Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Portable AP upright chest radiograph was provided . There is complete opacification of the left hemithorax with mild shift of midline structures to the left , suggesting a large component of lung collapse . The right lung appears clear . The imaged osseous structures are intact . The reported tracheal stent can not be clearly visualized .
    OUTPUT:
    
Complete opacification of the left hemithorax with slight shift of midline structures to the left suggesting left lung collapse .