Pulmonary embolism

 

Pulmonary embolism is a condition in which one or more emboli, usually arising from a thrombus (blood clot) formed in the veins (or, rarely, in the right heart), are lodged in and obstruct the pulmonary arterial system.  A pulmonary embolism can be categorised as either a provoked or unprovoked pulmonary embolism.  Provoked pulmonary embolism is a pulmonary embolism associated with a transient risk factor such as significant immobility, surgery, trauma, and pregnancy or puerperium. The combined contraceptive pill and hormone replacement therapy are also considered to be provoking risk factors. These risk factors can be removed, reducing the risk of recurrence.  Unprovoked pulmonary embolism is a pulmonary embolism occurring in the absence of a transient risk factor. The person may have no identifiable risk factor or a risk factor that is persistent and not easily correctable (such as active cancer or thrombophilia). Because these risk factors cannot be removed, the person is at an increased risk of recurrence

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When to suspect PE

Suspect pulmonary embolism (PE) in a person with dyspnoea, tachypnoea, pleuritic chest pain, or features of deep vein thrombosis. These features are present in 97% of people with PE

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Other features that may be present include:

  • Tachycardia (heart rate greater than 100 beats per minute)
  • Haemoptysis
  • Syncope
  • Hypotension (systolic blood pressure less than 90 mmHg)
  • Crepitations
  • Cough or fever

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Differential diagnoses

If PE is suspected, exclude other conditions that could explain symptoms including:

  1. Respiratory conditions such as pneumothorax, pneumonia, acute exacerbation of chronic lung disease
  2. Cardiac causes such as acute coronary syndrome, acute congestive heart failure, dissecting or rupturing aortic aneurysm, pericarditis
  3. Musculoskeletal chest pain
    1. NOTE Chest pain with chest wall palpation occurs in up to 20% of people with confirmed PE
  4. Gastro-oesophageal reflux disease (GORD)
  5. Pregnancy
  6. Any cause for collapse such as vasovagal syncope, orthostatic (postural) hypotension, cardiac arrhythmias, seizures, cerebrovascular disorders

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Investigations

NOTE:  Do not delay management of suspected PE for results of an ECG or chest X-ray. They have limited value in diagnosis because they are usually normal in someone with a PE. They may be done as part of investigations for breathlessness or chest pain when another diagnosis seems more likely

  • ECG signs that may be present include: sinus tachycardia, non-specific ST-segment and T-wave abnormalities, right axis deviation, incomplete or complete right bundle-branch block, and, less commonly, T-wave inversion in leads V1–V3, P pulmonale, or the classical S1, Q3, T3 (S wave in lead 1, Q wave in lead 3, and T-wave inversion in lead 3)
  • Chest X-ray features that may be present include: atelectasis, pleural effusion, or elevation of a hemidiaphragm

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Risk factors

If PE is suspected, assess for risk factors for PE:

  1. Major risk factors include:
    1. Deep vein thrombosis (DVT). Suspect if there is unilateral leg pain, swelling, redness, increased temperature, or venous distension. However, only 15% of people with pulmonary embolism have signs of DVT
    2. Previous DVT or pulmonary embolism
    3. Active cancer
    4. Recent surgery, hospitalization, lower limb trauma, or other immobilization (including long-distance travel)
    5. Pregnancy and, in particular, for 6 weeks' postpartum
  2. Other risk factors include:
    1. Increasing age (older than 60 years of age)
    2. Combined oral contraception and hormone replacement therapy
    3. Obesity (body mass index greater than 30 kg/m2)
    4. One or more significant medical comorbidities (for example: heart disease; metabolic, endocrine, neurological disability, or respiratory pathologies; acute infectious disease; or inflammatory conditions)
    5. Varicose veins
    6. Superficial venous thrombosis
    7. Known thrombophilias (thrombotic disorders)
    8. Other: indwelling central vein catheter, nephrotic syndrome, chronic dialysis, myeloproliferative disorders, paroxysmal nocturnal haemoglobinuria, or Behçet's disease

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Management of suspected PE

Arrange immediate admission for people with suspected pulmonary embolism:

  • If they are severely ill with any of the following features:
    • Altered level of consciousness
    • Systolic BP of less than 90 mmHg
    • Heart rate of more than 130 beats per minute
    • Respiratory rate of more than 25 breaths per minute
    • Oxygen saturation of less than 91%
    • Temperature of less than 35°C
  • If they are pregnant, or have given birth within the past 6 weeks

