Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Left lower lobe , mild - to - moderate pleural effusion is unchanged with compressive atelectasis . The patient had a recent sternotomy for CABG and the mediastinal and cardiac contours are unchanged and normal . There is no pneumothorax . The right lung is unremarkable . The tracheostomy has been removed .
    OUTPUT:
    
Left lower lobe compressive atelectasis with mild - to - moderate pleural effusion is unchanged since ___ .