Pulmonary Embolism

Clinical Notes : Respiratory

168. Pulmonary Embolism

Definition

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)

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)

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

Wells Criteria
Revised Geneva score
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 :

respiratoty support
intravenous fluids
vasoactive agents
anticoagulation
thrombolysis or embolectomy or catheter-directed therapy
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.

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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.

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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

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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.

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Guidelines on the diagnosis and management of acute pulmonary embolism

European Society of Cardiology

Published 2014

Corrigendum 2015

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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

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Pulmonary embolism

BMJ Best Practice

Last reviewed: March 2019

Last updated: July 2018

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