The typical presentation of the pulmonary embolism includes sudden onset of pleuritic chest pain, shortness of breath and hypoxia [7]. Most of the patients might have no clinical presentation at all. Symptoms may also vary from patient to patient. Hence, the diagnosis is made in the case of unexplained respiratory problems after excluding the other probable causes.

Other atypical symptoms include hemoptysis, productive cough, abdominal pain, flank pain, seizures, syncope, wheezing, fever and altered level of consciousness [8].

• Swelling

  Abstract A young man presented with the severe right upper limb swelling following a heavy weight lifting that was thought to be caused by a biceps tendon rupture. [ncbi.nlm.nih.gov]

  These include swelling of the leg or along a vein in the leg, pain or tenderness in the leg, a feeling of increased warmth in the area of the leg that's swollen or tender, and red or discolored skin on the affected leg. [web.archive.org]

• Fever

  High grade fever is a rare presentation of thromboembolic phenomenon. A middle aged woman presented with high grade fevers. Patient remained febrile despite broad spectrum antibiotics. All cultures were negative. [ncbi.nlm.nih.gov]

  Signs of a PE include low blood oxygen levels, rapid breathing, rapid heart rate, and sometimes a mild fever. Severe cases can lead to passing out, abnormally low blood pressure, and sudden death. [dbpedia.org]

• Congestive Heart Failure

  […] without congestive heart failure. [jamanetwork.com]

  […] and efforts to increase blood flow.[2] Congestive heart failure[edit] Congestive heart failure frequently presents with shortness of breath with exertion, orthopnea, and paroxysmal nocturnal dyspnea.[2] It affects between 1–2% of the general United States [en.wikipedia.org]

  As a result of another medical condition, such as cardiovascular disease (including congestive heart failure, atrial fibrillation and heart attack) or stroke. When clotting factors in the blood are increased, elevated, or in some cases, lowered. [my.clevelandclinic.org]

  It can mimic pneumonia, congestive heart failure, and a viral illness known as pleurisy. [vascularcures.org]

• Fatigue

  We present an 88-year-old female with dyspnea and fatigue, which became increasingly worse over a month in the absence of medication. Her weight was 64 kg. Routine coagulation assays and renal function were normal at time of admission. [ncbi.nlm.nih.gov]

  Symptoms can include loss of concentration, focus, fatigue, language faculty impairment and memory loss. [en.wikipedia.org]

  CLINICAL FEATURES • SYMPTOMS • Gradual onset, often greater than 6 months, of dyspnea – exertional, progressive • and/or a nonproductive cough Systemic symptoms (uncommon) • Weight loss • Low-grade fevers • Fatigue • Arthralgias • Myalgias 25. [slideshare.net]

  Furthermore, for those surviving the initial event, prognosis and quality of life may be markedly impaired with increased likelihood of developing long-term complications, such as RV dysfunction and pulmonary hypertension with associated exercise intolerance, fatigue [circ.ahajournals.org]

• Prolonged Immobilization

  Venous thromboembolism may result from prolong immobilization following intracerebral hemorrhage. [ncbi.nlm.nih.gov]

  Examples of these include: Prolonged immobilization Extended travel (sitting in a car, airplane, train) Hospitalization or prolonged bed rest Surgery Increased blood clotting potential Medications birth control pills estrogen supplementation phenothiazines [medicinenet.com]

  Introduction Definition mechanical obstruction of the pulmonary vascular secondary to a blood clot typically the blood clot is a thromboembolism from a deep vein thrombosis (DVT) Epidemiology risk factors prolonged immobilization ( e.g., long travel) [medbullets.com]

  immobilization or congestive heart failure). [clinicaladvisor.com]

  Stasis can also result from prolonged immobilization, as seen in patients who are bedridden or in relatively healthy people who travel long distances.1 Although traveling carries a relatively low rate of massive PE, the risk increases substantially for [rtmagazine.com]

• Cough

  The patient's cough and shortness of breath were slightly relieved. He still experienced pleural effusion and had symptoms of cough and shortness of breath. Chest X-ray demonstrated bilateral pleural effusion. [ncbi.nlm.nih.gov]

  Major Signs and Symptoms Signs and symptoms of pulmonary embolism (PE) include unexplained shortness of breath, problems breathing, chest pain, coughing, or coughing up blood. An arrhythmia (irregular heartbeat) also may suggest that you have PE. [web.archive.org]

