Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: An ET tube and NG tube and central venous catheter are unchanged in position . Since the prior radiograph , lung volumes are lower . There are increased opacities at the bases and around the aoritc knob , most likely atelectasis . Cardiomediastinal sillhoute is stable . There is no pneumothorax .
    OUTPUT:
    
Decreased lung volumes and increased opacification at the bases and around the aortic knob , most likely atelectasis .