Pleural Effusions

Question 1

Thoracentesis

Answer 1

Insert a needle through chest wall into pleural space
Drain pleural fluid
Diagnostic and therapeutic
Can be done with ultrasound guidance at bedside

Question 2

2 layers of pleura

Answer 2

Visceral (covers lungs, extends into fissures)

Parietal (lines inside of thoracic cavity)

Question 3

Histology of
1. visceral
2. parietal
pleura

Answer 3

1. primarily CT, contributes to elastic recoil of lung
2. thin layer of loose CT, contains blood vessels and lymphatic lacunae, covered by a thin layer of mesothelial cells, fluid is produced and re-absorbed here

Question 4

How much pleural fluid is formed per day in a 70 kg adult?

Answer 4

About 15-20 mL

Question 5

How much fluid is necessary to see a pleural effusion on chest X-ray?

Answer 5

About 150mL per side

Question 6

Does the fluid come from pulmonary or systemic blood vessels?

Answer 6

Systemic

Question 7

Hydrostatic pressure

Answer 7

Pressure exerted by liquid at equilibrium

In the lung this is the pulmonary venous pressure

Question 8

Oncotic pressure

Answer 8

Pressure due to proteins and osmoles in the plasma

Draws fluid into the capillaries

Question 9

2 reasons why pleural fluid can accumulate

Answer 9

Increased formation

Impaired absorption

Question 10

4 reasons for increased fluid entry

Answer 10

Increase in permeability (ex: disruption to endothelial layer)
Increased microvascular pressure (ex: CHF)
Decreased pleural pressure (ex: atelectasis)
Decreased plasma oncotic pressure (ex: nephrotic syndrome, hypoalbuminemia)

Question 11

Why would you get decreased fluid exit?

Answer 11

Factors that impair lymphatic drainage

Accumulation of fluid is likely multi-factorial in many diseases

Question 12

Transudate

Answer 12

Non-inflammatory

From heart failure, cirrhosis, nephrotic syndrome

Question 13

Exudate

Answer 13

Inflammatory

From infection, malignancy, PE, CT disease

Question 14

Chylothorax

Answer 14

Fat in the pleural fluid

From thoracic duct damage, high venous pressure, or primary lymphatic issue

Question 15

Hemothorax

Answer 15

Blood in pleural fluid

From blood vessel rupture/erosion or coagulopathy

Question 16

Differential diagnosis for transudate

Answer 16

LUCKI ME
L: Liver (hepatic hydrothorax)
U: urinothorax
C: CHF
K: kidney (low protein - nephrotic)
I: iatrogenic
M: myxedema (hypothyroidism)
E: embolic

Question 17

Malignant effusion

Answer 17

Can be primary (mesothelioma) or metastatic (more common)

Can be direct (hematogenous spread or obstruction of lymphatics) or indirect

Question 18

Pulmonary embolism

Answer 18

Increased R heart pressure = increased pulmonary capillary permeability = pleural effusion
30-50% of patients with PE have effusion