Pleural disease Flashcards
What is the function of the pleural space?
To lubricate viscera and parietal pleura to allow sliding as lungs inflate and deflate
Helps create a vacuum as we breath in order to suck air in
How is pleural fluid produced?
Blood vessels and lymphatics exist superficial to the parietal pleura which is permeable.
Fluid moves out of the capillaries into the pleura space regulated by Starling forces (hydrostatic pressure v oncotic pressure gradients).
Is drained by lymphatics
The visceral pleura is impermeable.
What are the basic ideas of how pleural effusions develop?
When rate of production of pleural fluid is greater than the rate of reabsorption of the fluid into lymphatics.
Leads to accumulation of fluid in the pleural space
What is the difference between a transudate and an exudate?
Transudate - change in starling forces, either inc in hydrostatic forces or dec in oncotic forces for example HF, liver cirrhosis - fluid out only
Exudate - due to inflammation, vasodilation, vascular stasis and endothelial cell spacing - allows fluid and protein out
What are the key diagnosis features of a transudate in the pleural fluid?
Low fluid protein/serum protein ratio <0.5, or fluid protein less than 25 g/L
Low LDH - FluidLDH/Serum LDH ratio <0.6
What are the key diagnostic features of a exudate in a pleural effusion?
High fluid protein = fluid protein/serum protein ratio >0.5 or fluid >35g/L
High LDH = Fluid LDH/serum LDH >0.6
Note fluid protein may be low if serum protein is also low.
What are some potential causes of pleural effusion TRANSUDATES?
Too much fluid in body - heart failure, renal failure, liver cirrhosis
Elsewhere - hypoalbuminaemia, ascites/peritoneal dialysis
Other - hypothyroidism, Meigs syndrome, PE
What are some common causes of exudate pleural effusion?
Too much fluid produced/failure to reabsorb due to damage to the pleural surface
Pleural malignancy
Pneumonia
Empyema - infection in pleural space
Pulmonary infarction
What is the common history/presentation of a patient with a pleural effusion?
Usual symptom is progressive breathlessness
Develops over days to weeks
Pleuritic chest pain (sharp pain worse on breathing)
Cough - dry or white phlegm
Symptoms of underling cause
What is a pleural aspiration?
Ultrasound guided
Pass needle in to pleural fluid
Aspirate sample
What investigations are often run on a pleural aspiration sample?
Colour
Viscosity
Smell
Biochem - protein, LDH, glucose
Fluid - pH
Microbiology
Cytology
Amylase, triglycerides
What are some common risk factors for a pleural effusion?
Strong:
CHF, pneumonia, malignancy, recent coronary artery bypass graft surgery
Weak:
PE, recent MI, RA, SLE, renal failure, drug-induced pleural effusion.
How is pleural effusion diagnosed?
History and examination
Bloods - U&Es, LFTs, FBCs, CRP, ESR, autoantibodies, amylase
CXR - PA
Ultrasound
Pleural aspiration - cell count, glucose, pH and cytology
Contrast CT may be required - often for cause of exudative
How should a pleural infection be managed?
If fluid purulent or cloudy should have a chest tube to allow drainage
If clear but fluid below 7.2 pJ - chest tube should be placed
What is the typical management for recurrent pleural effusion?
Recurrent aspiration
Pleurodesis
Indwelling pleural catheter
Drug management to alleviate symptoms e.g opioids to relieve dyspnoea.
