Editing Pleural empyema

{{Short description|Accumulation of pus in the pleural space around the lungs}}
{{Infobox medical condition (new)
| name            = Pleural empyema
| synonyms        = Pyothorax, purulent pleuritis, lung empyema
| image           = Hydro pneumothorax.jpg
| caption         = CT chest showing large right sided [[hydro-pneumothorax]] from pleural [[empyema]]. ''Arrows A: air, B: fluid''
| symptoms        = Fever, chest pain with breathing in, cough, shortness of breath
| complications   =
| onset           =
| duration        =
| types           =
| causes          = Bacteria (often Strep. pneumonia)
| risks           =
| diagnosis       = Chest X-ray, Ultrasound, CT scan, thoracentesis
| differential    = [[Pneumonia]], [[pleural effusion]], [[pulmonary embolism]]
| prevention      =
| treatment       = [[Supportive care]], [[antibiotic]]s, surgery, [[chest tube]]
| medication      =
| prognosis       =
| frequency       =
| deaths          =
}}

'''Pleural empyema''' is a collection of [[pus]] in the [[pleural cavity]]. It is caused by [[microorganism]]s, usually [[bacteria]].<ref name=Red2017/> It often happens in the context of a [[pneumonia]], injury, or chest surgery.<ref name=Red2017>{{cite journal | vauthors = Redden MD, Chin TY, van Driel ML | title = Surgical versus non-surgical management for pleural empyema | journal = Cochrane Database Syst Rev | volume = 2017 | pages = CD010651 | date = March 2017 | issue = 3 | pmid = 28304084 | pmc = 6464687 | doi = 10.1002/14651858.CD010651.pub2 |issn=1469-493X }}</ref> It is one of the various kinds of [[pleural effusion]]. Pleural empyema contain three stages: exudative: when there is an increase in [[pleural fluid]] with or without the presence of pus; fibrinopurulent: when fibrous septa form localized pus pockets, and the final organizing stage: when there is scarring of the pleura membranes with possible inability of the lung to expand. Simple pleural effusions occur in up to 40% of bacterial pneumonias. They are usually small and resolve with appropriate [[antibiotic]] therapy. However, if an [[empyema]] develops additional intervention is required.

== Signs and symptoms ==
The clinical presentation of both the adult and pediatric patient with pleural empyema depends upon several factors, including the causative micro-organism. Most cases present themselves in the setting of a pneumonia, although up to one third of patients do not have clinical signs of pneumonia and as many as 25% of cases are associated with trauma (including surgery).<ref name="Fernandez2007">{{cite journal | vauthors = Fernández-Cotarelo MJ, López-Medrano F, San Juan R, Díaz-Pedroche C, Lizasoain M, Chaves F, Aguado JM | title = Protean manifestations of pleural empyema caused by Streptococcus pneumoniae in adults | journal = Eur. J. Intern. Med. | volume = 18 | issue = 2 | pages = 141–5 | date = March 2007 | pmid = 17338967 | doi = 10.1016/j.ejim.2006.09.017 }}</ref> The symptoms include [[fever]], dry [[cough]], [[Perspiration|sweating]], difficulty breathing, and unintentional weight loss.<ref>{{Cite web|title=Empyema: MedlinePlus Medical Encyclopedia|url=https://medlineplus.gov/ency/article/000123.htm|access-date=2021-06-19|website=medlineplus.gov|language=en}}</ref> The elderly often do not have classic symptoms, instead they have [[anemia]] and exhaustion.<ref>{{Cite journal|last1=Feller-Kopman|first1=David|last2=Light|first2=Richard|date=2018-02-21|title=Pleural Disease|url=https://www.nejm.org/doi/10.1056/NEJMra1403503|journal=New England Journal of Medicine|volume=378 |issue=8 |pages=740–751 |language=en|doi=10.1056/NEJMra1403503|pmid=29466146 |s2cid=40061070 |url-access=subscription}}</ref>

== Mechanism ==
When there is inflammation at the pleural space, fluid production is increased. As the disease progresses, bacteria can arrive at the fluid, which creates an empyema.<ref>{{Citation|last1=Garvia|first1=Veronica|title=Empyema|date=2021|url=http://www.ncbi.nlm.nih.gov/books/NBK459237/|work=StatPearls|place=Treasure Island (FL)|publisher=StatPearls Publishing|pmid=29083780|access-date=2021-06-19|last2=Paul|first2=Manju}}</ref>

