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Empyema and complicated parapneumonic effusion
An effusion next to pneumonia that is purulent, has a pH below 7.2, or has a positive Gram stain or culture must be drained; if drainage and antibiotics are not enough, tPA and DNase are added into the pleural space, and if that also fails — VATS with decortication.
Why it matters in the exam
Questions on this topic test three decisions: when to drain, what to do when drainage is not working, and when to operate. Empyema passes through three stages: exudative (free fluid), fibrinopurulent (septations and pus) and organising (a thick peel that traps the lung). In the first stage antibiotics alone usually suffice, in the second drainage is needed and sometimes intrapleural agents, and in the third decortication is required. Signs of a complicated effusion that needs drainage: pus on aspiration, pH below 7.2, a positive Gram stain or culture, septations on ultrasound or a large effusion. Low glucose and high LDH support the diagnosis, but pH is the central measure according to BTS.
Antibiotics must also cover anaerobes (for example amoxicillin with clavulanate, or ceftriaxone with metronidazole), and usually last several weeks; aminoglycosides penetrate the pleural space poorly. When drainage is incomplete and there are septations, the MIST2 trial (2011) showed that the combination of tPA 10 mg with DNase 5 mg, twice daily for 3 days, improves drainage and reduces surgical referral; each agent alone did not help. If after 5–7 days of treatment the patient is still septic or the space has not cleared — VATS with debridement and decortication, and in the organising stage with a trapped lung sometimes thoracotomy. In a frail patient unfit for surgery an open chest window (Eloesser) can be made.
The RAPID score (urea, age, purulence, source of infection and albumin) estimates prognosis and helps identify high-risk patients. It is also important to think of a cause other than pneumonia — oesophageal perforation, a subphrenic abscess or post-operative infection — when the picture is atypical.
Key points
- Pus, pH below 7.2, positive Gram stain or culture — drain.
- Anaerobic cover in the antibiotics.
- MIST2: tPA with DNase.
- Failure after 5–7 days — VATS.
- Organising stage — decortication.
Summary table
| Stage | Findings | Treatment |
|---|---|---|
| Exudative | Free fluid, pH 7.2 or more | Antibiotics; monitoring |
| Fibrinopurulent | Septations, pH below 7.2, positive Gram stain or culture | Drain and antibiotics; tPA with DNase if drainage is partial |
| Organising | Thick peel, trapped lung | VATS or thoracotomy with decortication |
| Frail patient | Chronic empyema | Open chest window (Eloesser) |
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Sources
- BTS Guideline for Pleural Disease, 2023 — Pleural infection
- AATS consensus guidelines for the management of empyema, 2017 — Recommendations
- Rahman et al., MIST2, N Engl J Med, 2011 — Intrapleural use of tissue plasminogen activator and DNase in pleural infection
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-06. The text may contain errors; when in doubt, check the source.