Pleural Effusion

Question 1

What is the best imaging for a pleural effusion?

Answer 1

• plain chest radiograph, PA

- ultrasound recommended, helps with aspiration

Question 2

How should fluid be aspirated and what should be done with it?

Answer 2

• ultrasound is recommended to reduce the complication rate
• a 21G needle and 50ml syringe should be used
• fluid should be sent for pH, protein, lactate dehydrogenase (LDH), cytology and microbiology

Question 3

What about the fluid from a pleural effusion needs to be determined?

Answer 3

Distinguis between transudate and exudate

Light’s criteria was developed in 1972 to help distinguish between a transudate and an exudate. The BTS recommend using the criteria for borderline cases:

• exudates have a protein level of >30 g/L, transudates have a protein level of 0.5
  2) pleural fluid LDH divided by serum LDH >0.6
  3) pleural fluid LDH more than two-thirds the upper limits of normal serum LDH

Question 4

What are the leading causes of pleural effusion?

Answer 4

• Congestive heart failure (transudate), incidence 500,000/year
• Pneumonia (exudate), incidence 300,000/year
• Cancer (exudate), incidence 200,000/year
• Pulmonary embolus (transudate or exudate), incidence 150,000/year
• Viral disease (exudate), incidence 100,000/year
• Coronary-artery bypass surgery (exudate), incidence 60,000/year
• Cirrhosis with ascites (transudate), incidence 50,000/year

Question 5

What are the causes of an exudative pleural effusion?

Answer 5

• Abdominal fluid: Abscess in tissues near lung, ascites, Meigs syndrome, pancreatitis
• Connective-tissue disease: Churg-Strauss disease, lupus, rheumatoid arthritis, Wegener granulomatosis
• Endocrine: Hypothyroidism, ovarian hyperstimulation
• Iatrogenic: Drug-induced, esophageal perforation, feeding tube in lung
• Infectious: Abscess in tissues near lung, bacterial pneumonia, fungal disease, parasites, tuberculosis
• Inflammatory: Acute respiratory distress syndrome (ARDS), asbestosis, pancreatitis, radiation, sarcoidosis, uremia
• Lymphatic abnormalities: Chylothorax, malignancy, lymphangiectasia
• Malignancy: Carcinoma, lymphoma, leukemia, mesothelioma, paraproteinemia

Question 6

What are the causes of a transudative pleural effusion?

Answer 6

• Atelectasis: Due to increased negative intrapleural pressure
• Cerebrospinal fluid (CSF) leak into pleural space: Thoracic spine injury, ventriculoperitoneal (VP) shunt dysfunction
• Heart failure
• Hepatic hydrothorax
• Hypoalbuminemia
• Iatrogenic: Misplaced catheter into lung
• Nephrotic syndrome
• Peritoneal dialysis
• Urinothorax: Due to obstructive uropathy

Question 7

How does a transudate pleural effusion arise?

Answer 7

Transudates are usually bilateral and arise from either increased capillary hydrostatic pressure or decreased oncotic pressure secondary to congestive heart failure, fluid overload, cirrhosis or hypoalbuminemia.

Question 8

How does an exudate pleural effusion arise?

Answer 8

Exudates are usually unilateral and result from increased capillary permeability or decreased lymphatic resorption associated with infection, connective tissue disease, pancreatitis or cancer.

Question 9

What is the protocol with suspected infection in a pleural effusion?

Answer 9

• 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

Question 10

What are some characteristic features about the fluid in pleural effusions that could help point to a diagnosis?

Answer 10

• low glucose: rheumatoid arthritis, tuberculosis
• raised amylase: pancreatitis, oesophageal perforation
• heavy blood staining: mesothelioma, pulmonary embolism, tuberculosis