Pleural Effusion

What is a pleural effusion?

An abnormal accumulation of fluid in the pleural space caused by either transudative or exudative processes.

What are the major causes of transudative pleural effusions?

• CHF

• Cirrhosis

• Nephrotic syndrome

• Hypoalbuminemia

What are the major causes of exudative pleural effusions?

• Pneumonia

• Malignancy

• Tuberculosis

• Pulmonary embolism

• Inflammatory conditions

What is the pathophysiology of a transudative effusion?

An imbalance of hydrostatic and oncotic pressures causes low‑protein fluid to leak into the pleural space.

What is the pathophysiology of an exudative effusion?

Increased capillary permeability or impaired lymphatic drainage causes protein‑rich fluid accumulation.

What are the components of Light’s criteria?

• *Pleural fluid:serum protein ratio >0.5

• Pleural fluid:serum LDH ratio >0.6

• Pleural fluid LDH > two‑thirds upper normal serum limit

How is a pleural effusion classified using Light’s criteria?

Exudate if ≥1 criterion is met

What are classic symptoms of pleural effusion?

• Dyspnea

• Chest pain

• Shallow breathing

• Fever

• Dry cough

What physical exam findings suggest pleural effusion?

• Dullness to percussion

• Decreased tactile fremitus

• Decreased breath sounds

• Pleural friction rub (with pleuritis)

What chest X‑ray findings are associated with pleural effusion?

• Blunting of costophrenic angles

• Meniscus sign

• Large effusions causing mediastinal shift

What imaging modality is most sensitive for detecting small pleural effusions?

Ultrasound, especially for guiding thoracentesis.

What CT findings may be seen in pleural effusion?

Fluid layering, loculations, pleural thickening, or underlying lung pathology.

What is the diagnostic test of choice for evaluating pleural effusion?

Thoracentesis for fluid analysis when the cause is unclear.

What laboratory studies are performed on pleural fluid?

• Protein and LDH (Light’s criteria)

• Cell count

• Glucose

• pH

• Gram stain/culture

• Cytology

What pleural fluid findings suggest empyema or complicated parapneumonic effusion?

• Low glucose

• Low pH (<7.2)

• High WBC count

• Positive cultures

What pleural fluid findings suggest malignancy?

Positive cytology, bloody fluid, recurrent effusions.

What pleural fluid findings suggest TB?

Lymphocyte‑predominant exudate, elevated ADA.

What are the treatment goals for pleural effusion?

Identify the cause, relieve symptoms, and prevent recurrence or complications.

How are transudative pleural effusions treated?

Treat the underlying cause (e.g., diuresis for CHF, albumin for cirrhosis).

When is therapeutic thoracentesis indicated?

Large or symptomatic effusions causing dyspnea or hypoxia.

How are malignant pleural effusions managed?

• Therapeutic thoracentesis

• Indwelling pleural catheter

• for recurrent effusions

• Pleurodesis in select cases

How are parapneumonic effusions treated?

Drainage with chest tube if infected or complicated.

What is a loculated pleural effusion?

Fluid trapped in pockets due to fibrinous septations, often requiring VATS decortication if not drained by chest tube.

What is VATS decortication?

A surgical procedure removing fibrous pleural peel to allow lung re‑expansion.

What complications can arise from pleural effusion?

• Respiratory compromise

• Empyema

• Fibrothorax

• Recurrent effusions

What symptoms suggest a large pleural effusion?

Marked dyspnea, decreased breath sounds, and dullness to percussion.

What is the role of ultrasound in pleural effusion?

Guides thoracentesis and detects small or loculated effusions.

What is the most common cause of pleural effusion overall?

Congestive heart failure (transudative).

What is the most common cause of exudative pleural effusion?

Pneumonia (parapneumonic effusion).

What finding differentiates pleural effusion from consolidation?

Decreased tactile fremitus (effusion) vs increased fremitus (consolidation).

What is the prognosis of pleural effusion?

Depends on underlying cause