Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Portable AP upright chest radiograph obtained . Lung volumes are low which limits evaluation . Allowing for this there is no definite sign of pneumonia or CHF . Please note the retrocardiac region is poorly assessed . No large effusion or pneumothorax . The heart and mediastinal contour appear within normal limits . Bony structures are intact .
    OUTPUT:
    
Negative study , limited