Table 1.
Characteristics of subjects before methacholine testing.
FEV1: Forced expiratory volume in 1 second. FVC: Forced vital capacity. FEF25-75: Mean forced expiratory flow between 25% and 75% of FVC. PEF: Peak expiratory flow. TLC: Total lung capacity. RV: Residual volume. Raw: Airway resistance. sRaw: Specific airway resistance. VDaw: Airway volume. Slope3: Slope of the alveolar capnogram.
Table 2.
Correlation between baseline lung function parameters and baseline airway volume (VDaw) and the slope of the alveolar capnogram (slope3) in 93 subjects.
Linear regression was performed with VDaw and slope3 as dependent variables.
Fig 1.
Relationships between methacholine-induced variations in airway volume and the slope of the alveolar capnogram, in patients without BHR (empty circles) and in patients with BHR (filled grey circles).
Scales are linear to a value of 100 and exponential thereafter. ΔVDaw / Mch: Fractional change in aiway volume reported to the methacholine dose, expressed as -% / mg. Δslope3 / Mch: Fractional change in the slope of the alveolar capnogram reported to the methacholine dose, expressed as % / mg.
Table 3.
Univariate correlation between the FEV1 and FVC dose-response, baseline airway volume and Slope3, and Mch-induced variations in Vdaw and Slope3.
Linear regression was performed with FEV1 and FVC DRS as dependent variables.
Fig 2.
Relationships between methacholine-induced variations in volumetric capnography variables and the FEV1 dose-response curve in patients without BHR (empty circles) and in patients with BHR (filled grey circles).
A: Variations in airway volume (VDaw). B: Variation in the slope of the alveolar capnogram (slope3). Scales are linear to a value of 100 and exponential thereafter. ΔVDaw / Mch: Fractional change in aiway volume reported to the methacholine dose, expressed as -% / mg. Δslope3 / Mch: Fractional change in the slope of the alveolar capnogram reported to the methacholine dose, expressed as % / mg.
Fig 3.
Relationships between methacholine-induced variations in volumetric capnography variables and the FVC dose-response curve in patients without BHR (empty circles) and in patients with BHR (filled grey circles).
A: Variations in airway volume (VDaw). B: Variation in the slope of the alveolar capnogram (slope3). Scales are linear to a value of 100 and exponential thereafter. ΔVDaw / Mch: Fractional change in aiway volume reported to the methacholine dose, expressed as -% / mg. Δslope3 / Mch: Fractional change in the slope of the alveolar capnogram reported to the methacholine dose, expressed as % / mg.
Table 4.
Multivariate analysis of relationships between the FEV1 and FVC dose-response and Mch-induced variations in capnographic variables.
SC: Standardized coefficient.