Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Portable upright chest radiograph demonstrates a tracheostomy tube in unchanged position . There has been interval removal of a right upper extremity PICC . Median sternotomy wires are in place , the uppermost of which is broken , though this finding is chronic . There are post-surgical changes of CABG . The lungs are clear . There is no pleural effusion or pneumothorax . The cardiac silhouette remains mildly enlarged , the mediastinal contours are normal . The pulmonary vasculature is normal .
    OUTPUT:
    
No acute chest abnormality .