Pleural EffusionGENERAL PRINCIPLESD

Pleural Effusion
GENERAL PRINCIPLES
Definition
The accumulation of fluid in the pleural space.
Classification
Diagnosis and management is based on classifying a pleural effusion as either a transudate or exudates.
Etiology
• Most common causes (Pleural Disease. 4th Ed. Lippincott, Williams and Wilkins, 2001):
o Left heart failure (36%)
o Pneumonia (22%)
o Malignancy (14%): lung, breast, lymphoma
o Pulmonary embolism (11%)
o Viral disease (7%)
• Less common but important causes: rheumatologic/collagen vascular disease, hepatic cirrhosis, hepatic hydrothorax, pancreatitis, esophageal rupture, lymphatic obstruction, “trapped” lung.
Pathophysiology
• Normal pleural physiology:
o Each pleural space produces and reabsorbs up to 15 mL of fluid per day, and contains about 10 mL of fluid at any one time; not apparent on imaging.
o Normal pleural fluid chemistries: LDH < 0.6 of serum, protein < 0.5 of serum, glucose 0.6 to 0.8 of serum, pH 7.60.
• Transudative effusion: alteration of hydrostatic and/or oncotic factors that increase the formation and/or decrease reabsorption of pleural fluid.
o CHF: increased venous pressures and lung edema
o Hepatic cirrhosis and nephrotic syndrome: hypoalbuminemia
o Malignancy: infiltration/obstruction of pleural capillaries and/or lymphatics (up to 10% of malignant effusions are transudative)
• Exudative effusion: either direct or cytokine-induced disruption of normal pleural membranes and/or vasculature leading to increased capillary permeability.
o Infection/pneumonia
o Malignancy
o Inflammatory disease (i.e., SLE or RA)
o Trauma/surgery
o Pulmonary embolus
• Fluid markers of pleural infection, inflammation, and/or obstruction often coexist.
o Low glucose and pH levels
 Byproducts of microorganism and/or inflammatory cell metabolism
 Decreased acid removal due to pleural disruption from inflammation or malignancy
o High LDH level
 Cell turnover and lysis
DIAGNOSIS
The clinical setting, combined with pleural fluid analysis, is crucial to establishing a proper diagnosis.
Clinical Presentation
Symptoms and signs may be directly related to the pleural effusion itself, and/or to any underlying disease process.
History
• Dyspnea due to abnormal pulmonary mechanics: most common symptom, usually develops with greater than 500 to 1000 mL of pleural fluid, but may not correlate
• Often asymptomatic
• Pleurisy or referred chest/back/shoulder pain from pleural inflammation
• Should include survey of potential underlying causes
Physical Examination
• Vital signs: Assess for fever, hemodynamic instability, hypoxemia.
• Chest exam: Dullness to percussion, decreased breath sounds, and tactile fremitus.
o These signs are more sensitive with larger effusions, but the chest exam is often unreliable and should not be used solely to diagnose and approximate size (Clev Clin J Med 2008;75:297).
• A thorough system-based exam should evaluate for CHF, malignancy, pneumonia, hepatic cirrhosis, venous thrombosis, and other potential causes of pleural effusion.
Diagnostic Criteria
• Analysis of pleural fluid obtained by thoracentesis is the mainstay of diagnosing an etiology.
• Transudate: Presence of ALL of Light's criteria (Ann Intern Med 1972; 77:507).
o Fluid: serum protein ratio < 0.5
o Fluid: serum LDH ratio < 0.6
o Pleural fluid LDH < 0.67 of upper limit of normal for serum LDH
• Exudate: Presence of ANY of Light's criteria (Ann Intern Med 1972;77:507).
• Pseudo exudate: An effusion that meets one or more of Light's criteria, but is actually a transudate.
o Usually due to diuretic-treated CHF, cirrhosis, or nephrotic kidney disease.
o Serum to pleural fluid albumin gradient is >1.2
• Simple parapneumonic effusion: a sterile, small (encompassing less than one-half the hemithorax), free-flowing pleural effusion in the setting of pneumonia, with pH > 7.20 and glucose > 60 mg/dL
• Complicated parapneumonic effusion: ANY one of the following (Chest 2000; 118:1158):
o Large (encompassing more than one-half of the hemithorax), free-flowing
o Effusion of any size with loculations
o Thickened parietal pleura on chest CT
o Positive gram stain or culture
o pH < 7.20 or glucose < 60 mg/dL
• Empyema: gross pus in the pleural space or positive gram stain. Positive culture is NOT required for diagnosis (high false-negative rate).
