Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: A semi-upright portable AP radiograph of the chest demonstrates clear lungs aside from bilateral lower lobe atelectasis . The hilar and cardiomediastinal contours are normal . There is no pneumothorax or pleural effusion . Pulmonary vascularity is normal . A left lower chest implanted neurostimulator is again seen .
    OUTPUT:
    
No acute cardiopulmonary process .