Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The lung volumes are low , limiting evaluation and accentuating the bronchovascular structures . There is no focal airspace consolidation , pulmonary edema , pleural effusion , or pneumothorax . The mediastinal contours are normal . The heart size is at the upper limits of normal . Post - surgical changes from a prior CABG are unchanged . Sternal wires are intact . A small rounded opacity behind the heart is stable and may represent a small hiatal hernia .
    OUTPUT:
    
No acute cardiopulmonary process .