Complicated Parapneumonic Effusion

A parapneumonic effusion in which bacteria have invaded the pleural space, with pH less than 7.2, glucose less than 2.2 mmol/L, LDH greater than 1000 U/L, positive Gram stain or culture, loculation, or frank pus (empyema). It is the fibrinopurulent stage of pleural infection.

• Pleural infection affects about 8 to 10 per 100,000 adults per year and is rising; it complicates about 5 to 10% of pneumonias requiring admission, more in children. It is more common in men, in the elderly, and with diabetes, alcohol misuse, aspiration risk, immunosuppression, injection drug use and HIV.
• Organisms: Streptococcus pneumoniae, Streptococcus anginosus group (milleri), Staphylococcus aureus (including methicillin resistant strains), anaerobes (Fusobacterium, Prevotella), Gram negative bacilli (Klebsiella, Escherichia coli, Pseudomonas in hospital acquired disease), and Mycobacterium tuberculosis in endemic settings. Many cases are polymicrobial; about a third have negative cultures.
• Mortality is about 10 to 20% (up to 30 to 40% with hospital acquired infection and severe comorbidity). About 20 to 30% need surgery. Risk of death and surgery is predicted by urea, albumin, age, purulent fluid, non-community acquisition, malignancy and a low pleural pH.

• Fever that persists or recurs despite antibiotics, sweats, malaise, weight loss, pleuritic pain, cough, breathlessness; indolent presentations are common in older patients and alcohol users.
• Signs: stony dullness with absent breath sounds, tachycardia, toxicity, tender chest wall; empyema necessitans (subcutaneous swelling that discharges pus) in neglected cases.
• Differential diagnosis: simple parapneumonic effusion, tuberculous empyema, malignant effusion with infection, lung abscess, subphrenic abscess, haemothorax, chylothorax, oesophageal rupture (low pH with amylase), pancreatitis related effusion, and pyopneumothorax.
• Complications: sepsis, septic shock, trapped lung and fibrothorax, bronchopleural fistula, chronic empyema, empyema necessitans, osteomyelitis of the ribs, pericarditis, mediastinitis, metastatic abscess, and death.

• Ultrasound (echogenic fluid, septations, thick pleura) and contrast CT chest (split pleura sign, loculation, underlying parenchymal disease, abscess, tumour or fistula).
• Thoracentesis: pus or turbid fluid, pH less than 7.2 (use a blood gas syringe), glucose less than 2.2 mmol/L, LDH greater than 1000 U/L, protein, cell count, Gram stain, culture in blood culture bottles (inoculate at the bedside to raise yield), acid fast smear, Xpert MTB/RIF, adenosine deaminase, amylase and cytology.
• Blood tests: full blood count, CRP, urea (greater than 5 mmol/L is a marker of poor outcome), albumin (less than 27 g/L), creatinine, glucose, blood cultures, HIV test.
• Sputum culture, bronchoscopy for obstruction or foreign body when the cause is unclear, and swallow assessment in aspiration.

