High-resolution computed tomography evaluation of airway distensibility in asthmatic and healthy subjects.
OBJECTIVE
Airway-wall remodelling may result in reduced airway distensibility in bronchial asthma. This study evaluated the baseline airway calibre and distensibility in asthmatic patients by means of high-resolution computed tomography (HRCT).


METHODS
We studied seven patients (two men, age range 36-69 years) with chronic asthma [forced expiratory volume in the first second (FEV(1)) range: 30%-87% of predicted; FEV1/forced vital capacity (FVC) range 48%-75% of predicted) under stable clinical conditions and six healthy control subjects (three men, age range 29-50 years). In all subjects, HRCT scanning, at suspended end-expiratory volume, was performed at rest and during ventilation with 6 and 12 cmH(2)O by nasal insufflation with continuous positive airway pressure (nCPAP), both at baseline and after inhalation of 200 mug oxitropium bromide metered dose inhaler (MDI). External and lumen diameter (mm) of the right apical upper lobe bronchus were measured in all HRCT scans.


RESULTS
In asthmatics, 12 cmH(2)O insufflation significantly changed baseline lumen (3.3+/-0.7 mm vs. 3.8+/-0.6 mm; p<0.01) and external diameter (6.2+/-0.9 mm vs. 6.7+/-0.8 mm; p<0.05), whereas in healthy controls, both 6 and 12 cmH(2)O insufflation significantly changed baseline lumen diameter (4.0+/-1.6 mm vs. 4.8+/-1.6 mm and 4.7+/-1.7 mm; p<0.01). In asthmatic patients, oxitropium bromide inhalation significantly changed baseline lumen diameter (3.3+/-0.7 mm vs. 4.4+/-0.6 mm; p<0.05), whereas the application of 6 or 12 cmH(2)O insufflation did not modify any bronchial diameters. In healthy controls, oxitropium bromide inhalation significantly changed baseline lumen diameter (4.0+/-.6 mm vs. 5+/-1.5 mm; p<0.05). The application of 12 cmH(2)O but not of 6 cmH(2)O induced a significant change in lumen diameter (5.0+/-1.5 mm vs. 6,0+/-1.6 mm; p<0.05).


CONCLUSIONS
Our results show that airway distensibility in asthmatic patients, as assessed by HRCT, can differ compared with that of healthy controls. HRCT can provide useful information on airway distensibility.
Castagnaro
A
A
Dipartimento di Scienze Cliniche, Patologie Respiratorie, Azienda Ospedaliero-Universitaria di Parma, Viale G. Rasori 10, 43100 Parma, Italy.
Rastelli
A
A
Chetta
A
A
Marangio
E
E
Tzani
P
P
De Filippo
M
M
Aiello
M
M
D'Ippolito
R
R
Olivieri
D
D
Sverzellati
N
N
Zompatori
M
M
D000328:Adult; D000368:Aged; D001249:Asthma / Q000000981:diagnostic imaging / Q000503:physiopathology*; D001980:Bronchi / Q000187:drug effects; D001995:Bronchography; D045422:Continuous Positive Airway Pressure; D005260:Female; D005541:Forced Expiratory Volume / Q000187:drug effects / Q000502:physiology; D005652:Functional Residual Capacity / Q000187:drug effects / Q000502:physiology; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D007327:Insufflation; D008168:Lung / Q000000981:diagnostic imaging / Q000187:drug effects / Q000503:physiopathology; D008170:Lung Compliance / Q000187:drug effects / Q000502:physiology*; D008297:Male; D036501:Metered Dose Inhalers; D008875:Middle Aged; D010276:Parasympatholytics / Q000008:administration & dosage; D012602:Scopolamine Derivatives / Q000008:administration & dosage; D013147:Spirometry; D014057:Tomography, X-Ray Computed / Q000379:methods*
D010276:Parasympatholytics; D012602:Scopolamine Derivatives; C017590:oxitropium