Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Lung volumes remain low as on the prior study . There is no focal airspace opacity to suggest pneumonia . Heart size is normal . The mediastinal and hilar contours are normal . There is no pleural effusion or pneumothorax . There are numerous mediastinal surgical clips and median sternotomy wires .
    OUTPUT:
    
No acute cardiopulmonary abnormality . Low lung volumes .