Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: There is now nearly complete opacification of the left hemithorax with some aeration in the left upper lobe . There was leftward mediastinal shift . No pneumothorax is appreciated .
    OUTPUT:
    
Near complete opacification of the left hemi thorax with leftward mediastinal shift suggesting atelectasis perhaps secondary to mucous plugging . The subsequent radiograph demonstrates resolution of these findings following bronchoscopy .