Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: In the interval since the prior study , a Swan - Ganz catheter and 2 chest tubes have been removed . Lung volumes are low however no pneumothorax is seen . Small residual pneumomediastinum . There is minimal atelectasis at the left lung base . No pleural effusion seen . Median sternotomy sutures are unchanged in appearance . Moderate cardiomegaly is similar in appearance compared to the prior study .
    OUTPUT:
    
No pneumothorax seen . There is a small residual pneumomediastinum .