1. Pleural Effusion
Marvin Chang, PGY2
April 2015

2. Objectives Know how to diagnose pleural effusions.
Understand the indications for thoracentesis.
Understand the main classification and etiologies of pleural effusions.
Know the common laboratory studies used to analyze pleural fluid.

3. Clinical Presentation
History
Dyspnea
Pleuritic chest pain
Cough
Other symptoms related to underlying cause
Physical exam (Findings usually present for effusions > 300 mL )
Dullness to percussion, decreased tactile fremitus
Asymmetric chest expansion
Decreased breath sounds
Egophony

4. Imaging Studies-Chest Radiographs
Lateral Decubitus – very sensitive,
can detect effusions as small as
50 mL
PA - usually around mL needed before visible

5. Imaging Studies CT Scan Ultrasound
Better characterization of underlying lung parenchyma and certain processes that may be obscured on radiographs by large pleural effusions
Ultrasound
Cheap and available at bedside
Can help identify free vs. loculated effusions
Thoracentesis is facilitated by ultrasound guidance

6. Case
82 year old male with a history of DM2, HTN, CAD and CHF who presents with dyspnea on exertion and cough over the past 3 days. His CHF was diagnosed 1 year ago, symptoms relatively well controlled with 20mg PO Lasix daily.
Labs notable for BNP of 1300 (baseline ~300) and CXR showed moderate bilateral pleural effusions. Temp 37.0, WBC 8.0
What is the next step in management? Is a thoracentesis indicated at this point?
Clinical signs and laboratory studies all point towards acute decompensated CHF in this patient. This is the most likely etiology of the patient’s pleural effusions. A thoracentesis is not indicated at this point unless there are atypical features (fever, significant leukocytosis, unilateral effusion, etc.). In this case would attempt diuresis first.

7. Indications for thoracentesis
Pleural effusion of unknown etiology, with >10mm depth on lateral decubitus CXR or Ultrasound
Therapeutically for symptomatic relief
Concern for empyema
Air fluid level in pleural space
-Generally accepted that if the depth is greater than 1cm, the amount of fluid is significant

8. Common Mechanisms for Pleural Effusion
↑ hydrostatic pressure
↓ oncotic pressure
↑ vascular permeability
↓ lymphatic drainage
↑ negative pressure in pleural space
Can ask audience to give examples of each:
↑ hydrostatic pressure -> CHF
↓ oncotic pressure -> Hypoalbuminemia
↑ vascular permeability -> inflammatory mediators from pneumonia or sepsis
↓ lymphatic drainage -> obstruction from tumor or fibrosis

9. Case
A 37 year old female with a history of chronic alcohol use presents to the ER complaining of increased shortness of breath and abdominal pain. Chest x-ray shows large right sided pleural effusion
Thoracentesis is performed which reveals LDH of 120 (serum value 175), total protein 3.2 (serum protein 5.3) and markedly elevated pleural fluid amylase. Upper limit of normal serum LDH is 333.
Is this pleural effusion best classified as transudative or exudative. What is the most likely etiology?
Most likely exudative pleural effusion secondary to pancreatitis

10. Lights Criteria
Pleural effusion is exudative if one or more of the following:
Ratio of pleural fluid protein level to serum protein level > 0.5
Ratio of pleural fluid LDH level to serum LDH level > 0.6
Pleural fluid LDH level > 2/3 the upper limit of normal for serum LDH level.
98% sensitive and 83% specific for exudative effusion using Lights criteria.
Absence of all 3 criteria = transudative
Fun fact: Dr. Light practiced at Long Beach VA

11. Transudative vs Exudative
CHF ~36%
Nephrotic syndrome
Hypoalbuminemia
Hepatic hydrothorax
Atelectasis
Exudative
Pneumonia ~ 22%
Malignancy ~14%
PE ~11%
Inflammatory (pancreatitis, ARDS, uremic pleurisy etc.) ~7%
Connective tissue disease
Most common causes of transudative and exudative effusions

12. Pleural Fluid Evaluation – Cell count with diff
For analyzing pleural fluid, always get a cell count with diff. The table has suggestions on how to interpret these values

13. Pleural Fluid Evaluation
Other routine pleural fluid tests include LDH, protein, adenosine deaminase, cytology and glucose.
Optional tests include amylase, cholesterol, triglyceride, cultures, proBNP, tumor markers, and should be ordered based on clinical suspicion.
Other routine and optional thoracentesis labs

14. Algorithm for evaluation
Overall algorithm for the evaluation of patients with pleural effusion, summarizing some of the key points made earlier. Pulmonary embolism should be considered earlier in the evaluation if there are clinical symptoms or signs suggesting this diagnosis.

15. Summary Pleural effusions are commonly encountered on wards
Thoracentesis is not immediately indicated if there is a obvious explanation for pleural effusion without atypical features
Pleural effusions are classified as transudative vs exudative.
CHF, pneumonia, malignancy and PE comprise the vast majority of causes for pleural effusions.

16. References
Heffer, Uptodate.com “diagnostic evaluation of a pleural effusion in adults: initial testing”
Light. Clinical practice: Pleural effusion. New England Journal of Med 2002; 346; 1971.
Porcel. Diagnostic approach to pleural effusion in adults. American family physician 2006 Apr 1;73(7):
Reubins, Medscape.com. “pleural effusions”
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