Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Portable semi-erect chest radiograph ___ at 02 :48 is submitted .
    OUTPUT:
    
Overall , there is improving aeration throughout both lungs suggestive of resolving but persistent pulmonary and interstitial edema . The heart remains markedly enlarged . Mediastinal contours are stable . No pneumothorax . No developing airspace consolidation to suggest pneumonia at this time .