RT Journal Article
SR Electronic
T1 Greater parallel heterogeneity of airway narrowing and airway closure in asthma measured by high-resolution CT
JF Thorax
JO Thorax
FD BMJ Publishing Group Ltd and British Thoracic Society
SP 1163
OP 1170
DO 10.1136/thoraxjnl-2014-206387
VO 70
IS 12
A1 J R Dame Carroll
A1 J S Magnussen
A1 N Berend
A1 C M Salome
A1 G G King
YR 2015
UL http://thorax.bmj.com/content/70/12/1163.abstract
AB Background Heterogeneous airway narrowing and closure are characteristics of asthma. However, they have never been quantified by direct measurements of parallel sister airways obtained from image data, and the anatomical basis of these processes remains unknown.Methods Seven normal and nine asthmatic subjects underwent high-resolution CT, before and after methacholine challenge. Mean lumen areas of the entire airways were measured in 28 and 24 parallel sister airway pairs (a pair of airways arising from the same bifurcation) respectively (range 1.0–8.7 mm diameter). Heterogeneous narrowing was defined as the median difference in percentage narrowing between parallel sister airways. Forced oscillatory respiratory resistance (Rrs) and spirometry were measured before and after methacholine challenge conducted while supine.Results The airways of asthmatics were smaller at baseline, and following bronchoconstriction there were similar decreases in FEV1, increases in Rrs and mean narrowing of airways for asthmatic and non-asthmatic groups. Non-asthmatics required higher doses of methacholine than asthmatics to achieve the same changes. However, parallel heterogeneity (median (IQR) 33% (27–53%) vs 11% (9–18%), p<0.001) and airway closure (24.1% and 7.7%, p=0.001, χ2) were greater in asthmatics versus non-asthmatics.Conclusion We found clear evidence of differences in airway behaviour in the asthmatic group. Asthmatic airways were narrower at baseline and responded to inhaled methacholine by more heterogeneous narrowing of parallel sister airways and greater airway closure.