Journal Reading

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Journal Reading

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Parapneumonic Effusions and Empyema

• John E. Heffner, M.D. and Jeffrey Klein, M.D.

Seminars in Respiratory and Critical Care
Medicine Vol 22, Number 6 2001
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Introduction

• Parapneumonic effusions
• Pleural effusions occur as a complication of
  pneumonia
• 20-60 hospitalized patient with
  community-acquired pneumonia have radiographic
  evidence of pleural effusion
• 5-10 cases follow a complicated course and
  required pleural drainage
• 5-20 mortality rate in general patient
  populations while progress to an empyema (70 in
  elderly pts)

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Pathophysiology

• Pleural fluid
• Produced from systemic capillaries at the
  parietal pleural surface (about 1L/day)
• Absorbed into pulmonary capillaries at the
  visceral pleural surface (subpleural lymphatics,
  about 20L/day)
• The amount of fluid remains in pleural space
  0.1-0.2 mL/Kg)

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Pathophysiology

• Exudate v.s Transudate (Light criteria)
• Protein (pf)/protein(serum)gt0.5
• LDH(pf)/LDH(serum)gt0.6
• LDH(pf)gt2/3 of the upper limit for serum LDH
• Lung infection adjacent to the pleurae
• Pleural membrane characteristics
• Promote mesothelial cell activation
• An inflammatory response

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Pathophysiology

• The 3 phases of empyema formation
• Exudative phase
• Antibiotic treatment is effective
• Pleural fluid is nonviscous, free-flowing
• Pleural membrane remain pliable and minimally
  inflamed.

• Fibrinopurulent phase
• May require a pleural fluid drainage
• Increasing viscosity of fluid, the formation of
  intrapleural loculations within thickened pleural
  membranes

• Organizing phase
• Surgical drainage
• The presence of pleural peels
• Thickened pleural membranes trap the lung and
  prevent successful lung reexpansion with chest
  tube drainage alone

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Detection of Parapneumonic Effutions
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Detection of Parapneumonic Effutions

• Chest 2 Views
• May be normal with 200500 mL of pleural fluid.
• Subtle signs
• Absence of lung marking in the posterior sulcus
  on lateral views
• Flattening of medical portions of the diaphragm
• A hyperdence hemithorax with otherwise normal
  lung markings in supine AP views.

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Detection of Parapneumonic Effutions

• Chest CT
• Preferred if fluid is detected along the
  mediastinal regions of the pleurae
• Can detect esophageal of gastric perforation
• Contrast CTs hypervascular pleural membranes
• Chest Sono
• Can detect gt 5mL of pleural fluid
• Preferred when septae are suspected to exist
  within intrapleural fluid collections
• MRI only for pts who cannot undergo CT

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Diagnostic Thoracentesis

• Indication
• Free-flowing parapneumonic effusion gt 1 cm in
  thickness on decubitus views
• Loculated parapneumonic effusions
• Antibiotic treatment should not be delayed if the
  procedure cannot be performed quickly.

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Diagnostic Thoracentesis
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Diagnostic Thoracentesis

• Only 55-65 of pts with an empyema have a
  positive Gram stain finding.
• Injecting fluid samples into an anaerobic
  transport container rather than a liquid blood
  culture bottle.
• Keep sample at room temp

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Antibiotic Therapy

• Antibiotic treatment directed toward the
  underlying pneumonia until thoracentesis provide
  Gram stain evidence of the etiologic pathogen.
• In empyema, GM is not suitable (inactivated in a
  low PH environment).

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Antibiotic Therapy

• The duration of antibiotic treatment by the
  response of underlying pneumonia and the degree
  of pleural sepsis.
• Uncomplicated and complicated parapneumonic
  effusion
• The requirement of pleural drainage
• Treated with a course of antibiotics dictated by
  the pneumonia
• Empyema
• Antibiotic treatment until pleural infection is
  eradicated
• Actinomyces and Nocardia spp. prolonged anti tx.

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Staging a Parapneumonic Effusion

• The need for pleural fluid drainage
• The radiographic size of the effusion, the
  presence of loculations, the viscosity of the
  pleural fluid, the presence of pus, the results
  of pleural fluid microbiological and biochemical
  studies, the underlying etiologic pathogen, and
  the general condition of the patient.
• The presence of an air-fluid level in the pleural
  space is the only absolute radiographic
  indication for pleural fluid drainage a
  bronchopleural fistula or ruptured esophagus.
• Only 24 pts with parapneumonic effusion gt 40 of
  the hemithorax treated successfully with
  antibiotics alone.

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Staging a Parapneumonic Effusion

• Chest Sono findings
• Septated multiloculations
• Empyema (fibrin strands and necrotic debris in
  parapneumonic effusion)
• Chest CT findings
• Thickened pleural membranes (gt5mm)
• Multiple loculations
• Empyema (thickened extrapleural subcostal tissues
  and increased attenuation of extrapleural fat)

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Staging a Parapneumonic Effusion

• Pathogens
• Streptococcus pyogenes. Staphylococcus aureus,
  anaerobic pathogens, Klebsiella pneumonia.
• Streptoccus pneumoniae may treat with anti
  alone.
• Thoracentasis findings
• Pus (empyema)
• Positive pleural fluid Gram stain and culture
  (35 empyemas have negative results)

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Staging a Parapneumonic Effusion

• CBC/DC not useful (squamous cells a ruptured
  esophagus)
• PH?, Glu?, LDH? severe infection.
• Patient and pathogen-related factors defined
  risk.

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Staging a Parapneumonic Effusion

• A High risk patient
• Large effusion, loculations
• Advanced age, comorbid conditions
• A virulent pathogen (S. aureus, G(-) bacteria)
• Other cause of a low pleural fluid PH
• Tuberculous pleural effusions
• Pleural malignancy
• Rheumatoid pleurisy

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Staging a Parapneumonic Effusion
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Draining the Pleural Space

• Thoracentesis
• Chest Tube Drainage
• Image-guided Percutaneous Catheter Drainage
• Fibrinolytic Therapy
• Surgical Drainage

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Thoracentesis

• Exudative parapneumonic effusions have not yet
  become loculated or highly viscous
• May initiate pleural lavage with saline and
  antibiotics

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Chest Tube Drainage

• Success rates 5 to 78
• Exudative or early fibrinopurulent phase
• Multiple loculations or viscous pus surgical
  drainage
• Unlikely to benefit pts with CT evidence of
  anterior, paramediastinal, or apical fluid
  collections.
• Removal of tube
• No pleural fluid remains
• Drainage less than 50-100 mL/day
• Complication (5 mortality) misplacement,
  perforation of the lung, transdiaphragmatic
  placement with visceral damage.

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Image-guided Percutaneous Catheter Drainage

• Exudative or early fibrinopurulent phase
• Multiple loculations or viscous pus surgical
  drainage

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Fibrinolytic Therapy

• Lyse pleural adhesions and decrease the viscosity
  of pleural fluid for pts failing chest tube
  drainage may avoid surgery.
• Exudative or early fibrinopurulent phase
• No evidence for improvement in outcome.
• A recent clinical practice guideline by the
  American College of Chest Physicians
  fibrinolytic therapy for ALL patients undergoing
  chest tube drainage.
• Streptokinase and urokinase
• Streptokinase fever, Urokinase espensive
• Systemic fibrinolysis
• Avoiding for pts with brohchopleural fistulae.

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Surgical Drainage

• Video assisted thoracoscopy (VATS)
• Open thoracotomy

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Conclusion

• Early detection
• Early antibiotic treatment
• Early drainage

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Thanks For Your Attention !!