Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Portable AP upright chest radiograph is obtained . Midline sternotomy wires and mediastinal clips are again noted . No free air below the right hemidiaphragm . The lungs are clear bilaterally without signs of pneumonia or CHF . No pleural effusion or pneumothorax is seen . Overall , cardiomediastinal silhouette is stable with top normal heart size . Bony structures are intact .
    OUTPUT:
    
No acute intrathoracic process .