Case of the Week: December 5-December 12, 2003

13 year old with Wheezing..

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Case Details

PA chest radiograph demonstrates asymmetric lucency of the lungs with the right lung being hyperlucent compared with the left. This child presented with asymmetric right sided wheezing and history of

Answer

Diagnosis: Aspiration of foreign body (right mainstem bronchus)

Discussion:

When aspiration of a foreign body is clinically suspected, either because of a history of choking episode or asymmetric breath sounds or wheezing, inspiration AND expiration radiographs should be obtained. Most aspirated foreign bodies are not radiopaque. They are detectable indirectly due to their effect on air flow through the airway. Most commonly, a foreign body results in a “ball valve” effect, in which the air can flow into the lung around the object on inspiration but cannot flow out of the lung on expiration. This results in hyperaeration of the involved lung or lobe. The finding may be subtle or absent on inspiration views; however, expiration view will demonstrate the air trapping as a unilateral hyperlucent lung that does not deflate as does the normal side.

When the child is old enough to cooperate, as in this case, routine PA views can be obtained at full inspiration and expiration. In young children, bilateral decubitus films may substitute for the expiration view: the dependent lung should deflate and become more opaque. When the dependent lung remains expanded and hyperlucent, air trapping is confirmed. Passive or assisted expiration can also be done by gently compressing the child’s abdomen with a lead-gloved hand. In questionable cases, fluoroscopy of the chest may be useful to demonstrate air trapping; with each expiration, the heart and mediastinum shift toward the normal side that deflates properly during exhalation.

In young children, the aspiration episode is often not witnessed, and a strong suspicion needs to be entertained in children who present with a first episode of wheezing. Chronic foreign body obstruction can result in persistent or recurrent cough and fever, and persistent pneumonia or atelectasis on chest radiograph. A pneumonia or area of atelectasis that fails to clear should be considered suspicious for foreign body. However, in the case of chronic obstruction by a foreign body, inspiration and expiration views are not usually helpful due to chronic atelectasis of the involved portion of the lung and bronchoscopy may be required.

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VCU Department of Pediatric Radiology Virginia Commonwealth University VCU Medical Center