Week 3/4 - B - Pleural disease (effusion/mesothelioma/pneumothorax/infection) - Anatomy,Symptoms, Diagnosis, Treatment

Question 1

Body cavities and the organs they contain are lined with/covered by a serous membrane What is the function of the serous membrane in the lungs? What do the different parts of this serous membrane line/cover? Which pleural layer is attached to the thoracic wall?

Answer 1

The function of the serous membranes is to produce a small amount of fluid to lubricate the organ within its body cavity (normally around 4 mls of fluid present) The visceral pleura lines the surface of the lungs The parietal pleura lines the pulmonary cavity and is attached to thoracic wall

Question 2

What are the different parts of the parietal pleura? Where does the parietal pleura meet the visceral pleura? Therefore which part of the lung has no pleural coverage?

Answer 2

Parietal pleura - cervical, costal, diaphragmatic and mediastinal pleura The mediastinal parietal pleura meets the visceral pleura at the hilum of the lung (lung root) - the hila therefore has no leural coverage

Question 3

The visceral pleura connects with the parietal pleura (mediastinal part) at the hilum of the lung What is the reflection of the mediastinal parietal pleura on each side of the lung root known as? What is the function of this?

Answer 3

The reflection of the mediastinal parietal pleura on each side of the hila connect to form the pulmonary ligament - it runs inferiorly connecting to the diaphragm holding the lower part of the lungs in position

Question 4

* What is the membrane lying superior to the cervical parietal pleura that is important in restricting lung expansion into the root of the neck? * What attaches the parietal pleura to the thoracic wall?

Answer 4

Suprapleural membrane prevents lung expansion into the root of the neck. Endothoracic fascia is continuous and attaches the costal parietal pleura to the thoracic wall

Question 5

What helps keep the pleural surfaces connected to one another ?

Answer 5

The intrapleural fluid cohesiveness (surface tension of the pleural fluid) - the water molecules in the intrapleural fluid are attracted to each other and resist being pulled apart. Therefore the pleural membranes tend to stick together - when the chest wall expands, the lungs expands.

Question 6

What is the abnormal collection of fluid in the pleural space known as? When should a collection of fluid in this space raise concern (usually)?

Answer 6

Abnormal collection of fluid in the pleural space is known as a pleural effusion Large unilateral effusions should be a cause for concern - need to identify why

Question 7

Pleural effusion Firstly take a history and examine the patient Then need to carry out an investigation to diagnose the pleural effusion Then need to sample the pleural fluid and send it off for tests THIS gives the underlying cause so it can then be managed What are the symptoms / signs from history and examination caused by a pleural effusion?

Answer 7

Presenting symptoms - * dyspnoea (shortness of breath) - increases on exertion * Pleuritic chest pain - stabbing type pain in the chest, worse on eg coughing/sneezing On examination - * Ddull to percuss and diminished breath sounds on the affected side * Decreased tactile fremitus - vibration felt on patients chest during low frequency vocalisation (eg say ninety nine)

Question 8

What test is carried out to confirm suspicion of a pleural effusion? How many mls of fluid approx need to be present to be detected on this?

Answer 8

A PA CXR is carried out to confirm the pleural effusion Approx 200mls of fluid need to be present to be seen on a plain xray

Question 9

Once the pleural effusion is confirmed, we need to sample the fluid to carry out tests to hopefully discover the cause of the effusion Describe the sampling process of a pleural effusion? (how do we avoid the neurovascular bundle in the ribcage)

Answer 9

Diagnostic aspiration (thoracentesis) is carried out - you percuss 1or2 intercostal spaces below the upper border of the pleural effusion/ Anaesthesia is applied using a needle and then a needle and syringe are inserted to the upper border of the appropriate rib to avoid the NVB and pleural fluid is drained

Question 10

Where is the aspirated pleural fluid sent for tests?

Answer 10

Pleural fluid aspirate - Sent to * Biochemistry - transudate or exudate * Microbiology-for microscopy and culutre - looking for infection * Cytology - abnormal cells * Immunology if indicated

Question 11

If the pleural tap (diagnostic aspiation) fluid analysis is inconclusive, what can be carried out?

Answer 11

Consider repeating pleural tap (thoracentesis) Consider a parietal pleural biopsy * Blind percutaneous biopsy or * Thoracoscopic pleural biopsy or * CT guided parietal pleural biopsy

Question 12

When is aspirating the pleural fluid not recommended?

