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Empyema

Development

• The development of an empyema associated with pneumonia is a progressive process classified in three stages.
  • Initially, there is a free-flowing exudate with a normal pH termed a simple parapneumonic effusion.
  • This progresses to a fibrinopurulent stage with increasing fluid and bacterial invasion causing a decrease in pH.
  • If the fluid is clear but the pH <7.2, this is termed a complicated parapneumonic effusion while frank pus is termed an empyema.
  • The third stage is an organizing stage with the formation of a solid fibrous peel.
• Streptococcal species account for 50% of positive cultures with the other 50% comprising Staphylococcus species, anaerobes, and gram-negative organisms.

Indication for Drainage

• Frankly purulent or turbid/cloudy fluid
• Presence of organisms identified by gram stain+culture in non-purulent pleural fluid pH <7.2 with suspected infection
• Loculated pleural collection
• Poor clinical progress with antibiotics alone

Considerations for Thoracic Anesthesia

Problem	Surgical Options	Airway Management	Single-Lung Ventilation Required	Immediate Lung Isolation Required (i.e. Risk of Soiling)	Suggested Postop Analgesia
Empyema with no recent thoracic surgery	Rib resection and drainage	SLT or DLT/bronchial blocker (in extremis LA + sedation possible)	No	No	Intercostal block and PCA
	VATS	DLT or bronchial blocker	Yes	No	Intercostal block and PCA
	Thoracotomy and decortication	DLT or bronchial blocker	Yes	No	Epidural* or intercostal block and PCA
Empyema with recent thoracic surgery—potential BPF	Drainage (through old thoracotomy scar, new incision or VATS)	DLT	Yes	Yes	PVC and PCA or epidural*
Lung abscess	Drainage	DLT	Yes	Yes	Intercostal block and PCA
	Lobectomy	DLT	Yes	Yes	PVC and PCA or epidural*

1. PFT, CPET may be misleading if the patient has acutely deteriorated.
2. Problems encountered with lung isolation should have been documented if the patient has undergone thoracic surgery previously.
3. The main questions that need answering during the assessment are:
   • Is there a BPF?
     • The potential presence of a BPF is very important.
     • If the pleural fluid is in communication with the airways, this can cause two problems.
       • First, positive pressure ventilation may result in failure to ventilate the unaffected lung and potentially cause a tension pneumothorax around the affected lung.
       • Secondly, soiling of the unaffected lung is a real risk causing a significant morbidity.
     • A good rule of thumb is that any patient who has had recent thoracic surgery has a BPF unless proved otherwise. Lung isolation before positive pressure ventilation is an absolute indication in BPF.
     • Techniques to secure the unaffected lung are widely debated and include gas induction, awake fibreoptic intubation, and, most commonly, rapid sequence induction. A DLT rather than a bronchial blocker is preferred as suctioning is easier and large volumes of pus can dislodge a blocker, particularly during surgical manipulation.
   • Will lung isolation facilitate surgery?
     • Single-lung ventilation (in the absence of a BPF) to facilitate surgery is a relative indication for lung isolation. Surgical access is usually improved if the operative lung is deflated and not moving.
     • However, this is not always the case with empyema due to adhesions and pleural thickening. Importantly, single-lung ventilation will result in a shunt, compromising oxygenation, compounding any existing hypoxaemia, and, therefore, may not be tolerated. As such, this decision must be taken in the context of the patient’s overall status and discussion with the surgeons
   • What are the options for analgesia?
     • Thoracic epidural analgesia is the ‘gold standard’ for post-thoracotomy pain relief, but paravertebral blocks, with the insertion of a paravertebral catheter (PVC), are gaining in popularity.
       • PVCs have the advantage that they only cause a unilateral block. This means that arterial pressure is maintained due to less sympathetic block, urinary catheters can be avoided, and motor weakness is minimized, allowing early mobilization. Avoiding hypotension prevents the inevitable fluid boluses and associated risk of pulmonary oedema.
       • The disadvantage of PVCs is that they often do not provide sufficient analgesia alone and require the addition of opiates, usually in the form of a patient-controlled analgesia (PCA) device. The anterior boundary of the paravertebral space is the parietal pleura. Paravertebral block, therefore, is not suitable when the parietal pleura has been (or will be) removed (decortication).

Physiological Changes of Lateral Decubitus Position

• 1. Awake: V/Q is preserved ← Dependent Lung (DL) is ventilated more due being on a more favourable part of the curve and more efficient contraction of its hemidiaphragm
• 2. Asleep: V/Q mismatch ← ↓ FRC moves both lungs lower on the compliance curve ⇒ Non-Dependent Lung (NDL) is now on a more favourable part → V̇ > Q̇
• 3. PPV: V/Q worsens
• PPV favours NDL due to better compliance (path of lowest resistance)
• NMB forces abdominal contents against DL hemidiaphragm
• DL hemidiaphragm movement is further restricted by bean bag
• Open chest accentuates differences in compliance (NDL is now unrestricted)

Links

• One lung Ventilation and VATS
• Double lumen and Bronchial blocker

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References:

1. Walters, J., Foley, N., & Molyneux, M. (2011). Pus in the thorax: management of empyema and lung abscess. Continuing Education in Anaesthesia Critical Care &Amp; Pain, 11(6), 229-233. https://doi.org/10.1093/bjaceaccp/mkr036

Summaries:
OLV

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© 2025 Francois Uys. All Rights Reserved.

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