Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Single AP portable frontal view of the chest was obtained . There are low lung volumes . Perihilar and bibasilar opacities may relate to fluid overload , although underlying aspiration or even infection is not excluded . The patient is status post median sternotomy . No large pleural effusion is seen , although a small effusion would be difficult to exclude on the left . There is no pneumothorax . The cardiac and mediastinal silhouettes are stable and unremarkable .
    OUTPUT:
    
Low lung volumes and evidence of fluid overload . Bibasilar opacities may relate to fluid overload , although underlying aspiration or even infection can not be excluded .