Bronchial reactivity in hyperresponsive patients and healthy individuals: demonstration with high resolution computed tomography.
OBJECTIVE
High resolution computed tomography (HRCT) was used to assess the extent of bronchial reactivity after inhalative bronchoprovocation and dilation in hyperresponsive patients and healthy subjects.


METHODS
Patients with mild intermittent asthma, 15 with a >20% decrease in FEV1 and a >10 mmHg (PC20+) in PaO2, 12 with a <20% decrease in FEV1 and a >10 mmHg (PC20-) in PaO2 after provocation, and eight healthy humans were included in the study. Changes in cross-sectional area in a total of 1256 bronchi and in bronchial wall area (792 bronchi) were evaluated after histamine-triggered bronchoprovocation and salbutamol-induced bronchodilation at high lung volumes (FVC 80%). Data were compared with the results of pulmonary function tests (FEV1, PaO2, PaCO2).


RESULTS
In all groups, a significant decrease in bronchial cross-sectional area (P<0.001) and a significant increase in bronchial wall area (P<0.001) were observed subsequent to bronchoprovocation. After bronchodilation, the increase in cross-sectional area (P<0.001) and the further increase in airway wall area (P<0.01) were significant in all groups. In PC20+ and PC20- asthmatics, significant differences (P<0.05) in PaO2, >10 mmHg between baseline and provocation were observed. In healthy persons, the PaO2 decrease was <10 mmHg (P>0.05). After histamine provocation, the decrease in FEV1 was measured in the PC20+ group, whereas a <20% FEV1 decrease was found in the PC20- and the control groups, respectively. No significant correlations were observed between radiological data and the results of pulmonary function tests.


CONCLUSIONS
HRCT demonstrated bronchial reactivity in hyperresponsive patients and, unexpectedly, in healthy subjects. The applied pulmonary function tests failed to characterize bronchial reactions in the healthy subjects. Based on these results, HRCT is a useful tool by which to achieve a comprehensive understanding of the pathophysiological processes in asthmatic patients.
Department of Radiology, University of Vienna Medical School, Vienna, Austria. gerd.schueller@univie.ac.at <gerd.schueller@univie.ac.at>
G
G
Schueller
K
K
Neumann
T
T
Helbich
H
H
Riemer
W
W
Backfrieder
K
K
Sertl
C J
CJ
Herold
D000293:Adolescent; D000328:Adult; D001249:Asthma / Q000000981:diagnostic imaging* / Q000276:immunology*; D001980:Bronchi / Q000276:immunology*; D016535:Bronchial Hyperreactivity / Q000000981:diagnostic imaging* / Q000276:immunology*; D006801:Humans; D008875:Middle Aged; D014057:Tomography, X-Ray Computed