  Symptoms Vary: In almost all cases of serious pulmonary embolism, symptoms include the sudden onset of shortness of breath, along with chest pain that increases with breathing or coughing, and a cough that produces blood-tinged sputum. [uspharmacist.com]

  Symptoms of PE include chest pain, shortness of breath, severe cough, coughing up of blood and even sudden death. Pulmonary embolism is the major concern for patients experiencing deep vein thrombosis (DVT). [inovaheart.org]

• Dyspnea

  Herein, we report a case of high-risk APE with a wide range of manifestations, including chest pain, dyspnea, low-blood pressure, and syncope. [ncbi.nlm.nih.gov]

• Hemoptysis

  Eight variables were included in a block rule: Age < 50 years, pulse < 100 bpm, SaO(2) > 94%, no unilateral leg swelling, no hemoptysis, no recent trauma or surgery, no prior PE or DVT, no hormone use. [ncbi.nlm.nih.gov]

  It manifests as pleural chest pain and hemoptysis. In contrast, multiple micro-emboli occlude the capillary beds of the lungs. [symptoma.com]

• Pneumonia

  She was found to have left lower lobe consolidation and pleural effusion and was treated as a case of pneumonia. During the hospital course, her respiratory status worsened, and she was intubated on the third hospital day. [ncbi.nlm.nih.gov]

  A few include • Other Idiopathic Interstitial Pneumonias (IIPs) – nonspecific interstitial pneumonia, – cryptogenic organizing pneumonia, – acute interstitial pneumonia – lymphoid interstitial pneumonia 67. [slideshare.net]

  The Pulmonary Function Tests (PFTs) videos and Ventilator-associated pneumonia lectures have been particularly popular with RTs. NPs and PAs have provided great feedback on Pneumonia Treatment and Liver Function Tests among many others. [youtube.com]

• Tachypnea

  CASE PRESENTATION: A nine-year-old female with spinal muscular atrophy type 1, chronic respiratory failure with tracheostomy and ventilator dependence presented with tachypnea and hypoxia. [ncbi.nlm.nih.gov]

  Septic embolism causes symptoms and signs of pneumonia (eg, fever, cough, sputum production, pleuritic chest pain, dyspnea, tachypnea, and tachycardia) or sepsis (eg, fever, hypotension, oliguria, tachypnea, tachycardia, and confusion). [msdmanuals.com]

  […] forward failure with decreased cardiac output → hypotension and tachycardia References:[3][1] Clinical features Acute onset of symptoms, often triggered by a specific event (e.g., on rising in the morning, sudden physical strain/exercise) Dyspnea and tachypnea [amboss.com]

• Chest Pain

  On the day of admission, she presented to ED with vomiting, watery diarrhea, abdominal pain, chest pain, and respiratory distress. Laboratory findings showed hypoalbuminemia and proteinuria. [ncbi.nlm.nih.gov]

• Hypotension

  In this scenario, after the development of sudden, severe hypotension, pulmonary embolism must be considered and included in a differential diagnosis according to the cause of admission. [ncbi.nlm.nih.gov]

  This patient was given full dose thrombolytics due to persistent hypotension in the setting of massive PE. Take home points: Every patient with undifferentiated hypotension needs a bedside echo, better yet, a RUSH Exam. [ultrasoundoftheweek.com]

• Tachycardia

  Neurological examination returned to base line status but sinus tachycardia and low saturation value on room air were continuing. Un-enhanced CT of the chest demonstrates hyperdense material within the right main pulmonary artery. [ncbi.nlm.nih.gov]

  Symptoms are often nonspecific, including chest pain, coughing, dyspnea, and tachycardia. The diagnosis of PE is based primarily on the clinical findings and is confirmed by detection of an embolism in contrast CT pulmonary angiography (CTA). [amboss.com]

  The most common ECG finding in the setting of a pulmonary embolism is sinus tachycardia. However, the “S1Q3T3” pattern of acute cor pulmonale is classic; this is termed the McGinn-White Sign. [healio.com]

• Cyanosis

  […] obstruction of a pulmonary artery or one of its branches that is usually produced by a blood clot which has originated in a vein of the leg or pelvis and traveled to the lungs and that is marked by labored breathing, chest pain, fainting, rapid heart rate, cyanosis [merriam-webster.com]

