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Author: Salim Rezaie
- Annual incidence: About 1 million Americans each year
- Pleural Effusion is an abnormal accumulation of fluid in the pleural space.
- The first step in evaluating pleural effusions is determining whether it is Transudative or Exudative.
- Transudative effusions are a result of pressure filtration without capillary injury (i.e hydrostatic and oncotic pressure abnormalities).
- Exudative effusions are a result of inflammatory fluid leaking between cells.
- Most common causes of transudative effusion: 1. LV failure, 2. Cirrhosis
- Most common causes of exudative effusion: 1. Bacterial PNA, 2. Viral infection, 3. Malignancy
- Most common malignant effusions: 1. Lung Ca (1/3), 2. Breast ca (1/4), & 3. Lymphoma (1/5)
- Clinical manifestations of pleural effusion can be variable and related to the underlying disease process and small pleural effusions can be asymptomatic.
- History: Dyspnea, cough, chest pain can be common, but look for other symptoms such as:
- CHF: lower extremity edema, orthopnea, paroxysmal nocturnal dyspnea
- TB: night sweats, fever, hemoptysis, weight loss
- PNA: fever, purulent sputum
- Physical exam depends on size of the effusion: diminished breath sounds, dullness to percussion, decreased tactile fremitus, & occasionally a localized pleural friction rub
On CXR: blunting of the costophrenic angle; a volume of less than 500mL may not be seen on upright CXR, but can be seen on lateral films; Decubitus CXR can help determine if fluid is free flowing or loculated
- Lights Criteria: all 3 conditions must be met for an effusion to be transudative; if you fail one of the criterion, the effusion is exudative.
- E/S = Effusion to Serum
- Eff = Effusion
- Thoracentesis: This is the gold standard test; must differentiate between transudative and exudative; Always perform CXR after procedure to rule out pneumothorax;
- Pleural Fluid WBC > 1000: think exudate
- Pleural Fluid WBC >10000: think parapneumonic effusion
- Pleural Fluid WBC >100,000: think empyema
- Pleural Fluid Eos >10%: PTX, drug reaction, paragonimiasis (trematode: fluke), fungal infection, & asbestosis exposure
- Pleural fluid Lymphocytes > 50%: Think Tb or malignancy
- Pleural fluid Neutrophil predominance: Think PNA, pancreatitis, PE, peritonitis
- Pleural Fluid Glucose: 80 = Tb; 60 = Cancer, empyema; <30 = rheumatoid arthritis
- Pleural Fluid Amylase: pancreatic fistula, esophageal rupture, & malignancy
- Pleural Fluid pH: <7 - complicated effusion
- Pleural Fluid ANA: >1:160 - drug induced SLE & native SLE; if ANA positive - anti-dsDNA (native SLE) vs anti-histone ab (drug- induced lupus)
- Pleural fluid Tg: > 115 (due to chylomicrons) à trauma, lymphoma, mediastinal cancer, & lymphangioleiomyomatosis (LAM); < 50 (due to triglycerides) - Tb & Rhematoid Arthritis
- Pleural biopsy: always do if you suspect Tb (20% sensitivity with fluid cultures & 90% sensitivity with bx) or if cytologic analysis is neg for malignancy
- Malignancy: Fluid cytology is the gold standard to evaluate for malignancy (3 effusion samples have a combined yield of 90%)
- Bacterial: Pleural effusion gram stain and culture are the gold standard tests to order for this etiology
- Transudative effusion: due to systemic disorder - treat the underlying etiology
- Exudative effusion: requires further testing - due to local disorders
- Indications for Chest Tube Placement:
- Pus in pleural space (>10,000 WBC)
- Positive culture and/or gram stain on pleural space fluid
- Complicated (loculated) parapneumonic effusion
- Thoracotomy: if loculated empyema does not respond to chest tube and antibiotics
- Always do pleural biopsy if you suspect TB
- Effusion cytology is diagnostic test of choice in malignancy
- Pulmonary embolism is the most overlooked disorder in the workup of a pleural effusion
- After performing thoracentesis always order post-procedure CXR to rule out pneumothorax
- Removal of >1.5L in one session may result in re-expansion pulmonary edema
- Le et al. First Aid for the Internal Medicine Boards. 2006.
- Light RW. Clinical Practice: Pleural Effusion. NEJM 2002; 346 (25): 1971 – 1977.
- Marx: Rosen’s Emergency Medicine, 7th Ed. 2009.
- Mcgrath, EE et al. Diagnosis of Plerual Effusion: A Systematic Approach. AMJCC March 2011; 20 (2): 119 – 127.
- Med Study. Internal Medicine Review: Core Curriculum. Book 2. 2007/2008.
- Porcel et al. Diagnositic Approach to Pleural Effusion in Adults. American Family Physician. 2006.