Diagnosis

Pleural effusion

Etiology

Cause [twi]

• 75% of the cases: Heart failure, cancer, pneumonia, and tuberculosis [r3t]

• Transudate: low protein due to imbalance in hydrostatic and oncotic forces

  • Heart failure, cirrhosis, decreased albumin, atelectasis (due to malignancy or pulmonary embolism), nephrotic syndrome, peritoneal dialysis, constrictive pericarditis, urinothorax, cerebrospinal fluid (ventriculopleural shunting or thoracic spine surgery), extravascular migration of central venous catheter

• Exudate: high protein in areas of inflammation due to increased capillary permeability

  • Bacterial pneumonia, lung or breast cancer, lymphoma, leukemia; less commonly, ovarian carcinoma, stomach cancer, sarcomas, melanoma), pulmonary embolism, rheumatoid arthritis, systemic lupus erythematosus, tuberculosis, pancreatitis, trauma, esophageal perforation, radiation pleuritis, sarcoidosis, fungal infection, pancreatic pseudocyst, abdominal abscess, pericardial disease, Meigs syndrome, ovarian hyperstimulation syndrome, drug side effects (methotrexate, amiodarone, phenytoin, and dasatinib), yellow nail syndrome, renal failure, chylothorax, pseudochylothorax, fistula

Pathophysiology [twi]

1. Normal pleural fluid serves as a lubricant to facilitate movement of the pleural surfaces against each other in the course of respirations

2. This small volume of fluid is maintained through the balance of hydrostatic and oncotic pressure and lymphatic drainage

3. Exudate:

   • Altered pleural permeability: pneumonia, malignancy, pulmonary embolism

   • Increased capillary permeability: trauma, malignancy, inflammation, pulmonary embolism, drug hypersensitivity, renal failure, pancreatitis

4. Transudate:

   • Decreased intravascular oncotic pressure: decreased albumin, cirrhosis

   • Increased capillary hydrostatic pressure: heart failure, vena cava syndrome

   • Decreased pressure in the pleural space (preventing full lung expansion): atelectasis, mesothelioma

   • Decreased lymphatic drainage: malignancy, trauma

   • Transudation from ascites or pulmonary edema

5. The net result may be compression of the lungs --> restrictive ventilatory defect:

   • Dyspnea

   • Chest pain

   • Cough

Complications [twi]

• Empyema

• Sepsis

• Respiratory compromise

• Pleural thickening --> restrictive lung disease

Epidemiology

Incidence per 100.000 [ksd][pzp][yms][nuy][4kb][i4p][sab]

Approach

• Blood test: WBC, CRP, NT-proBNP

• Blood gas

• Chest x-ray

• CT thorax

• Ultrasound

• Thoracentesis: pH, glucose, protein, LD, amylase, cholesterol, ANA, RF, differential cell counts, Gram stain, culture, cytology and biopsy

Light’s criteria to distinguish transudates and exudates [twi]

Exudative meets ≥1 of the following criteria; a transudate meets none of the criteria:

• Pleural fluid protein/serum protein >0.5

• Pleural fluid LDH/serum lactate dehydrogenase (LDH) >0.6

• Pleural fluid LDH >2/3rds of the upper normal limit of serum LDH

Heffner's criteria for exudative effusion [twi]

• Pleural fluid protein level exceeding 2.9 g/dL

• Pleural fluid cholesterol level greater than 45 mg/dL

• Pleural LDH level greater than two-thirds of the upper limit of normal serum LDH

Pleural effusion analysis

• Pleural fluid:

  • pH 7.60-7.64

  • Protein 1-2 g/dl

  • WBC < 1000

  • Lactate Dehydrogenase 50% of plasma

• Pleural LD > 1000 IU/L:

  • Empyema

  • Malignant effusion

  • Rheumatoid effusion

  • Pleural paragonimiasis.

• Low pleural glucose/pH:

  • Malignant effusion

  • Tuberculous pleuritis

  • Esophageal rupture

  • Lupus pleuritis

• Pleural lymphocytosis:

  • TB

  • Lymphoma

  • Sarcoidosis

  • Chronic rheumatoid pleurisy

  • Yellow nail syndrome

  • Chylothorax

  • Malignancy

Treatment

1. Treating the underlying cause [hdn]

2. Goals:

   • Sterilization of pleural fluid

   • Reexpansion of the lung

   • Restoration of normal lung function

3. Antibiotics

4. Thoracocentesis: compromising respiratory function

   • Pleural drainage

   • Chest tube drainage with or without instillation of fibrinolytic agents

5. Surgery:

   • Video-assisted thoracoscopic surgery

   • Open thoracotomy with decortication

Differential diagnoses

Abdominal abscess, Acute pancreatitis, Acute renal failure, Acute respiratory distress syndrome, Amyloidosis, Atelectasis, Breast cancer, Chronic renal failure, Chylothorax, Crohn disease, Esophageal perforation, Esophageal rupture, Heart failure, Hemothorax, Hypothyroidism, Leukemia, Lung cancer, Lymphoma, Meigs syndrome, Mesothelioma, Nephrotic syndrome, Pericarditis, Peritonitis, Pneumonia, Pulmonary edema, Pulmonary embolism, Renal failure, Rheumatoid arthritis, Sepsis, Superior vena cava syndrome, Systemic lupus erythematosus, Tuberculosis, Ulcerative colitis, Yellow nail syndrome