Clinical Notes : Respiratory
168. Pulmonary Embolism

Definition
Pulmonary embolism (PE) is a consequence of thrombus formation within a deep vein of the body, most frequently in the lower extremities.
Thrombus formation in the venous system occurs as a result of venous stasis, trauma, and hypercoagulability.
These factors are collectively known as Virchow's triad. (1)
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Vessel wall damage (2)
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after a number of insults including
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trauma
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previous DVT, surgery
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venous harvest
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central venous catheterisation.
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Venous stasis:
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associated with
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age >40 years
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immobility
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general anaesthesia
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paralysis
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spinal cord injury,
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mocardial infarction
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prior stroke
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varicose veins
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advanced congestive
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heart failure
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advanced COPD.
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Hypercoagulability
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increased the risk from :
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cancer
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high-oestrogen states (oral contraceptives, hormone replacement, obesity, pregnancy)
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inflammatory bowel disease
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nephrotic syndrome
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sepsis
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blood transfusion
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inherited thrombophilia (factor V Leiden mutation, prothrombin gene mutation, protein C and S deficiency, antithrombin deficiency, and antiphospholipid antibody syndrome).
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Approximately 51% of deep venous thrombi will embolise to the pulmonary vasculature, resulting in a PE. (3)
Diagnosis
History and physical examination alone are rarely sufficient to confirm or rule out PE
A high index of suspicion and prompt management are required as the highest risk of dying is within the first 2 hours of presentation (4)
Clinical probability, assessed by a validated prediction rule and/or clinical judgement, is the basis for all diagnostic strategies for PE
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Wells Criteria
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Revised Geneva score
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Pulmonary Embolism Rule-Out Criteria (PERC)


Where PE is likely, refer to A+E for D-Dimer testing

Management
Refer all patient where PE is likely, or where one or more PERC criteria is met, to A+E.
Emergency management of PE may include :
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respiratoty support
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intravenous fluids
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vasoactive agents
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anticoagulation
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thrombolysis or embolectomy or catheter-directed therapy
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venous filter

1. Virchow's legacy: deep vein thrombosis and pulmonary embolism.
Cervantes J, Rojas G.
World J Surg. 2005;29 Suppl 1:S30-4.
2. Thromboembolic Risk Factors (THRIFT) Consensus Group. Risk of and prophylaxis for venous thromboembolism in hospital patients.
Lowe GDO et al.
BMJ. 1992 Sep 5;305(6853):567-74.
3. The clinical features of submassive and massive pulmonary emboli.
Bell WR, Simon TL, DeMets DL. T
Am J Med. 1977 Mar;62(3):355-60
4. Pulmonary embolism, part I: Epidemiology, risk factors and risk stratification, pathophysiology, clinical presentation, diagnosis and nonthrombotic pulmonary embolism.
Bĕlohlávek J, Dytrych V, Linhart A.
Exp Clin Cardiol. 2013 Spring;18(2):129-38.
Guidelines on the diagnosis and management of acute pulmonary embolism
European Society of Cardiology
Published 2014
Corrigendum 2015
Evaluation of patients with suspected acute pulmonary embolism: best practice advice from the Clinical Guidelines Committee of the American College of Physicians
American College of Physicians
November 2015
BMJ Best Practice
Last reviewed: March 2019
Last updated: July 2018


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