title: Total respiratory resistance and reactance as a measurement of response to bronchial challenge with histamine.
abstract: The potential of the forced oscillation technique to detect the airway response on histamine bronchial challenge tests was compared with that of FEV1 and plethysmographic SGaw. In 53 subjects with a history of episodic wheezing and a normal baseline airway resistance, we carried out bronchial challenges with successively doubling concentrations of histamine until FEV1 had dropped by 15% or more or a concentration of 16 mg/ml histamine was reached. For the baseline values, a mean within-subject coefficient of variation was found of 2.8% for FEV1, 7.4% for SGaw, 8.7% for the oscillatory respiratory conductance at 6 Hz (1/Rrs6), and 7.7% for the mean oscillatory respiratory conductance (between 2 and 26 Hz) (1/Rrs). The latter coefficients allow the calculation of the following threshold values: PD15FEV1, PD40SGaw, PD47 1/Rrs6, and PD42 1/Rrs. The probability of exceeding these levels by chance is virtually zero. Histamine challenge caused significant absolute changes in Rrs at 6 Hz (Rrs6), in mean level of Rrs and of respiratory reactance (Xrs), in slope of Rrs and Xrs versus frequency, and in mean curvature of Rrs-frequency curve. A multivariate analysis of the differences between prechallenge and postchallenge values showed that the parameters with the best sensitivity to detect the effect of histamine were, in decreasing order: the relative change of SGaw, of 1/Rrs6, of 1/Rrs, of FEV1, of FVC, and of 1/Vtg, followed by the absolute change of Xrs and of the average slope of the Rrs-frequency relationship.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Departement voor Pathofysiologie, Catholic University, Leuven, Belgium.
authors.forename: J A
authors.initials: JA
authors.lastname: van Noord
authors.forename: J
authors.initials: J
authors.lastname: Clement
authors.forename: K P
authors.initials: KP
authors.lastname: van de Woestijne
authors.forename: M
authors.initials: M
authors.lastname: Demedts
mesh_terms: D000293:Adolescent; D000328:Adult; D000403:Airway Resistance; D001249:Asthma / Q000175:diagnosis*; D001985:Bronchial Provocation Tests; D001986:Bronchial Spasm / Q000175:diagnosis; D005260:Female; D005541:Forced Expiratory Volume; D006632:Histamine; D006801:Humans; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results
chemical_list: D006632:Histamine