positive provocation test. If this value is defined as "gold standard", the measured data allow derivation of the equivalent changes. Our studies showed that an increase of Rt by 195% (triplication), a sGaw drop by 44%, a PEF drop by 20% and a drop of MEF75, MEF50 by 30% each, compared with the original value, is equivalent to a significant change in the sense of a positive inhalative provocation test.