Pulmonary Embolism

• What does pulmonary embolism (PE) describe?

  A blood clot in the pulmonary arteries
• What is an embolus?

  A thrombus that has traveled in the blood
• What condition often leads to an embolus?

  Deep vein thrombosis (DVT) in a leg
• What do DVTs and PEs collectively refer to?

  Venous thromboembolism (VTE)
• What are the risk factors for developing a DVT or PE?

  • Immobility
  • Recent surgery
  • Long-haul travel
  • Pregnancy
  • Hormone therapy with oestrogen
  • Malignancy
  • Polycythaemia
  • Systemic lupus erythematosus
  • Thrombophilia
• What should you ask about when a patient presents with possible features of a DVT or PE?

  Risk factors such as periods of immobility, surgery, and long-haul flights
• What is the purpose of VTE prophylaxis in hospitals?

  • Assess risk of venous thromboembolism (VTE)
  • Provide prophylaxis with low molecular weight heparin for higher-risk patients
  • Use anti-embolic compression stockings unless contraindicated
• What is the common prophylactic treatment for higher-risk patients in hospitals?

  Low molecular weight heparin (e.g., enoxaparin)
• What are contraindications for using low molecular weight heparin?

  Active bleeding or existing anticoagulation with warfarin or a DOAC
• What are some presenting features of pulmonary embolism?

  Shortness of breath, cough, and haemoptysis
• What is the significance of a low threshold for suspecting a PE?

  It allows for timely diagnosis and treatment
• What are the pulmonary embolism rule-out criteria (PERC)?

  • Recommended by NICE guidelines
  • Used when estimating less than a 15% probability of PE
  • If all criteria are met, further investigations are not required
• What does the Wells score predict?

  The probability of a patient having a PE
• What is the usual first step in diagnosing a pulmonary embolism?

  A chest x-ray to rule out other pathology
• What does a positive d-dimer indicate?

  It helps exclude VTE where there is low suspicion
• What are the three imaging options for diagnosing a pulmonary embolism?

  CT pulmonary angiogram, V/Q SPECT scan, and planar V/Q scan
• What is the purpose of a CT pulmonary angiogram (CTPA)?

  To highlight the pulmonary arteries and demonstrate blood clots
• How does a V/Q scan work?

  It compares ventilation with perfusion of the lungs
• What happens to lung tissue with a pulmonary embolism during a V/Q scan?

  The lung tissue will be ventilated but not perfused
• What is a common finding in patients with pulmonary embolism on an ABG?

  Respiratory alkalosis
• What is the mainstay of management for pulmonary embolism?

  Anticoagulation
• What is the first-line treatment for most patients with PE according to NICE (2020)?

  Treatment-dose apixaban or rivaroxaban
• What should be started immediately in patients where PE is suspected and there is a delay in getting a scan?

  Low molecular weight heparin (LMWH)
• How is massive PE with haemodynamic compromise treated?

  With a continuous infusion of unfractionated heparin and considering thrombolysis
• What does thrombolysis involve?

  Injecting a fibrinolytic medication that rapidly dissolves clots
• What are some examples of thrombolytic agents?

  Streptokinase, alteplase, and tenecteplase
• How can thrombolysis be performed?

  Intravenously using a peripheral cannula or catheter-directed thrombolysis
• What are the options for long-term anticoagulation in VTE?

  • Direct-acting oral anticoagulants (DOACs)
  • Warfarin
  • Low molecular weight heparin (LMWH)
• What are direct-acting oral anticoagulants (DOACs)?

  Oral anticoagulants that do not require monitoring
• What are some examples of DOACs?

  Apixaban, rivaroxaban, edoxaban, and dabigatran
• In which situations are DOACs not suitable?

  Severe renal impairment, antiphospholipid syndrome, and pregnancy
• What is warfarin?

  A vitamin K antagonist used for anticoagulation
• What is the target INR for warfarin when treating DVTs and PEs?

  Between 2 and 3
• When is warfarin the first-line treatment?

  In patients with antiphospholipid syndrome
• What is the first-line anticoagulant in pregnancy?

  Low molecular weight heparin (LMWH)
• How long should anticoagulation be continued for different causes of VTE?

  • 3 months with a reversible cause (then review)
  • Beyond 3 months with unprovoked PE, recurrent VTE, or irreversible causes
  • 3-6 months in active cancer (then review)