Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Single portable chest radiograph was provided . The tracheal stent is not visualized on this exam . There is new collapse of the left upper lobe . Lung volumes are low . There is no pneumothorax . Cardiac silhouette is top normal .
    OUTPUT:
    
1 . Tracheal stent is not visualized . 2 . New left upper lobe collapse and low lung volumes .