Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Portable semi-upright radiograph of the chest demonstrates low lung volumes with bronchovascular crowding . There is an unchanged appearance of the cardiac silhouette . There is persistent massive subcutaneous emphysema , which is stable to slightly decreased from the prior study . No pneumothorax is present .
    OUTPUT:
    
No evidence of pneumothorax .