Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Portable AP upright chest radiograph . Left basally directed chest tube appears unchanged in position . The extent of pleural effusion assuming similar degrees of inclination is mildly increased with resultant , likely chronic , left lower lobe atelectasis . Effusion remains significantly decreased from pre-chest tube placement film on ___ . The right lung is clear . Cardiomediastinal contours are obscured but unchanged .
    OUTPUT:
    
Slight interval increase in moderate left pleural effusion and atelectasis .