Answer 12

It is not recommended in a patient with congestive cardiac failure with symmetric effusion/no fever - likely due to increased pressure in the blood vessels causing a fluid leak Treat with diuretics

Question 13

Pleural fluid aspirate tests * Gross appearance of the fluid; Biochemistry; Microbiology; Cytology; Immunology What do you expect the potential causes of the effusion to be if the appearance of the aspirate is: * Clear/straw coloured * Turbid/yellow * Bloody * Foul smellin * Food particles

Answer 13

Clear/straw coloured - transudative usually Turbid/yellow - empyema, chylothorax (lymph with fat) Bloody - trauma, malignancy, pulmonary infarct, infection Foul smelling - anaerobic empyema Food particles - oesophageal rupture

Question 14

Now we define transudaive and exudative What is the protein level in each? How do condtions that lead to a pleural effusion cause a transudative or exudative effusion?

Answer 14

Transudative - protein * May be due to increased venous pressure or a hypoalbuminaemia

Exudative (extra) - * Mostly due to increased leakiness of the pleural capillaries - pleura damaged by eg cytokines

Question 15

What is the difference in protein in protein in the pleural fluid to distinguish between transudative and exudative pleural effusions?

What can you see on CT scans which would also show exudative effusion?

Answer 15

exudates have a protein level of >30 g/L, transudates have a protein level of <30 g/L
if the protein level is between 25-35 g/L, Light’s criteria should be applied.

If loculations are present on CT scan, then the effusion will be an exudative effusion (red arrow pointing towards loculation)

Question 16

Light’s criteria uses effusion/serum protein and LDH to classify whether the effusion is an exudative process or not What is Light’s criteria for classifying exudate effusions?

Answer 16

Light’s criteria for exudative - at least one of the following Effusion protein/serum protein >0.5 Effusion LDH/serum LDH >0.6 Effusion LDH >2/3rds of normal upper limit of serum LDH (In the absence of these findings, the effusion is likely to be a transudate.)

Question 17

Transudative - protein * May be due to increased venous pressure or a hypoalbuminaemia What are some conditions causing a transudative pleural effusion? (CHARM - mnemonic to help remember causes)

Answer 17

Tansudative pleural effusion * May be due to increased venous pressure - eg cardiac failure, * or * Due to hypoalbuminaemia - Cirrhosis, nephrotic syndrome, malabsorption * Cardiac failure/cirrhosis * Hypothyroidism * Albuminaemia (hypo) * Renal failure * Meig’s syndrome/malabsorption

Question 18

Exudative (extra) - protein >30g/L Mostly due to increased leakiness of the pleural capillaries due to damage to the pleura by eg cytokines In patients presenting with an exudative pleural effusion - always look for serious pathlogy What may cause this?

Answer 18

Usually the increased leakiness of the capillaries is secondary to infection, inflammation, infarction, malignancy or trauma

Question 19

A good acronym for remembering transudative and pleural effusion causes
3 PINTS

Answer 19

Transudative 3
* Heart failure (venous back pressure)
* Renal failure (loss of albumin)
* Liver failure (reduced production of albumin)

Exudative
* PTE
* Infection
* Neoplasm
* TB
* SLE/RA (Connective tissue diseases)

Question 20

Pleural fluid aspirate tests (usually for exudative effusions) * Gross appearance of the fluid; Biochemistry; Bacteriology; Cytology; Immunology Biochemistry tests look at the protein, LDH, pH, glucose and amylase For an exudative effusion, what is the pattern of pH, glucose and LDH levels? What would a pleural fluid pH <7.2 signify?

Answer 20

Exudative effusion - usually have a low pH and low glucose with a high LDH pH 7.6 - normal pH of pleural fluid pH <7.3 - suggests pleural inflammation pH <7.2 - requires drainage in the setting of infection

Question 21

Pleural fluid aspirate tests * Gross appearance of the fluid; Biochemistry; Microbiology; Cytology; Immunology Microbiology simply looks at the cells under microscopy and can look at cultures collected Cytology analyses the cells present * What cells are we mostly looking for here? * What does increased lymphocytes make you think? * What does increased neutrophils make you think?

