Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: PA and lateral views of the chest . Sternotomy wires and mediastinal clips are seen . A left double - lumen catheter is seen ending in the right atrium . Mild - to - moderate cardiomegaly is unchanged . Mediastinal and hilar contours are normal . Bibasilar opacities represent atelectasis ; however , pneumonia can not be excluded . Small left pleural effusion . The upper lung zones are clear . Left rib fractures are unchanged . No pneumothorax .
    OUTPUT:
    
1 . Bibasilar opacities likely represent atelectasis ; however , pneumonia can not be ruled out . 2 . Small left pleural effusion . 3 . No pneumothorax .