Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: AP single view of the chest has been obtained with patient in semi-upright position . Comparison is made with the next preceding similar study of ___ . Tracheostomy cannula in place as before . No pneumothorax identified . Previously described right lower hemithorax abnormalities at that time suspected for possible pneumothorax can not be confirmed . Identified is now clearly a plate - like density representing an atelectasis probably in the right middle lobe . No new parenchymal abnormalities are present . Left base with some densities in retrocardiac position as before . No new abnormalities are seen . An external facemask is overlying the upper apical area of the right hemithorax .
    OUTPUT:
    
Stable chest findings , no new infiltrates . No pneumothorax .