Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Portable supine chest film ___ at 20 :39 is submitted .
    OUTPUT:
    
Intra-aortic balloon pump is unchanged in position but its tip is within the aortic knob which is somewhat high . Pull - back of several cm may be indicated . Clinical correlation is advised . The cardiac and mediastinal contours appear stably enlarged . There is a small layering right effusion with patchy adjacent opacity likely reflecting compressive atelectasis . Lung volumes remain low with crowding of the vasculature but no overt pulmonary edema is seen . No pneumothorax although the sensitivity to detect pneumothorax is diminished given supine technique .