== Diagnosis ==
The initial investigations for suspected empyema remains [[chest X-ray]], although it cannot differentiate an empyema from uninfected parapneumonic effusion.<ref name="King2002">{{cite journal |vauthors=King S, Thomson A | year = 2002 | title = Radiological perspectives in empyema | journal = British Medical Bulletin | volume = 61 | pages = 203–14 | doi=10.1093/bmb/61.1.203| pmid = 11997307 | doi-access = free }}</ref> [[Ultrasound]] must be used to confirm the presence of a pleural fluid collection and can be used to estimate the size of the effusion, differentiate between free and loculated pleural fluid and guide [[thoracocentesis]] if necessary. Chest [[X-ray computed tomography|CT]] and [[MRI]] do not provide additional information in most cases and should therefore not be performed routinely.<ref name="Balfour2005">{{cite journal |vauthors=Balfour-Lynn IM, Abrahamson E, Cohen G, Hartley J, King S, Parikh D, Spencer D, Thomson AH, Urquhart D | year = 2005 | title = BTS guidelines for the management of pleural infection in children | journal = Thorax | volume = 60 | issue = Suppl 1| pages = 1–21 | doi=10.1136/thx.2004.030676| pmid = 15681514 | pmc = 1766040}}</ref> On a CT scan, empyema fluid most often has a [[radiodensity]] of about 0-20 [[Hounsfield unit]]s (HU),<ref name="YildizCece2010">{{cite journal | vauthors = Yildiz S, Cece H, Turksoy O | title = Discriminative role of CT in exudative and transudative pleural effusions | journal = AJR Am J Roentgenol | volume = 195 | issue = 4 | pages = W305; author reply W306 | date = October 2010 | pmid = 20858794 | doi = 10.2214/AJR.10.4437 |issn=0361-803X}}</ref> but gets over 30 HU when becoming more thickened with time.<ref>{{cite book|title=Source Control: A Guide to the Management of Surgical Infections|author=Moshe Schein, John C. Marshall|publisher=Springer Science & Business Media|year=2013|isbn=9783642559143}}</ref>

The most often used "golden" criteria for empyema are pleural effusion with macroscopic presence of pus, a positive [[Gram stain]] or culture of pleural fluid, or a pleural fluid pH under 7.2 with normal peripheral blood pH.<ref name="Ahmed2006" /><ref name="Ferrer1999">{{cite journal | vauthors = Ferrer A, Osset J, Alegre J, Suriñach JM, Crespo E, Fernández de Sevilla T, Fernández F | title = Prospective clinical and microbiological study of pleural effusions | journal = Eur. J. Clin. Microbiol. Infect. Dis. | volume = 18 | issue = 4 | pages = 237–41 | date = April 1999 | pmid = 10385010 | doi = 10.1007/s100960050270 | s2cid = 6550696 }}</ref> Clinical guidelines for adult patients therefore advocate diagnostic pleural fluid aspiration in patients with pleural effusion in association with [[sepsis]] or pneumonic illness.<ref name="Davies2010">{{cite journal |vauthors=Davies H, Davies R, Davies C | year = 2010 | title = Management of pleural infection in adults: British Thoracic Society Pleural Disease Guideline 2010 | journal = Thorax | volume = 65 | issue = Suppl 2| pages = 41–53 | doi=10.1136/thx.2010.137000 | pmid=20696693| doi-access = free }}</ref> Because pleural effusion in the pediatric population is almost always parapneumonic and the need for [[chest tube]] drainage can be made on clinical grounds, British guidelines for the management of pleural infection in children do not recommend diagnostic pleural fluid sampling.<ref name="Balfour2005" />

[[Blood culture|Blood]] and [[sputum culture]] has often already been performed in the setting of community acquired pneumonia needing hospitalization. It should however be noted that the micro-organism responsible for development of empyema is not necessarily the same as the organism causing the pneumonia, especially in adults. As already mentioned before, [[sensitivity and specificity|sensitivity]] of pleural fluid culture is generally low, often partly due to prior administration of antibiotics. It has been shown that culture yield can be increased from 44% to 69% if pleural fluid is injected into blood culture bottles (aerobic and anaerobic) immediately after aspiration.<ref name="Ferrer1999" /> Furthermore, diagnostic rates can be improved for specific pathogens using [[polymerase chain reaction]] or antigen detection, especially for Streptococcus pneumoniae, Streptococcus pyogenes and Staphylococcus aureus. In a study including 78 children with pleural empyema, the causative micro-organism could be identified using direct culture of fresh pleural fluid in 45% of patients, with an additional 28% using PCR on pleural fluid of negative cultures. Pneumococcal antigen detection in pleural fluid samples by latex agglutination can also be useful for rapid diagnosis of pneumococcal empyema. In the previously noted study, positive and negative predictive value of pneumococcal antigen detection was 95% and 90%, respectively.<ref name="LeMonnier2006" />

