Diseases of the pleura Flashcards
What does the visceral plura cover and form?
Covers the lungs and forms the interlobar fissures
What does the parietal plura cover?
Mediastinum, diaphragm and inner surface of the thorax
How much fluid does the plural cavity contain and what is its function?
4ml of fluid
Functions: lubrication and surface tension (sticks the lungs to the chest wall)
Where do the two layers of pleura combine and where is there no plural coverage?
The visceral and parietal plura combine around the hilar of the lungs therefore the hilar have no plural coverage
What forms the pulmonary ligament and where is it found?
Plural layers form the pulmonary ligament which runs to attach the root of the lung to the diaphragm
What is a plural effusion?
An abnormal collection of fluid in the plural space
When is a plural effusion concerning?
Large unilateral effusion
If a large unilateral plural effusion is found on a CXR what should be done next?
A plural ultrasound to confirm its fluid.
Then do a plural aspirate (thoracentesis) to send to biochemistry, cytology and microbiology
Plural aspirates: what does the following imply?
1) Straw coloured
2) Red/bloody
3) Turbid/milky
4) Foul smelling
5) Food particles
1) Straw coloured = cardiac failure, hypoalbuminaemia
2) Red/bloody = Trauma, malignancy, infection, infarction
3) Turbid/milky = Empyema, chylothorax
4) Foul smelling = Anaerobic empyema
5) Food particles = oesophageal rupture
What is a chylothorax?
Type of pleural effusion. Lymph formed in the digestive system called chyle accumulates in the pleural cavity due to either disruption or obstruction of the thoracic duct.
What can cause a bilateral plural effusion?
Left ventricular failure,
PTE (pulmonary thromboendarterectomy)
Drugs- diuretics not working
Systemic pathology
What is a PTE?
PTE (pulmonary thromboendarterectomy) an operation that removes organized clotted blood from the pulmonary arteries, which supply blood to the lungs.
Plural effusion: what is a transudates and what can cause it?
Tranudate is a fluid with a protein <30g/L
Caused by heart failure, liver cirrhosis, hypoalbumanaemia or peritoneal dialysis
Less concerning
Plural effusion: what is an exudate and what can cause it?
Exudate is a fluid with a prtein >30g/L
Caused by malignancy, infection (TB?), primary infarct, asbestosis
More concerning
If a fluid protein is >2/3 of the serum protein level it is an exudate. True or false?
True
Plural effusion: apart from protein content, what other biochemical levels should you check in an aspirate?
Fluid pH- normal is 7.6. <7.3 suggests infection and <7.2 needs draining
Glucose- low in infection, TB, rheumatoid, malignancy and oesophageal rupture
What are you looking for in cytology of plural effusions?
Malignant cells- 2 samples will diagnose 2/3 of malignant effusions
Lymphocyes inmply TB, malignancy, chronic
Neurophils imply an acute process
What are you looking for in microbiology of plural effusions?
Gram stain and microscopy
PCR, Acid fast bacilli stain and culture (trying to identify TB)
How many plural aspirates should you do for diagnostic purposes and how much fluid should you take?
Up to 2- 2 samples will increase diagnostic yield but anymore will not.
Increasing volume doesn’t increase yield
What causes of plural effusion should resolve in <2 months?
CCF, Parapneumonic effusion, Acute pancreatitis, Post CABG, Post trauma, PE, Sarcoidosis, Traumatic chylothorax
What causes of plural effusion should resolve in 2-6 months?
Post CABG, TB, Cardiac injury, Sarcoidosis, Benign asbestosis, Chronic pancreatitis
What causes of plural effusion should resolve in 6-12 months?
Rheumatoid, benign asbestosis
What can cause a benign persistent plural effusion?
Trapped lung- one of the outcomes of fibrinous or granulomatous pleuritis
Lymphangiectasia-pathologic dilation of lymph vessels
YNS- yellow nail syndrome
Plural fluid cytology will diagnose what percentage of mesotheliomas?
30%
How can you obtain a tissue biopsy of the pleura?
1) CT guided biopsy
2) Blind pericutanious plural biopsy- uncommon
3) Thoracoscopy- ultra sound the pleural space. Insert needle and pump air into the plural space s lung deflates and insert a thoracoscope to take 5 biopsys
Why are biopsies often negative?
Poor technique
Involvement of plural disease is discontinuous
The effusion is caused by a malignancy but the effusion is not malignant
What is a mesothelioma?
Malignant tumour of the lining of the lung or rarely, the lining of the abdomen.