Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Lung volumes are low . The patient is status post median sternotomy . Heart size remains borderline enlarged , unchanged . Mediastinal contours are similar . There is crowding of the bronchovascular structures without overt pulmonary edema . Patchy opacities are noted in both lung bases , not substantially changed in the previous exam . No new focal consolidation , pleural effusion or pneumothorax is seen . No acute osseous abnormalities seen . Percutaneous catheter is noted within the upper abdomen .
    OUTPUT:
    
Low lung volumes with patchy bibasilar airspace opacities , possibly reflective of infection or aspiration .