Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: There has been interval placement of a left chest tube with tip projecting towards the left apex . Subcutaneous emphysema within the left chest wall is new . There has been slight interval improvement in aeration of the left upper lung field with persistently large left pleural effusion . Left basilar opacification is compatible with atelectasis . The right lung is grossly clear though the right costophrenic angle is excluded from the field of view . Deformity within the ribs bilaterally is compatible old fractures . The cardiac , mediastinal and hilar contours are relatively unchanged .
    OUTPUT:
    
Interval improvement in aeration of the left upper lung field status post placement of a left sided chest tube . Large left pleural effusion , slightly improved in the interval .