Chest radiography is usually recommended in all asthmatic patients who are ill enough to justify admission to a hospital. Hyperinflation may be seen in both relapse and remission. The prevalence of hyperinflation is generally higher in children and in patients needing hospital admission. While hyperinflation is initially often transient, it may become a permanent change. Bronchial wall thickening is more frequent in children, but in adults when it becomes visible it is usually an irreversible phenomenon. The walls of end-on segmental airways become thickened and the normally invisible airways appear on radiographs as parallel or single line opacities which may be seen in up to two-thirds of patients. Chest radiography may depict complications including consolidation, atelectasis, mucoid impaction, pneumothorax and pneumomediastinum. Consolidation is commonly infective but, in some cases, it is due to eosinophilic consolidation probably associated with allergic aspergillosis. Collapse ranges from subsegmental to lobar and occasionally involves the whole lung. Collapse is due to mucoid impaction in large airways or more commonly mucus plugging in many small airways.

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