Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Single portable upright AP image of the chest . There are low lung volumes . There is an interval increase in the alveolar opacities bilaterally , consistent with moderate to severe new onset pulmonary edema . The cardiomediastinal silhouette appears to be somewhat enlarged from prior exam , particularly in the right mediastinum . There is no large pleural effusion or pneumothorax . A pacer is seen overlying the left anterior chest with intact leads in appropriate position .
    OUTPUT:
    
Interval development of moderate to severe pulmonary edema . Can not exclude underlying pneumonia .