Pleural effusion Flashcards
Definition
Presence of fluid between the visceral and parietal pleura
Detected
- clinically when there is >500ml present
- radiologically when >300ml present
- massive effusions are malignant in origin
Two types of pleural effusion
Divided by their protein concentraiton into
- transudatates <25g/l
- exudates >35g/l
Transudates
pleural fluid protein <25g/l - hydrostatic/oncotic forces cause extravasation of fluid through a normal membrane
Commonest causes
- heart failure (90%)
- hypoalbuminameia (ie liver failure, nephrotic syndrome, malnutrition)
Exudates
Protein content >30g/l - Inflammation causes increased permeability of pleural surface/capillaries leaking intravascular fluid (including their cells, their cotnents and protins)
Commonest causes
- inflammation
- infection
- infarction (PE)
- Malignancy
Symptoms
May be asymptomatic or
- dyspnoea
- pleuritic chest pain
Signs
- decreased expansion
- stony dull percusision
- diminished breath sounds occur on the affected side
- tactile vocal fremitus and vocal resonance are decreased
- tracheal deviation away from the effusion
- aspiration marks and signs of associated disease
Investigations
CXR
- small effusions blunt the costophrenic angles
- white out of hemithorax
- meniscus demonstrates fluid level
Ultrasound
- useful in identifying the presence of pleural fluid and in guiding diagnostic or therapeutic aspiration
- small effusions not seen on chest xray
Diagnostic pleural fluid aspiration
- initial investigation
- appearance of pleural fluid is noted and sample sent for protein, LDH, glucose, P, cytology and microbiology
pleural biopsy
- for tissue diagnosis (TB, culuture and histology) is obtained by CT guided biopsy, blind biopsy (abrhams neede) or VATS that allows multiple biopies to be taken under direct visualisation
Types of pleural effusion
Serous fluid (hydrothorax)
- transudate or exudate
Blood (haemothorax)
- exudate
- trauma, malignancy, PE with infarct
Chyle (chylothorax)
- transudate or exudte
- leakage from thoracic duct caused by lymphoma or thoracic surgical trauma
Pus (empyema)
- exudate with pH <7.2
- secondary to pneumonia/abscess
Appearances
- straw: serous effusion (clear=transudate, cloudy= exudate)
- blood stained: trauma, malignany, PE with infarct
- frank blood: trauma, malignancy (esp mesothelioma)
- pus: empyema
- Food: oesophageal rupture
Lights criteria
Pleural fluid with a protein concentration of 25-35g/L requires analysis against ligths criteria. These state that if:
- the ratio of pleural fluid protein to serum protein is >0.5 or
- the ratio of pleural fluid LDH and serum LDH is >0.6 or
- Pleural Fluid LDH >2/3 upper limit of normal serum LDH
then the fluid is an exudate.
Treatment
Treatment depends on the underlying cause. Exudates are drained and transudates are managed by the treatment of the underlying cause
- drainage - If the effusion is symptomatic, drain it, repeatedly if necessary. Fluid is best removed slowly .
- Pleurodesis: with tetracycline, bleomcin or talc may be helpful for recurrent effusins. Thorascopic talc pleurodesis is most effective for malignant effusions- sclerosing agents
Tests for pleural fluid