• Antibiotics IV at once (adjust to culture; at least 2 to 3 weeks IV, then oral to a total of 4 to 6 weeks, guided by drainage and clinical response):
  • Community onset: ceftriaxone 2 g IV daily plus metronidazole 500 mg IV every 8 hours, or co-amoxiclav 1.2 g IV every 8 hours, or ampicillin sulbactam 3 g IV every 6 hours.
  • Add vancomycin 15 to 20 mg/kg IV every 8 to 12 hours (trough 15 to 20 mg/L) or linezolid 600 mg every 12 hours for methicillin resistant Staphylococcus aureus; flucloxacillin 2 g IV every 6 hours for methicillin susceptible Staphylococcus aureus.
  • Hospital onset or Pseudomonas risk: piperacillin tazobactam 4.5 g IV every 6 to 8 hours or meropenem 1 g IV every 8 hours.
  • Penicillin allergy: levofloxacin 750 mg IV daily plus metronidazole 500 mg every 8 hours, or clindamycin 600 mg IV every 8 hours.
  • Avoid aminoglycosides (poor penetration in an acid pleural space). Oral step down: co-amoxiclav 625 mg three times daily, or clindamycin 300 to 450 mg four times daily with ciprofloxacin 500 to 750 mg twice daily when Gram negative organisms are involved.
• Drainage:
  • Insert an ultrasound guided chest drain without delay: small bore 10 to 14 French with saline flushes (20 to 30 mL every 6 to 8 hours), or 24 to 28 French for very thick pus, connected to an underwater seal with suction at 10 to 20 cmH2O. Place the tip dependent in the largest collection; add a second drain for separate loculations.
  • Intrapleural alteplase 10 mg plus dornase alfa 5 mg (each in 30 to 50 mL saline, instilled together, clamped for 1 hour) twice daily for 3 days (6 doses), started within 48 hours of drain placement if drainage is poor. Do not use alteplase alone; monitor for pleural bleeding (stop with haemorrhage), and avoid in a large bronchopleural fistula or anticoagulated patients.
  • Remove the drain when output is less than 50 to 100 mL/day of clear fluid, the patient is afebrile, CRP is falling and the lung is expanded.
• Surgery:
  • Video assisted thoracoscopic debridement or decortication when there is no improvement after 5 to 7 days of drainage and fibrinolytics (persistent fever, high CRP, residual collection greater than one quarter of the hemithorax on CT), or primary surgery for large loculated empyema in a fit patient.
  • Open thoracotomy for failed thoracoscopy, thick peel or chronic empyema (greater than 6 weeks); open window thoracostomy (Eloesser flap) or muscle flap and thoracoplasty for chronic empyema in unfit patients.
  • Operative mortality about 2 to 5%; success of thoracoscopic debridement about 80 to 90%.
• Tuberculous empyema: rifampicin 10 mg/kg (maximum 600 mg), isoniazid 5 mg/kg (maximum 300 mg), pyrazinamide 25 mg/kg (maximum 2 g) and ethambutol 15 mg/kg (maximum 1.2 g) daily for 2 months, then rifampicin and isoniazid for 7 months or longer, with pyridoxine 25 to 50 mg daily, plus drainage and decortication when needed; in HIV start antiretroviral therapy within 2 to 8 weeks with dolutegravir 50 mg twice daily during rifampicin.
• Supportive care: oxygen, IV fluids, vasopressors for septic shock (noradrenaline 0.05 to 0.5 micrograms/kg/min), analgesia (paracetamol 1 g four times daily, morphine 2.5 to 5 mg, intrapleural lidocaine 3 mg/kg, maximum 250 mg, before drain flushing when needed), nutrition (30 to 35 kcal/kg/day and 1.2 to 1.5 g/kg/day of protein), enoxaparin 40 mg SC daily, physiotherapy, and control of diabetes.
• Special groups:
  • Children: ceftriaxone 50 to 100 mg/kg/day (maximum 4 g) with clindamycin 10 to 13 mg/kg every 8 hours or flucloxacillin 50 mg/kg every 6 hours; early thoracoscopic debridement or intrapleural urokinase 40,000 units in 40 mL saline (10,000 units in 10 mL under 1 year) twice daily for 3 days (evidence is limited).
  • Pregnancy: ceftriaxone, ampicillin sulbactam, or piperacillin tazobactam; avoid fluoroquinolones, tetracyclines and, where possible, metronidazole in the first trimester.
  • HIV and immunosuppression: test for tuberculosis and fungi; broader antibiotic cover.
  • Renal impairment: adjust vancomycin, piperacillin tazobactam and levofloxacin; avoid NSAIDs.
• Red flags: sepsis, persistent fever beyond 5 to 7 days, falling pleural pH, large fistula, bleeding after fibrinolytics, empyema necessitans.
• Follow up: daily review in hospital; chest X-ray at discharge, 2 weeks and 6 to 12 weeks; CT if residual thickening or collection persists; assess for underlying cancer, immunodeficiency, or aspiration.