Description of the condition
Pleural empyema refers to pus in the pleural cavity and is a sequelae of bacterial seeding of the pleural space. Possible causes include complications from pneumonia, penetrating chest wall injury and thoracic procedures (Ferguson 1996). Pleural empyema is most commonly the result of pneumonia, with 20% to 57% of patients with pneumonia invariably developing parapneumonic effusion which can progress to pleural empyema (Sahn 2007). Parapneumonic effusion may resolve without further complications or progress to pleural empyema. The stages of progression are as follows: the initial exudative stage is characterised by a shift of pulmonary interstitial fluid into the pleural space from an increased capillary permeability. The second stage is the fibropurulent stage, where the pleural space becomes infected and loculation occurs. Lastly, organisation of the chronic inflammation results in proliferation of fibroblasts and a thickening of the pleural space, known as a pleural peel, can be seen on imaging (Light 2006). Clinically, the three stages can be referred to as uncomplicated parapneumonic effusion (UPPE), complicated parapneumonic effusion (CPPE) and pleural empyema respectively. UPPE usually resolves with antibiotic therapy alone but CPPE and empyema require additional interventions. The diagnosis of CPPE requires either positive pleural fluid biochemistry (pH < 7.2, glucose < 2.2 mM/L, lactate dehydrogenase (LDH) > 1000 IU/L) (Appendix 1), suggestion of pleural empyema on medical imaging examinations such as ultrasound or computed tomography (CT), or definitive diagnosis of positive culture or gram stain from pleural aspirate (Sahn 2007). This review will examine the available evidence for the optimal management strategy in the treatment of CPPE and pleural empyema. We will compare surgical options and minimally invasive non-surgical procedures and note potential complications from the different procedures.
Description of the intervention
Both surgical and non-surgical options are available for the management of pleural empyema. Surgical interventions include video-assisted thoracoscopic surgery (VATS) with adhesiolysis or open thoracotomy and decortication of the pleural space (Appendix 1). Non-surgical, minimally invasive procedures include thoracentesis and chest tube drainage, with or without the use of intrapleural fibrinolytics (Appendix 1). A description of these interventions is provided below. Both patient groups will be treated equally apart from the intervention, which means that patients will be on targeted antibiotic therapy based on microscopy, culture and sensitivity (Davies 2010).
Currently there is no consensus as to which patient groups will benefit from surgical intervention over management by minimally invasive procedures. VATS (Appendix 1) enables visualisation of the pleural cavity for drainage of pus and disruption of septations. A temporary chest tube is left in place for postoperative drainage of any re-accumulated effusions (Light 2006). Open thoracotomy involves making an incision into the chest wall to gain direct access to the chest cavity. This enables complete drainage of the empyema or CPPE and direct decortication (Light 2006). Complications of both VATS and thoracotomy include postoperative pneumothorax, intercostal neuralgia and anaesthetic risks (Yim 1996). There is potentially a higher risk of postoperative complications associated with open thoracotomy as it involves a much larger incision and longer operation (Jaffé 2003), hence VATS is the more commonly performed procedure in the surgical management of empyema. Nonetheless, conversion to open thoracotomy may be required (Lardinois 2005).
Procedural management of pleural empyema involves thoracentesis and chest tube drainage. Thoracentesis involves aspirating the pleural fluid through a catheter under imaging guidance of either ultrasound or CT. Potential complications from this procedure include haemothorax, pneumothorax and lung puncture (bronchopleural fistula) (Jones 2003). Alternatively, chest tube insertion involves dissection of a small area of the chest wall muscle and the placement of a chest tube (Oddel 1994). The length of treatment is usually no longer than 7 to 10 days or when drainage is minimal, as guided by clinical or radiographic evidence of empyema resolution (or both) (Oddel 1994). In patients not responding to treatment or requiring a prolonged period of chest tube placement, surgical intervention may be considered. Complications associated with tube thoracostomy include chest tube malposition, tissue trauma and re-expansion pulmonary oedema (Miller 1987).
Intrapleural fibrinolysis uses a mixture of streptokinase and streptodornase and is an adjunct to chest tube drainage to facilitate fibrinolysis of loculations (Tillett 1951). Side effects due to impurities led to a decline in its use but the availability of a more purified form and successful trial of urokinase have led to a reappraisal of this modality (Aye 1991; Temes 1996). More recently, a 2008 Cochrane Review by Cameron et al concluded that intrapleural fibrinolytic therapy conferred significant benefit in reducing the requirement for surgical interventions. However, when subgroup analysis was performed on high-quality trials, the benefit was not significant (Cameron 2008).
Why it is important to do this review
There are various surgical and non-surgical options for the treatment of CPPE and pleural empyema currently used in practice, yet there is no clear consensus on optimal methods for intervention. Coote's 2005 review of the topic concluded that there were insufficient large trials to suggest the use of any particular intervention (Coote 2005). Our review aims to reconcile the issue by comparing the results of surgical and non-surgical therapies for the treatment of CPPE and pleural empyema, thereby providing clinicians with evidence-based guidance for its management.