Respiratory: Pulmonary Fibrosis, Bronchiectasis & Pleural Effusion Flashcards
What is a pleural effusion?
A pleural effusion is a collection of fluid in the pleural space.
What are the 2 categories of pleural effusion?
1) Exudative
2) Transudative
What defines an exudative pleural effusion?
HIGH protein count (>35g/L)
What defines a transudative pleural effusion?
LOWER protein count (<25g/L)
What criteria is used for establishing an exudative effusion?
Light’s criteria
What does Light’s criteria for establishing an exudative effusion take into account?
1) Fluid protein/serum protein –> >0.5
2) Fluid LDH/serum LDH –> >0.6
3) Pleural fluid LDH greater than 2/3 of the normal upper limit of the serum LDH
When would Light’s criteria be used
If the pleural fluid protein is between 25 and 35 g/L
What is the pathophysiology behind an exudative pleural effusion?
Inflammation –> results in protein leaking out of the tissues into the pleural space due to increased pleural and capillary permeability
What are the most common causes of exudative pleural effusions?
1) Infection – pneumonia, tuberculosis
2) Malignancy – bronchial carcinoma, mesothelioma, lung metastases
3) Rheumatoid arthritis (less common)
What is the pathophysiology behind transudative pleural effusions?
1) Disruption in hydrostatic pressure → increase in pulmonary hydrostatic pressure forces fluid out of pulmonary capillaries into pleural space
2) Disruption in oncotic pressure → impaired reabsorption of fluid from pleural space into pulmonary capillaries
What are the most common causes of transudative pleural effusions?
1) Congestive cardiac failure (most common)
2) Liver failure (most common)
3) Hypoalbuminaemia
4) Hypothyroidism
5) Meig’s syndrome
How does liver failure cause transudative pleurral effusion?
Pleural effusion is caused by high pressure in the portal vein (portal hypertension).
How does hypoalbuminemia cause transudative pleural effusion?
Hypoalbuminemia can cause a decrease in oncotic pressure causing extravasation of fluid into the interstitial space
What type of pleural effusion does malignancy cause?
Exudative
What type of pleural effusion does infection cause?
Exudative
What type of pleural effusion does liver failure cause?
Transudative
Give 3 other types of pleural effusion
1) Haemothorax –> blood in the pleural space
2) Empyema –> pus
3) Chylothorax –> chyle
What causes a chylothorax?
Chyle in the pleural space due to disruption of the thoracic duct (due to a neoplasm, trauma or infection/inflammation)
What is Meig’s syndrome? What is the triad of features?
1) Benign ovarian tumour (typically a fibroma)
2) Pleural effusion
3) Ascites
Management of Meig’s syndrome
The pleural effusion and ascites resolve with the removal of the tumour.
Would nephrotic syndrome cause a transudative or exudative pleural effusion?
Transudative
Would hypoalbuminaemia cause a transudative or exudative pleural effusion?
Transudative
Disruption of which structure leads to a chylothorax?
Thoracic duct
Typical symptoms of a pleural effusion?
Small and moderate pleural effusions are commonly asymptomatic. As the pleural effusion increases in size, symptoms begin to develop.
- Shortness of breath (typical presenting symptom)
- Cough
- Pleuritic chest pain