  […] or wheezing Fast heart rate Feeling anxious Leg pain, redness, or swelling Low blood pressure Sudden cough, possibly coughing up blood or bloody mucus Shortness of breath that starts suddenly during sleep or on exertion Low grade fever Bluish skin (cyanosis [nlm.nih.gov]

  Pay close attention to the patient's skin; diaphoresis and clammy skin are common, and peripheral cyanosis in the hands and feet may rapidly progress to central cyanosis on the face, neck and trunk. [emsworld.com]

  […] sleep or on exertion Dizziness, lightheadedness, or fainting Low oxygen level in blood (hypoxemia) Fast breathing or wheezing Fast heart rate Feeling of anxiety Leg pain, redness, or swelling Low blood pressure Low-grade fever Clammy or bluish skin (cyanosis [utswmed.org]

• Retrosternal Chest Pain

  Pleuritic chest pain, retrosternal chest pain. Cough and haemoptysis. Any chest symptoms in a patient with symptoms suggesting a deep vein thrombosis (DVT). In severe cases, right heart failure causes dizziness or syncope. [patient.info]

• Back Pain

  Some individuals may also experience uncommon symptoms such as dizziness, back pain or wheezing. Because PE can be fatal, if you experience these signs or symptoms seek medical attention right away. [vascularcures.org]

  But as the week progressed so did her symptoms — back pain, chest pain, uncontrollable chills — until she could no longer ignore them. [heartinsight.heart.org]

  These two conditions are usually found in patients with few or no classic symptoms such as coughing (including coughing up blood), chest or upper back pain, acute shortness of breath, or general or specific failure of the circulation that is either cardiac [doi.org]

• Dizziness

  The patient's dizziness improved in ED. Neurological examination returned to base line status but sinus tachycardia and low saturation value on room air were continuing. [ncbi.nlm.nih.gov]

  Others may experience shortness of breath, chest pain, dizziness, and possibly swelling in the legs. If you have a pulmonary embolism, you need medical treatment right away to prevent a blood clot from blocking blood flow to the lungs and heart. [radiologyinfo.org]

  However, each individual may experience symptoms differently: Sudden shortness of breath (most common) Chest pain, usually worse with breathing A feeling of anxiety A feeling of dizziness, lightheadedness, or fainting Palpitations and heart rarcing Coughing [inovaheart.org]

  The risk of pulmonary embolism increases with age Symptoms include chest pain, dizziness, and rapid breathing The risk of pulmonary embolism is high for individuals who have had a blood clot in the leg or arm In rare cases, a pulmonary embolism can be [medicalnewstoday.com]

  However, each individual may experience pulmonary embolism symptoms differently: sudden shortness of breath (most common) chest pain (usually worse with breathing) a feeling of anxiety a feeling of dizziness, lightheadedness, or fainting palpitations [beaumont.org]

• Agitation

  Hypoxia, which may cause anxiety, restlessness, agitation and impaired consciousness. Pyrexia. Elevated jugular venous pressure. Gallop heart rhythm, a widely split second heart sound, tricuspid regurgitant murmur. Pleural rub. [patient.info]

  But epinephrine also has many adverse reactions, such as agitation, restlessness, headache, tachycardia, hypertension, and some significantly more dangerous conditions including myocardial ischemia, ventricular arrhythmia, cerebral hemorrhage and pulmonary [jsms.sch.ac.kr]

  A CNS toxicity phase (agitation evolving to frank seizures or CNS depression) may precede cardiovascular collapse. [doi.org]

The history and clinical examination of a case of pulmonary embolism are usually not sufficient to establish the diagnosis of pulmonary embolism with certainty. Hence, in cases of unexplained respiratory problems, certain investigations must be carried out to reach the final diagnosis [9].

A hypercoaguable workup must be carried out to screen for antithrombin 3 deficiency, protein C or protein S deficiency, connective tissue disorders and homocystinurea.

White blood count, arterial blood gases, D dimer testing, brain natriuretic peptide, serum troponin levels and ischemia modified albumin level are potentially useful laboratory tests that can indicate the presence or absence of pulmonary embolism in the patient.

Imaging techniques that are helpful in confirming the diagnosis of pulmonary embolism include computed tomography angiography, pulmonary angiography, chest radiography, ECG, magnetic resonance imaging (MRI), venography and duplex ultrasonography.

