Pulmonary embolism: Facts, Discussion Forum, and Encyclopedia Article

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Pulmonary embolism

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	Pulmonary embolism
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	Topics Pulmonary embolism Topic Home Pulmonary embolism (PE) is a blockage of the pulmonary arteryPulmonary artery Overview The pulmonary arteries carry blood from the heart to the lungs.... or one of its branches, usually occuring when a venousVein In biology, a vein is a blood vessel which carries blood toward the heart.... thrombusThrombus A thrombus, or blood clot, is the final product of the blood coagulation step in hemostasis.... (blood clot from a vein) becomes dislodged from its site of formation and embolizesEmbolism In medicine, an embolism occurs when an object migrates from one part of the body and cause a blockage of a blood vessel in ... to the arterialPulmonary artery The pulmonary arteries carry blood from the heart to the lungs.... blood supply of one of the lungs. This process is termed thromboembolism. Symptoms may include difficulty breathingDyspnea Dyspnea or shortness of breath is perceived difficulty breathing or pain on breathing.... , painPain Pain is an unpleasant feeling which may be associated with actual or potential tissue damage and which may have physical and... in the chestChest pain In medicine, chest pain is a symptom of a number of serious conditions and is generally considered a medical emergency, unle... during breathing, and in more severe cases collapseCollapse (medical) Collapse is a sudden and often unannounced loss of postural tone , often but not necessarily accompanied by loss of consciou... , circulatory instability and sudden deathCardiac arrest A cardiac arrest, or circulatory arrest, is the abrupt cessation of normal circulation of the blood due to failure of ... . Treatment, usually, is with anticoagulantAnticoagulant An anticoagulant is a substance that prevents coagulation; that is, it stops blood from clotting.... medication, such as heparinHeparin Heparin is a highly sulfated glycosaminoglycan widely used as an injectable anticoagulant.... and warfarinWarfarin Warfarin is an anticoagulant medication that is administered orally or, very rarely, by injection.... , and rarely (in severe cases) with thrombolysisThrombolysis Thrombolysis is the breakdown by pharmacological means, of blood clots.... or surgery. In other, rarer forms of pulmonary embolism, material other than a blood clot is responsible; this may include fatLipid Lipids are a class of hydrocarbon-containing organic compounds essential for the structure and function of living cells.... or boneBone Bone, also called osseous tissue, is a type of hard endoskeletal connective tissue found in many vertebrate animals.... (usually in association with significant trauma), airAIR Summary AIR is a three-letter abbreviation with multiple meanings, as described below:... (often when divingUnderwater diving This article refers to underwater diving done by humans.... ), clumped tumor cells, and amniotic fluidAmniotic fluid Amniotic fluid is the nourishing and protecting liquid contained by the amnion of a pregnant woman.... (affecting motherMother In the case of a mammal such as a human, the biological mother gestates her child in the womb from conception until the fetus is s... s during childbirthChildbirth Childbirth is the culmination of a human pregnancy with the emergence of a newborn infant from its mother's uterus.... ). Signs and symptoms Symptoms of PE are sudden-onset dyspneaDyspnea Dyspnea or shortness of breath is perceived difficulty breathing or pain on breathing.... (shortness of breath), tachypneaTachypnea Overview Tachypnea is characterized by rapid breathing and is not identical with hyperventilation - tachypnea may be necessary for ... (rapid breathing), chest painChest pain In medicine, chest pain is a symptom of a number of serious conditions and is generally considered a medical emergency, unle... of a "pleuritic" nature (worsened by breathing), coughCough A cough is a sudden, often repetitive, spasmodic contraction of the thoracic cavity, resulting in violent release of air fro... , hemoptysisHemoptysis Overview Hemoptysis or haemoptysis is the expectoration of blood or of blood-stained sputum from the bronchi, larynx, trachea, ... (coughing up blood), and may aid in the diagnosis. More severe cases can include signs such as pleural rub, cyanosisCyanosis Cyanosis refers to the bluish coloration