Pleural effusion Flashcards
What is a pleural effusion?
Collection of fluid in the pleural cavity
What are the different types of pleural effusions?
Exudate = > 3g/dL of protein
Transudate = < 3g/dL of protein
What is Light’s criteria?
pleural fluid protein / serum protein = > 0.5
pleural fluid LDH / serum LDH = > 0.4
pleural fluid LDH is > 2/3 the upper limit of the lab normal value for serum LDH
Exudate = one or more of the criteria above met
What are the common causes of transudates?
‘the failures’
- heart failure
- liver failure (cirrhosis)
What are the less common causes of transudates?
- hypoalbuminaemia
- nephrotic syndrome
- peritoneal dialysis
- hypothyroidism
What are the rare causes of transudates?
Meigs’ syndrome (benign ovarian tumour, ascites, pleural effusion?
What are the common causes of exudates?
- infection (parapneumonic, TB)
- malignancy
What are the less common causes of exudates?
- pulmonary infarction
- autoimmune diseases (e.g., rheumatoid arthritis)
- pancreatitis
- post-MI (Dressler’s syndrome)
- post coronary artery bypass grafting (CABG)
- asbestos
What are the rare causes of exudates?
- yellow nail syndrome
- drugs (e.g., methotrexate, amiodarone, nitrofurantoin, phenytoin)
What are other causes of fluids in the pleural cavity?
Haemothorax
Empyema
Chylothorax - chyle in the pleural space due to disruption of the thoracic duct (due to a neoplasm, trauma or infection/inflammation)
What are the clinical features of a pleural effusion?
SOB
Percussion dullness over the effusion
Reduced breath sounds
Trachea deviation/mediastinal shift away from effusion if it is big
Pleuritic chest pain
Apart from SOB, cough and pleuritic chest pain, what are the other important areas to cover in the Hx?
Symptoms suggestive of lung cancer:
- haemoptysis
- weight loss
Symptoms suggestive of heart failure:
- orthopnoea
- paroxysmal nocturnal dyspnoea
- leg swelling
Symptoms suggestive of infection:
- productive cough
- fever
Social history
- smoking history (lung cancer risk)
- asbestos exposure (mesothelioma)
What lab Ix would you do for a pleural effusion?
FBC/CRP/blood culture : look for infection
ABG : if oxygenation is affected
D-dimer : if PE is suspected
LFTs, U&Es, albumin, coagulation profile : look for liver and renal disease
Amylase : if pancreatitis is suspected
TFTs : if hypothyroidism is suspected
What should be done with the pleural fluid?
Note appearance : purulent = infection, blood = malignancy/PE/trauma
Send for:
- biochemistry
*protein
*LDH
*glucose
- microbiology (gram stain and culture)
- cytology
If fluid not purulent use blood gas machine to analyse pH
If the pleural fluid protein is 25-35g/L, how would you distinguish transudative from exudative pleural effusions?
Light’s criteria
What does a pleural fluid pH < 7.3 indicate?
Malignancy
Pleural infection
Rheumatoid arthritis
TB
Oesophageal rupture
Which pH indicates that drainage is needed in parapneumonic effusions?
< 7.2
What is the medical Mx of pleural effusions?
Smaller pleural effusion = could observe
Diuretic in HF
Antibiotics in infection
Pleural fluid aspiration/chest drain insertion under USS for symptomatic patients with larger pleural effusions
If the pleural fluid reaccumulates despite medical Mx, what can be done?
Long-term indwelling chest drain
Pleurodesis - by chest drain or medical thoracoscopy
What is the surgical Mx of pleural effusions?
Video assisted thoracic surgery (VATS) by a thoracic surgeon
What are the complications of pleural effusions?
Increasing resp compromise
In parapneumonic effusions = empyema and sepsis
Pneumothorax - can be due to pleural procedures done during Dx and Mx
Patients with malignancy or pneumonia have poorer prognosis if pleural effusion develops
How do chest drains work?
Creates a one-way mechanism - lets air/fluid out of pleural space but prevents air/fluid entering pleural space
Accomplished via an underwater seal
Distal end of drainage tube is submerged in 2cm of H2O
Flexible plastic tube inserted through chest wall in between pleural space between 5th and 6th intercostal space in mid-axillary line
How do you know a chest drain is working?
Swinging = movement of fluid up and down the tube
Bubbling = air bubbles inside fluid contained in chest-drain bottle
If the chest drain is swinging but not bubbling what does this indicate?
Chest drain should be removed - no longer needed
What is an empyema?
Pus in the pleural space
When should you suspect an empyema?
If a patient with a resolving pneumonia develops a recurrent fever
What are the characteristics of a aspirated pleural fluid that is suspected to be an empyema?
Typically yellow + turbid
pH < 7.2
Reduced glucose
Increased LDH
How should an empyema be managed?
Drain using a chest drain inserted under radiological guidance
Intrapleural alteplase and dornase alfa can help with empyema
How should you do a diagnostic aspiration/chest drain insertion in a pleural effusion?
Percuss the upper border of the pleural effusion and choose a site 1 or 2 intercostal spaces below it (don’t go too low or you’ll be in the abdomen!).
Infiltrate down to the pleura with 5–10mL of 1% lidocaine.
Attach a 21G needle to a syringe and insert it just above the upper border of an appropriate rib (avoids neurovascular bundle).
Draw off 10–30mL of pleural fluid and send it to the lab for clinical chemistry (protein, glucose, pH, LDH, amylase), bacteriology (microscopy and culture, auramine stain, TB culture), cytology, and, if indicated, immunology (rheumatoid factor, ANA, complement).
For draining, fluid is best removed slowly (i.e., 0.5-1.5L/24h)
Sources
https://zerotofinals.com/medicine/respiratory/pleuraleffusion/
https://geekymedics.com/pleural-effusion/
https://www.physio-pedia.com/Chest_Drains
https://www.guysandstthomas.nhs.uk/health-information/chest-drain
Empyema + how to do diagnostic aspiration/chest drain info = pg 170, 193 Oxford Handbook of Clinical Medicine 10th Edition
