Pocket Medicine




•  Systemic factors (eg, ↑ PCWP, ↓ oncotic pressure) → transudative effusion

•  Local factors (ie, Δ pleural surface permeability) → exudative effusion


•  Congestive heart failure (40%): 80% bilateral, ± cardiomegaly on CXR occasionally exudative (esp. after aggressive diuresis or if chronic), but ~75% of exudative effusions in CHF Pts found to have non-CHF cause (Chest 2002;122:1518)

•  Constrictive pericarditis (knock on exam, calcification or thickening on imaging)

•  Cirrhosis (“hepatic hydrothorax”): diaphragmatic defect w/ passage of ascitic fluid often right-sided (2/3) & massive (even w/o marked ascites)

•  Nephrotic syndrome: usually small, bilateral, asymptomatic (r/o PE b/c hypercoag)

•  Other: PE (usually exudate), malignancy (lymphatic obstruction), myxedema, CAPD


•  Lung parenchymal infection (25%)

bacterial (parapneumonic): can evolve along spectrum of exudative (but sterile) → fibropurulent (infected fluid) → organization (fibrosis & formation of rigid pleural peel). Common causes: Strep pneumo, Staph aureus, Strep milleri, Klebsiella, Pseudomonas, Haemophilus, Bacteroides, Peptostreptococcus, mixed flora in aspiration pneumonia.

mycobacterial: >50% lymphs 80% of the time, ADA >40, pleural bx ~70% Se

fungal, viral (usually small), parasitic (eg, amebiasis, echinococcosis, paragonimiasis)

•  Malignancy (15%): primary lung cancer most common, metastases (esp. breast, lymphoma, etc.), mesothelioma (✓ serum osteopontin levels; NEJM 2005;353:15)

•  Pulmonary embolism (10%): effusions in ~40% of PEs; exudate (75%) > transudate (25%); hemorrhagic—must have high suspicion b/c presentation highly variable

•  Collagen vascular disease: RA (large), SLE (small), Wegener’s, Churg-Strauss

•  Gastrointestinal diseases: pancreatitis, esophageal rupture, abdominal abscess

•  Hemothorax (Hcteff/Hctblood >50%): trauma, PE, malignancy, coagulopathy, leaking aortic aneurysm, aortic dissection, pulmonary vascular malformation

•  Chylothorax (triglycerides >110): thoracic duct damage due to trauma, malignancy, LAM

•  Other:

post-CABG: left-sided; initially bloody, clears after several wks

Dressler’s syndrome (pericarditis & pleuritis post-MI), uremia, postradiation therapy

Asbestos exposure: benign;  eosinophils

Drug-induced (eg, nitrofurantoin, methysergide, bromocriptine, amiodarone):  eos

Uremia; post-XRT; sarcoidosis

Meigs’ syndrome = benign ovarian tumor → ascites & pleural effusion

Yellow-nail syndrome: yellow nails, lymphedema, pleural effusion, bronchiectasis

Diagnostic studies

•  Thoracentesis (NEJM 2006;355:e16)

Indications: all effusions >1 cm in decubitus view if suspect due to CHF, can diurese and see if effusions resolve (75% do so in 48 h) asymmetry, feverchest pain or failure to resolve → thoracentesisparapneumonics should be tapped ASAP (cannot exclude infxn clinically)

Diagnostic studies: ✓ total protein, LDH, glucose, cell count w/ differential, Gram stain & culture, pH; remaining fluid for additional studies as dictated by clinical scenario

Complications: PTX (5–10%), hemothorax (~1%), re-expansion pulm edema (if >1.5 L removed), spleen/liver lac.; post-tap CXR not routinely needed (Annals 1996;124:816)

↓ PTX w/ U/S and experienced supervisor (Chest 2009;135:1315; Archives 2010;170:332)

•  Transudate vs. exudate (Annals 1972;77:507)

Light’s criteria: exudate = TPeff/TPserum >0.5 or LDHeff/LDHserum >0.6 or LDHeff >2/3 ULN of LDHserum; 98% Se, 83% Sp; best Se of all methods (Chest 1995;107:1604); however, will misidentify 25% of transudates as exudates; ∴ if clinically suspect transudate but meets criterion for exudate, confirm w/ test w/ higher Sp

exudative criteria w/ better Sp: serum-effusion alb gradient ≤1.2, Se 87%, Sp 92%; serum-effusion TP gradient ≤3.1, Se 84%, Sp 91%; choleff >45 mg/dL and LDHeff >200, 90% Se, 98% Sp (no serum required)