• Pulmonary Infiltrate

  Focal pulmonary infiltrates may result. [msdmanuals.com]

  Several findings may be associated with acute PE, including pulmonary infiltrates, atelectasis, diaphragmatic elevation, pleural effusion, Westermark sign, and Hampton hump. [journals.lww.com]

• Pulmonary Infiltrates

  Focal pulmonary infiltrates may result. [msdmanuals.com]

  Several findings may be associated with acute PE, including pulmonary infiltrates, atelectasis, diaphragmatic elevation, pleural effusion, Westermark sign, and Hampton hump. [journals.lww.com]

• Left Pleural Effusion

  Echography showed slight increase in left pleural effusion. She had the same diagnosis. The chest pain remained at the same level. [ncbi.nlm.nih.gov]

• Right Axis Deviation

  Electrocardiographic findings ACS ( n =198) APE ( n =81) TC ( n =21) p value P pulmonale (%) 8 (4) 10 (12) 0 0.014 Right axis deviation (%) 0 6 (7) 0 Left axis deviation (%) 12 (6) 5 (6) 3 (14) 0.35 S 1 S 2 S 3 pattern (%) 3 (2) 11 (14) 1 (5) S 1 Q 3 [ncbi.nlm.nih.gov]

  […] heart strain pattern incomplete or complete right bundle branch block prominent R wave in lead V1 right axis deviation T-wave inversion in the right precordial leads +/- the inferior leads is seen in up to 34% of patients and is associated with high [radiopaedia.org]

  Other diagnostic measures Electrocardiography (ECG) Sinus tachycardia most commonly seen Signs of right ventricular pressure overload SIQIIITIII -pattern New right bundle branch block Bradycardia < 50 or tachycardia > 100 bpm Right or extreme right axis [amboss.com]

  ECG - may be normal, or show any of these changes: sinus tachycardia, atrial fibrillation, nonspecific ST or T-wave abnormalities, right ventricular strain pattern V1-3, right axis deviation, right bundle branch block (RBBB), or deep S-waves in I with [patient.info]

• Thrombocytosis

  Other conditions include polycythemia, paroxysmal nocturnal hemoglobinuria and essential thrombocytosis amongst others. [myheart.net]

  […] include: Factor V Leiden deficiency MHFTHR mutation Protein C or Protein S deficiencies antithrombin III deficiency Homocystinemia Homocystinuria Hyperlipidemia Blood disorders Polycythemia increased number of red blood cells (the opposite of anemia) Thrombocytosis [medicinenet.com]

  […] trips or hospitalization), pregnancy, use of estrogen-containing hormonal contraceptives, postmenopausal hormones, atrial fibrillation, vascular injury, IV drug abuse, polycythemia vera, heart failure, autoimmune hemolytic anemia, sickle cell anemia, thrombocytosis [medical-dictionary.thefreedictionary.com]

  […] factors resulting in a hypercoagulable state Acute medical illness Drug abuse (intravenous [IV] drugs) Drug-induced lupus anticoagulant Hemolytic anemias Heparin-associated thrombocytopenia Homocystinemia Homocystinuria Hyperlipidemias Phenothiazines Thrombocytosis [emedicine.medscape.com]

  […] factors Risk factors for pulmonary embolism also include the following: Drug abuse (intravenous [IV] drugs) Drug-induced lupus anticoagulant Hemolytic anemias Heparin-associated thrombocytopenia Homocystinemia Homocystinuria Hyperlipidemias Phenothiazines Thrombocytosis [emedicine.com]

• Hypocapnia

  Arterial blood gas analysis showed hypoxemia-hypocapnia and D-dimer level was high. Computed tomographic pulmonary angiography (CTPA) demonstrated pulmonary embolism in both main pulmonary arteries, through lobar and segmental branches. [ncbi.nlm.nih.gov]

  […] evaluate if there are DVTs Studies ECG findings sinus tachycardia atrial fibrillation right ventricular strain S1Q3T3 presence of S wave in lead I and Q wave and inverted T wave in lead III T-wave inversions in V1-V4 Arterial blood gas findings hypoxemia hypocapnia [medbullets.com]

  […] obstruction Infarction and inflammation of the lungs and pleura Causes pleuritic chest pain and hemoptysis Leads to surfactant dysfunction → atelectasis → ↓ PaO2 Triggers respiratory drive → hyperventilation and tachypnea → respiratory alkalosis with hypocapnia [amboss.com]

