med 610 clinical respiratory diseases & critcare med

Pleural Effusions

Case 9

A 55 year-old woman underwent thoracotomy for a resection of a posterior mediastinal mass. She had a right subclavian line placed, which was working properly.  She has not been eating well since the surgery and has been on maintenance fluid with half-normal saline. Her chest tube was removed on post-operative day #1. Two days later she developed dyspnea, hypoxemia and a headache that was worse in the upright position. A chest x-ray was performed and showed a large right pleural effusion. Thoracentesis is performed and reveals clear “water-like” fluid. The LDH is 80 (serum value 190) and the total protein is < 1 (serum value 6.9). There are no WBCs and the gram’s stain is negative. The WBC differential contains primarily monocytes.

How do you interpret the pleural fluid results?


What is the differential diagnosis for colorless pleural fluid with a total protein < 1?


In addition to ordering an LDH and protein level on the pleural fluid, what additional diagnostic studies should you consider to confirm the diagnosis?


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