Pleural effusion 356988 220594840 2008-06-20T16:49:36Z DOI bot 6652755 Citation maintenance. You can [[WP:DOI|use this bot]] yourself! Please [[User:DOI_bot/bugs|report any bugs]]. {{Infobox_Disease | Name = {{PAGENAME}} | Image = | Caption = | DiseasesDB = | ICD10 = {{ICD10|J|90||j|90}}-{{ICD10|J|91||j|90}} | ICD9 = {{ICD9|511.9}} | ICDO = | OMIM = | MedlinePlus = | eMedicineSubj = | eMedicineTopic = | MeshID = D010996 | }} [[Image:Pleural effusion.jpg|right|250px|thumb|'''Pleural effusion''' Chest x-ray of a pleural effusion. The arrow A shows fluid layering in the right pleural cavity. The B arrow shows the normal width of the lung in the cavity]] '''Pleural effusion''' is excess fluid that accumulates in the [[pleural cavity]], the fluid-filled space that surrounds the [[lung]]s. Excessive amounts of such fluid can impair breathing by limiting the expansion of the lungs during [[inhalation]]. ==Types of fluids== Four types of fluids can accumulate in the pleural space: * [[Serous fluid]] ([[hydrothorax]]) * [[Blood]] ([[hemothorax]]) * [[Chyle]] ([[chylothorax]]) * [[Pus]] ([[pyothorax]] or [[empyema]]) ==Pathophysiology== Healthy individuals have less than 15 ml of fluid in each pleural space. Normally, fluid enters the pleural space from the [[capillaries]] in the [[Pleural cavity|parietal pleura]], from interstitial spaces of the lung via the [[Pleural cavity|visceral pleura]], or from the [[peritoneal cavity]] through small holes in the [[diaphragm (anatomy)|diaphragm]]. This fluid is normally removed by [[lymphatics]] in the parietal pleura, which have the capacity to absorb 20 times more fluid than is normally formed. When this capacity is overwhelmed, either through excess formation or decreased lymphatic absorption, a pleural effusion develops. ==Diagnosis== Pleural effusion is usually diagnosed on the basis of [[medical history]] and [[physical exam]], and confirmed by [[chest x-ray]]. Chest films acquired in the lateral [[decubitus]] position (with the patient lying on their side) are more sensitive, and can pick up as little as 50 ml of fluid. At least 300 ml of fluid must be present before upright chest films can pick up signs of pleural effusion (e.g., blunted [[costophrenic angle]]s). Once accumulated fluid is more than 500 ml, there are usually detectable [[clinical sign]]s in the patient, such as decreased movement of the chest on the affected side, dullness to percussion over the fluid, diminished [[breath sounds]] on the affected side, decreased vocal [[fremitus]] and resonance, pleural friction rub, and [[egophony]]. [[Image:Pleura effusion.jpg|thumb|[[Computed tomography|CT]] scan of chest showing left sided pleural effusion. Effusion fluid often settles at the lowest space due to [[gravity]]; here at the back as the patient is lying under scanner.]] Once a pleural effusion is diagnosed, the cause must be determined. Pleural fluid is drawn out of the pleural space in a process called [[thoracentesis]]. A needle is inserted through the back of the chest wall into the pleural space. The fluid may then be evaluated for the following: # Chemical composition including [[protein]], [[lactate dehydrogenase]] (LDH), [[serum albumin|albumin]], [[amylase]], [[pH]] and [[glucose]] # [[Gram stain]] and culture to identify possible bacterial infections # [[cell (biology)|Cell]] count and differential # [[Cytology]] to identify cancer cells, but may also identify some infective organisms # Other tests as suggested by the clinical situation - [[lipid]]s, [[fungus|fungal culture]], [[virus|viral culture]], specific [[immunoglobulin]]s ===Transudate vs. exudate=== The third step in the evaluation of pleural fluid is to determine whether the effusion is a transudate or an exudate. Transudative pleural effusions are caused by ''systemic'' factors that alter the balance of the formation and absorption of pleural fluid (e.g., [[heart failure|left ventricular failure]], [[pulmonary embolism]], and [[cirrhosis]]), while exudative pleural effusions are caused by alterations in ''local'' factors that influence the formation and absorption of pleural fluid (e.g., [[bacterial pneumonia]], cancer, and viral infection). Transudative and exudative pleural effusions are differentiated by comparing chemistries in the pleural fluid to those in the blood. According to a [[meta-analysis]], exudative pleural effusions meet at least one of the following criteria <ref name="pmid9106577">{{cite journal |author=Heffner J, Brown L, Barbieri C |title=Diagnostic value of tests that discriminate between exudative and transudative pleural effusions. Primary Study Investigators |journal=Chest |volume=111 |issue=4 |pages=970–80 |year=1997 |pmid=9106577 |doi=10.1378/chest.111.4.970}}</ref>: # Pleural fluid protein >2.9 g/dL (29 g/L) # Pleural fluid cholesterol >45 mg/dL (1.16 mmol/L) # Pleural fluid LDH >60 percent of upper limit for serum Previously criteria proposed by Light for an exudative effusion are met if at least one of the following exists (Light's criteria) <ref name="pmid4642731">{{cite journal |author=Light R, Macgregor M, Luchsinger P, Ball W |title=Pleural effusions: the diagnostic separation of transudates and exudates |journal=Ann Intern Med |volume=77 |issue=4 |pages=507–13 |year=1972 |pmid=4642731}}</ref>: # The ratio of pleural fluid protein to serum protein is greater than 0.5 # The ratio of pleural fluid LDH and serum LDH is greater than 0.6 # Pleural fluid LDH is more than two-thirds normal upper limit for serum Twenty-five percent of patients with