Pleural effusion, Light's Criteria

Light's Criteria:

Exudates will have at least one of the following:

• • Pleural/Serum protein ratio >0.5.

  • Pleural/Serum LDH ratio >0.6

  • Pleural LDH >200 U/L (>2/3 upper limit of normal for a simultaneously taken Sr LDH.)

Thoracentesis can be performed safely in the absence of d/o of hemostasis, on effusions that extend >10 mm from the inner chest wall on a lateral decubitus film.

Pleural effusion - causes:

• • Transudates: Usually bilateral on CXR

    • CHF

    • Cirrhosis with ascites

    • Nephrotic syndrome, renal failure

  • Exudates: Usually unilateral on CXR

    • Pneumonia

    • Parapneumonic effusion

    • Malignancy

    • PE: the only effusion which may be either exudative or transudative.

    • Collagen vascular disease

    • Pancreatitis

    • TB

    • Post-cardiac injury syndrome, chylothorax

    • Uremia

    • Esophageal perforation

    • Mesothelioma

    • Viral infection

    • sarcoidosis

    • yellow-nail syndrome

    • myxedema

    • urinothorax.

Orders: 4 tubes.

Tube 1: LDH, Protein, Glucose, Amylase, TG

Tube 2: GS, C&S, Fungal C&S, AFB

Tube 3: Cell count, diff

Tube 4: Cytology, pH, Adenosine deaminase (TB)

Transudate:

• WBC <100/mm³; and RBC <10,000/mm³

• Pleural fluid pH is > than Sr. pH

• Pleural fluid glucose = serum glucose

Exudate:

• Sr. albumin - Pleural albumin. If it is <1.2 mg/dL, then effusion is exudates.

• Bloody pleural fluid = malignancy, PE, or trauma

• Hemothorax: pleural fluid Hct : Serum Hct ratio >0.5 (50%). Insert Chest tube.

• Eosinophilia >10% suggest air or blood in pleural space; fungal, parasitic inf; drug induced; PE; asbestos related; or Churg-Strauss syndrome.

• Lymphocytes >50% = TB or malignancy.

• Plasma cells = multiple myeloma

• Mesothelial cells = not likely to be TB, likely mesothelioma.

• LDH is indicator of pleural inflammation

• Glucose <60 mg/dL - TB, cancer, RA, parapneumonic effusion

  • If glu <40 - insert CT.

• pH <7.3 - Empyema, TB, cancer, collagen vascular dz, esophageal rupture

  • Empyema needs drainage (CT or VATS).

• Amylase (salivary) - pancreatic dz, cancer, esophageal rupture.

• Chylothx: TG >110 mg/dL, turbid. Also in lymphoma.

• When the pt has lymphocytic pleocytosis in pleural fluid, suspect TB even if there are negative sputum stains for AFB.

• Cytology +ve in 60% of malignant pleural effusions. Collect in fluid collection bag that is primed with Heparin, 1000 IU.