Differential Diagnosis
See Table 27.
Diagnostic Testing
• Pleural effusion is detected by chest imaging and characterized through sampling by thoracentesis.
• All parapneumonic effusions, and new, undiagnosed effusions should be sampled.
Laboratories
• Pleural fluid (Table 27):
o Note color and consistency
o Chemistries: Protein, albumin, LDH, glucose, pH
o Cell count with differential
o Hematocrit if suspicion for hemothorax (> 0.5 of serum is diagnostic)
o Microbiologic stains and culture per suspicion
o Cytology (yield approximately 60%)
o Consider triglyceride, amylase, ADA as indicated
• Serum: CBC, CMP, LDH, urinalysis, coagulation studies, BNP
• Additional labs guided by suggestion of underlying illness
Electrocardiography
Assess for structural heart disease. Otherwise usually nonspecific and noncontributory.
Imaging
• Standard upright PA/lateral CXR:
o Diagnostic for a suspected pleural effusion and approximates size (Radiology: Diagnosis, Imaging, Intervention. Lippincott, 2000:1).
 75 mL obscures the posterior costophrenic sulcus
 175 mL obscures the lateral costophrenic sulcus
 500 mL obscures the entire diaphragmatic contour
 1,000 mL reaches the level of the anterior 4th rib
o Helps suggest associated conditions (CHF, pneumonia).
• Lateral decubitus radiograph:
o Demonstrates fluidity.
o Usually amenable for thoracentesis if fluid layers to >1 cm.
• Thoracic ultrasonography:
o Accurate and practical in detecting loculations.
o Provides real-time guidance for thoracentesis or thoracostomy tube placement, reducing complication rates.
• Chest CT with contrast:
o Helpful in distinguishing fluid from lung mass, atelectasis, pneumonia, or suggesting hemothorax.
o Defines and characterizes pleural loculations, thickening, nodularity, or other abnormalities.
Table 27 Clues to Diagnosing the Cause of a Pleural Effusion Based on Fluid Analysis
Gross appearance
• Clear/serous/light yellow: Transudate of any etiology (cardiac, liver, kidney disease)
Urinothorax (consider if smells like ammonia)
• Bloody/serosanguineous: Hemothorax (surgery/trauma); PE; malignancy
• Purulent/turbid/brown: Infectious/empyema; esophageal rupture
• Milky/white: Chylothorax (lymphatic disruption from malignancy, thoracic duct injury, LAM, filariasis, others)
Nucleated cells
• Total > 50k, neutrophilia: Infectious/empyema
• Total < 5k: Transudate of any etiology; chronic malignant; tuberculous
• Lymphocytosis (>85%): Tuberculous; lymphoma; chronic rheumatoid; sarcoid; pseudo exudates
• Eosinophilia (>10%): Pneumothorax; hemothorax; fungal; parasitic; meds; malignancy; benign asbestos effusion
• Mesothelial cells (>5%): Normal; transudate Excludes tuberculous pleurisy
Chemical analysis
• Elevated protein: >3 g/dL: Most exudates; pseudo exudates (serum-fluid albumin gradient >1.2 g/dL)
• >4: Tuberculous
• >7-8: Blood cell dyscrasias
• Elevated LDH: >1,000 IU/L: Empyema; rheumatoid; paragonimiasis; high burden malignant
• Fluid:serum ratio >1: Pneumocystis or urinothorax
• Glucose < 60 mg/dL: Infectious/empyema; rheumatoid; lupus; tuberculous; esophageal rupture; malignant
• pH < 7.3: Infectious/empyema; rheumatoid; lupus; tuberculous; esophageal rupture; high burden malignant
• Elevated amylase (>serum): Pancreatitis; esophageal rupture; malignant
• Adenosine deaminase > 50 U/L: Tuberculous (unlikely if level < 40)
• Triglycerides >110 mg/dL: Chylothorax

Diagnostic Procedures
• Thoracentesis: can be performed safely at the bedside on effusions layering >1 cm on lateral decubitus CXR.
