Pleural Diseases

Question 1

What are 2 mechanisms of pleural fluid accumulation?

Answer 1

DECREASED FLUID EXIT
-Lymphatic flow is dependent on patency of lymphatic vessels, contractility of vessels, and downstream pressure in lymphatics ex. malignancy leading to invasion of lymphatics draining pleural space

INCREASED PRODUCTION OF PLEURAL FLUID

• Transudates can arise via: increased hydrostatic pressure (CHF), decrease in plasma osmotic pressure (hypoproteinemia/hypoalbuminemia) and entry to the pleural space of low protein fluid not normally found there (fluid tracking up from abdomen, urine, CSF, IV fluids)
• Exudates can arise via vascular bed that is very leaky to proteins either pleural or pulmonary (parapneumonic effusion)

Question 2

What is Light’s Criteria?

Answer 2

Light’s Criteria:
Pleural Fluid Protein/Serum Protein >0.5
Pleural Fluid LDH/Serum LDH >0.6
Pleural Fluid LDH > 2/3 serum upper limit of normal

If any one of these criteria are met the fluid is exudative.

Question 3

What are the causes of an exudative fluid?

Answer 3

Exudative Fluid may have a pulmonary or gastrointestinal origin.

Pulmonary:

• Infectious
• Neoplastic
• Inflammatory (RA, SLE)
• Pulmonary embolus
• Chylothorax
• Hemothorax

Gastrointestinal:

• Rupture esophagus
• Pancreatitis

Question 4

What is the mechanism for exudative fluid?

Answer 4

Exudates can arise via vascular bed that is very leaky to proteins either pleural or pulmonary (ex. parapneumonic effusion).

Question 5

A low pH for pleural fluid from an effusion may indicate what potential causes?

Answer 5

Low pH (less than 7.2); low glucose (pleural fluid to serum ratio less than 0.5) indicates the following potential causes:

• Parapneumonic effusion, empyema, TB
• RA, SLE
• Malignancy

Question 6

What investigation is most sensitive for malignancy and TB in pleural effusions?

Answer 6

Thoracoscopy is above 90% sensitive for malignancy and TB.

Question 7

Malignant pleural effusions (MPEs) predict a _____ prognosis.

Answer 7

Malignant pleural effusions (MPEs) predict a poor prognosis. (For the most part, it means stage 4 disease).

Question 8

Benign or malignant?

Pleural plaques

Answer 8

Benign

Pleural plaques are the most common manifestation of asbestos exposure.

Question 9

Benign or malignant?

Mesothelioma

Answer 9

Malignant mesothelioma