of the skin due to the presence of deoxygenated hemoglobin in blood vessels near th... (blue discoloration, usually of the lips and fingers), collapseCollapse (medical) Summary Collapse is a sudden and often unannounced loss of postural tone , often but not necessarily accompanied by loss of consciou... , and circulatory instability. About 15% of all cases of sudden deathSudden Cardiac Death Overview The term Sudden Cardiac Death refers to natural death from cardiac causes, heralded by abrupt loss of consciousness within o... are attributable to PE. Diagnosis The diagnosis of PE is based primarily on validated clinical criteria combined with selective testing because the typical clinical presentation cannot be definitively differentiated from other causes of chest pain and shortness of breath. The decision to do medical imaging is usually based on clinical grounds, i.e. the medical historyMedical history The medical history or anamnesis of a patient is information gained by a physician or other healthcare professional by... , symptoms and findings on physical examinationPhysical examination In medicine, the physical examination or clinical examination is the process by which the physician investigates the b... . The most commonly used method to predict clinical probability, the Wells score, is clinical prediction ruleClinical prediction rule A clinical prediction rule is type of medical research study in which researchers try to identify the best combination of me... , whose use is complicated by multiple versions being available. In 1995, Wells et al initially developed a prediction rule (based on a literature search) to predict the likelihood of PE, based on clinical criteria. The prediction rule was revised in 1998 This prediction rule was further revised when simplified during a validation by Wells et al in 2000. In the 2000 publication, Wells proposed two different scoring systems using cutoffs of 2 or 4 with the same prediction rule. In 2001, Wells published results using the more conservative cutoff of 2 to create three categories. An additional version, the "modified extended version", using the more recent cutoff of 2 but including findings from Wells's initial studies were proposed. Most recently, a further study reverted to Wells's earlier use of a cutoff of 4 points to create only two categories. There are additional prediction rules for PE, such as the Geneva rule. More importantly, the use of any rule is associated with reduction in recurrent thromboembolism. The Wells score: clinically suspected DVT - 3.0 points alternative diagnosis is less likely than PE - 3.0 points tachycardia - 1.5 points immobilization/surgery in previous four weeks - 1.5 points history of DVT or PE - 1.5 points hemoptysis - 1.0 points malignancy (treatment for within 6 months, palliative) - 1.0 points Traditional interpretation Score >6.0 - High (probability 59% based on pooled data) Score 2.0 to 6.0 - Moderate (probability 29% based on pooled data) Score <2.0 - Low (probability 15% based on pooled data) Alternate interpretation Score > 4 - PE likely. Consider diagnostic imaging. Score 4 or less - PE unlikely. Consider D-dimerD-dimer D-dimer is a blood test performed in the medical laboratory to diagnose thrombosis.... to rule out PE. Blood tests In low/moderate suspicion of PE, a normal D-dimerD-dimer Overview D-dimer is a blood test performed in the medical laboratory to diagnose thrombosis.... level (shown in a blood testBlood test Summary Blood tests are laboratory tests done on blood to gain an appreciation of disease states and the function of organs.... ) is enough to exclude the possibility of thrombotic PE. When a PE is being suspected, a number of blood testFacts About Blood test Blood tests are laboratory tests done on blood to gain an appreciation of disease states and the function of organs.... s are done, in order to exclude important secondary causes of PE. This includes a full blood count, clotting statusCoagulation The coagulation of blood is a complex process during which blood forms solid clots.... , and some screening tests. If one of these is abnormal, further investigations might be warranted. Medical imaging The gold standardGold standard (test) In medicine, a gold standard test is the diagnostic test that is regarded as definitive in determining whether an individual... for diagnosing pulmonary embolism (PE) is pulmonary angiographyPulmonary angiography Pulmonary angiography is a cardiological medical procedure.... . Pulmonary angiography is used less often due