<gallery>
File:UOTW 28 - Ultrasound of the Week 1.webm|Pleural empyema as seen on ultrasound<ref name=UOTW28>{{cite web|title=UOTW #28 - Ultrasound of the Week|url=https://www.ultrasoundoftheweek.com/uotw-28/|website=Ultrasound of the Week|access-date=27 May 2017|date=3 December 2014}}</ref>
File:UOTW 28 - Ultrasound of the Week 2.webm|Pleural empyema as seen on ultrasound<ref name=UOTW28/>
File:UOTW 28 - Ultrasound of the Week 3.webm|Pleural empyema as seen on ultrasound<ref name=UOTW28/>
File:UOTW 28 - Ultrasound of the Week 4.jpg|Pleural empyema as seen on ultrasound<ref name=UOTW28/>
</gallery>

== Treatment ==

=== Pleural fluid drainage ===
Proven empyema (as defined by the "golden" criteria mentioned earlier) is an indication for prompt [[chest tube]] drainage.<ref name="Davies2010" /> This has been shown to improve resolution of the infection and shorten hospital admission.<ref name="Sasse1997">{{cite journal | vauthors = Sasse S, Nguyen TK, Mulligan M, Wang NS, Mahutte CK, Light RW | title = The effects of early chest tube placement on empyema resolution | journal = Chest | volume = 111 | issue = 6 | pages = 1679–83 | date = June 1997 | pmid = 9187193 | doi = 10.1378/chest.111.6.1679 | s2cid = 7554750 }}</ref> Data from a meta-analysis has shown that a pleural fluid pH of <7.2 is the most powerful indicator to predict the need for chest tube drainage in patients with non-purulent, culture negative fluid.<ref name="Heffner1995">{{cite journal | vauthors = Heffner JE, Brown LK, Barbieri C, DeLeo JM | title = Pleural fluid chemical analysis in parapneumonic effusions. A meta-analysis | journal = Am. J. Respir. Crit. Care Med. | volume = 151 | issue = 6 | pages = 1700–8 | date = June 1995 | pmid = 7767510 | doi = 10.1164/ajrccm.151.6.7767510 }}</ref>

Because of the viscous, lumpy nature of infected pleural fluid, in combination with possible septation and loculation, it has been proposed that intrapleural [[fibrinolytic]] or [[mucolytic]] therapy might improve drainage and therefore might have a positive effect on the clinical outcome.<ref name="Maskell2005" /> [[Intrapleural fibrinolysis]] with [[urokinase]] decreased the need for surgery but there is a trend to increased serious side effects.<ref name="pmid24428897">{{cite journal | vauthors = Nie W, Liu Y, Ye J, Shi L, Shao F, Ying K, Zhang R | title = Efficacy of intrapleural instillation of fibrinolytics for treating pleural empyema and parapneumonic effusion: a meta-analysis of randomized control trials | journal = The Clinical Respiratory Journal | volume = 8 | issue = 3 | pages = 281–91 | date = July 2014 | pmid = 24428897 | doi = 10.1111/crj.12068 | s2cid = 30223456 }}</ref>

Approximately 15 to 40 percent of people require surgical drainage of the infected pleural space because of inadequate drainage due to clogging of the chest tube or loculated empyema.<ref name="Ferguson1996">{{cite journal | vauthors = Ferguson AD, Prescott RJ, Selkon JB, Watson D, Swinburn CR | title = The clinical course and management of thoracic empyema | journal = QJM | volume = 89 | issue = 4 | pages = 285–9 | date = April 1996 | pmid = 8733515 | doi = 10.1093/qjmed/89.4.285 | doi-access = free }}</ref> Patients should thus be considered for surgery if they have ongoing signs of sepsis in association with a persistent pleural collection despite drainage and antibiotics.<ref name="Davies2010" />

