Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Single AP view of the chest demonstrates mildly underinflated lungs with normal cardiac , hilar , and mediastinal contours . The lungs are clear and there is no pleural effusion or pneumothorax . Old upper left rib fractures are seen laterally .
    OUTPUT:
    
No acute cardiopulmonary process . Mildly underinflated lungs .