Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Portable AP upright chest radiograph obtained . There is chronic scarring at the left lung base . There is no definite sign of pneumonia or CHF . The overall cardiomediastinal silhouette appears stable , though the heart size is not well visualized . There is no pneumothorax . Bony structures appear intact . Midline sternotomy wires are noted .
    OUTPUT:
    
No acute findings in the chest . Limited exam .