Nonspecific bronchial reactivity and its relationship to the clinical expression of asthma. A longitudinal study.

摘要: The contribution of nonspecific bronchial reactivity to the day-to-day clinical expression asthma is uncertain. We have examined this relationship in a longitudinal study eight children and 12 adults. Measurements methacholine were made every 2 3 wk over period 18 months, deriving dose that caused 20% fall FEV1 (PD20). Throughout study, all patients kept daily record symptoms treatment twice measurements peak expiratory flow (PEF). A significant was found between subjects' overall (median PD20) both their average variation morning PEF (Spearman's rho = -0.53, p 0.016) diurnal -0.60, 0.004). However, examining temporal within subjects, individual PD20 not consistently related concurrent severity: only six subjects did changes generally reflect simultaneous trends or PEF. In several patients, exacerbations occurred absence hyperreactivity (PD20 greater than 12.8 mumol). conclude one mechanism underlying airflow obstruction asthma, its state sufficiently close be practical use.