Clinical Notes : Respiratory

168. Pulmonary Embolism

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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)

  • Vessel wall damage (2)

    • after a number of insults including

      • trauma

      • previous DVT, surgery

      • venous harvest

      • central venous catheterisation.

  • Venous stasis:

    • associated with

      • age >40 years

      • immobility

      • general anaesthesia

      • paralysis

      • spinal cord injury,

      • mocardial infarction

      • prior stroke

      • varicose veins

      • advanced congestive

      • heart failure

      • advanced COPD.

  • Hypercoagulability

    • increased the risk from :

      • cancer

      • high-oestrogen states (oral contraceptives, hormone replacement, obesity, pregnancy)

      • inflammatory bowel disease

      • nephrotic syndrome

      • sepsis

      • blood transfusion

      • inherited thrombophilia (factor V Leiden mutation, prothrombin gene mutation, protein C and S deficiency, antithrombin deficiency, and antiphospholipid antibody syndrome).

Approximately 51% of deep venous thrombi will embolise to the pulmonary vasculature, resulting in a PE. (3)



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

  • Wells Criteria

  • Revised Geneva score

  • Pulmonary Embolism Rule-Out Criteria (PERC)

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

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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 :

  • respiratoty support

  • intravenous fluids

  • vasoactive agents

  • anticoagulation

  • thrombolysis or embolectomy or catheter-directed therapy

  • venous filter

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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


Pulmonary embolism

BMJ Best Practice

Last reviewed: March 2019

Last updated: July  2018


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