Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: AP portable upright view of the chest . Low lung volumes with atelectasis in the mid and lower lungs noted . Given this , evaluation for subtle pneumonia is limited and difficult to exclude . No large effusion or pneumothorax . The heart size can not be assessed . Mediastinal contour is unchanged . No large pneumothorax . Bony structures appear grossly intact .
    OUTPUT:
    
Low lung volumes with bilateral lower lung atelectasis . No convincing signs of pneumonia though lower lung assessment is limited .