Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Portable AP upright chest film ___ at 18 58 is submitted .
    OUTPUT:
    
Lung volumes are low with bibasilar patchy opacities likely reflecting atelectasis , although pneumonia or aspiration can not be entirely excluded . There is likely a small layering left effusion . Given the low lung volumes , assessment of the cardiac and mediastinal contours is difficult . There is crowding of the pulmonary vasculature with no overt pulmonary edema appreciated . No pneumothorax .