Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: A frontal supine view of the chest was obtained portably . Low lung volumes result in bronchovascular crowding . Part of the lung fields are obscured by bilateral pacemakers . The endotracheal tube ends 4 .3 cm above the carina . Opacity at the left lung base may represent a small effusion and atelectasis or infection . The cardiac silhouette is difficult to evaluate due to the left lung opacity . The upper lung zones are clear . No large pneumothorax . A nasogastric tube follows the expected course , although the tip is not visualized , possibly in the proximal duodenum .
    OUTPUT:
    
Left lower lung opacity may represent small left pleural effusion and atelectasis or infection .