o Complicated/organized effusions should be accessed using real-time ultrasound or CT guidance.
o Optimize hemostasis: PT/PTT < 2× normal, Platelets > 25k, Cr 80% when combined with pleural fluid AFB stain and culture since tuberculous pleuritis is usually diffuse (Chest 1997;112:702).
o Consider for the undiagnosed, suspected malignant effusion
 Obtaining four to six consecutive samples from a locally thickened pleura (as seen on chest CT), may offer diagnostic yields > 50%, and up to >70% when combined with fluid cytology (J Bronchol 1998;5:327; Chest 2006;129:1549).
• Thoracoscopic pleural biopsy: performed under direct pleural visualization.
o Indicated for the undiagnosed suspected malignant effusion.
o Diagnostic yield is >70% to 90% (Ann Intern Med 1991;114:271; ANZ J Surg 2006;76:722).
TREATMENT
• Transudates: usually resolve with treatment of the underlying cause (heart failure, hepatic disease, nephrotic syndrome).
o Therapeutic thoracentesis as indicated for persistent larger effusions.
o Uncommonly, more aggressive measures including pleurodesis, shunts, or placement of a chronic indwelling pleural catheter are indicated for comfort or palliation.
• Simple/uncomplicated parapneumonic effusion: antibiotics and close observation.
• Complicated parapneumonic effusion and empyema (Fig. 6): antibiotics and early thoracostomy tube drainage to avoid inflammatory adhesion and organization (Chest 2000;118:1158).
o Antibiotics should also target anaerobic organisms as they often complicate empyema (Lancet 1974;1:338; Chest 1993;103

Kết quả (Việt) 1:

Màng phổi phùNGUYÊN TẮC CHUNGĐịnh nghĩaSự tích tụ của chất lỏng trong màng phổi không gian.Phân loạiChẩn đoán và quản lý dựa trên phân loại một phù màng phổi là một transudate hoặc dịch tiết.Nguyên nhân• Phổ biến nhất gây ra (màng phổi bệnh. 4 Ed. Lippincott, Williams và Wilkins, 2001):o suy tim trái (36%)o bệnh viêm phổi (22%)o bệnh ác tính (14%): phổi, vú, ung thư hạcho phổi thuyên (11%)o virus bệnh (7%)• Ít hơn nguyên nhân phổ biến nhưng quan trọng: khớp/collagen bệnh mạch máu, gan, xơ gan, gan hydrothorax, viêm tụy, thực quản vỡ, tắc nghẽn bạch huyết, "bị mắc kẹt" phổi.Sinh lý bệnh• Sinh lý học bình thường của màng phổi:o mỗi màng phổi không gian sản xuất và reabsorbs lên đến 15 mL của chất lỏng cho một ngày, và chứa khoảng 10 mL của chất lỏng một lúc; không rõ ràng trên hình ảnh.o bình thường màng phổi chất lỏng chemistries: LDH < 0.6 huyết thanh, chất đạm < 0,5 huyết thanh, đường trong 0.6 đến 0.8 huyết thanh, pH 7,60.• Phù transudative: thay đổi của thủy tĩnh và/hoặc oncotic các yếu tố đó làm tăng sự hình thành và/hoặc giảm huyệt của màng phổi chất lỏng.o CHF: tăng áp lực tĩnh mạch và phù nề phổio gan xơ gan và nephrotic hội chứng: hypoalbuminemiao bệnh ác tính: xâm nhập/tắc nghẽn của Mao mạch màng phổi và/hoặc hệ bạch huyết (lên đến 10% của ác tính effusions là transudative)• Exudative phù: hoặc trực tiếp hoặc cytokine gây ra sự gián đoạn của màng màng phổi bình thường và/hoặc mạch máu dẫn đến tăng tính thấm mao mạch.o Infection/pneumoniao Malignancyo Inflammatory disease (i.e., SLE or RA)o Trauma/surgeryo Pulmonary embolus• Fluid markers of pleural infection, inflammation, and/or obstruction often coexist.o Low glucose and pH levels Byproducts of microorganism and/or inflammatory cell metabolism Decreased acid removal due to pleural disruption from inflammation or malignancyo High LDH level Cell turnover and lysisDIAGNOSISThe clinical setting, combined with pleural fluid analysis, is crucial to establishing a proper diagnosis.Clinical PresentationSymptoms and signs may be directly related to the pleural effusion itself, and/or to any underlying disease process.History• Dyspnea due to abnormal pulmonary mechanics: most common symptom, usually develops with greater than 500 to 1000 mL of pleural fluid, but may not correlate• Often asymptomatic• Pleurisy or referred chest/back/shoulder pain from pleural inflammation• Should include survey of potential underlying causesPhysical Examination• Vital signs: Assess for fever, hemodynamic instability, hypoxemia.