Pleural Effusion Flashcards
What are the two ways of classifying pleural effusions?
Transudative (<30g/L protein)
Exudative (>30g/L protein)
***Light’s criteria for transudate/exudate differentiation: exudate is defined as any of the following:
- pleural protein:serum >0.5
- pleural lactate dehydrogenase (LDH):serum >0.6
- pleural LDH greater than two thirds of upper limit of normal serum
What are the causes of a transudate pleural effusion?
- Heart failure
- Hypoalbuminaemia
- Hypothyroidism
- Meigs’ syndrome
Caused by increased venous pressure of hypoproteinaemia.
What are the causes of exudative pleural effusions?
Mostly due to increased leakiness of the pleural capillaries secondary to infection, inflammation or malignancy.
- Pneumonia
- Pulmonary infarction
- Rheumatoid arthritis
- SLE
- Bronchogenic carcinoma
- Malignant metastases
- Lymphoma
- Mesothelioma
- Lymphangitis carcinomatosis
What criteria is used to classify pleural effusions?
Light’s criteria
An effusion which is pleural LDH and protein-rich is called an exudate
In simple terms, why do pleural effusions occur?
Because there is an imbalance between fluid production and removal in the pleural space. This is due to local(1) or systemic(2) derangements.
Normally there is 20mL of fluid in each hemithorax and the layer is 2-10microm thick.
Describe the pathophysiology behind exudative and transudative pleural effusions.
Exudative = due to alterations in LOCAL factors
- leaky capillaries from inflammation secondary to infection (TB/pneumonia)
- infarction (PE)
- connective tissue disease (RA/SLE)
- neoplasia
Transudative = due to alterations in SYSTEMIC factors, often heart/kidney and multifactorial
- elevated pulmonary capillary pressure with HF
- excess ascites with cirrhosis
- low oncotic pressure due to hypoalbuminaemia (e.g. with nephrotic syndrome)
- hypothyroidism
What are the most common causes of a pleural effusion?
- Heart failure
- Infection
- Malignancy
How can you diagnose a pleural effusion?
CX(PA) - visible when >200mL
Ultrasound
Examination: dullness, decreased or absent tactile fremitus.
How do you treat a pleural effusion caused by…
- TB?
- Empyema?
- Bacterial pneumonia?
- HF?
TB - give antibiotics and the pleural effusion will go away by itself
Empyema -always have to drain it
Bacterial pneumonia - antibiotics only
HF - or any transudative effusion due to systemic causes, is treated by treating the underlying cause
Why do you get breathlessness in pleural effusions?
Due to the weight of the fluid
What tests would you do in a pleural effusion?
- Chest X ray - blunt costophrenic angles, water-dense shadows, meniscus. Horizontal upper border can also indicate a pneumothorax
- US - for therapeutic or diagnostic aspiration
- CT - pelvis and abdomen
- Send pleural fluid to the lab for…
- Clinical chemistry (protein, glucose, pH, LDH, amylase)
- Bacteriology (microscopy, culture, auramine stain, TB culture)
- Cytology
- Immunology (RA, ANA, complement)
- Pleural biopsy
What are the different ways of treating a recurrent pleural effusion?
- Drainage - if symptomatic, best removed slowly (0.5L/24hr) by intercostal drain(empyema) or diagnostic tap.
- Pleurodesis - talc for recurrent effusions.
- Intra-pleural anteplase and dornase alfa may help empyema
- Surgery - for persistent collections and increasing pleural thickness
Describe tactile vocal fremitus and vocal resonance in pleural effusion.
They are decreased (incostant and unreliable)
There may also be bronchial breathing where the lung is compressed.
What is the management of pleural effusion secondary to CCF?
Diuretic - furosemide 40mg/dose increased every 6-12hrs, maximum 600mg/day
Physiotherapy - movement and breathing exercises help
+/- Oxygen
+/- Therapeutic thoracentesis
What is the management of an infective pleural effusion?
Empirical antibiotics
Therapeutic thoracentesis - US guided to prevent pneumothorax
Physiotherapy
Remember: thoracentesis needle should be inserted at the upper border of the rib to avoid the neurovascular bundle that runs along the bottom of the ribs.
