Modifications in forced vital capacity during adenosine monophosphate-induced bronchoconstriction in asthma: relationship with the response to methacholine and the effect of inhaled corticosteroids.

Background The effect of adenosine monophosphate (AMP) on forced vital capacity (FVC) has never been systematically investigated. Objective To compare methacholine- and AMP-induced changes in FVC, as a marker of air trapping, in asthmatic patients treated and not treated with inhaled corticosteroids (ICSs). Methods Airway responsiveness to equipotent concentrations of AMP and methacholine was obtained in asthmatic patients treated (n = 32) and not treated (n = 18) with ICSs. The response was expressed by the provocation concentration of agonist that caused a decrease in forced expiratory volume in 1 second (FEV 1 ) of 20% (PC 20 ) and by the slope of the FVC values recorded at each step of …