Respiratory - Pleural Effusion

Question 1

Lights criteria

Answer 1

1. Pleural fluid protein/serum protein ratio >0.5
2. Pleural fluid ldh/serum ldh ratio >0.6
3. Pleursl fluid ldh >2/3 ULN serum level

(Any 1 of the 3 present is exudative.)
Lights criteria misclassifies up to 25% effusions as exudates.

Additional rules to classify effusion as exudate:
Measure serum - pleural protein gradient: if 31g/L or less -> exudate
If >31g/L, measure serum - pleural albumin graduebt and <13g/L -> consistent with exudate

Question 2

Causes of exudative pleural effusion

Answer 2

1. Malignancy
2. Parapneumonic infection
3. TB
4. Medications such as amiodarone and nitrofurantoin, methothrexate, clozapine
5. Pancreatitis
6. PE
7. Sarcoidosis
8. Meig’s syndrome
9. Malignant ascites
10. Radiation therapy

Question 3

Causes of Transudstive pleural effusion

Answer 3

1. Nephrotic syndrome
2. Peritoneal dialysis
3. Heart failure
4. Cirrhosus
5. Low albumin
6. Duro-pleural fistula

Question 4

Pleural biomarkers, pH, glucose, adenosine deaminase

Answer 4

1. Low pH and low glucose ans crp>45 in pleural fluid is indicative of parapneumonic effusion
2. ADA >250 - empyema or lymphoma, high ADA but less than 250 - mainly TB but can still be empyema.