Overall contribution of chest wall hyperinflation to breathlessness in asthma.
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.


METHODS
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 DeltaFEV(1) and DeltaVcw,ee. Multiple regression analysis with the Borg score as dependent variable and all other ventilatory indexes as independent variables showed that DeltaVcw,ee and DeltaFEV(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).
Filippelli
Mario
M
Department of Internal Medicine, Section of Respiratory Disease, University of Florence, and Fondazione Don C.Gnocchi, IRCCS, Pozzolatico, Viale Morgagni 87, 50134 Florence, Italy.
Duranti
Roberto
R
Gigliotti
Francesco
F
Bianchi
Roberto
R
Grazzini
Michele
M
Stendardi
Loredana
L
Scano
Giorgio
G
D000328:Adult; D001249:Asthma / Q000503:physiopathology*; D016085:Bronchoconstrictor Agents / Q000494:pharmacology*; D004417:Dyspnea / Q000209:etiology*; D005652:Functional Residual Capacity / Q000187:drug effects; D006801:Humans; D008297:Male; D016210:Methacholine Chloride / Q000494:pharmacology*; D008875:Middle Aged; D012044:Regression Analysis; D035441:Thoracic Wall / Q000187:drug effects*
D016085:Bronchoconstrictor Agents; D016210:Methacholine Chloride