Parapneumonic Effusions and Empyema Journal Club Preethi Yeturu and Navneesh Sharma February 18, 2009

Pleural Effusions Abnormal accumulation of fluid in the pleural space due to a disruption of the equilibrium across pleural membranes Normal pleural fluid clear ultrafiltrate of plasma pH 7.6 - 7.64 Protein content <2%, WBC <1000 LDH <50% of plasma LDH Two types Transudate Exudate

Transudate Increased capillary hydrostatic pressure or decreased colloid oncotic pressure Pleural membranes intact Permiability of capillary membranes normal Fluid is an ultrafiltrate of plasma Causes CHF Cirrhosis Nephritic syndrome

Exudate Altered permeability of pleural membranes and capillaries or obstruction of lymphatic drainage of pleural space Light’s criteria: one or more of following must be present Pleural fluid/serum protein >0.5 Pleural fluid/serum LDH>0.6 Pleural fluid specific gravity >1.018 Causes Parapneumonic TB Malignancy PE

Parapneumonic Effusions Any pleural effusion associated with bacterial pneumonia, lung abscess or bronchiectasis Most common cause of exudative pleural effusions in US 40-60% of bacterial pneumonias result in pleural effusions Three types Uncomplicated parapneumonic effusion Complicated parapneumonic effusion Empyema

Uncomplicated Effusions Parenchymal infection leads to increased interstitial fluid that causes accumulation of sterile pleural effusion Pleural fluid is often small (<10mm) sterile w/ small amount of PMNs glucose and pH wnl Resolve with resolution of pneumonia and treatment w/ antibiotics

Complicated Effusions Persistent bacterial infection of previously sterile pleural fluid Pleural fluid Many PMNs, bacteria and cell debris Acidosis - pH and glucose decrease LDH increases Possible deposition of fibrin on pleura - formation of multiple locules

Empyema Characterized by bacteria seen on gram stain or aspiration of pus 60% from complicated parapneumonic effusions 20% after thoracic surgery Pleural fluid Possible formation of pleural peel that can encase the lung and hinder reexpansion

Clinical Manifestations History Acute febrile episode Dyspnea Cough - w/ purulent sputum Pleuritic chest pain Weight loss Physical exam Dullness to percussion Diminished breath sounds in affected hemithorax Decreased tactile fremitus Egophony Pleuritic friction rub

Diagnosis - Imaging CXR blunting of costrophrenic angle on upright films Lateral decubitus films - better view of subpulmonic effusions, show if effusion is freely-flowing, thickness of effusion

Diagnosis - Imaging CT - w/ IV contrast is optimal Allow for differentiation betwn parenchymal and pleural disease Contrast enhances pleural surface

Diagnosis Thoracentesis Sample if any of following are present Free flowing but >10mm in lateral decubitus film Loculated Associated w/ thickened parietal pleura on CT - suggests empyema Complications - pain, bleeding, pneumothorax, puncture of liver or spleen

Analysis of Pleural Fluid Gross examination for color, turbidity and odor Microbiology - gram stain and cultures pH or glucose, LDH, protein CBC w/ differential

Analysis of Pleural Fluid Characteristics of Pleural Fluid   Simple parapneumonic effusion Complicated parapneumonic effusion Empyema Appearance May be slightly turbid Cloudy Pus Biochemical markers pH >7.30 pH <7.20 n/a LDH maybe slightly elevated LDH >1000 IU/L Glucose >60 mg/dL or pleural/serum ratio >0.5 Glucose <35 mg/dL Nucleated cell count Neutrophils usually <10,000 cells/μL Neutrophils + + (usually >10,000 cells/μL) Microbiology: Gram stain Negative May be positive Microbiology: culture

Categories risk for poor outcomes Pleural Space Anatomy   Pleural Fluid Bacteriology Pleural Fluid Chemistry Category Risk of Poor Outcome Drainage A0: Minimal, free-flowing effusion (<10 mm on lateral decubitus) and Bx: Culture and Gram stain results unknown Cx: pH, glucose unknown 1 Very low No A1: Small to moderate free-flowing effusion (>10 mm and <½ hemithorax) B0: Negative culture and Gram stain C0: pH ≥ 7.20, glucose > 60 mg/dL 2 Low A2: Large, free-flowing effusion (≥½ hemithorax), loculated effusion, or effusion with thickened parietal pleura or B1: Positive culture and Gram stain C1: pH < 7.20, glucose < 60 mg/dL 3 Moderate Yes B2: Pus 4 High

Treatment Depends on type and category of effusion Uncomplicated - category 1 or 2 Resolves w/ antibiotic treatment alone Does not need drainage Complicated - category 3 Variable response to antibiotics alone - thus often treated like empyema Empyema - category 4 Requires complete drainage Goal of therapy: Sterilization of cavity - antibiotics for 4-6 weeks Complete drainage as evidenced by minimal chest tube output and CT documentation that no residual loculations persist Obliteration of empyema cavity w/ adequate lung expansion

Drainage of Effusion Theurapeutic thoracentesis Tube thoracotomy Often left until rate of drainage <50mL/day and cavity is closed W/ fibrinolytics - intrapleural administration was suggested for loculated effusions Reported data does not demonstrate benefit in most pts Thoracoscopy Alternative treatment for multiloculated empyema Open thoracostomy Open drainage at inferior border of empyema cavity w/ chest tube Preferred in pts who cannot tolerate thoracotomy

Drainage of Effusion Thoracotomy w/ decortication For pts who require additional drainage after trial of tube thoracostomy and thoracoscopy Or pt who have fibrin deposition that hinders ability of lung to expand

Thank you!!