Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: AP portable semi upright view of the chest . Patient 's chin obscures the superior mediastinum and left lung apex . Lung volumes are low with bibasilar atelectasis and bronchovascular crowding . Allowing for technical limitations , there is no convincing evidence for pneumonia or edema . No large effusion or pneumothorax is identified . Cardiomediastinal silhouette appears grossly unremarkable .
    OUTPUT:
    
Lower lung atelectasis without definite signs of pneumonia . Limited exam .