Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The patient is status post median sternotomy and CABG . Low lung volumes are present which accentuates mediastinal widening and the size of the heart . The cardiac silhouette size is at least mildly enlarged . The aorta is tortuous . There is crowding of the bronchovascular structures without overt pulmonary edema . Patchy bibasilar airspace opacities may reflect atelectasis but infection can not be excluded . No pleural effusion or pneumothorax is identified . No acute osseous abnormality is seen .
    OUTPUT:
    
Low lung volumes which accentuate mediastinal widening and cardiac size . Bibasilar airspace opacities , possibly atelectasis but infection is not excluded .