title: Bronchoconstriction due to isocapnic cold air inhalation minimally influences bronchial hyperresponsiveness to methacholine in asthmatic subjects.
abstract: The aim of this study was to investigate if bronchial hyperresponsiveness to methacholine could be influenced by a previous bronchoconstriction due to isocapnic inhalation of cold air. Twelve adult asthmatic subjects in a clinical steady state were seen on four different days in a randomized way according to three different sequences. After assessment of spirometry, bronchial responsiveness to inhaled methacholine was determined on each occasion by the provocative concentration causing a fall of 20% in FEV1 (PC20). On two occasions, the methacholine test was preceded by the inhalation of dry cold air which caused significant (greater than 20% change in FEV1) bronchoconstriction. The methacholine test was performed after functional recovery. There was a significant (t = 2.53; p less than 0.05) but minimal (mean changes of 0.65 single two-fold concentration difference) reduction in PC20 after cold air inhalation. It is concluded that cold air-induced bronchoconstriction causes significant but minimal changes in bronchial responsiveness to methacholine in asthmatic subjects.
mesh_terms: D001249:Asthma / Q000503:physiopathology*; D001985:Bronchial Provocation Tests / Q000379:methods*; D003080:Cold Temperature; D005541:Forced Expiratory Volume; D006801:Humans; D016210:Methacholine Chloride; D008688:Methacholine Compounds; D011897:Random Allocation
chemical_list: D008688:Methacholine Compounds; D016210:Methacholine Chloride