Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The patient is status post median sternotomy . The heart size is normal . The mediastinal and hilar contours are within normal limits . No focal consolidation , pleural effusion or pneumothorax is demonstrated . There is crowding of bronchovascular structures due to slightly low lung volumes . No overt pulmonary edema is present . There are mild multilevel degenerative changes in the thoracic spine .
    OUTPUT:
    
No acute cardiopulmonary abnormality .