CHF effusions: TP may ↑ with diuresis or chronicity → “pseudoexudate”; alb gradient ≤1.2, choleff >60 mg/dL (Se 54%, Sp 92%) or clin judgment to distinguish (Chest 2002;122:1524)

•  Complicated vs. uncomplicated parapneumonic (Chest 1995;108:299)

complicated =  Gram stain or culture or pH <7.2 or glucose <60

complicated parapneumonic effusions usually require drainage to achieve resolution

empyema = frank pus, also needs drainage to achieve resolution

•  Additional pleural fluid studies (NEJM 2002;346:1971)

NT-proBNP ≥1,500 pg/mL has 91% Se & 93% Sp for CHF (Am J Med 2004;116:417)

WBC & diff.: exudates tend to have ↑ WBC vs. transudates but nonspecific neutrophils → parapneumonic, PE, pancreatitis lymphocytes (>50%) → cancer, TB, rheumatologic eos (>10%) → blood, air, drug rxn, asbestos, paragonimiasis, Churg-Strauss, PE

RBC: Hcteff 1–20% → cancer, PE, trauma; Hcteff/Hctblood >50% → hemothorax

AFB: yield in TB 0–10% w/ stain, 11–50% w/ culture, ~70% w/ pleural bx

adenosine deaminase (ADA): seen w/ granulomas, >70 suggests TB, <40 excludes TB

cytology: ideally ≥150 mL and at least 60 mL should be obtained (Chest 2010;137:68)

glucose: <60 mg/dL → malignancy, infection, RA

amylase: seen in pancreatic disease and esophageal rupture (salivary amylase)

rheumatoid factor, CH50, ANA: limited utility in dx collagen vascular disease

triglycerides: >110 → chylothorax, 50–110 → ✓ lipoprotein analysis for chylomicrons

cholesterol: >60; seen in chronic effusions (eg, CHF, RA, old TB)

creatinine: effusion/serum ratio >1 → urinothorax

fibulin-3: ↑ plasma and/or effusion levels → mesothelioma (NEJM 2012;367:1417)

•  Chest CT; pleural biopsy; VATS

•  Undiagnosed persistent pleural effusions (Clin Chest Med 2006;27:309)

Transudative: most commonly CHF or hepatic hydrothorax. ✓ s/s CHF or cirrhosis, NT-proBNPeff; consider intraperitoneal injection of technetium-99m sulfur colloid

Exudative (ensure using Sp test listed above): most commonly malig, empyema, TB, PE. ✓ s/s malig, chest CT (I+), ADA or IFN-g release assay; consider thoracoscopy.


•  Symptomatic effusion: therapeutic thoracentesis, treat underlying disease process

•  Parapneumonic effusion (Chest 2000;118:1158)

uncomplicated → antibiotics for pneumonia

>1/2 hemithorax or complicated or empyema → tube thoracostomy (otherwise risk of organization and subsequent need for surgical decortication)

loculated→ tube thoracostomy or VATS; intrapleural t-PA + DNase ↓ need for surgical referral (NEJM 2011;365:518)

•  Malignant effusion: serial thoracenteses vs. tube thoracostomy + pleurodesis (success rate ~80–90%) vs. indwelling pleural catheter (  JAMA 2012;307:2383); choice of pleurodesis agent (talc, bleo, doxy) controversial; systemic steroids & pH <7.2 a/w ↑ pleurodesis failure rate

•  TB effusions: effusion will often resolve spontaneously; however, treat Pt for active TB

•  Hepatic hydrothorax

Rx: Δ pressure gradient (ie, ↓ ascitic fluid volume, NIPPV)

avoid chest tubes; prn thoracenteses, pleurodesis, TIPS or VATS closure of diaphragmatic defects if medical Rx fails; NIPPV for acute short-term management

spontaneous bacterial empyema (SBEM) can occur (even w/o SBP being present), ∴ thoracentesis if suspect infection

transplant is definitive treatment and workup should begin immediately