6533b861fe1ef96bd12c5aed

RESEARCH PRODUCT

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

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description

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 the challenge against the corresponding FEV 1 values (sFVC). Results Although methacholine and AMP PC 20 values were similar in patients treated and not treated with ICSs, the mean (95% confidence interval) methacholine sFVC (but not AMP sFVC) was higher in those treated with ICSs (0.91; 0.77-1.06) than in those not taking ICSs (0.69; 0.57-0.81; P = .03). No significant correlation was found between sFVC and PC 20 values obtained with either methacholine or AMP. Methacholine and AMP sFVC values were significantly related, but only in the group treated with ICSs ( r = 0.60, P Conclusions Although the AMP-induced decline in FVC in asthmatic patients is similar to that observed with equipotent concentrations of methacholine, the apparently different effect of ICSs on changes in FVC induced by each agonist suggests that the information provided by the 2 bronchoconstrictor agents is not interchangeable and that the information generated by the analysis of the effect of each agonist on FEV 1 and FVC may be complementary.