Pleural Effusion

Question 1

What is the normal width of the pleural fluid layer?
• how much is typically there?
• How should the fluid appear?

Answer 1

Width, typically 10-27 µm with 1-20 ml of fluid present

**Also should be clear and odorless and pretty much acellular with 70-80% macrophages 10% PMNs and 2% lymphocytes

Question 2

What is the normal protein concentration of pleural fluid?

Answer 2

*** 1.0-1.5 g/dL **

Question 3

What 4 factors contribute to development of pleural effusions.

Answer 3

1. Hydrostatic Pressure
2. Colloid Pressure
3. Tissue Pressure
4. Lymphatic Drainage

Question 4

Under normal circumstances does hydrostatic pressure tend to push fluid into or out of the pleural cavity?
• What about oncotic pressure?

Answer 4

Hydrostatic Pressure:
• Tends to push fluid INTO the pleural cavity from both parietal and visceral sides BUT HYDROSTATIC PRESSURE on the PARIETAL SIDE IS LARGER

Oncotic Pressure:
• Oncotic Pressure tends to pull fluid out of the pleural space on both sides equally because the blood is more protein rich than the pleural space

This means the overall driving force in the normal cases is hydrostatic pressure driving fluid flow

Question 5

Congestive Heart Failure is associated with what kind of effusion?

• why?
• What determines the amount of effusion?

Answer 5

Transudate, because you are pushing fluid through the capillary walls harder but there is still the same amount of oncotic so the tendency will be for fluid to push through.

PCWP (pulmonary capillary wedge pressure) - determines the amount of effusion

*There is no barrier breakdown so you don’t have an exudate

Question 6

What are some common conditions that may cause an exudative effusion?

Answer 6

• Inflammation
• Infection
• Cancer

Question 7

Define Exudate and Transudate by the following parameters:
• Pleural/Serum Protein Ratio
• Pleural/Serum Lactate Dehydrogenase Ratio
• Serum Lactate Dehydrogenase

Answer 7

Exudate:
• Pleural/Serum Protein Ratio > 0.5
• Pleural/Serum Lactate Dehydrogenase Ratio > 0.6
• Serum Lactate Dehydrogenase > 0.6

Transudate:
• Pleural/Serum Protein Ratio less than 0.5
• Pleural/Serum Lactate Dehydrogenase Ratio less than 0.6
• Serum Lactate Dehydrogenase less than 200

***Note only one of these criteria needs to be met

Question 8

What benchmarks are set by the following levels of WBCs in pleural fluid? 
• less than 1000/ µl
•more than 5000/ µl
• more than 10000/ µl
• more than 50000/ µl

Answer 8

• less than 1000/ µl - transudate
• more than 5000/ µl - tuberculosis, malignancy
• more than 10000/ µl - parapneumonic, pancreatitis, pulmonary infarction
• more than 50000/ µl - parapneumonic effusions only

Question 9

What type of pleural effusion is defined by the presence of the following WBCs?
• neutrophils
• lymphocytes
• more than 5% mesothelial cells

Answer 9

Neutrophils - acute inflammation

Lymphocytes - chronic inflammation
85%-95% = TB, Lymphoma, Sarcoid, RA
More than 50% in 2/3 of carcinomatous effusions

Mesothelial cells greater than 5% EXCLUDES tuberculosis pleurisy

Question 10

If an effusion is less than 10mm thick on lateral decubitous or is asymptomatic and has an obvious etiology do you need to draw the fluid?

Answer 10

NO - otherwise (if its larger than 10mm or you don’t know what’s causing it then draw it)

Question 11

T or F: if someone has positive acid fast bacillus with a lymphocytosis, then they probably have TB.

Answer 11

TRUE, + AFB is found in 5% of cases and it is very specific, but lack of AFB does NOT rule out TB.

Question 12

Who typically present with a primary spontaneous pneumothorax and what is the cause?

Answer 12

Typically young, tall, thin, previously healthy male that presents with pleuritic chest pain and dyspnea.

Most likely this is due to rupture of a Visceral Pleural bleb

Question 13

Note: Spontaneous pneumonthorax may also be cause by a bronchial obstruction that has a ball-valve mechanism (resorption atelectasis)

Answer 13

Note: Spontaneous pneumonthorax may also be cause by a bronchial obstruction that has a ball-valve mechanism (resorption atelectasis)

Question 14

What 3 key features will you see on the Chest XRAY of someone with a tension pneumothorax?
• what will you see clinically?
• how will you treat them?

KNOW THIS COLD*

Answer 14

1. Lung Collapse
2. Contralateral Mediastinal Shift
3. Depression of the Diaphragm

Clinical:
• Hypotension
• Hypoxemia

Treatment:
• Emergent decompression with large bore needle