  Analysis of blood gases reveals arterial hypoxia and hypocapnia. Pulmonary embolism is detected by chest radiographic films, pulmonary angiography, and radioscanning of the lung fields. [medical-dictionary.thefreedictionary.com]

  Arterial or venous blood gas measurement may show an increased alveolar to arterial oxygen (A-a) difference (sometimes called A-a gradient) or hypocapnia; one or both of these tests are moderately sensitive for PE, but neither is specific. [merckmanuals.com]

• Neutrophilia

  BAL fluid neutrophilia has been demonstrated to predict early mortality. 52. [slideshare.net]

• Hypoglycemia

  Due to Insulin Overdose "We report a very rare case of acute pulmonary edema caused by hypoglycemia from insulin overdose during an attempted suicide. [clinicclinic2.cafe24.com]

• Incomplete Right Bundle Branch Block

  The ECG shows sinus rhythm, right bundle-branch block, and a S1Q3T3 pattern ( Figure 1 ). Chest x-ray is normal. [circ.ahajournals.org]

  The most common abnormalities observed in the study and control groups were sinus tachycardia (18.8% versus 11.8%), incomplete right bundle branch block (4.2% versus 0.0%), complete right bundle branch block (4.2% versus 6.0%), and S1Q3T3 pattern (2.1% [journals.lww.com]

  QT prolongation, and incomplete or complete right bundle-branch block. 30, 93 – 110 Of these, sinus tachycardia, new-onset atrial arrhythmias, new right bundle-branch block (complete or incomplete), Qr pattern in V 1, S1Q3T3, negative T waves in V 1 [doi.org]

• P Pulmonale

  P pulmonale, right and left axis deviation, S 1 S 2 S 3 and S 1 Q 3 T 3 patterns, low voltage and clockwise rotation were specific, but not sensitive for APE. [ncbi.nlm.nih.gov]

  Right axis deviation (R > S in V1) and P-pulmonale may be present. T-wave inversion in leads V1 to V4 also occurs. [merckmanuals.com]

  Abnormalities reported with acute PE include sinus tachycardia, atrial arrhythmias, low voltage, Q waves in leads III and aVF (pseudoinfarction), S1Q3T3 pattern, Qr pattern in V 1, P pulmonale, right-axis deviation, ST-segment elevation, ST-segment depression [doi.org]

• Electrocardiogram Change

  Pre-specified data such as clinical presentation, electrocardiogram changes, transthoracic echocardiographic findings, cardiac biomarkers, diagnostic imaging, therapy, and outcomes were collected. We identified a total of 34 case reports. [ncbi.nlm.nih.gov]

• Pleural Effusion

  The patient refused treatment for pleural effusion and requested for discharge. At the time of discharge, shortness of breath was relieved, and the pleural effusion had decreased. The patient was lost to follow-up. [ncbi.nlm.nih.gov]

  Oligemia (the Westermark sign), prominent central pulmonary artery (the Fleischner sign), pleural-based area of increased opacity (the Hampton hump), vascular redistribution, pleural effusion, elevated diaphragm, and enlarged hilum were also poor predictors [doi.org]

In patients with suspected deep venous thrombosis or pulmonary embolism, anti-coagulant therapy is initiated immediately [10].

Anticoagulant therapy with heparin administration decreases the mortality rate from 30% to less than 10%. Various anti-coagulation medications include unfractionated heparin, low weight heparin, warfarin, fondaparinux and factor Xa inhibitors.

Thrombolytic agents such as alteplase/reteplase and urokinase/streptokinase are also used in the treatment of pulmonary embolism.

Surgical options for management of pulmonary embolism include:

• Catheter embolectomy and fragmentation or surgical embolectomy
• Placement of vena cava filters

Along with these treatment options, supportive care to the patient is ensured.

As far as the common causes of sudden death are concerned, pulmonary embolism is second only to sudden cardiac death.

Up to 10% of the patients who develop pulmonary embolism die within the first hour. Recurrence of pulmonary embolism subsequently causes death in 30% of the patients.

With appropriate anti-coagulant therapy, the mortality rate reduced to less than 5%.

More than 90% of the pulmonary emboli result from the dislodging of thrombi from the deep veins of the lower limb. Other less common sites of thrombus formation include prostatic and pelvic veins. Pulmonary emboli usually do not originate in the upper limb except in intravenous drug abusers.

