Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Again seen relative lucency of the upper lungs in comparison to the more inferior lungs may be due to underlying COPD . No focal consolidation , pleural effusion , or evidence of pneumothorax is seen . Again seen rounded retrocardiac structure on the frontal view most likely relates to a hiatal hernia . The cardiac and mediastinal silhouettes are stable . No displaced fracture is seen .
    OUTPUT:
    
No acute cardiopulmonary process .