Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Portable upright chest film ___ at 21 :39 is submitted .
    OUTPUT:
    
The patient is status post median sternotomy with stable postoperative cardiac and mediastinal contours . There has been interval appearance of a layering right effusion and increasing consolidation at the right base which may reflect atelectasis , although pneumonia or aspiration should also be considered . Lung volumes remain low with crowding of the vasculature . However , there now is mild perihilar edema . No large pneumothorax .