• Chest exam: Dullness to percussion, decreased breath sounds, and tactile fremitus.o These signs are more sensitive with larger effusions, but the chest exam is often unreliable and should not be used solely to diagnose and approximate size (Clev Clin J Med 2008;75:297).• A thorough system-based exam should evaluate for CHF, malignancy, pneumonia, hepatic cirrhosis, venous thrombosis, and other potential causes of pleural effusion.Diagnostic Criteria• Analysis of pleural fluid obtained by thoracentesis is the mainstay of diagnosing an etiology.• Transudate: Presence of ALL of Light's criteria (Ann Intern Med 1972; 77:507).o Fluid: serum protein ratio < 0.5o Fluid: serum LDH ratio < 0.6o Pleural fluid LDH < 0.67 of upper limit of normal for serum LDH• Exudate: Presence of ANY of Light's criteria (Ann Intern Med 1972;77:507).• Pseudo exudate: An effusion that meets one or more of Light's criteria, but is actually a transudate.o Usually due to diuretic-treated CHF, cirrhosis, or nephrotic kidney disease.o Serum to pleural fluid albumin gradient is >1.2• Simple parapneumonic effusion: a sterile, small (encompassing less than one-half the hemithorax), free-flowing pleural effusion in the setting of pneumonia, with pH > 7.20 and glucose > 60 mg/dL• Complicated parapneumonic effusion: ANY one of the following (Chest 2000; 118:1158):o Large (encompassing more than one-half of the hemithorax), free-flowingo Effusion of any size with loculationso Thickened parietal pleura on chest CTo Positive gram stain or cultureo pH < 7.20 or glucose < 60 mg/dL• Empyema: gross pus in the pleural space or positive gram stain. Positive culture is NOT required for diagnosis (high false-negative rate).Differential DiagnosisSee Table 27.Diagnostic Testing• Pleural effusion is detected by chest imaging and characterized through sampling by thoracentesis.• All parapneumonic effusions, and new, undiagnosed effusions should be sampled.Laboratories• Pleural fluid (Table 27):o Note color and consistencyo Chemistries: Protein, albumin, LDH, glucose, pHo Cell count with differentialo Hematocrit if suspicion for hemothorax (> 0.5 of serum is diagnostic)o Microbiologic stains and culture per suspiciono Cytology (yield approximately 60%)o Consider triglyceride, amylase, ADA as indicated• Serum: CBC, CMP, LDH, urinalysis, coagulation studies, BNP• Additional labs guided by suggestion of underlying illnessElectrocardiographyAssess for structural heart disease. Otherwise usually nonspecific and noncontributory.Imaging• Standard upright PA/lateral CXR:o Diagnostic for a suspected pleural effusion and approximates size (Radiology: Diagnosis, Imaging, Intervention. Lippincott, 2000:1). 75 mL obscures the posterior costophrenic sulcus 175 mL obscures the lateral costophrenic sulcus 500 mL obscures the entire diaphragmatic contour 1,000 mL reaches the level of the anterior 4th ribo Helps suggest associated conditions (CHF, pneumonia).• Lateral decubitus radiograph:o Demonstrates fluidity.o Usually amenable for thoracentesis if fluid layers to >1 cm.• Thoracic ultrasonography:o Accurate and practical in detecting loculations.o Provides real-time guidance for thoracentesis or thoracostomy tube placement, reducing complication rates.