Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: AP single view of the chest has been obtained with patient in upright position . Comparison is made with the next preceding similar study of ___ . The heart size is normal . No configurational abnormality is seen . The pulmonary vasculature is not congested . No signs of acute or chronic parenchymal infiltrates are present and the lateral pleural sinuses are free . No pneumothorax in apical area . A previously described left subclavian approach central venous line remains in unchanged position terminating in the lower SVC . Comparison with the next preceding examination , a significant smaller size of the heart shadow is noted simultaneously . Also , a less plethoric appearance of the pulmonary vasculature is noted but there were never any signs of congestion , pleural effusion , or cardiac configurational abnormality . The change can be explained by differences in total circulating blood volume .
    OUTPUT:
    
No pulmonary abnormalities .