Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Portable semi-upright chest radiograph demonstrates low lung volumes . The lungs show superior segmental collapse of the right lower lobe . The pleural surfaces are normal . The cardiac silhouette and mediastinal contours appear normal . Patient is status post aortic valve replacement with changes of median sternotomy . Mild edema has progressively improved . An NG tube tip and sidehole are superimposed on the stomach . Endotracheal tube tip is positioned at least 2 .7 cm from the level of the carina . A left IJ approach central venous catheter tip is located in the mid SVC . Left shoulder arthroplasty is again noted .
    OUTPUT:
    
1 . Low lung volumes , without acute chest abnormality . 2 . Appropriate positioning of support devices .