to wider acceptance of CT scans, which are non-invasive. Non-invasive imaging CT pulmonary angiographyCT pulmonary angiogram CT pulmonary angiogram is a medical diagnostic test that employs computed tomography to obtain an image of the pulmonary ar... (CTPA) is a pulmonary angiogram obtained using computed tomographyComputed tomography Overview Computed tomography , originally known as computed axial tomography and body section roentgenography, is a med... (CT) with radiocontrastRadiocontrast Radiocontrast agents are compounds used to improve the visibility of internal bodily structures in an X-ray image.... rather than right heart catheterization. Its advantages are clinical equivalence, its non-invasive nature, its greater availability to patients, and the possibility of identifying other lung disorders from the differential diagnosisDifferential diagnosis In medicine, differential diagnosis is the systematic method physicians use to identify the disease causing a patient's symp... in case there is no pulmonary embolism. Assessing the accuracy of CT pulmonary angiography is hindered by the rapid changes in the number of rows of detectors available in multidetector CT (MDCT) machines. A study with a mixture of 4 slice and 16 slice scanners reported a sensitivitySensitivity (tests) The sensitivity of a binary classification test with respect to some class is the probability that the test correctly classi... of 83% and a specificitySpecificity (tests) The specificity of a binary classification test with respect to a given class is the probability that the test correctly cla... of 96%. This study noted that additional testing is necessary when the clinical probability is inconsistent with the imaging results. CTPA is non-inferior to VQ scanning, and identifies more emboli (without necessarily improving the outcome) compared to VQ scanning. Ventilation/perfusion scanVentilation/perfusion scan A ventilation/perfusion lung scan, also called a V/Q lung scan, is a type of medical imaging used to evaluate the circulatio... (or V/Q scan or lung scintigraphy), which shows that some areas of the lung are being ventilatedVentilation (physiology) In respiratory physiology, ventilation is the rate at which gas enters or leaves the lung.... but not perfusedPerfusion In physiology, perfusion is the process of nutritive delivery of arterial blood to a capillary bed in the biological tissue.... with blood (due to obstruction by a clot). This type of examination is used less often because of the more widespread availability of CT technology, however, it may be useful in patients who have an allergy to iodinated contrastIodinated contrast Iodinated contrast is a form of intravenous radiocontrast containing iodine, which enhances the visibility of vascular struc... or in pregnancyPregnancy Pregnancy is the carrying of one or more embryos or fetuses by female mammals, including humans, inside their bodies.... due to lower radiation exposure than CT. Low probability diagnostic tests/non-diagnostic tests Tests that are frequently done that are not sensitiveSensitivity (tests) Overview The sensitivity of a binary classification test with respect to some class is the probability that the test correctly classi... for PE, but can be diagnostic. Chest X-rayChest X-ray A chest X-ray, commonly abbreviated CXR, is a projection radiograph, taken by a radiographer, of the thorax which is u... s are often done on patients with shortness of breath to help rule-out other causes, such as congestive heart failureCongestive heart failure Congestive heart failure, also called congestive cardiac failure or just heart failure, is a condition that can ... and rib fractureRib fracture A break or fracture in one or more of the bones making up the human rib cage... . Chest X-rays in PE are rarely normal, but usually lack signRadiologic sign A radiologic sign is an "objective" indication of some medical fact or quality that is detected by a physician during examin... s that suggest the diagnosis of PE (e.g. Westermark signWestermark sign In chest radiography, the Westermark Sign, is a sign that represents a focus of oligemia seen distal to a pulmonary embolus... , Hampton's hump). Ultrasonography of the legs, also known as leg doppler, in search of deep venous thrombosis (DVT). The presence of DVT, as shown on ultrasonography of the legs, is in itself enough to warrant anticoagulation, without requiring the V/Q or spiral CT scans (because of the strong association between DVT and PE). This may be valid approach in pregnancyPregnancy