Pleural Diseases

Question 1

Which two forces balance the pleural fluid?

Answer 1

Hydrostatic and oncotic across capillary & pleural space

Normally: you have a net production of fluid but your body drains fluid too which maintains the balance

Question 2

Pleural fluid: sources in health & dz

Answer 2

Health: pleural capillaries

Dz: lung interstitium, lymphatics, peritoneal space

Question 3

3 mechanisms for pleural dz

Answer 3

Loss of pleural integrity: pneumothorax, pneumomediastinum, subcutaneous emphysema

Abnormality of pleural fluid production

Additions to the pleural space

Question 4

Pneumothorax

Answer 4

Question 5

Subcutaneous emphysema

Answer 5

Air is leaking out of the lungs and into the soft tissues

Can present with face swelling

Crackling feel to the touch

Question 6

Hepatic hydrothorax

Answer 6

Loss of pleural integrity where ascites leaks up to the chest

Almost always happens on the right side

Question 7

Which systemic factors can cause increased pleural fluid production?

Answer 7

Heart failure, renal failure, liver failure –> transudates

Question 8

How can you have an exudative addition to the pleural space?

Answer 8

Infection: bacterial, TB

Malignancy: primary, metastatic

• on chx, doesn’t level off bc trapped by tumor
• i.e. breast cancer, mesothelioma

Misc: chyle, urine, lipids

Question 9

What types of pleural fluid can it be if it’s present?

Answer 9

Serous fluid

Blood

Infection/pus

Lymphatic fluid (chyle)

Urine

Question 10

How do you decide which type of pleural fluid you might have?

Answer 10

Clinical context

Appearance of the fluid

Tests: transudate or exudate? infected- complicated effusion, empyema?

Question 11

Transudate v. exudate

Answer 11

• *Transudate**: pleural effusions caused by systemic factors that alter the balance of the formation & absorption of pleural fluid
• HF, cirrhosis
• *Exudate**: pleural effusions are caused by alterations in local factors that influence the formation & absorption of pleural fluid
• infection
• inflammation
• malignancy

Question 12

What’s light’s criteria for transudate v. exudate?

Answer 12

An effusion is exudative if:

Protein fluid/protein serum >0.5

or

LDH fluid/LDH serum >0.6

or

LDH fluid > 2/3 upper limit of normal for serum LDH

Question 13

What’s LDH?

Answer 13

lactate dehydrogenase, an enzyme made in every cell in the body & found in serum & in tissue; elevated levels seen in dz states with tissue breakdown or damage

Question 14

What infections are associated with pleural fluid?

Answer 14

Parapneumonic: effusion due to pneumonia
can be simple, complicated, empyema

TB

Fungal

Parasitic

Question 15

Parapneumonic effusions: simple v. complicated v. empyema

Answer 15

• *Simple**: infection is not in the pleural space
• inflammatory process extends to the pleura, causing a mediator induced change in permeability of local tissues and fluid accumulation
• not infected, does not require drainage
• *Complicated**: Bacterial invasion from parenchyma into pleural space
• requires drainage to prevent “trapped lung”
• *Empyema**: frank pus in the pleural space; extreme of complicated
• requires drainage

Question 16

What is trapped lung?

Answer 16

A consequence of a remote inflammatory condition that has left behind a collagenous or fibrotic rind

Note that it’s distingushed from lung entrapment, when the lung is unexpandable due to visceral pleural restriction from active pleural dz i.e. malignancy or infection

Question 17

What are treatments for the pleural space?

Answer 17

Thoracentesis: suck pleural fluid out; can be diagnostic or therapeutic

Chest tube drainage: put a tube and leave it in

Direct pleural examination: blind pleural biopsy, pleuroscopy, VATS, open thoracotomy