Answer 21

Cytology is most looking for malignant cells to rule out cancer Increased lymphocytes would make you think either TB or malignancy - however any long standing effusion will eventually become lymphocytic Increased neutrophils makes you think an acute process

Question 22

When uncertain of the diagnosis from the initial pleural tap (thoracentesis), what are the next options?

Answer 22

Options * Observation * Repeat pleural tap Biopsy parietal pleura * Percutaneous blind biopsy * CT guided cutting needle biopsy * Thoracoscopic biopsy

Question 23

Why are pleural biopsies often negative?

Answer 23

Often because the involvement of pleural disease is often discontinous or the biopsies dont actually contain any pleura

Question 24

What are the cells that line the body’s serous cavities and organs (eg pleura/peritoneum/pericardium) and produce the lubricating fluid that faciliates non-friction movement of the organ within its cavity?

Answer 24

The mesothelial cells are specialised cells which line the bodies serous cavities and the organs and produce the lubricating fluid ie pleural fluid, that facilitates non-friction movement of the organ within its cavity

Question 25

MALIGNANT MESOTHELIOMA - Uncommon malignant tumour of the lining of the lung or very occasionally of the lining of the abdominal cavity (or pericardium) - this cancer arises from the abnormal division of the mesothelial cells What is the majority of cases of malignant mesothelioma linked to and what is the latent period between exposure and development of the tumour?

Answer 25

Approx 90% of cases of mesothelioma is linked to previous asbestos exposure - with a 20-40 year latent period between exposure and development of the tumour

Question 26

What are the symptoms of mesothelioma?

Answer 26

Symptoms may include shortness of breath, chest pain, weight loss, fever, cough, recurrent pleural effusions

Question 27

What tests are carried out in mesothelioma and what is seen in these investigations? How is the diagnosis made?

Answer 27

CXR and CT chest/abdomen are usually carried out - will show pleural thickening and effusions Diagnosis is made via aspirating fluid from the pleural effusion usually and if results are inconclusive, a pleural biopsy is carried out (thoracoscopy or CT guided)

Question 28

What is the treatment option for the actual malignant mesothelioma? (not the complications such as pleural effusion here)

Answer 28

Treatment options for mesothelioma usually involves pemetrexed + cisplatin chemotherapy Surgery and radiotherapy effects are controversial

Question 29

Malignant mesothelioma isnt the only cancer to cause malignant pleural effusion - just about all cancers may metastasize to here What are the treatment options for malignant pleural effusions? (1st line)

Answer 29

For pleural effusions, can give therapeutic thoracentesis - however if effusions are recurrent, there are other options that prevent reinserting or needle to drain again and again

Question 30

If not wanting to carry out recurrent thoracentesis for malignant pleural effusions, what are 2nd line treatment options?

Answer 30

* Pleurodesis - Pleurodesis is a medical procedure in which the pleural space is artificially obliterated. It involves the adhesion of the two pleurae - a sclerosing agent causes adhesions to form - talc pleurodesis usually used * Can also insert a long term pleural catheter (indwelling catheter) - allows patients to control their symptoms by drianing when needed Surgery rarely carried out

Question 31

What type of effusion will an infection cause? What will an infection show on biochemistry/microscopy if it is an empyema? (pus in the pleural cavity)

Answer 31

Infection would cause damage to the pleura causing leakiness of the pleural capillaries - exudative Empyema * Turbid/yellow fluid aspirate * Biochemistry shows a reduced pH

Question 32

What is the 1st line treatment for those with empyema? - to treat the infection and the effusion What is the usual cause of empyema?

Answer 32

Empircal intravenous antibiotics and drain the pleural effusion * Thoracentesis drainage for normal infection but usually chest drain if empyema The usual cause of the empyema is due to a primary pneumonia

Question 33

What can an empyema cause that makes drainage and antibitoic treatment of the condition more difficult?

Answer 33

Empyema can have adhesions/septations and form loculations (Loculation should be considered when a density on CXR is considered to be fluid and does not correspond to anatomical location of fissures), preventing effective drainage of the fluid

Question 34

Because of the viscous, lumpy nature of infected pleural fluid, in combination with possible septation and loculation, what treatments can be tried to help breakdown this thickened fluid and therefore improve chest drianage/antibiotic outcomes?

Answer 34

Fibrinolytic (eg alteplase) or mucolytic (eg dornase alfa) might improve drainage

Question 35

In patients with persistent collections or persistent sepsis despite appropriate chest tube drianage and antibiotic treatment, what may need to be considered?

