Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: AP portable upright chest radiograph obtained . Midline sternotomy wires and mediastinal clips are unchanged . The lungs appear clear bilaterally without focal consolidation , effusion , or pneumothorax . The cardiomediastinal silhouette appears grossly stable . Bony structures are intact . No free air is seen below the right hemidiaphragm .
    OUTPUT:
    
No acute intrathoracic process . Post - CABG changes .