Most common etiologies for BLOODY pleural effision:

• Trauma
• Malignancy
• Pulmonary infarct
• Post-cardiac injury

Lights Criteria: one criteria = EXUDATIVE effusion

1. Pleural total protein / serum total protein > 0.5
2. Pleural LDH / serum LDH > 0.6
3. Pleural LDH ≥ 2/3 ULN for serum LDH

* Lights criteria is SENSITIVE, but NOT SPECIFIC – you do not want to miss an exudative effusion, so you want to a low false negative rate.

* For patients with a high suspicion for transudative effusion, but meets Lights criteria (i.e. CHF following initiation of diuresis), check serum albumin and pleural albumin (if serum – pleural < 1.2 mg/dL, confirms diagnosis of exudative effusion).

Transudative Effusions (not a complete list):

• CHF (~90%)
• Cirrhosis (hepatic hydrothorax)
• Severe hypoalbuminemia
• Nephrotic syndrome
• Peritoneal dialysis
• Myexedma
• Constrictive pericarditits
• SVC syndrome

Exudative Effusion (not a complete list):

• Infection (PNA/TB)
• Malignancy
• CTD
• Pancreatitis
• Trauma
• PE/Pulmonary infarct
• Post heart surgery
• Esophageal rupture

If exudative effusion, start with cell count/diff

• PMNs > 50% – parapneumonic, PE, pancreatitis
• Lymphs > 50% – Cancer, TB, fungal, post-surgery
• Eosinophils >10% – Hemothorax, drug reaction, parasite infection