Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Lungs are well expanded . Cardiomediastinal hilar contours are unchanged . Patient is status post median sternotomy , with intact sternotomy wires . Chronic interstitial changes are more pronounced at the bilateral lung bases , and are increased from prior . There is a large hiatal hernia . No pneumothorax , pleural effusion , or consolidation .
    OUTPUT:
    
Interval progression of bibasilar interstitial changes , which likely reflect a combination of pulmonary fibrosis and aspiration . Superimposed infection is not excluded .