Bronchodilator Response in Asthmatic Children is Significantly Reduced When Measured Immediately After Methacholine Challenge

Abstract

A preceding methacholine challenge significantly reduces BDR in asthmatic children. Therefore, a BDR, measured immediately after completing a methacholine challenge, cannot be used as a substitute for a separate bronchodilator test.

Can bronchodilator response predict bronchial response to methacholine in preschool coughers?

“…On the other hand, it has been shown that during bronchial challenge in asthmatic adult 30 and children, 31 bronchodilator administered after FEV1 had spontaneously returned to baseline (i.e., after 30-90 min) resulted in a BDR similar to the BDR measured without preceding bronchial challenge. These two studies together with the study of Kamps et al 28 are in favor of a non exclusive airway smooth muscle-related bronchial response during bronchial challenge and postchallenge BDR. Oedema of the tracheobronchial mucosa is a consequence of increased vascular permeability that occurs during bronchial challenge, particularly in asthmatics.…”

“…We did not wait for spontaneous recovering of the bronchoconstriction and administered 400 mg of salbutamol immediately after bronchial challenge. In Kamps et al 28 study, 800 mg of salbutamol administered immediately after MTC in asthmatic children, failed to provoke a BDR as large as the BDR obtained without preceding MTC. Therefore, we feel that the timing of the bronchodilator administration was more important than the delivered dose.…”

“…While this difference was detected in most of the nonresponders (71.4%), it was present in only 33.3% of the responders. In a study conducted in asthmatic children, Kamps et al 28 showed a smaller BDR expressed as mean (SD) percentage of FEV1, with than without preceding MTC (5.2 (1.5)% and 10.4 (1.4)%; respectively). Furthermore, an in vitro study on adult guinea pigs showed that airway smooth muscle level of tension after a maximal contraction varied according to baseline tone.…”