Pleural Effusion

IM

An imbalance between the oncotic and hydrostatic forces that govern pleural fluid formation and lymphatic drainage can result in excessive fluid accumulation.

Pleural Effusion: Clinical Features

• Asymptomatic: Small pleural effusion (< 300 mL).
• Characteristic symptoms:
  • Dyspnea
  • Pleuritic chest pain (sharp retrosternal pain)
  • Dry, nonproductive cough.
  • Symptoms of hypoxia
• Symptoms of the underlying disease:
  • Fever in empyema
  • Cachexia in cases of malignancy
  • Symptoms of left-sided heart failure; back pressure
• Physical exam findings: Clinically detected if > 500 ml.
  • Inspection and palpation (affected side):
    • Asymmetric expansion (↓Chest movement)
    • Mediastinal displacement (Trachea shifted away from the side of the lesion in massive effusion).
    • Reduced tactile fremitus.
  • Percussion: Stony dullness
  • Auscultation:
    • Faint or absent breath sounds over the area of effusion
    • Vocal resonance - reduced or absent

Pleural Effusion: Diagnostics

Imaging to confirm the diagnosis:

Chest X-ray: Lateral decubitus view (most sensitive): > 200 ml.

• Unilateral blunting of the costophrenic angle
• Homogeneous density with a meniscus-shaped margin (meniscus sign)
• Complete opacification of the lung (Large effusion) and Mediastinal shift and tracheal deviation.

Ultrasound: Quick, bedside assessment, if planning thoracentesis.

• Very sensitive: 20 ml. Hypoechoic collection.
• Detection of pleural thickening and pleural nodules.

CT: Gold standard for small effusions.

• Guiding placement of indwelling pleural catheters.
• Directed thoracentesis of a loculated effusion.
• Suspected parenchymal or pleural pathology. contrast CT is now increasingly performed to investigate the underlying cause, particularly for exudative effusions

Thoracentesis:

• 21G needle, 20 ml syringe under aseptic condition through intercostal space towards the top area of dullness.
• Contrast CT is now increasingly performed to investigate the underlying cause, particularly for exudative effusions.

Diagnostic Thoracentesis

For diagnostic and/or therapeutic purposes.

• Indications:
  • New unilateral effusion
  • Hx malignant tumor with effusion
  • Pneumonia with parapneumonic effusion
  • Heart failure with atypical findings (e.g., pleuritic chest pain, fever, unilateral effusion).
• Contraindications: Local infection, bleeding risk.
• Studies (5 Cs):
  • Color
  • Cytology
  • Culture
  • Cell count
  • Chemistry
• TB testing: Adenosine deaminase, AFB smear microscopy

Transudate vs Exudate

Transudate: Fluid permeates into the pleural cavity through intact pulmonary vessels (e.g., in congestive heart failure).

Clear, extravascular fluid caused by:

• Increased capillary hydrostatic pressure (CHF)
• Decreased capillary oncotic pressure (hypoalbuminemia).
• Low in protein and cells.

Common causes

• Congestive heart failure
• Hepatic cirrhosis
• Nephrotic syndrome
• Protein-losing enteropathy
• Hypo-albuminemia

Exudate: *Fluid escapes into the pleural cavity through lesions in blood and lymph vessels (e.g., due to inflammation or tumors). Yellow/cloudy extravascular fluid caused by:

• Increased capillary permeability (inflammation or malignancy).

• High in protein and cells.

  • Common:

    • Bacterial pneumonia (parapneumonic), empyema, TB
    • Carcinoma of the bronchus, lymphoma
    • Pulmonary infarction

  • Rare:

    • Post-MI
    • Acute pancreatitis (↑amylase)
    • SLE, Rheumatoid arthritis (Connective tissue disorders)
    • Mesothelioma (Asbestosis)

  • Very rare causes:

    • Sarcoidosis
    • Yellow nail syndrome (lymph oedema)
    • Familial Mediterranean fever
    • Parasitic illness (amebiasis, echinococcal disease)
    • Trauma (high vascular permeability)

Differential Diagnosis of Exudative Effusions

Pleural Fluid Parameter	Associated Conditions
WBC count > 10,000 cells/mm3	Parapneumonic effusion, Pancreatitis, Pulmonary embolism
Neutrophils > 50% of total leukocytes	Acute infection, Pulmonary infarct
Lymphocytes > 50% of total leukocytes	Tuberculous infection, Malignant effusion, Chylothorax
RBC count > 5,000 cells/μL	Hemothorax, Malignant effusion, Pulmonary embolism/infarct
pH < 7.2	Complicated parapneumonic effusion, Empyema, Malignant effusion, Esophageal perforation
Positive Gram stain or culture	Parapneumonic effusion, Empyema
Adenosine deaminase > 50 mcg/L	Tuberculous effusion
Positive AFB smear microscopy	Tuberculous effusion
Abnormal cytology	Malignant effusion
Amylase > 200 mcg/dL	Pancreatitis, Esophageal perforation, Ruptured ectopic pregnancy, Pleural infection

All patients with a pleural effusion in association with sepsis or a pneumonic illness require diagnostic pleural fluid sampling.

• If the fluid is purulent or turbid/cloudy, a chest tube should be placed to allow drainage.
• If the fluid is clear but the pH is less than 7.2 in patients with suspected pleural infection, a chest tube should be placed.

Pleural Fluid Analysis: Light Criteria - Differentiating Transudates from Exudates

• MEAT has low glucose: Malignancy, Empyema, Arthritis (rheumatoid pleurisy), and Tuberculosis are causes of pulmonary effusion associated with low glucose levels.
• Criteria for borderline cases:
  • Exudates have a protein level of >30 g/L, transudates have a protein level of <30 g/L
  • If the protein level is between 25 and 35 g/L, Light’s criteria should be applied.

The BTS recommend using the criteria for borderline cases:

exudates have a protein level of >30 g/L, transudates have a protein level of <30 g/L

if the protein level is between 25-35 g/L, Light’s criteria should be applied. An exudate is likely if at least one of the following criteria are met:

Pleural Effusion: Management

• Treat the underlying condition.
• Large effusion: Drainage. Maximum aspiration of pleural fluid at one time is 1000 ml.
• Malignant pleural effusion: Symptomatic and reaccumulate - aspirated to dryness followed by PLEURODESIS. Instillation of a sclerosing agent such as tetracycline or talc (Magnesium silicate).

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Flash pulmonary edema

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Pediatrics

Pleural effusion or empyema

• Persistent or recurrent fever after 48 h treatment for pneumonia should raise suspicion of a parapneumonic effusion or empyema.

• An AP or PA CXR and ultrasound should allow diagnosis and evaluation of the nature of pleural fluid.

• A small unloculated effusion may resolve with IV antibiotics alone. A diagnostic pleural tap is usually unnecessary.

• A large loculated empyema with obvious pus and thickened pleura will require drainage.

• Options include a pigtail chest drain with intrapleural fibrinolytics, video-assisted thoracoscopic surgery (VATs), or early minithoracotomy following chest CT scan.