Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: AP upright and lateral chest radiograph demonstrates low lung volumes . When compared to prior study , the cardiomediastinal and hilar contours appear stable with a tortuous aorta . Patient is status post median sternotomy . Upper Lungs appear clear . There is no pulmonary edema . Bibasilar atelectasis is present . Dextroscoliotic deformity of the thoracic spine is re - demonstrated . There is no pneumothorax .
    OUTPUT:
    
No acute intra thoracic abnormality . Low lung volumes with bibasilar atelectasis .