Empyema (Pleural Empyema)

What happens in empyema

The lungs are covered by a thin membrane (pleura), and the chest wall is lined by another. Between them is a small amount of fluid that lets the lungs glide as you breathe. In pneumonia, inflammation often causes extra fluid to collect: a parapneumonic effusion. Most of these are sterile and resolve with antibiotics. If bacteria invade the fluid, it becomes infected and thick. Doctors describe three stages:

1. Exudative stage: thin, free-flowing fluid.
2. Fibrinopurulent stage: bacteria and white cells multiply; fibrin strands form pockets (loculations) that trap fluid.
3. Organizing stage: a thick peel forms over the lung, which can stop it expanding (trapped lung).

Once there is frank pus, or bacteria are found in the fluid, it is called empyema.

Causes and risk factors

• bacterial pneumonia, the most common cause (Streptococcus pneumoniae, Staphylococcus aureus, Streptococcus anginosus group and anaerobes)
• aspiration of mouth contents, with poor dental health, alcohol use, reduced consciousness or swallowing problems
• chest surgery, trauma or a chest tube
• lung abscess rupturing into the pleural space
• esophageal perforation
• tuberculosis, which causes a slower, chronic empyema
• risk factors: diabetes, COPD, older age, immunosuppression, injection drug use

Symptoms

• fever, chills and night sweats, often persisting or recurring despite antibiotics
• sharp chest pain on one side, worse with deep breaths or coughing
• cough, sometimes with foul-smelling sputum
• shortness of breath
• fatigue, loss of appetite and weight loss
• reduced breath sounds on one side when a doctor listens

In children, empyema typically follows pneumonia with ongoing fever and breathing difficulty.

Empyema vs pleural effusion

A pleural effusion is any fluid around the lung, and has many causes, such as heart failure, cancer and pneumonia. Empyema is an infected effusion containing pus. Testing the fluid tells them apart:

Diagnosis

• chest X-ray: shows fluid
• ultrasound: shows fluid volume, loculations, and guides needle sampling
• CT scan with contrast: shows thickened pleura (the "split pleura" sign) and underlying lung disease
• thoracentesis: a needle draws fluid for pH, glucose, LDH, Gram stain and culture
• blood tests: white cell count, CRP and blood cultures

Treatment

Antibiotics

IV antibiotics covering the likely bacteria, including anaerobes, followed by oral antibiotics. The total course is typically several weeks, guided by response.

Drainage

• Chest tube (thoracostomy): a tube placed between the ribs drains the pus, often under ultrasound or CT guidance.
• Intrapleural fibrinolytics: tissue plasminogen activator (tPA) with DNase, given through the chest tube, breaks down fibrin pockets and thick pus, improving drainage and reducing the need for surgery.

Surgery

If drainage fails, or the lung is trapped:

• video-assisted thoracoscopic surgery (VATS): keyhole surgery to clear pus and break down pockets
• decortication: peeling the thick layer off the lung so it can re-expand, sometimes via open surgery (thoracotomy)

Complications

• sepsis
• trapped lung with long-term reduced lung function
• bronchopleural fistula, an abnormal connection between the airway and pleural space
• empyema necessitans, where pus tracks through the chest wall
• prolonged hospital stay

Outlook

Most people recover fully with drainage and antibiotics, although recovery can take weeks to months and chest X-ray changes may persist for some time. Outcomes are worse in older adults and those with serious other illnesses. Children usually recover completely.

Prevention

• pneumococcal and annual flu vaccines
• prompt treatment of pneumonia, and returning for review if not improving
• good dental hygiene
• reducing alcohol and stopping smoking

Frequently asked questions

What is empyema?

Empyema is a collection of pus in the pleural space between the lung and the chest wall. It is usually a complication of pneumonia and causes fever, chest pain and breathlessness. It needs drainage and antibiotics.

What causes empyema?

Most cases follow bacterial pneumonia, when infected fluid collects next to the lung. Other causes include chest surgery or injury, a ruptured lung abscess, aspiration, a torn esophagus and tuberculosis.

How is empyema treated?

Treatment is IV antibiotics plus drainage with a chest tube. Clot-dissolving medicines can be given through the tube to break up pockets of pus. Keyhole surgery (VATS) or decortication is needed if drainage does not work.

How long does it take to recover from empyema?

Hospital stay is often 1 to 2 weeks, followed by several weeks of oral antibiotics. Energy and breathing usually return over 1 to 3 months. Follow-up chest imaging checks that the lung has re-expanded.