Pregnancy is the carrying of one or more embryos or fetuses by female mammals, including humans, inside their bodies.... , in which the other modalities would increase the risk of birth defects in the unborn child. However, a negative scan does not rule out PE, and low-radiation dose scanning may be required if the mother is deemed at high risk of having pulmonary embolism. Electrocardiogram findings An electrocardiogramElectrocardiogram An electrocardiogram is a graphic produced by an electrocardiograph, which records the electrical voltage in the heart... (ECG) is routinely done on patients with chest pain to quickly diagnose myocardial infarctionMyocardial infarction Acute myocardial infarction , commonly known as a heart attack, is a disease that occurs when the blood supply to a pa... s (heart attacks). An ECGElectrocardiogram An electrocardiogram is a graphic produced by an electrocardiograph, which records the electrical voltage in the heart... may show signs of right heart strain or acute cor pulmonaleCor pulmonale Cor pulmonale is a medical term used to describe a change in structure and function of the right ventricle of the heart as a... in cases of large PEs - the classic signs are a large S wave in lead I, a large Q wave in lead III and an inverted T wave in lead III ("S1Q3T3"). This is occasionally (up to 20%) present, but may also occur in other acute lung conditions and has therefore limited diagnostic value. The most commonly seen signs in the ECG is sinus tachycardia, right axis deviation and right bundle branch block. Echocardiography findings In massive and submassive PE, dysfunction of the right side of the heart can be seen on echocardiographyEchocardiography The echocardiogram is an ultrasound of the heart.... , an indication that the pulmonary arteryPulmonary artery The pulmonary arteries carry blood from the heart to the lungs.... is severely obstructed and the heart is unable to match the pressure. Some studies (see below) suggest that this finding may be an indication for thrombolysisThrombolysis Thrombolysis is the breakdown by pharmacological means, of blood clots.... . Not every patient with a (suspected) pulmonary embolism requires an echocardiogram, but elevations in cardiac troponinsTroponin Troponin is a protein complex that confers calcium sensitivity to muscle cells.... or brain natriuretic peptideBrain natriuretic peptide Brain natriuretic peptideis a 32-amino-acid polypeptide secreted by the ventricles of the heart in response to excessive str... may indicate heart strain and warrant an echocardiogram. The specific appearance of the right ventricle on echocardiography is referred to as the McConnell sign. This is the finding of akinesia of the mid-free wall but normal motion of the apex. This phenomenon has a 77% sensitivity and a 94% specificity for the diagnosis of acute pulmonary embolism. Combining tests into algorithms Recent recommendations for a diagnostic algorithm have been published by the PIOPED investigators; however, these recommendations do not reflect research using 64 slice MDCT. These investigators recommended: Low clinical probability. If negative D-dimer, PE is excluded. If positive D-dimer, obtain MDCT and based treatment on results. Moderate clinical probability. If negative D-dimer, PE is excluded. However, the authors were not concerned that a negative MDCT with negative D-dimer in this setting has an 5% probability of being false. Presumably, the 5% error rate will fall as 64 slice MDCT is more commonly used. If positive D-dimer, obtain MDCT and based treatment on results. High clinical probability. Proceed to MDCT. If positive, treat, if negative, addition tests are needed to exclude PE. Treatment In most cases, anticoagulant therapy is the mainstay of treatment. Acutely, supportive treatments, such as oxygenOxygen therapy Oxygen therapy is the administration of oxygen as a therapeutic modality.... or analgesia, are often required. Massive PE causing hemodynamic instability (marked decreased oxygen saturationOxygen saturation Oxygen saturation is a relative measure of the amount of oxygen that is dissolved or carried in a given medium.... , tachycardiaTachycardia Tachycardia is an abnormally rapid beating of the heart, defined as a resting heart rate of 100 or more beats per minute in ... and/or hypotensionHypotension In physiology and medicine, hypotension refers to an abnormally low blood pressure.... ) is an indication for thrombolysisThrombolysis Thrombolysis is the breakdown by pharmacological means, of