• Chest CT with contrast:o Helpful in distinguishing fluid from lung mass, atelectasis, pneumonia, or suggesting hemothorax.o Defines and characterizes pleural loculations, thickening, nodularity, or other abnormalities.Table 27 Clues to Diagnosing the Cause of a Pleural Effusion Based on Fluid AnalysisGross appearance• Clear/serous/light yellow: Transudate of any etiology (cardiac, liver, kidney disease)Urinothorax (consider if smells like ammonia)• Bloody/serosanguineous: Hemothorax (surgery/trauma); PE; malignancy• Purulent/turbid/brown: Infectious/empyema; esophageal rupture• Milky/white: Chylothorax (lymphatic disruption from malignancy, thoracic duct injury, LAM, filariasis, others)Nucleated cells• Total > 50k, neutrophilia: Infectious/empyema• Total < 5k: Transudate of any etiology; chronic malignant; tuberculous• Lymphocytosis (>85%): Tuberculous; lymphoma; chronic rheumatoid; sarcoid; pseudo exudates• Eosinophilia (>10%): Pneumothorax; hemothorax; fungal; parasitic; meds; malignancy; benign asbestos effusion• Mesothelial cells (>5%): Normal; transudate Excludes tuberculous pleurisyChemical analysis• Elevated protein: >3 g/dL: Most exudates; pseudo exudates (serum-fluid albumin gradient >1.2 g/dL)• >4: Tuberculous• >7-8: Blood cell dyscrasias• Elevated LDH: >1,000 IU/L: Empyema; rheumatoid; paragonimiasis; high burden malignant• Fluid:serum ratio >1: Pneumocystis or urinothorax
• Glucose < 60 mg/dL: Infectious/empyema; rheumatoid; lupus; tuberculous; esophageal rupture; malignant
• pH < 7.3: Infectious/empyema; rheumatoid; lupus; tuberculous; esophageal rupture; high burden malignant
• Elevated amylase (>serum): Pancreatitis; esophageal rupture; malignant
• Adenosine deaminase > 50 U/L: Tuberculous (unlikely if level < 40)
• Triglycerides >110 mg/dL: Chylothorax

Diagnostic Procedures
• Thoracentesis: can be performed safely at the bedside on effusions layering >1 cm on lateral decubitus CXR.
o Complicated/organized effusions should be accessed using real-time ultrasound or CT guidance.
o Optimize hemostasis: PT/PTT < 2× normal, Platelets > 25k, Cr <6 (Transfusion 1991;31:164).
o Microbiologic studies of a parapneumonic effusion may be falsely negative after antibiotic administration.
o Repeat thoracentesis increases diagnostic yield.
o Cytology for malignancy positive up to 60%, but probably not dependent on fluid volume obtained (Chest 2002;122:1913).
o AFB stain and culture sensitivity < 30% (Chest 2007;131:880).
• Closed pleural biopsy: performed by transthoracic needle approach.
o Indicated for the undiagnosed, suspected tuberculous or rheumatoid effusion.
 Sensitivity > 80% when combined with pleural fluid AFB stain and culture since tuberculous pleuritis is usually diffuse (Chest 1997;112:702).
o Consider for the undiagnosed, suspected malignant effusion
 Obtaining four to six consecutive samples from a locally thickened pleura (as seen on chest CT), may offer diagnostic yields > 50%, and up to >70% when combined with fluid cytology (J Bronchol 1998;5:327; Chest 2006;129:1549).
• Thoracoscopic pleural biopsy: performed under direct pleural visualization.
o Indicated for the undiagnosed suspected malignant effusion.
o Diagnostic yield is >70% to 90% (Ann Intern Med 1991;114:271; ANZ J Surg 2006;76:722).
TREATMENT
• Transudates: usually resolve with treatment of the underlying cause (heart failure, hepatic disease, nephrotic syndrome).
o Therapeutic thoracentesis as indicated for persistent larger effusions.
o Uncommonly, more aggressive measures including pleurodesis, shunts, or placement of a chronic indwelling pleural catheter are indicated for comfort or palliation.
• Simple/uncomplicated parapneumonic effusion: antibiotics and close observation.
• Complicated parapneumonic effusion and empyema (Fig. 6): antibiotics and early thoracostomy tube drainage to avoid inflammatory adhesion and organization (Chest 2000;118:1158).
o Antibiotics should also target anaerobic organisms as they often complicate empyema (Lancet 1974;1:338; Chest 1993;103