Pearl of the Day: Empyema

Empyema Background - pleural space infection with pus, positive Gram stain/culture, or parapneumonic effusion - predisposing factors: aspiration pneumonia, respiratory disease impairing ciliary function, alcoholism, malignancy, immuncompromise

Causes and Common Organisms - pneumonia -> Streptococcus pneumoniae, Staphylococcus aureus, Haemophilus influenza - lung abscess, esophageal rupture -> mixed oropharyngeal anaerobes - thoracotomy -> Gram-negative bacilli - immunocompromised pneumonia -> tuberculosis, fungal infections - chest trauma -> S. aureus, Gram-negative bacilli - contiguous abdominal infection -> Gram-negative bacilli, anaerobes

Signs/Symptoms - unresolving fever, cough, dyspnea, pleuritic chest pain, malaise - weight loss, night sweats, anemia - decreased tactile fremitus, friction rub, dullness to percussion

Diagnosis - diagnostic criteria: aspiration of grossly purulent material on thoracentesis and at least one of the following: thoracentesis fluid with positive Gram stain or culture, pleural fluid glucose < 40 mg/dL, pH < 7.1, or LDH > 1000 IU/L

Stages of Disease 1. Exudative: <48 hours, free-flowing pleural effusion amenable to chest tube drainage 2. Fibrinopurulent: fibrin strands form in pleural fluid -> loculations; chest tube drainage is unlikely 3. Organizational: several weeks later; extensive fibrosis with "pleural peel" that restricts lung expansion

Treatment - treat underlying cause - definitive treatment: drainage + antibiotics - respiratory or cardiac distress -> thoracentesis - recommended antibiotics: piperacillin/tazobactam 3.375 - 4.5 g IV q6h or imipenem 0.5 - 1 g IV q6h - may add vancomycin for increased risk of MRSA (e.g., patients recently hospitalized, invasive medical device, from long-term healthcare facility, in contact sports, live in unsanitary conditions) - exudative empyema -> chest tube thoracostomy with antibiotics +/- intrapleural fibrinolytic agents if in fibrinopurulent stage - loculated empyema -> video-assisted thoracoscopic surgery - organizational stage -> surgical removal of fibrous peel

Resources Tintinalli's Emergency Medicine, 8th Edition