blood clots.... , the enzymatic destruction of the clot with medication. Some advocate its use also if right ventricular dysfunction can be demonstrated on echocardiographyEchocardiography The echocardiogram is an ultrasound of the heart.... . Anticoagulation In most cases, anticoagulantAnticoagulant Summary An anticoagulant is a substance that prevents coagulation; that is, it stops blood from clotting.... therapy is the mainstay of treatment. HeparinHeparin Heparin is a highly sulfated glycosaminoglycan widely used as an injectable anticoagulant.... , low molecular weight heparinLow molecular weight heparin In medicine, low molecular weight heparin is a class of medication used as an anticoagulant in diseases that feature thrombo... s (such as enoxaparinEnoxaparin Enoxaparin is a low molecular weight heparin manufactured by Sanofi-Aventis.... and dalteparinDalteparin Dalteparin is a low molecular weight heparin.... ), or fondaparinuxFondaparinux Fondaparinux is a medication that is an anticoagulant.... is administered initially, while warfarinWarfarin Warfarin is an anticoagulant medication that is administered orally or, very rarely, by injection.... therapy is commenced (this may take several days, usually while the patient is in hospital). Warfarin therapy often requires frequent dose adjustment and monitoring of the INR. In PE, INRs between 2.0 and 3.0 are generally considered ideal. If another episode of PE occurs under warfarin treatment, the INR window may be increased to e.g. 2.5-3.5 (unless there are contraindications) or anticoagulation may be changed to a different anticoagulant e.g. low molecular weight heparinLow molecular weight heparin In medicine, low molecular weight heparin is a class of medication used as an anticoagulant in diseases that feature thrombo... . In patients with an underlying malignancy, therapy with a course of low molecular weight heparinLow molecular weight heparin In medicine, low molecular weight heparin is a class of medication used as an anticoagulant in diseases that feature thrombo... may be favored over warfarin based on the results of the CLOT trial. Similarly, pregnant women are often maintained on low molecular weight heparin to avoid the known teratogenic effects of warfarin, especially in the early stages of pregnancy. People are usually admitted to hospital in the early stages of treatment, and tend to remain under inpatient care until INR has reached therapeutic levels. Increasingly, low-risk cases are managed on an outpatient basis in a fashion already common in the treatment of DVT. Warfarin therapy is usually continued for 3-6 months, or "lifelong" if there have been previous DVTs or PEs, or none of the usual risk factors is present. An abnormal D-dimerD-dimer D-dimer is a blood test performed in the medical laboratory to diagnose thrombosis.... level at the end of treatment might signal the need for continued treatment among patients with a first unprovoked pulmonary embolus. Inferior vena cava filter If anticoagulant therapy is contraindicatedContraindication In medicine, a contraindication is a condition or factor that increases the risk involved in using a particular drug, carryi... and/or ineffective an inferior vena cava filterInferior vena cava filter An inferior vena cava filter, also IVC filter and Greenfield filter, a type of filter named after the successful... may be implanted. Thrombolysis ThrombolysisThrombolysis Thrombolysis is the breakdown by pharmacological means, of blood clots.... can be given for severe PEs when surgery is not immediately available or possible (e.g. periarrest or during cardiac arrest). The only trial that addressed this issue had 8 patients; the four receiving thrombolysis survived, while the four who received only heparin died. The use of thrombolysis in moderate PEs is still debatable. The aim of the therapy is to dissolve the clot, but there is an attendant risk of bleeding or stroke. Surgical management Surgical management of acute pulmonary embolism is uncommon and has largely been abandoned because of poor long-term outcomes. However, recently, it has gone through a resurgence with the revision of the surgical technique and is thought to benefit selected patients. Chronic pulmonary embolism leading to pulmonary hypertensionPulmonary hypertension In medicine, pulmonary hypertension is an increase in blood pressure in the pulmonary artery or lung vasculature.... (known as chronic thromboembolic hypertension) is treated with a surgical procedure known as a pulmonary thromboendarterectomyPulmonary