Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Patient 's clinical condition required examination in sitting position using AP frontal and left lateral view . Available for comparison is the next preceding PA and lateral chest examination of ___ . The heart size remains within normal limits and is unchanged . Mild degree of thoracic widening and elongation is noted , but no new local contour abnormalities are seen . The pulmonary vasculature is not congested ; however , similar as on the preceding examination , irregular peripheral pulmonary distribution is consistent with COPD . No pneumothorax is identified in the apical area . There is evidence of free air in the peritoneal cavity collecting under the right diaphragm . In the left hemithorax , the patient had on previous examinations , rather advanced scar formations in the pleura on the left base with partial obliteration of the lateral pleural sinus . In addition , the patient had a pneumonic infiltrate in the left upper lobe laterally and on the right side in the lower lobe base . At that time , acute infiltrates have disappeared , but the left basal pleural scar formations remain . When comparing the frontal views , one can identify a new triangular - shaped density in retrocardiac position , which is also seen on the lateral view . There is no evidence of new pleural free effusion and no pneumothorax is present in the apical area .
    OUTPUT:
    
New parenchymal infiltrate in left lower lobe posterior segment comparison with next previous chest examination of ___ . Considering that the patient is postoperative day 3 following laminectomy operation , the newly described density is indicative of an atelectasis . Combination of atelectasis and fever speaks in favor of overlying infection and treatment is recommended with radiographic followup . Referring physician , ___ , was paged at 3 :20 p .m . As no response was achieved , telephone call to the intensive care unit ___ was made and the responsible nurse , ___ , was contacted . She received the message that a new pulmonary infiltrate was noted which should be treated .