#62 – Pleural Effusions


Pleural Anatomy and Physiology

  • 2 types of pleura in the thorax
    • Parietal pleura
      • Which covers the chest wall and diaphragm
      • 30-40 micrometers thick
      • Contains lymphatic stomata
        • Holes between the mesothelial and subpleural layers that allow for drainage into the lymphatic system
      • Contains intercostal microvessels
        • Produce interpleural fluid
    • Visceral pleura
      • Which covers the lung parenchyma
      • 20-80 micrometers thick
      • Contain bronchial microvessels
        • Arise from pulmonary veins and produce interpleural fluid
  • The interpleural space is between them and produces 0.1-0.2 mL/kg (10-20 mL per hemithorax) of fluid to keep these pleura from adhering to each other and maintain lubrication
    • This fluid is constantly produced (0.01 mL/kg/hr) and absorbed
    • Originates from the systemic pleural microvessels
      • Theorized that parietal is more important
        • Intercostal microvessels are closer to the interpleural space
        • Higher filtration pressure than pulmonary veins
    • Dependent on balance of hydrostatic pressure opposed by the counterbalancing osmotic pressure and membrane permeability
      • Transudative fluid collection
        • Increased hydrostatic pressure
        • Decreased oncotic pressure
      • Exudative fluid collection
        • Decreased pleural membrane permeability
        • Lymphatic blockage

Associated Diseases and Causes

Clinical Presentation

  • Symptoms      
    • Patients can be asymptomatic, have fluid specific symptoms, and have disease specific symptoms
    • Fluid specific
      • Dyspnea
      • Cough
      • Pleuritic chest pain
    • Disease specific
      • Fever, hemoptysis, orthopnea, peripheral edema, weight changes, ascites
  • Physical Examination
    • Fluid specific
      • Decreased or asymmetric chest wall movement
      • Decreased breath sounds
      • Dullness to percussion
      • Decreased tactile fremitus
      • Pleural friction rub
      • (+) egophony
    • Disease specific
      • Crackles, JVD, hepatosplenomegaly, lymphadenopathy, S3 gallop, pitting edema,

Imaging in Suspected Pleural Effusions

  • Chest Radiograph
    • Blunting of the costophrenic angle
      • At least 150mL needed on PA
      • At least 50mL needed on lateral decubitus
    • At least 500mL needed for diaphragm obliteration
  • Computed Tomography
    • Can detect as little as 2mL of fluid
  • Ultrasound
    • Can detect as little as 20mL
    • Phased array probe with patient sitting upright
    • Scan posterior/lateral caudal to cranial to find fluid line
    • (+) spine sign


  • Once the diagnosis is made, a thoracentesis needs to be performed for biochemical fluid analysis

Fluid Analysis

  • Routine fluid labs
    • Cell count and differential
    • pH
    • Protein
    • LDH
    • Glucose
    • Cholesterol
  • Non-routine
    • N-terminal BNP
    • Triglycerides
    • Creatinine
    • Amylase
    • Cancer-related biomarkers
  • Lights Criteria
    •  Exudative if one (1) of following present:
      • Pleural/serum protein ratio > 0.5
      • Pleural/serum LDH > 0.6
      • Pleural fluid LDH > 2/3rd ULN of serum LDH
    • Lights Criteria Criticism
      • Needs both pleural fluid and serum
      • Newer studies use only pleural fluid
        • Exudative if one (1) of the following:
          • Pleural fluid cholesterol > 45 mg/dL
          • Pleural fluid protein > 2.6 g/dL
          • Pleural fluid LDH > 0.45x ULN of serum LDH


  • Non-malignant effusions
    • Treat underlying condition
    • Repeated drainage for symptomatic patients
    • If persistent:
      • Repeat thoracentesis as needed
      • Revisit primary diagnosis
      • Consider pleurodesis
        • Chemical
          • Talc slurry or doxycycline through chest tube
        • Mechanical
          • VATS
      • Indwelling pleural catheter
        • Reserved for patients who decline, fail, or not candidates for pleurodesis
  • Malignant effusions
    • Can be complicated

Cottage Physician (1898)


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  8. Light RW. Disorders of the Pleura. In: Jameson J, Fauci AS, Kasper DL, Hauser SL, Longo DL, Loscalzo J. eds. Harrison’s Principles of Internal Medicine, 20e. McGraw-Hill; Accessed July 05, 2020. https://accessmedicine-mhmedical-com.ezproxy.uthsc.edu/content.aspx?bookid=2129&sectionid=192031615
  9. Moskowitz H, Platt RT, Schachar R, Mellins H. Roentgen visualization of minute pleural effusion. An experimental study to determine the minimum amount of pleural fluid visible on a radiograph. Radiology. 1973; 109(1):33-5. [pubmed]
  10. Radiopaedia. Pleural Effusions. https://radiopaedia.org/articles/pleural-effusion?lang=us
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  13. Steger V, Mika U, Toomes H, et al. Who gains most? A 10-year experience with 611 thoracoscopic talc pleurodeses. Ann Thorac Surg. 2007; 83(6):1940-5. [pubmed]
  14. Patil M, Dhillon SS, Attwood K, Saoud M, Alraiyes AH, Harris K. Management of Benign Pleural Effusions Using Indwelling Pleural Catheters: A Systematic Review and Meta-analysis. Chest. 2017; 151(3):626-635. [pubmed]
  15. Feller-Kopman DJ, Reddy CB, DeCamp MM, et al. Management of Malignant Pleural Effusions. An Official ATS/STS/STR Clinical Practice Guideline. Am J Respir Crit Care Med. 2018; 198(7):839-849. [pubmed]
  16. Bibby AC, Dorn P, Psallidas I, et al. ERS/EACTS statement on the management of malignant pleural effusions. Eur Respir J. 2018; 52(1):. [pubmed]

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