thromboendarterectomy In thoracic surgery, a pulmonary thromboendarterectomy, PTE, is an operation that removes organized clotted blood from... . Prognosis Mortality from untreated PE is said to be 26%. This figure comes from a trial published in 1960 by Barrit and Jordan, which compared anticoagulation against placebo for the management of PE. Barritt and Jordan performed their study in the Bristol Royal InfirmaryBristol Royal Infirmary The Bristol Royal Infirmary, also known as the BRI, is a large teaching hospital situated in the centre of Bristol, En... in 1957. This study is the only placebo controlled trial ever to examine the place of anticoagulants in the treatment of PE, the results of which were so convincing that the trial has never been repeated as to do so would be considered unethical. That said, the reported mortality rate of 26% in the placebo group is probably an overstatement, given that the technology of the day may have detected only severe PEs. Prognosis depends on the amount of lung that is affected and on the co-existence of other medical conditions; chronic embolisation to the lung can lead to pulmonary hypertensionPulmonary hypertension Summary In medicine, pulmonary hypertension is an increase in blood pressure in the pulmonary artery or lung vasculature.... . There is controversy over whether or not small subsegmental PEs need to be treated at all and some evidence exists that patients with subsegmental PEs may do well without treatment. Predicting mortality The PESI and Geneva prediction rules can estimate mortality and so may guide selection of patients who can be considered for outpatient therapy. Evaluation for underlying causes for recurrence After a first PE, the search for secondary causes is usually brief. Only when a second PE occurs, and especially when this happens while still under anticoagulantAnticoagulant Summary An anticoagulant is a substance that prevents coagulation; that is, it stops blood from clotting.... therapy, a further search for underlying conditions is undertaken. This will include testing ("thrombophilia screen") for Factor V Leiden mutation, antiphospholipid antibodies, protein C and S and antithrombin levels, and later prothrombin mutation, MTHFR mutation, Factor VIII concentration and rarer inherited coagulationCoagulation The coagulation of blood is a complex process during which blood forms solid clots.... abnormalities. Epidemiology Risk factors The most common sources of embolism are proximalFacts About Anatomical terms of location In human and zoological anatomy, several terms are used to describe the location of organs and other structures in the body of bil... leg deep venous thrombosis (DVTs) or pelvic vein thromboses. Any risk factor for DVT also increases the risk that the venous clot will dislodge and migrate to the lung circulation, which happens in up to 15% of all DVTs. The conditions are generally regarded as a continuum termed venous thromboembolism (VTE). The development of thrombosis is classically due to a group of causes named Virchow's triadVirchow's triad Overview The following are considered the contributors of Virchow's Triad:... (alterations in blood flow, factors in the vessel wall and factors affecting the properties of the blood). Often, more than one risk factor is present. Alterations in blood flow: immobilization (after surgery, injuryPhysical trauma Physical trauma refers to a physical injury.... or long-distance air travelEconomy class syndrome Economy class syndrome is the occurrence of deep vein thrombosis in air travelers.... ), pregnancyPregnancy Overview Pregnancy is the carrying of one or more embryos or fetuses by female mammals, including humans, inside their bodies.... (also procoagulant), obesityObesity Obesity is a condition in which the natural energy reserve, stored in the fatty tissue of humans and mammals, is increased t... (also procoagulant) Factors in the vessel wall: of limited direct relevance in VTE Factors affecting the properties of the blood (procoagulant state): EstrogenEstrogen Estrogens are a group of steroid compounds, named for their importance in the oestrus cycle, functioning as the primary fem... -containing hormonal contraceptionHormonal contraception Hormonal contraception refers to birth control methods that act on the hormonal system.... Genetic thrombophilia. Acquired thrombophilia External links - NATF is a nonprofit organization that aims to promote public education, policy and advocacy for clotting diseases of the cardiovascular system.