Bronchodilator response to salbutamol after spontaneous recovery from nonspecific bronchial provocation tests in asthma

Abstract

Assessment of airway responsiveness by bronchoprovocation and bronchodilatation tests is important in the diagnostic work-up protocol of bronchial asthma and it would be convenient to undertake both tests on the same occasion. However, it is not known whether this can be done accurately. Therefore, this study evaluated the effect of a prior bronchial provocation test on the bronchodilator response to salbutamol after spontaneous recovery of the forced expiratory volume in one second (FEV1) in a group of asthmatic subjects. On two separate occasions at the same time of day, concentration-response studies with inhaled histamine or methacholine, or a sham challenge with normal saline were carried out in a blinded, randomized manner. Changes in airway calibre were followed as FEV1 and agonist responsiveness expressed as the provocative concentration causing a 20% fall in FEV1 (PC20). After either spontaneous recovery or a fixed-duration wait of 45 min (when appropriate), the subjects received 2x100 microg of salbutamol from a metered dose inhaler with a spacer. The bronchodilator response to salbutamol was expressed as a percentage of initial FEV1 (deltaFEV1% init). Bronchial challenge with both agonists failed to alter significantly the airway response to salbutamol, with the deltaFEV1% init mean value (range) being 16.9% (9.0-31.9) and 17.5% (11.6-31.2) on the sham and histamine/methacholine challenge day respectively. It was shown that the degree of bronchodilatation achieved after salbutamol 200 microg is not affected by prior bronchoprovocation testing when enough time is allowed for the airways to recover spontaneously to baseline forced expiratory volume in one second. Thus evaluation of airway responsiveness by both bronchial provocation tests and bronchodilator testing can be assessed reliably within a few hours in asthmatic patients.

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.…”

Strain dependence of the airway response to dry-gas hyperpnea challenge in the rat

“…The technique of high-performance liquid chromatography (HPLC) was employed in the experiments of this thesis for the separation and quantitation of cysteinyl-leukotrienes in bile (106). Reversed phase HPLC (RP-HPLC) is commonly used for the separation and analysis of eicosanoids.…”

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

“…It has been shown that after allowing the FEV 1 to return to !95% of the prechallenge value a BDR can be reliably measured. [3,4] However, because this may take up to 2 hr, [3,5] and no bronchodilator can be given to alleviate bronchoconstrictor-induced dyspnea, this approach is not very attractive.…”

“…A possible explanation for our results is that deposition of bronchodilator into the peripheral airways and binding to the b2 receptor is reduced when the airways are narrowed by methacholine. [3,4,8] The dose of salbutamol that we used (800 mg) causes (near) maximal bronchodilatation in the majority of children. [3] Future studies are needed to examine whether the BDR, measured immediately after completing a methacholine challenge, is higher if salbutamol is administered in a stepwise fashion or in a higher dose.…”

“…[3,4] In asthmatic children this may, however, take up to 2 hr. [3,5] A bronchoconstrictor challenge is terminated when FEV 1 drops by more than 20%, after which a bronchodilator is administered to reverse this induced airways obstruction.…”