Respiratory: Pleural Effusion

Question 1

Describe pleural fluid physiology [3]

Answer 1

Hydrostatic pressure is higher in parietal than the visceral pleura

Oncotic pressures are similar

Net effect:
- Most of fluid coming into the pleural space orignates from the parietal pleura
- Fluid in the pleural space is drained by lymphatic channels

Question 2

What causes (in physiological terms) excess pleural fluid? [2]

Answer 2

Excess parietal fluid produced AND / OR
Blockage of lympahtics, inhibiting drainage

Causes pleural effusions!

Question 3

State 4 overarching pathophysiological local factors that cause pleural disease [4]

Answer 3

Local factors (referred to as exudates)
- Increasing capillary permeability
- Increasing pleural permeability
- Decreased lymphatic drainage
- Increased negative pleural pressure: draws fluid into the fluid space

Question 4

For each of the following, state what can cause them and therefore pleural diseases:
- Increasing capillary permeability [4]
- Increasing pleural permeability [3]
- Decreased lymphatic drainage [2]
- Increased negative pleural pressure [2]

Answer 4

Local factors (referred to as exudates) that cause accumulation of pleural fluid

Increasing capillary permeability:
- Trauma
- Malignancy
- Inflammation
- Infection
- Pancreatitis

Increasing pleural permeability:
- Inflammation
- Malignancy
- PE

Decreased lymphatic drainage
- Malignancy
- Trauma

Increased negative pleural pressure
- Atelectasis (focal lung collapse)
- Mesothelioma

Often a combination of all of these mechanisms

Question 5

What is the difference between exudative and transudative pleural effusions? [2]

Answer 5

Exudative – a high protein content: more than 30g/L

Transudative – a lower protein content less than 30g/L

Question 6

Describe how you determine if pleural fluid protein is an exudate or transudate if the protein is borderline (25 - 30g/L) OR if is abnormal serum criteria [3]

Answer 6

Use Light’s criteria:
Pleural fluid is an exudate if one of the following is met:

• Pleural fluid protein / serum protein > 0.5
• Pleural fluid LDH / serum LDH > 0.6
• Pleural fluid LDH greater than 2/3 of the normal upper limit of the serum LDH

Really important to know to help narrow the differential diagnosis

Question 7

State 4 overarching pathophysiological systemic factors that cause pleural disease [4]

Answer 7

• Increased capillary hydrostatic pressure
• Increased pulmonary interstitial fluid
• Decreased intravascular oncotic pressure
• Increased flow of fluid from other cavities

Question 8

State reasons that would cause pleural disease due to the following:

• Increased capillary hydrostatic pressure [1]
• Increased pulmonary interstitial fluid [1]
• Decreased intravascular oncotic pressure [2]
• Increased flow of fluid from other cavities [2]

Answer 8

• Increased capillary hydrostatic pressure: heart failure
• Increased pulmonary interstitial fluid: heart failure
• Decreased intravascular oncotic pressure: hyperalbuminaemia; cirrhosis
• Increased flow of fluid from other cavities; peritoneal dialysis; cirrhosis

Question 9

What is the most common exudatate cause of pleural effusion

Pneumonia
TB
Mesolethioma
PE
Pancreatitis

Answer 9

What is the most common exudatate cause of pleural effusion

Pneumonia
TB
Mesolethioma
PE
Pancreatitis

Question 10

Describe the clinical presentation of a patient with pleural effusion [5]

Answer 10

asymptomatic
‘shoulder pain / heaviness’
dyspnoea
non-productive cough
pleuritic chest pain

Question 11

What is the most common cause of pleural effusion? [1]

Answer 11

Heart failure

Question 12

State the 4 most common causes of pleural effusion [4]

State if they are exudative or transudative [4]

Answer 12

Heart failure (transudative
Pneumonia (called parapneumonic effusions; exudative
Malignancy (most commin in patients > 50; exudative
Recent CABG; exudative

Question 13

What examination findings would suggest pleural effusion? [5]

Answer 13

Decreased chest expansion
Decreased VF
Tracheal deviation
Stony dull percussion
Reduced breath sounds

Question 14

What are the most common [5] and more rare [7] causes of exudate pleural effusion

Answer 14

Common:
* Parapneumonic
* Malignancy
* PE
* RA
* Mesothelioma

More rare:
- Drugs
- Empyema
- TB
- Pancreatitis
- Oesophageal rupture
- Post cardiac injury (Dresslers syndrome)
- Post CABG
- Benign aspestos related effusions

Question 15

State 5 drugs that cause exudative pleuritic effusion

Answer 15

nitrofurantoin
valproate
propylthiouracil
dantrolene (used for motor neurone)
methotrexate

Question 16

State common [4] and less common [3] causes of transudative pleuritc effusion

Answer 16

Common:
* LVF
* Cirrhotic liver disease
* Peritoneal dialysis
* Nephrotic syndrome

Less common:
- Constrictive pericarditis
- hypothyroidism
- Meigs’ syndrome

Question 17

Describe the clinical presentation of Meig’s syndrome [3]

Answer 17

TOM TIP: Meigs syndrome involves a triad of a :
- benign ovarian tumour (usually a fibroma)
- pleural effusion
- ascites.

This often appears in exams. The pleural effusion and ascites resolve with the removal of the tumour.

