What is a common CXR finding associated with primary blast injuries?

The butterfly pattern related to lung contusion is a common chest X-ray finding associated with primary blast injuries. This pattern often presents as symmetric opacities in the perihilar regions, resembling the wings of a butterfly. This radiological appearance is indicative of pulmonary contusion, which can result from the high-pressure waves generated by an explosion. The blast force can cause direct damage to lung tissue, leading to bleeding and swelling, which manifest as these characteristic contusions.

In contrast, the other findings mentioned in the options may not be specifically linked to primary blast injuries. For example, bilateral pleural effusion can occur in various conditions, including heart failure or pneumonia, but is less specific to blast injuries. The air bronchogram sign typically indicates alveolar consolidation, which may be present in pulmonary infections or other pulmonary pathologies rather than being distinctively associated with blast injuries. Similarly, consolidation in the lower lobes may occur due to many causes but is not particularly characteristic of primary blast injuries. Thus, recognizing the butterfly pattern is essential for diagnosing lung contusions resulting from primary blast trauma effectively.