===Antibiotics===

There is no readily available evidence on the route of administration and duration of antibiotics in patients with pleural empyema. Experts agree that all patients should be hospitalized and treated with antibiotics intravenously.<ref name="Balfour2005" /><ref name="Davies2010" />  The specific antimicrobial agent should be chosen based on Gram stain and culture, or on local epidemiologic data when these are not available. Anaerobic coverage must be included in all adults, and in children if [[Pulmonary aspiration|aspiration]] is likely. Good pleural fluid and empyema penetration has been reported in adults for [[penicillins]], [[ceftriaxone]], [[metronidazole]], [[clindamycin]], [[vancomycin]], [[gentamicin]] and [[ciprofloxacin]].<ref name="Teixeira2000">{{cite journal | vauthors = Teixeira LR, Sasse SA, Villarino MA, Nguyen T, Mulligan ME, Light RW | title = Antibiotic levels in empyemic pleural fluid | journal = Chest | volume = 117 | issue = 6 | pages = 1734–9 | date = June 2000 | pmid = 10858410 | doi = 10.1378/chest.117.6.1734 }}</ref><ref name="Umut1993">{{cite journal | vauthors = Umut S, Demir T, Akkan G, Keskiner N, Yilmaz V, Yildirim N, Sipahioğlu B, Hasan A, Barlas A, Sözer K | title = Penetration of ciprofloxacin into pleural fluid | journal = J Chemother | volume = 5 | issue = 2 | pages = 110–2 | date = April 1993 | pmid = 8515292 | doi = 10.1080/1120009X.1993.11739217 }}</ref> [[Aminoglycosides]] should typically be avoided as they have poor penetration into the pleural space. There is no clear consensus on duration of intravenous and oral therapy. Switching to oral antibiotics can be considered upon clinical and objective improvement (adequate drainage and removal of chest tube, declining [[C-reactive protein|CRP]], temperature normalization). Oral antibiotic treatment should then be continued for another 1–4 weeks, again based on clinical, biochemical and radiological response.<ref name="Balfour2005" /><ref name="Davies2010" />

== Prognosis ==
All patients with empyema require outpatient follow-up with a repeat chest X-ray and inflammatory biochemistry analysis within 4 weeks following discharge. Chest radiograph returns to normal in the majority of patients by 6 months. Patients should, of course, be advised to return sooner if symptoms redevelop. Long-term sequelae of pleural empyema are rare but include [[bronchopleural fistula]] formation, recurrent empyema and pleural thickening, which may lead to functional lung impairment needing surgical [[decortication]].<ref name="Davies2010" />

Mortality in children is generally reported to be less than 3%.<ref name="Balfour2005" /> No reliable clinical, radiological or pleural fluid characteristics accurately determine patients' prognosis at initial presentation.<ref name="Davies1999">{{cite journal | vauthors = Davies CW, Kearney SE, Gleeson FV, Davies RJ | title = Predictors of outcome and long-term survival in patients with pleural infection | journal = Am. J. Respir. Crit. Care Med. | volume = 160 | issue = 5 Pt 1 | pages = 1682–7 | date = November 1999 | pmid = 10556140 | doi = 10.1164/ajrccm.160.5.9903002  }}</ref>

== Epidemiology ==
The incidence of pleural empyema and the prevalence of specific causative microorganisms varies depending on the source of infection (community acquired vs. hospital acquired pneumonia), the age of the patient and host immune status. Risk factors include [[alcoholism]], drug use, [[HIV infection]], [[neoplasm]] and pre-existent [[pulmonary disease]].<ref name="Alfageme1993">{{cite journal | vauthors = Alfageme I, Muñoz F, Peña N, Umbría S | title = Empyema of the thorax in adults. Etiology, microbiologic findings, and management | journal = Chest | volume = 103 | issue = 3 | pages = 839–43 | date = March 1993 | pmid = 8449078 | doi = 10.1378/chest.103.3.839 | s2cid = 23185011 }}</ref> Pleural empyema was found in 0.7% of 3675 patients needing hospitalization for a community acquired pneumonia in a recent Canadian single-center prospective study.<ref name="Ahmed2006">{{cite journal |vauthors=Ahmed R, Marri T, Huang J | year = 2006 | title = Thoracic empyema in patients with community-acquired pneumonia | journal = American Journal of Medicine | volume = 119 | issue = 10| pages = 877–83 | doi=10.1016/j.amjmed.2006.03.042| pmid = 17000220 }}</ref> A multi-center study from the UK including 430 adult patients with community acquired pleural empyema found negative pleural-fluid cultures in 54% of patients, [[Streptococcus milleri group]] in 16%, [[Staphylococcus aureus]] in 12%, [[Streptococcus pneumoniae]] in 8%, other [[Streptococci]] in 7% and [[anaerobic bacteria]] in 8%.<ref name="Maskell2005">{{cite journal |vauthors=Maskell NA, Davies CW, Nunn AJ, Hedley EL, Gleeson FV, Miller R, Gabe R, Rees GL, Peto TE, Woodhead MA, Lane DJ, Darbyshire JH, Davies RJ | year = 2005 | title = U.K. controlled trial of intrapleural streptokinase for pleural infection | url = http://discovery.ucl.ac.uk/6764/| journal = New England Journal of Medicine | volume = 352 | issue = 9| pages = 865–74 | doi=10.1056/nejmoa042473 | pmid=15745977| doi-access = free }}</ref>