Question 18

Describe the different investigations might conduct for pleural effusion [5]

Answer 18

CXR
Pleural ultrasound: useful locating an area of fluid collection for thoracentesis, especially if the effusion is loculated or small.
Pleural fluid analysis
Chest CT
Pleural biospy
VATS

Question 19

In some causes of pleural effusions, RBC might be found in the pleural fluid. State the causes where this could occur [4]

Answer 19

malignancy
trauma
parapneumonic effusions
pulmonary embolism

Question 20

A raised lymphocyte count in pleural fluid would most likely indicate which two causes of pleural effusion? [2]

Answer 20

If the lymphocyte population is >90%, lymphoma and TB are the two most likely diagnoses.

Question 21

Which findings on a CXR would indicate pleural effusion? [4]

Answer 21

Blunting of the costophrenic angle

Fluid in the lung fissures

Larger effusions will have a meniscus (a curving upwards where it meets the chest wall and mediastinum)

Tracheal and mediastinal deviation away from the effusion in very large effusions

Question 22

Describe the findings of this CXR

Answer 22

• Opacification of right mid / lower zones
• Right hemidiaphragm obscured
• Meniscus / concave upper and outer boarder

Question 23

Which borders make the triangle of safety? [3]

Answer 23

Question 24

How would pH analysis of pleural fluid help to determine cause? [3]

Answer 24

< 7.20 in complicated parapneumonic effusion & empyema, rheumatoid arthritis, or advanced malignancy

Question 25

How would glucuose analysis of pleural fluid help to determine cause? [4]

Answer 25

Low glucose (< 3.3 mmol/L (60 mg/dL)) in empyema, rheumatoid arthritis, TB, and malignancy

Question 26

Abnormal cells present in pleural effusion would indicate what cause? [1]

Answer 26

Malignancy

Question 27

Describe the diagnostic algorithm for pleural effusion

Answer 27

Question 28

What size needle [1] and syringe [1] should be used for pleural aspiration?

Answer 28

A 21G needle and 50ml syringe should be used

Question 29

Which pathologies would a raised amylase in pleural fluid indicate? [2]

Answer 29

pancreatitis, oesophageal perforation

Question 30

What is a quick way of working out if a pleural effusion is exudative or transudative in source? [2]

Answer 30

Exudates are due to Enflammation (inflammatory processes)
Transudates are due to the failures. (Heart failure, kidney failure, liver failure)

Question 31

What pathologies would a pleural fluid finding indicate if there was:

• Low glucose [2]
• Raised amylase [2]
• Heavy blood staining? [3]

Answer 31

Other characteristic pleural fluid findings:
low glucose:
- rheumatoid arthritis
- tuberculosis

raised amylase:
- pancreatitis
- oesophageal perforation

heavy blood staining:
- mesothelioma
- pulmonary embolism
- tuberculosis

Question 32

A pleural effusion is found to have raised amylase after a pleural tap. What is the most likely cause of this?
What is the other differential? [1]

TB
RA
Mesothelioma
PE
Oesophageal perforation

Answer 32

Oesophageal perforation
or
Pancreatitis

Question 33

A pleural effusion is found to have low blood glcose after a pleural tap. What is the most likely cause of this? [2]

TB
RA
Mesothelioma
PE
Oesophageal perforation

Answer 33

TB
RA

Question 34

A 74-year-old male is found to have bilateral pleural effusion. A sample is aspirated and is found to contain 15 g/l of protein.

Based on this finding, what is the possible cause of the pleural effusion?

Inflammation from SLE

Pancreatitis

Renal failure

Right-sided mesothelioma

Right-sided pneumonia

Answer 34

Renal failure

Question 35

What general type of pathologies cause an exudate c.f a transudate? [1]

Answer 35

An exudate is usually caused by inflammation and disruption to the cell architecture

Transudates are primarily caused by ‘systematic’ illnesses which cause either a decrease in oncotic pressure or an increase in hydrostatic pressure.

Question 36

Name two endocrine causes of transudative pleural effusions [2]

Answer 36

Hypothyroidism
Ovarian hyperstimulation syndrome

Question 37

Explain the characteristics of pH; LDH and CO2 in empyema caused pleural effusion [6]

Answer 37

• low glucose because bacteria use it for respiration
• low pH because bacteria producing CO2 in repsiration
• high LDH because lactate dehydrogenase is needed for the bacteria to convert glucose into energy

Question 38

Describe the most common cause of haemothorax? [1]

Answer 38

The most common cause of haemothoraces is following trauma, typically from rib fractures that damage the intercostal vessels, bleeding directly into the pleural cavity.

Question 39

How do you manage haemothoraxes? [4]

Answer 39

• Sufficient analgesia
• For trauma cases: tranexamic acid
• The majority of haemothorax require the insertion of a surgical chest drain, to evacuate the blood from the pleural cavity
• For patients with large volume blood loss (approx. >1500ml) or continuing moderate volume blood loss (approx. >200ml per hour), surgical exploration should be considered, in attempt to identify and stop the bleeding vessel - usually via VATS

Timing of VATS is crucial when evacuating a haemothorax, ideally being performed within 48-72 hours, to enable successful evaluation and early re-expansion of the lung.

Question 40

Describe what is meant by a flail segment in a patient with haemothorax [1]

Answer 40

A flail chest is described when a segment of the rib cage breaks due to blunt thoracic trauma and becomes unattached from the chest wall.[1]It can occur when 3 or more ribs are broken in at least two places, although not everyone with this type of injury will develop a flail chest. However, when these injuries cause a segment of the chest to move independently, the generation of negative intrapleural pressure indicates a true paradoxical flail segmen