Density dependence of expiratory flow and bronchodilator response in asthma.
Change in the magnitude of density dependence of the maximal expiratory flow (D/MEF) following inhalation of isoproterenol was used as a test for predicting the long term response to isoproterenol vs atropine in 24 adult patients with longstanding asthma. Eleven subjects showed a decrease in D/MEF manifested by increase in volume of isoflow (VisoV) and/or decrease in Vmax50 Helox/air following isoproterenol inhalation (group 1). Thirteen subjects manifested an opposite response (group 2). Atropine sulphate (0.08 mg/kg) and isoproterenol hydrochloride (2.5 mg) were then administered by inhalation, each four times a day for seven days in a randomized double-blind cross over fashion to all subjects. One of group 1 but ten of group 2 subjects had a greater subjective and objective improvement with atropine than with isoproterenol (P less than .005). An increase in D/MEF following isoproterenol can be used as a test to predict a better response to atropine than to isoproterenol over a one week period. Such a response occurs in almost half of the adult chronic asthmatic patients. The results are consistent with a preferential dilatation of the large airways by atropine.
D000328:Adult; D001249:Asthma / Q000188:drug therapy* / Q000503:physiopathology; D001285:Atropine / Q000009:adverse effects / Q000627:therapeutic use*; D004311:Double-Blind Method; D005069:Evaluation Studies as Topic; D005260:Female; D005540:Forced Expiratory Flow Rates; D006801:Humans; D007545:Isoproterenol / Q000009:adverse effects / Q000627:therapeutic use*; D008297:Male; D008448:Maximal Expiratory Flow Rate; D008875:Middle Aged
D001285:Atropine; D007545:Isoproterenol