Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Portable semi-upright radiograph of the chest demonstrates bilateral pleural effusions with linear opacity at the left lung base , which is new since the most recent examination , and likely represents atelectasis . Again noted are bibasilar , patchy opacities , which are not significantly changed since at least ___ , except for some more nodular regions in the right peripheral lung . A possible retrocardiac opacity is present , which in the appropriate clinical context , may be consistent with pneumonia . No pneumothorax is identified . Tracheostomy tube is appropriately positioned .
    OUTPUT:
    
Persistent , bilateral pleural effusion and bilateral opacities . Retrocardiac opacity , in the appropriate clinical context , may represent pneumonia . Consider re-imaging after treatment to document resolution .