The factors that predispose to venous thrombosis in the lower limbs include the following.

Venous stasis:

• Immobility (bed-rest, surgery and limb paralysis)
• Low cardiac output
• Varicose veins

Venous trauma:

• Trauma
• Intravenous cannulation

Increased coagubility:

• Use of drugs such as oral contraceptives
• Malignancy
• Dehydration
• Polycythemia
• Nephritic syndrome
• Ulcerative colitis
• AIDS (Acquired Immunodeficiency Syndrome) [1]

Inherited coagulation defects:

• Antithrombin III, Protein S and Protein C deficiency

Miscellaneous:

• Smoking [2]

The per annum incidence of pulmonary embolism in the United States is 1 case per 1000 persons [3]. Although most of these patients are asymptomatic, 60-80% of the patients with DVT develop pulmonary embolism.

In hospitalized patients, pulmonary embolism is the third most common cause of death (up to 650,000 deaths per year). Venous thromboembolism is a major health problem with an incidence of about 250,000 incident cases per year [4] [5].

The incidence of pulmonary embolism and the mortality occurring from it varies from country to country. A research indicates that male sex is more prone to the development of pulmonary embolism with a mortality rate 20-30% higher as compared to females. Pulmonary embolism is much more common in blacks as compared to whites [6].

Pulmonary emboli arise most commonly from the deep veins of the calves. Any factor or disease that cases stasis of blood in the veins can predispose to the formation of thrombi. Dislodged thrombi reach the lung after traveling through the right side of the heart.

Large emboli occlude the proximal arteries and the right ventricular outflow, causing a rapid decrease in the the cardiac output and leading to right ventricular failure. The prominent features are those of vascular collapse e.g. hypotension and syncope.

On the other hand, small and medium sized emboli occlude the segmental arteries causing infarction of the lung segment involved. It manifests as pleural chest pain and hemoptysis.

In contrast, multiple micro-emboli occlude the capillary beds of the lungs. Due to collateral vascular supply, there is no pulmonary infarction  but there insidious loss of the microvascular bed supplying the gas exchange units of the lungs leading to pulmonary hypertension and right ventricular failure.

Prevention of the development of venous thromboembolism can effectively reduce the likelihood of the development of pulmonary embolism. This is done by the following measures:

Avoid venous stasis:

Venous stasis during surgery can be avoided by stimulation of the calf muscles. Following surgery, early mobilization and leg exercises are helpful in reducing the likelihood of venous thromboembolism.

Use of anticoagulants in susceptible individuals:

Anticoagulants such as warfarin and heparin are used in the patients who are at high risk for developing thromboembolism.

Pulmonary emboli are thrombi that dislodge into the lungs usually from the deep veins of the lower limbs. Less common sites of thrombus formation include the veins of the pelvis, prostate and the upper limbs.

Pulmonary emboli may be small, medium or large. Each of these cause respiratory and hemodynamic compromise by different mechanisms. Hence, pulmonary embolism is not a disease; rather it is the complication of deep venous thrombosis (DVT).

It is a life threatening emergency and needs to be diagnosed and treated promptly.

Pulmonary embolism refers to the state in which masses of clotted blood that form in the lower limbs dislodge into the lungs. Males are more prone to the development of this complication.

Smoking, obesity, decreased physical activity and intake of unbalanced diet make the person more prone to the development of pulmonary embolism. It is a very dangerous condition and the patient needs to be hospitalized immediately. High risk patients must be identified and preventive measures must be carried out.

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3. Horlander KT, Mannino DM, Leeper KV. Pulmonary embolism mortality in the United States, 1979-1998: an analysis using multiple-cause mortality data. Archives of internal medicine. Jul 28 2003;163(14):1711-1717.
4. Heit JA. The epidemiology of venous thromboembolism in the community: implications for prevention and management. Journal of thrombosis and thrombolysis. Feb 2006;21(1):23-29.
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8. Carrascosa MF, Batan AM, Novo MF. Delirium and pulmonary embolism in the elderly. Mayo Clinic proceedings. 2009;84(1):91-92.
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10. Kearon C, Kahn SR, Agnelli G, et al. Antithrombotic therapy for venous thromboembolic disease: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition). Chest. Jun 2008;133(6 Suppl):454S-545S.