Pleural Effusion

Question 1

What volume effusion is visible on erect CXR?

Answer 1

175ml +

Question 2

Transudate vs exudate:

Answer 2

Transudate is normal permeability, but increased fluid squeezes out due to change in colloid and/or oncotic pressure.
Eg.
–> CCF
–> Liver failure
–> Low albumin

Ie. Systemic pathology.

Clear
LOW:
- Protein <3
- LDH <200
- Cell count <1000

____________________

Exudate freely crosses leaky capillaries. Has more stuff in it
Eg.
–> Inflammation
–> Cancer
–> CT disease

Ie. Local pathology.

Turbid
HIGH:
- Protein
- LDH
- Cell count

Question 3

Causes of exudative pleural effusion:

Answer 3

INFLAMM
- PE
- ARDS
- RTx
- Uraemia
- Pancreatitis

INFECTION
- Pneumonia
- TB
- Liver or spleen abscess
- Booerhaves

MALIG
- Lymphoma
- Mesothelioma
- Carcinoma

Trauma
Chylothorax

Question 4

Causes of transudative pleural effusion:

Answer 4

HYDROSTATIC
- CCF
- Constrictive pericarditis
- Cirrhosis

ONCOTIC
- Nephrotic syndrome
- Low albumin
- Peritoneal dialysis

Question 5

Light’s Criteria:

Answer 5

Determines if pleural effusion is transudate or exudate.

May overdiagnose exudative
____________

EXUdate, if any of:

1- Pleural protein / serum protein
= > 0.5

2- Pleural LDH / serum LDH
= > 0.6

3- Pleural LDH
= > 2/3 upper limit normal**

Question 6

When does a pleural effusion require tapping?

Answer 6

A- Symptomatic/ compromised

B- Cause unclear

C- Parapneumonic- ?actually empyema

Occasionally, eg. known CCF with recurrent effusion, or severely hypoalbuminaemic, can just treat underlying cause and watch for resolution

Question 7

What tests should be requested on pleural fluid

Answer 7

At least 50ml required

Cytology

MCS
–> Put some into culture bottle to increase yield

Biochem
–> Protein
–> LDH
–> Glucose
–> pH
–> Amylase
–> Haematocrit
+/- triglycerides (chylo)

Question 8

What is the risk with draining a very large pleural effusion?

Answer 8

Re-expansion APO.

Drain no more than 1.5L at a time

Can drain in stages, 12 hours apart.

Question 9

What biochemical features might you see in empyema vs other exudates?

Answer 9

PH < 7.2 (acidic)

Low glucose.

Question 10

Ultrasound features of pleural effusion:

Answer 10

Loss of lung sliding
Lung point sign
Spine sign (vertebrae seen through lung field on RUQ view)
Sinusoid sign (respiratory variation in space between V and P pleuras)
Quad sign
Plankton sign (swirling debris)