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Pleural Disease
Preventing, Diagnosing and Treating Pleural Infection and
Malignant Pleural Effusion
John M Wrightson
1
and Robert JO Davies
2
1. Academic Clinical Fellow and Specialist Registrar; 2. Professor of Respiratory Medicine,
Oxford Centre for Respiratory Medicine, NIHR Oxford Biomedical Research Centre, University of Oxford
Abstract
Pleural diseases create numerous problems related to the local perturbation of the mechanics of respiration and the systemic effects of
the underlying disease process. This article discusses two common pleural diseases that will be encountered by physicians from a wide
range of specialities: pleural infection and malignant pleural effusion. We present evidence-based investigative and treatment strategies
and discuss potential factors relevant to disease prevention.
Keywords
Pleural empyema, tuberculous empyema, pleural neoplasms, pleural effusion, pleural diseases
Disclosure: John M Wrightson has no conflicts of interest to declare. Robert JO Davies holds the patent rights for the use of Lipoteichoic Acid-T for pleurodesis. Rocket Medical
have donated indwelling catheters to a BLF-funded clinical trial led by the Oxford Centre for Respiratory Medicine.
Received: 7 January 2009 Accepted: 10 June 2009
Correspondence: Robert JO Davies, Oxford Centre for Respiratory Medicine, NIHR Oxford Biomedical Research Centre, Churchill Hospital, Old Road, Headington,
robert.davies@ndm.ox.ac.uk
The pleura is an elastic, serous membrane that lines the inner aspect Various terms are used to describe pleural infection, including
of the thoracic cage and the outer surface of the lung; it empyema and parapneumonic effusion. Such terms represent a
has a surface area of approximately 2,000cm
2
. This membrane continuum of development of pleural infection. Pneumonia will
encloses a slit-like cavity that is usually 10–20µm in depth – the pleural often have an associated effusion, without evidence of pleural
space. Each pleural space contains approximately 10ml of fluid,
1
infection; this is described as a simple parapneumonic effusion.
maintained in equilibrium by the balance of hydrostatic and oncotic Such an effusion may become infected; the continuum between a
pressures. This sliver of fluid reduces the friction of the pleural complex parapneumonic effusion and empyema (frank pus)
surfaces, allowing them to glide during respiration. Any perturbation to describes such a process.
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the pleural space can cause a mechanical disruption affecting
pulmonary function, blood gas tension, exercise tolerance and Pleural infection can be caused by a great diversity of organisms,
diaphragmatic and cardiac function, among other factors. Two including bacteria (and mycobacteria), fungi and parasites. Worldwide,
common disease processes causing such disruption are pleural tuberculous pleural infection is a common cause of pleural effusion.
infection and malignant pleural effusions. These diseases bring about Parasitic infections such as amoebiasis, echinococcosis and
myriad problems, partly due to their wide-ranging systemic effects in paragonimiasis may cause pleural infections in endemic regions.
addition to their local effects on the mechanical properties of the Bacterial pleural infection is a common presentation in both the
pleura and lung. developing and developed world, and this article will primarily focus
on infection with a bacterial aetiology.
Pleural Infection
Pleural infection is a significant cause of mortality and morbidity Concurrent bacterial pneumonia is the most common cause of
worldwide. There are an estimated 60,000–80,000 cases annually in bacterial pleural infection, causing 70% of cases. Curiously,
the UK and the US;
2
recent data suggest that the incidence is 4% of pleural infections evolve without obvious cause or
increasing.
3,4
The disease has a mortality rate of around 20%.
5,6
radiographic evidence of pneumonia, a so-called primary empyema.
Healthcare economic costs are high – the median duration of Other causes of pleural infection include post-operative and other
inpatient care is 15 days, with 20% of cases requiring inpatient stays iatrogenic infections, traumatic injuries (both blunt and penetrating),
of one month or greater.
7
abdominal infections (e.g. subphrenic abscess) and others, including
oesophageal perforation, bacteraemia and rupture of lung abscess
Pleural infection typically presents with dyspnoea, chest pain, fever into the pleural space.
10
and other systemic symptoms. However, some patients – especially
those with anaerobic infections
8
or the elderly – can suffer a more Streptococci (including the S. milleri group of S. intermedius,
insidious course with malaise, weight loss and anorexia in the S. anginosus and S. constellatus) are the most commonly isolated
absence of overt fever. types of bacteria in community-acquired bacterial pleural infection,
© TOUCH BRIEFINGS 2009 49
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