Importance of the time interval between FEV1 measurements in a methacholine provocation test

摘要: We examined the hypothesis that a forced expiratory volume in one second (FEV1) manoeuvre (and preceding deep inhalation) before inhalation of methacholine might influence FEV1 measured after methacholine, if time between measurements was short. Six to nine healthy subjects inhaled single dose known cause about 20% decrease FEV1, on different days test protocols. If an performed immediately first 3 min provocation higher (77% basal FEV1) than pre-methacholine not (64%). This effect also demonstrated at 2, 4 and 6, but 10 start inhalation. subsequent constricted airways first, similar magnitude tests where pre-challenge performed. In another trial, two stepwise tests, with either 6 or steps. The percentage per mg decreased from 2.6 (1.9-5.2) 1.7 (0.8-2.3) (median, interquartile-range) when interval shortened. results suggest associated decreases bronchial tone by for up min, possibly due yielding cross-links airway smooth muscles.