title: Reversible volume changes of trapped gas in nonspecific bronchoprovocation tests.
abstract: Thirty patients with a history of asthma and ten patients with suspected bronchial hyperreactivity underwent nonspecific provocation testing. The control group consisted of ten normal volunteers without a history of lung disease. The patients' baseline FEV1 (percent predicted) revealed mild obstructive disease (72.9 +/- 8.9 percent and 74.6 +/- 7.7 percent) compared with controls (87.2 +/- 8.5 percent, p less than 0.001). The mean volume of trapped gas (D) (ie, TLCB-TLCHe) was not significantly different between groups (0.11 +/- 0.49 L vs 0.15 +/- 0.4 L vs 0.18 +/- 0.45 L), and no correlation was established with any of the remaining lung function data. Bronchial hyperreactivity in response to inhaling acetylcholine could be observed in the asthma group only. Their mean D increased significantly from 0.11 +/- 0.49 L to 0.62 +/- 0.66 L (p less than 0.001), and returned to baseline (0.26 +/- 0.55, NS) subsequent to inhaling salbutamol. D changes induced by acetylcholine correlated weakly with concurrent changes of FEV1 (r = -0.44, p = 0.01), RV (r = 0.59, p less than 0.001), and Rs (r = 0.59, p less than 0.001). In response to bronchodilating doses of salbutamol, however, D was changed in close correlation with FEV1 (r = -0.82, p less than 0.0001), RV (r = 0.85, p less than 0.0001), and Rs (r = 0.76, p less than 0.0001). Provided that D is a valid parameter of small airways function, these data may give a clue to the site of action of both drugs. Acetylcholine affects small and large airways alike with no clear-cut preference, whereas salbutamol's predominant target appears to be the small airways. These conclusions are only partially supported by the pertinent literature.
authors.affiliation: Medical Department III, University of Cologne, Germany.
authors.forename: K
authors.initials: K
authors.lastname: Wassermann
authors.forename: G
authors.initials: G
authors.lastname: Pothoff
authors.forename: J
authors.initials: J
authors.lastname: Bahra
authors.forename: H H
authors.initials: HH
authors.lastname: Hilger
mesh_terms: D000109:Acetylcholine; D000420:Albuterol; D001249:Asthma / Q000175:diagnosis / Q000503:physiopathology; D016535:Bronchial Hyperreactivity / Q000175:diagnosis / Q000503:physiopathology; D001985:Bronchial Provocation Tests / Q000295:instrumentation / Q000379:methods*; D005541:Forced Expiratory Volume / Q000187:drug effects / Q000502:physiology; D006801:Humans; D012680:Sensitivity and Specificity; D014109:Total Lung Capacity / Q000187:drug effects / Q000502:physiology*
chemical_list: D000109:Acetylcholine; D000420:Albuterol