transudative pleural effusions are mistakenly identified as having exudative pleural effusions by Light's criteria. Therefore, additional testing is needed if a patient identified as having an exudative pleural effusion appears clinically to have a condition that produces a transudative effusion. In such cases [[serum albumin|albumin]] levels in blood and pleural fluid are measured. If the difference between the albumin levels in the blood and the pleural fluid is greater than 1.2 g/dL (12 g/L), it can be assumed that the patient has a transudative pleural effusion. If the fluid is definitively identified as exudative, additional testing is necessary to determine the local factors causing the exudate. ===Exudative pleural effusions=== Once identified as exudative, additional evaluation is needed to determine the cause of the excess fluid, and pleural fluid amylase, glucose, pH and cell counts are obtained. The fluid is also sent for [[Gram staining]] and culture, and, if suspicious for tuberculosis, examination for TB markers ([[adenosine deaminase]] > 45 IU/L, [[interferon gamma]] > 140 pg/mL, or positive [[polymerase chain reaction]] (PCR) for tuberculous DNA). Pleural fluid amylase is elevated in cases of esophageal rupture, [[Pancreatic fistula|pancreatic pleural effusion]], or cancer. Glucose is decreased with cancer, bacterial infections, or [[rheumatoid pleuritis]]. Pleural fluid pH is low in empyema (<7.2) and may be low in cancer. If cancer is suspected, the pleural fluid is sent for cytology. If cytology is negative, and cancer is still suspected, either a [[thoracoscopy]], or needle biopsy of the pleura may be performed. ==Causes== The most common causes of '''transudative''' pleural effusions in the United States are [[heart failure|left ventricular failure]], [[pulmonary embolism]], and [[cirrhosis]] (causing [[hepatic hydrothorax]]), while the most common causes of '''exudative''' pleural effusions are bacterial [[pneumonia]], cancer (with [[lung cancer]], [[breast cancer]], and [[lymphoma]] causing approximately 75% of all malignant pleural effusions), viral infection, and [[pulmonary embolism]]. Although pulmonary embolism can produce either transudative or exudative pleural effusions, the latter is more common. Other causes of pleural effusion include [[tuberculosis]] (though pleural fluid smears are rarely positive for AFB, this is the most common cause of pleural effusion in some developing countries), autoimmune disease such as [[systemic lupus erythematosus]], bleeding (often due to chest trauma), chylothorax (most commonly caused by trauma), and accidental infusion of fluids. Less common causes include esophageal rupture or pancreatic disease, intraabdominal abscess, [[rheumatoid arthritis]], asbestos pleural effusion, [[Meig's syndrome]] (ascites and pleural effusion due to a benign ovarian tumor), and [[ovarian hyperstimulation syndrome]]. Pleural effusions may also occur through medical/surgical interventions, including the use of medications (pleural fluid is usually [[eosinophilic]]), [[coronary artery bypass surgery]], abdominal surgery, [[endoscopic variceal sclerotherapy]], [[radiation therapy]], [[Liver transplantation|liver]] or [[lung transplantation]], and intra- or extravascular insertion of [[Central venous catheter|central lines]]. ==Treatment== [[Image:Chest Drainage Device.PNG|thumb|right|The free end of the Chest Drainage Device is usually attached to an underwater seal, below the level of the chest. This allows the air or fluid to escape from the pleural space, and prevents anything returning to the chest.]] Treatment depends on the underlying cause of the pleural effusion. Therapeutic aspiration may be sufficient; larger effusions may require insertion of an [[chest tube|intercostal drain]] (either pigtail or surgical). Repeated effusions may require chemical ([[talc]], [[bleomycin]], [[tetracycline]]/[[doxycycline]]) or surgical [[pleurodesis]], in which the two pleural surfaces are attached to each other so that no fluid can accumulate between them. ==See also== * [[Empyema]] * [[Heart failure]] * [[Pulmonary embolism]] * [[Thoracentesis]] ==External links== * [http://www.nlm.nih.gov/medlineplus/ency/article/000086.htm Medline Plus Article on Pleural Effusion] * [http://www.virtualcancercentre.com/symptoms.asp?sid=59 Pleural Effusion] Virtual Cancer Centre * [http://rad.usuhs.edu/medpix/medpix.html?mode=image_finder&action=search&srchstr=pleural%20effusion&srch_type=all#top Pleural Effusion] Images from MedPix ==References== <references/> * {{cite book | author = Light RW | year = 2001 | title = Pleural Diseases | edition = 4th ed. | publisher = Lippincott Williams & Wilkins | location = New York }} ISBN 0-7817-2777-4 * {{cite book | author = Light RW | year = 2005 | title = Harrison's Principles of Internal Medicine | chapter = Chapter 245: Disorders of the pleura, mediastinum, diaphragm, and chest wall | editor = Kasper DL, Braunwald E, Fauci A, Hauser S, Longo D, Jameson JL | edition = 16th ed. | publisher = McGraw-Hill Professional | location = New York, NY }} ISBN 0-07-140235-7 * {{cite book | author =Dowdeswell IRG | year = 1998 | title = Internal Medicine | chapter = Chapter 64: Pleural Diseases | editor = Stein JH | edition = 5th ed. | publisher = C.V.Mosby | location = New York }} ISBN 0-8151-8698-3 {{Respiratory pathology}} [[Category:Diseases involving the fasciae]] [[Category:Pulmonology]] [[de:Pleuraerguss]] [[es:Derrame pleural]] [[eu:Pleurako isuri]] [[ja:胸水]] [[pt:Derrame pleural]] [[tr:Effüzyon]]