Evaluation of emphysema in patients with asthma using high-resolution CT

Bronchial asthma is a clinical syndrome characterized by reversibility of airway obstruction. However, many asthmatics have evidence of residual airway obstruction. It has become evident that the repair of the chronic inflammatory process can lead to various irreversible changes. It is generally accepted that the most common cause for the change is cigarette smoking but it is controversial whether asthma progresses to emphysema. High resolution computed tomography (HRCT) is more sensitive and more accurate than chest plain films in determining the type and extent of emphysema. This study was carried out to determine whether asthma can be a cause of emphysema without the effect of cigarette smoking and to evaluate clinical characteristics in asthmatics with emphysema.

We studied 58 asthmatic patients with reversible airway obstruction and evaluated the presence of emphysema using HRCT and pulmonary function test. According to HRCT findings, they were divided into 2 groups: Asthmatics with emphysema and the ones without emphysema.

Of the 58 patients, 7 were revealed to have emphysema. (1) 6 asthmatics with emphysema were smokers, but one patient was a nonsmoker. (2) Highly significant differences between asthmatics with and without emphysema were found in cigarette smoking (p < 0.01) and smoking consumption (p < 0.01). (3) There were no significant differences in the duration of asthma, age or sex between patients with and without emphysema. (4) There were no significant differences in FEV1(%), FEV1/FVC (%), diffusing capacity for carbon monoxide (DLco) (%) and DLco/alveolar volume between patients with and without emphysema (5) Differences between asthma patients without emphysema and those with emphysema were found to be significant in bronchial wall thickness (p < 0.05) and in total Ig E levels (p = 0.07).

These results indicate that smoking is a main factor in causing emphysema in asthmatics.