Background: Studies suggest that the increased volume of both abdominal and rib cage compartments of the chest wall contribute to dyspnea during methacholine-induced airway narrowing. Material: Eight male patients with asthma aged 34 ± 13 years (mean ± SD) before and during methacholine challenge. Methods: The volume of the chest wall (Vcw), volume of the abdomen (Vab), and volume of the rib cage (Vrc) were measured by using a three-dimensional optoelectronic plethysmography. Results: During methacholine challenge, the increase in end-expiratory Vcw (Vcw,ee) [0.55 ± 0.23 L, p <0.001] was due to increased Vrc (0.37 ± 0.20 L, p <0.01) and, to a lesser extent, Vab (0.18 ± 0.10 L, p <0.005). Linear univariate regression analysis showed that changes in dyspnea (Borg scale) with the highest methacholine dose correlated with both ΔFEV 1 and ΔVcw,ee. Multiple regression analysis with the Borg score as dependent variable and all other ventilatory indexes as independent variables showed that ΔVcw,ee and ΔFEV 1 were the only significant contributors to the Borg score. Taken together Vcw,ee and FEV 1 explained 56% of variance in the Borg score (r 2 = 0.56), although Vcw,ee explained 48% of it. Conclusions: During methacholine challenge in patients with asthma, the overall increase in Vcw,ee is a better predictor of dyspnea that the reduction in FEV 1.
- Chest wall
ASJC Scopus subject areas
- Pulmonary and Respiratory Medicine