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For all other people, assess the two-level PE Wells score to estimate the clinical probability of PE:

  1. For people with a Wells score of more than 4 points (PE likely):
    1. Either, arrange hospital admission for an immediate computed tomography pulmonary angiogram (CTPA)
    2. Or, if there will be a delay in the person receiving a CTPA, give immediate interim low molecular weight heparin or fondaparinux and arrange hospital admission
  2. For people with a Wells score of 4 points or less (PE unlikely), arrange a D-dimer test:
    1. If the test is positive, either arrange admission to hospital for an immediate CTPA or, if a CTPA cannot be carried out immediately, give immediate low molecular weight heparin or fondaparinux and arrange hospital admission
    2. If the test is negative consider an alternative diagnosis

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Management of confirmed PE

If pulmonary embolism is confirmed:

  1. For people who are haemodynamically stable, parenteral anticoagulation is started as soon as possible (low molecular weight heparin, or fondaparinux) and continued for at least 5 days or until the international normalized ratio (INR) is above 2 for at least 24 hours, whichever is longer. People who have renal impairment or are at increased risk of bleeding should be treated with unfractionated heparin
    1. For pregnant women, low molecular weight heparin is continued until the end of pregnancy
    2. For people with active cancer, low molecular weight heparin is continued until the cancer is considered cured or for at least 6 months
    3. For other people, warfarin (or occasionally rivaroxaban) is commenced within 24 hours of confirmation of the diagnosis and continued for 3 months
      1. Treatment is usually continued for more than 3 months in people with an unprovoked pulmonary embolism (people with no identifiable risk factor or a risk factor that is persistent and unmodifiable such as obesity or active cancer)
      2. For people with a provoked pulmonary embolism treatment may be continued for longer than 3 months after a assessment of the risks and benefits of continuing treatment
  2. For people who are haemodynamically unstable thrombolytic therapy or embolectomy may be offered

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Follow up:

  1. For people on warfarin ensure adequate monitoring
    1. The target international normalized ratio (INR) is usually 2.5, keeping within the range of 2.0–3.0
    2. Specialists will usually make clinical decisions on the duration of treatment
  2. Ensure people with unprovoked pulmonary embolism (PE) are investigated for the possibility of an undiagnosed cancer if they are not already known to have cancer
    1. Initially undertake:
      1. A full history and physical examination to look for evidence of malignancy
      2. A chest X-ray
      3. Blood tests including a full blood count, serum calcium, and liver function tests
      4. Urinalysis
    2. Consider referral for further investigations for cancer with an abdomino-pelvic CT scan (and mammogram in women) in all people over 40 years with a first unprovoked PE who do not have features of cancer based on the initial investigations above
  3. In people with an unprovoked PE, consider antiphospholipid testing (anti-cardiolipin or anti-beta glycoprotein I antibodies) before stopping anticoagulants
  4. In people with an unprovoked PE who have a first-degree relative who has had a DVT or PE, consider arranging hereditary thrombophilia testing (antithrombin, protein C, and protein S testing)

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Assess the two-level PE Wells score to estimate the clinical probability of PE:

  1. For people with a Wells score of more than 4 points (PE likely):
    1. Either, arrange hospital admission for an immediate computed tomography pulmonary angiogram (CTPA)
    2. Or, if there will be a delay in the person receiving a CTPA, give immediate interim low molecular weight heparin or fondaparinux and arrange hospital admission
  2. For people with a Wells score of 4 points or less (PE unlikely), arrange a D-dimer test:
    1. If the test is positive, either arrange admission to hospital for an immediate CTPA or, if a CTPA cannot be carried out immediately, give immediate low molecular weight heparin or fondaparinux and arrange hospital admission
    2. If the test is negative consider an alternative diagnosis

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Chest radiography

For chest x-rays, you can refer the patient to the Radiology Department at East Kent Hospitals (find details here)

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Electrocardiogram

An electrocardiogram (ECG) can usually be undertaken in primary care.  If your practice does not offer ECGs, please request an ECG from East Kent Hospitals

Advice and Guidance is being made available for all specialties, and is being provided by consultant specialists at East Kent Hospitals.  To make a request or to check to if a query has been answered, you will need to log in via the electronic Referral System (eRS)

Click here for the "how to access" e-Referral Advice and Guidance Manual for instructions on how to make a request and check responses

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