The risk of empyema in children seems to be comparable to adults. Using the United States Kids' Inpatient Database the incidence is calculated to be around 1.5% in children hospitalized for community acquired pneumonia,<ref name="Li2010">{{cite journal |vauthors=Li S, Tancredi D | year = 2010 | title = Empyema hospitalizations increased in US children despite pneumococcal conjugate vaccine | journal = Pediatrics | volume = 125 | issue = 1| pages = 26–33 | doi=10.1542/peds.2009-0184 | pmid=19948570| s2cid = 33176058 }}</ref> although percentages up to 30% have been reported in individual hospitals,<ref name="Byington2002">{{cite journal |vauthors=Byington CL, Spencer LY, Johnson TA, Pavia AT, Allen D, Mason EO, Kaplan S, Carroll KC, Daly JA, Christenson JC, Samore MH | year = 2002 | title = An epidemiological investigation of a sustained high rate of pediatric parapneumonic empyema: risk factors and microbiological associations | journal = Clinical Infectious Diseases | volume = 34 | issue = 4| pages = 434–40 | doi=10.1086/338460 | pmid=11797168| doi-access = free }}</ref> a difference which may be explained by an transient endemic of highly invasive [[serotype]] or overdiagnosis of small parapneumonic effusions. The distribution of causative organisms does differ greatly from that in adults: in an analysis of 78 children with community acquired pleural empyema, no micro-organism was found in 27% of patients, [[Streptococcus pneumoniae]] in 51%, [[Streptococcus pyogenes]] in 9% and [[Staphylococcus aureus]] in 8%.<ref name="LeMonnier2006">{{cite journal |vauthors=Le Monnier A, Carbonnelle E, Zahar JR, Le Bourgeois M, Abachin E, Quesne G, Varon E, Descamps P, De Blic J, Scheinmann P, Berche P, Ferroni A | year = 2006 | title = Microbiological diagnosis of empyema in children: comparative evaluations by culture, polymerase chain reaction, and pneumococcal antigen detection in pleural fluids | journal = Clinical Infectious Diseases | volume = 42 | issue = 8| pages = 1135–40 | doi=10.1086/502680 | pmid=16575731| doi-access = free }}</ref>

Although [[Pneumococcal vaccine|pneumococcal vaccination]] dramatically decreased the incidence of pneumonia in children, it did not have this effect on the incidence of complicated pneumonia. It has been shown that the incidence of empyema in children was already on the rise at the end of the 20th century, and that the widespread use of pneumococcal vaccination did not slow down this trend.<ref name="Grijalva2010">{{cite journal |vauthors=Grijalva CG, Nuorti JP, Zhu Y, Griffin MR | year = 2010 | title = Increasing incidence of empyema complicating childhood community-acquired pneumonia in the United States | journal = Clinical Infectious Diseases | volume = 50 | issue = 6| pages = 805–13 | doi=10.1086/650573 | pmid=20166818 | pmc=4696869}}</ref> This might in part be explained by a change in prevalence of (more invasive) pneumococcal [[serotypes]], some of which are not covered by the vaccine, as well a rise in incidence of pneumonia caused by other streptococci and staphylococci.<ref name="Obando2012">{{cite journal | vauthors = Obando I, Camacho-Lovillo MS, Porras A, Gandía-González MA, Molinos A, Vazquez-Barba I, Morillo-Gutierrez B, Neth OW, Tarrago D | title = Sustained high prevalence of pneumococcal serotype 1 in paediatric parapneumonic empyema in southern Spain from 2005 to 2009 | journal = Clin. Microbiol. Infect. | volume = 18 | issue = 8 | pages = 763–8 | date = August 2012 | pmid = 21910779 | doi = 10.1111/j.1469-0691.2011.03632.x | doi-access = free }}</ref>

== References ==
{{Reflist|30em}}

== External links ==
{{Medical resources
|  DiseasesDB     = 4200
|  ICD10          = {{ICD10|J|86||j|85}}
|  ICD9           = {{ICD9|510}}
|  MedlinePlus    = 000123
|  eMedicineSubj  = med
|  eMedicineTopic = 659
|  MeshID         = D016724
}}
* {{eMedicine|med|659|Empyema, Pleuropulmonary}}

{{Respiratory pathology}}

[[Category:Diseases of pleura]]