Pleural Effusion

CAUSES – anything!

• Blood – post-op, trauma, malignancy, pulmonary infarct
• Exudate – parapneumonic effusion, empyema, subphrenic abscess, pancreatitis
• Transudate – increased hydrostatic pressure (heart and liver failure, fluid overload), decreased oncotic pressure (nephrotic syndrome, loosing protein), negative pleural pressure (atelectasis)
• Chyle

CXR FINDINGS (supine)

< 500mL

• homogenous density over lower lung zone
• veil appearance to lung
• lung markings not obliterated
• air bronchograms absent

500-3000mL

• silhouetting of diaphragm
• contralateral mediastinal shift >3000mL
• opacification of hemithorax
• contralateral mediastinal shift

PLEURAL FLUID

Things to put on the lab form:

• Protein
• LDH
• Glucose
• pH
• WCC
• Cytology
• Amylase
• HCT
• Gram stain
• Culture

Appearance

• straw coloured: normal
• blood: trauma, malignancy, pulmonary infarct, post pericardiotomy
• turbid: parapneumonic effusion or empyema

Protein

• PF:serum < 0.5 = transudate – PF:serum > 0.5 = extudate

LDH

• PF:serum < 0.6 = transudate – PF:serum > 0.6 = extudate

Glucose

• if less than half of serum: empyema, malignancy, RA, SLE

pH

• < 7.3 = empyema

WCC

• neutrophilia: parapneumonic effusion, empyema, PE
• lymphocytosis: Tb, RA, SLE, sarcoid, malignancy

Cytology

• malignancy
• mesothelial cells increased: mesothelioma
• mutinucleating giant cells: RA

Other

• chyomicrons and triglycerides: chylothorax
• amylase (PF > serum): ruptured oesophagus, pancreatitis, malignancy, bacterial pneumonia
• HCT > 0.5: haemothorax