Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: AP upright portable chest radiograph demonstrates low lung volumes bilaterally . There is no consolidation concerning for an pneumonia . Heart size is enlarged though slightly exaggerated by image technique and low lung volumes . There is no pneumothorax , pulmonary edema , or pleural effusion . Hilar contours are within normal limits . Patient is status post median sternotomy . A midline trach is identified , its tip difficult to see given projection . Imaged osseous structures and upper abdomen are unremarkable .
    OUTPUT:
    
No pneumothorax . Low lung volumes with cardiomegaly .