Answer 35

Surgery is often considered - to remove visceral pleura from lung or to tackle the adhesions/lobulations

Question 36

Treatment of pleural effusions will depend on the cause (we have discussed cardiac failure (LVF), malignant mesothelioma and infection) STATE again how the effusion should be treated in these cases * What type of effusion will LVF cause and how should it be treated? * What type of effusion will malignant pleural effusion cause and how should it be treated? * What type of effusion will an infection cause and how should it be treated?

Answer 36

* LVF will cause an increase in venous pressure causing a transudative effusion - treat with IV diuretics * Malignant pleural effusion- exudative effusion due to damaging the pleura leading to leakage of pleural capillaries - drain, pleurodesis, long term catheter * Infection - exudative effusion also - thoracentesis/chest tube (empyema), antibiotics, may require surgery, fibrinolytics (alteplase) or mucolytics (dornase alfa) to reduce viscosity

Question 37

PNEUMOTHORAX Describe the negative intrapleural pressure and how this affects lung expansion Pip - pressure intrapleural Pa - pressure atmosphere Pia - pressure intralaveola

Answer 37

Negative intrapleural pressure - the Pip (subatmospheric intrapleural pressure) is lower than Pa - creating a transmural pressure gradient across both the lung wall and the chest wall. Therefore during inspiration the lungs are forced outwards (as Pia > Pip) and the chest wall is forced to squeeze inwards (as Pa > Pip)

Question 38

What are the symptoms and signs of a pneumothorax?

Answer 38

Symptoms - shortness of breath, acute chest pain Signs - * Reduced expansion on affected side * Hyper-resonant percussion on affected side * Reduced breath sounds on affected side Tension pneumothorax - the trachea will be deviated away from the side of the injury. potential hypoxia

Question 39

How does a pneumothorax abolish the transmural pressure gradient? What may this lead to?

Answer 39

Be it a spontanoeus pneumothorax (hole in the lung) or traumatic (puncture wound in chest wall), air will enter the pleural space (from atmosphere or lungs) This can abolish the transmural pressure gradient and prevent the lung expanding therefore leading to lung collapse

Question 40

What patients are pneumothorax’s more common in? What investigation is carried out to diagnose?

Answer 40

More common in * Tall thin men * Smokers * Cannabis users * Underlying lung disease Carry out a CXR - should not be performed before treatment if tension pneumothorax is suspected

Question 41

Treatment of the pneumothorax depends on the type and the side What is the treatment of a tension pneumothorax? (emergency) What is inserted after emergency treatment to prevent another tension pneumothorax from immediately occurring?

Answer 41

Treatment - emergency needle decompression using a large bore needle into the 2nd interocstal space mid-clavicular line After emergency treatment - insert a chest tube to prevent immediate recurrence of the tension pneumothroax

Question 42

What is the difference between a primary and secondary pneumothorax?

Answer 42

A primary pneumothorax occurs without an apparent cause in the absence of underlying lung disease A secondary pneumothorax occurs in someone with underlying lung disease or a smoker aged above 50 years old

Question 43

Treatment differs for primary and secondary spontaneous penumothorax Primary, what is the treatment if - * No SOB, no rim between lung margin and chest wall >2cm on CXR? * SOB but no rim >2cm on CXR? * Rim >2cm but no SOB on CXR?

Answer 43

If no SOB, and 2cm on CXR - percutaneous aspiration 2nd intercostal space mid-clavicular line

Question 44

If the patient presents with a primary pneumothorax, SOB and/or rim >2cm on CXR - treat with percutaneous aspiration 2nd intercostal space mid-clavicular line What if this fails?

Answer 44

If this fails then insert a chest drain into the safe triangle - axilla (5th (4th - 6th) intercostal space anterior to mid-axillary line)

Question 45

Secondary pneumothorax What treatment is given if - No SOB, no rim between lung margin and chest wall >1cm on CXR? No SOB but rim 1-2cm on CX? SOB or Rim >2cm on CXR?

Answer 45

* No SOB, no rim between lung margin and chest wall >1cm on CXR - observe and oxygen * No SOB but rim 1-2cm on CXR - percutaneous aspiration in 2nd intercostal space midclavicular line (chest drain if this fails) * SOB or Rim >2cm on CXR- chest drain