Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Portable AP semi upright view was provided . Tracheostomy tube is noted . PICC line is unchanged with tip extending to the region of the SVC . Lung volumes are markedly low and the retrocardiac space can not be assessed . No large effusion or pneumothorax is seen . No definite sign of pneumonia . Mild edema not excluded . Cardiomediastinal silhouette is stable . Bony structures appear intact .
    OUTPUT:
    
Limited study with possible mild edema . Retrocardiac space poorly assessed .