Pleural Diseases

Pleural Effusion Essentials - Fluid Follies

Excess fluid in pleural space.

• Types:

  Feature	Transudate	Exudate
  Mechanism	Systemic (↑ hydrostatic, ↓ oncotic P)	Local (↑ permeability, ↓ drainage)
  Appearance	Clear	Cloudy/Bloody
  Protein (Pleural/Serum)	< 0.5	> 0.5
  LDH (Pleural/Serum)	< 0.6	> 0.6
  LDH (Pleural)	< 2/3 ULN Serum	> 2/3 ULN Serum
  Causes	CCF, Cirrhosis, Nephrotic	Pneumonia, TB, Malignancy

• 📌 Light's Criteria (Exudate if $\ge \mathbf{1}$):

  • Pleural fluid protein / Serum protein > 0.5 (i.e., $P_{prot}/S_{prot} > \mathbf{0.5}$)
  • Pleural fluid LDH / Serum LDH > 0.6 (i.e., $P_{LDH}/S_{LDH} > \mathbf{0.6}$)
  • Pleural fluid LDH > 2/3 ULN Serum LDH (i.e., $P_{LDH} > \frac{2}{3} \times \text{ULN Serum LDH}$)

⭐ India: Commonest transudate - CCF. Commonest exudate - TB/Parapneumonic.

• Dx:
  • CXR: Costophrenic angle blunting (~200 mL), meniscus. Lateral decubitus (~50 mL).
  • USG: Sensitive (detects ~5-20 mL), guides thoracentesis.
  • Thoracentesis: Diagnostic (biochem, cytology, micro) & therapeutic.

Effusion Varieties - The Usual Suspects

• Parapneumonic Effusion & Empyema: Associated with pneumonia.

  • Uncomplicated: Free-flowing; pH >7.2, Gluc >60 mg/dL, LDH <1000 IU/L. Rx: Antibiotics.
  • Complicated: Loculated OR pH <7.2, Gluc <60 mg/dL, LDH >1000 IU/L. Rx: ICD + antibiotics.
  • Empyema: Pus; +ve Gram/Culture. Rx: ICD, fibrinolytics (e.g. streptokinase), surgery if needed (decortication).
    • 📌 Stages: 1. Exudative → 2. Fibrinopurulent → 3. Organising.

  

• Tuberculous Pleural Effusion: Common extrapulmonary TB.

  • Exudative, straw-coloured; lymphocytes >80%.
  • ADA >40 IU/L highly suggestive. Pleural biopsy if doubt. Rx: ATT (6 months).

  ⭐ Adenosine Deaminase (ADA) >40 IU/L is a key diagnostic marker for tuberculous pleural effusion, especially in high TB prevalence areas.

• Malignant Pleural Effusion: Primary (mesothelioma) or metastases (lung, breast, lymphoma).

  • Large, recurrent, often hemorrhagic. Dx: Cytology/pleural biopsy.
  • Rx: Therapeutic tap, pleurodesis (talc), IPC.

Air & Agony - Pneumothorax Puzzles

• Types & Features:

  Type	Cause	Key Feature
  Spontaneous
  - Primary (PSP)	Ruptured subpleural bleb/bulla	Young, tall, thin males; smokers
  - Secondary (SSP)	Underlying lung disease (e.g., COPD)	More severe symptoms
  Traumatic	Penetrating/blunt trauma, iatrogenic	History of trauma/procedure
  Tension	Air entry > air exit (one-way valve)	Life-threatening; shock

• Tension Pneumothorax: Medical emergency!

  • 📌 TRACHEA Mnemonic: Tracheal deviation (away), Respiratory distress (severe), Absent breath sounds (ipsilateral), Cyanosis, Hypotension, Engorged neck veins (JVD), Acute.
  • Immediate needle decompression: 2nd ICS mid-clavicular line OR 5th ICS mid-axillary line, then Intercostal Drain (ICD).

⭐ Tension pneumothorax is a clinical diagnosis; immediate needle thoracostomy should precede radiographic confirmation if suspected due to its life-threatening nature.

Other Pleural Pathologies - Thoracic Troubles

• Hemothorax: Blood in pleural space.
  • Causes: Trauma, iatrogenic, malignancy.
  • Dx: Pleural Hct > 0.5 × blood Hct.
  • Rx: Chest tube; thoracotomy if >1500mL initial or >200mL/hr for 2-4 hrs.
• Chylothorax: Chyle (lymph) in pleural space.
  • Causes: Trauma (surgical), malignancy (lymphoma).
  • Dx: Milky fluid; ↑Triglycerides (>110 mg/dL), chylomicrons.
  • Rx: Treat cause, low-fat/MCT diet, octreotide.
• Mesothelioma: Pleural malignancy.
  • 📌 Risk: Asbestos exposure (primary).
  • Imaging: Unilateral effusion, rind-like pleural thickening.

  ⭐ Strongly linked to occupational asbestos exposure; long latency (20-40 yrs).

• Light's criteria are crucial for differentiating exudative from transudative pleural effusions.
• Tuberculous pleural effusion is typically exudative, lymphocyte-predominant, with high ADA (>40 U/L).
• Malignant pleural effusion is often exudative, hemorrhagic, and cytology is key for diagnosis.
• Empyema requires drainage (thoracostomy); characterized by pus or positive Gram stain/culture.
• Pneumothorax types: spontaneous (primary/secondary), traumatic, tension (medical emergency, needle decompression).
• Mesothelioma is strongly associated with asbestos exposure; presents with pleural thickening/effusion.
• Chylothorax shows milky fluid with high triglycerides (>110 mg/dL) and cholesterol/triglyceride ratio <1.