Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: AP portable upright view of the chest . Lung volumes are low limiting evaluation . Sternotomy wires , fragmented , again noted . The heart remains moderately enlarged . No large effusion or pneumothorax . No congestion or edema . No convincing signs of pneumonia . Mediastinal contour is normal . Bony structures are intact .
    OUTPUT:
    
Limited due to low lung volumes . Cardiomegaly without signs of pneumonia or edema .