The inspiratory chest x-ray shows increased lucency in the left lung field, and the expiratory x-ray shows evidence of a significant amount of trapped air. The images are highly suggestive of a foreign body in the left main bronchus.
The child had an urgent bronchoscopy and removal of a peanut from the LMB.
In very young children, who are unable to cooperate for an expiratory chest x-ray, a decubitus chest x-ray (with the affected side facing downwards) can be conducted. If a foreign body is present, the affected side fails to collapse as it should if the bronchus is patent.
These chest x-ray findings can be difficult to interpret and are not very sensitive. Any suspected bronchial foreign body should be referred to a specialist urgently, even if the chest x-ray is normal.