Respiratory System >
Pulmonary Embolism (PE)

“A blockage of the artery of the lungs by a substance that has moved from elsewhere in the body through the bloodstream (embolism)”

Risk Factors
  • Modifiable:
    • Prolonged bed rest / reduced mobility
  • Non-Modifiable:
    • Recent surgery
    • Thrombophilia
    • Leg fracture
    • Malignancy
    • Pregnancy/postpartum
    • Previous PE
Aetiology & Pathophysiology
  • Venous thrombosis → clots break off and pass through veins to the right side of the heart → lodge in the pulmonary circulation
  • Rare causes:
    • Right ventricular thrombus (post-MI)
    • Septic emboli (right-sided endocarditis)
    • Fat
    • Air
    • Amniotic fluid embolism
    • Neo-plastic cells
    • Parasites.
Clinical Presentation

Small emboli may be asymptomatic, whereas large emboli are often fatal.

  • Symptoms:
    • Acute breathlessness
    • Pleuritic chest pain
    • Haemoptysis
    • Dizziness
    • Syncope
  • Ask about risk factors, past history or family history of thromboembolism
  • Signs:
    • Pyrexia
    • Cyanosis
    • Tachypnoea
    • Tachycardia
    • Hypotension
    • Raised JVP
    • Pleural rub
    • Pleural effusion
  • Look for signs of a cause, e.g. deep vein thrombosis.
  • Bloods:
    • FBC, U&E, baseline clotting, D-dimers
    • ABG – may show Low PaO2 and Low PaCO2
  • Imaging:
    • Chest X-Ray – may be normal, or show:
      • Oligaemia of the affected segment
      • Dilated pulmonary artery
      • Linear atelectasis
      • Small pleural effusion
      • Wedge-shaped opacities
      • Cavitation (rare)
    • Chest CT pulmonary angiogram
  • Special:
    • ECG – may be normal, or show:
      • Tachycardia
      • Right bundle branch block
      • Right ventricular strain (inverted T in V1 to V4)
      • The classical SI QIII TIII pattern is rare
  • Haemodynamically stable patient:
    • LMW Heparin OR Unfractionated Heparin if underlying renal impairment
    • Treat for 5 days
    • Then start DOAC or Warfarin
    • For Warfarin, stop Heparin when INR is 2-3 due to initial prothrombotic effect of Warfarin
    • Consider Vena Caval Filter if a contraindication to anticoagulation
  • Haemodynamically unstable patient:
    • Thrombolysis for massive PE – Alteplase
  • Give Heparin to all immobile patients
  • Stop HRT + COCP pre-op

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