TY - JOUR
T1 - Effect of airway smooth muscle tone on airway distensibility measured by the forced oscillation technique in adults with asthma
AU - Kelly, Vanessa Jane
AU - Brown, Nathan J
AU - Sands, Scott
AU - Borg, Brigitte M
AU - King, Gregory G
AU - Thompson, Bruce Robert
PY - 2012
Y1 - 2012
N2 - Airway distensibility appears to be unaffected by airway smooth muscle (ASM) tone, despite the influence of ASM tone on the airway diameter-pressure relationship. This discrepancy may be because the greatest effect of
ASM tone on airway diameter-pressure behavior occurs at low transpulmonary pressures, i.e., low lung volumes, which has not been
investigated. Our study aimed to determine the contribution of ASM
tone to airway distensibility, as assessed via the forced oscillation
technique (FOT), across all lung volumes with a specific focus on low
lung volumes. We also investigated the accompanying influence of
ASM tone on peripheral airway closure and heterogeneity inferred
from the reactance versus lung volume relationship. Respiratory
system conductance and reactance were measured using FOT across
the entire lung volume range in 22 asthma subjects and 19 healthy
controls before and after bronchodilator. Airway distensibility (slope
of conductance vs. lung volume) was calculated at residual volume
(RV), functional residual capacity (FRC), and total lung capacity. At
baseline, airway distensibility was significantly lower in subjects with
asthma at all lung volumes. After bronchodilator, distensibility significantly
increased at RV (64.8 , P 0.001) and at FRC (61.8 ,
P 0.01) in subjects with asthma but not in control subjects. The
increased distensibility at RV and FRC in asthma were not associated
with the accompanying changes in the reactance versus lung volume
relationship. Our findings demonstrate that, at low lung volumes,
ASM tone reduces airway distensibility in adults with asthma, independent
of changes in airway closure and heterogeneity.
AB - Airway distensibility appears to be unaffected by airway smooth muscle (ASM) tone, despite the influence of ASM tone on the airway diameter-pressure relationship. This discrepancy may be because the greatest effect of
ASM tone on airway diameter-pressure behavior occurs at low transpulmonary pressures, i.e., low lung volumes, which has not been
investigated. Our study aimed to determine the contribution of ASM
tone to airway distensibility, as assessed via the forced oscillation
technique (FOT), across all lung volumes with a specific focus on low
lung volumes. We also investigated the accompanying influence of
ASM tone on peripheral airway closure and heterogeneity inferred
from the reactance versus lung volume relationship. Respiratory
system conductance and reactance were measured using FOT across
the entire lung volume range in 22 asthma subjects and 19 healthy
controls before and after bronchodilator. Airway distensibility (slope
of conductance vs. lung volume) was calculated at residual volume
(RV), functional residual capacity (FRC), and total lung capacity. At
baseline, airway distensibility was significantly lower in subjects with
asthma at all lung volumes. After bronchodilator, distensibility significantly
increased at RV (64.8 , P 0.001) and at FRC (61.8 ,
P 0.01) in subjects with asthma but not in control subjects. The
increased distensibility at RV and FRC in asthma were not associated
with the accompanying changes in the reactance versus lung volume
relationship. Our findings demonstrate that, at low lung volumes,
ASM tone reduces airway distensibility in adults with asthma, independent
of changes in airway closure and heterogeneity.
U2 - 10.1152/japplphysiol.01259.2011
DO - 10.1152/japplphysiol.01259.2011
M3 - Article
VL - 112
SP - 1494
EP - 1503
JO - Journal of Applied Physiology
JF - Journal of Applied Physiology
SN - 8750-7587
IS - 9
ER -