Chest Medicine













Pulmonary embolism (PE)
  • Embolism in the pulmonary circulation, often from the thrombus in the pelvis or legs
  • Rarer causes include septic emboli, fat emboli, amniotic fluid, neoplastic cells and parasites
  • Risk factors: recent surgery, leg fracture, prolonged immobility, malignancy, thrombophilia, antiphospholipid syndrome, pregnancy, previous PE

Signs and symptoms
  • Acute dyspnoea
  • Pleuritic chest pain
  • Haemoptysis
  • May have dizziness, syncope
  • Signs: cyanosis, tachycardia, tachypnoea, raised JVP, pleural rub, pleural effusion, hypotension (in massive PE)

Investigation and management
  • Calculate the modified Well’s score
    PE Well's Scores
    FeatureScore
    Clinical signs and symptoms of DVT3
    HR > 1001.5
    Recently bed-ridden (> 3 days) or major surgery (< 4 weeks)1.5
    Previous DVT or PE1.5
    Haemoptysis1
    Cancer (on active treatment or last 6 months)1
    Alternative diagnosis less likely than PE3
  • If Well’s score ≥ 4: immediate CTPA (consider V/Q scan if pregnant) +/- treat with LMWH if delay
  • If Well’s score < 4: send bloods for D-dimer
    • If D-dimer positive → immediate CTPA + empirical treatment with LMWH
    • If D-dimer negative → consider alternative diagnosis
  • CTPA +ve + haemodynamically stable → LMWH or unfractionated heparin (if renal impairment) for 5 days then DOAC or warfarin
  • NB:
    • for warfarin → use heparin to bridge the treatment until INR 2-3 (warfarin has initial prothrombotic effect)
    • if anticoagulation contraindicated → consider vena cava filter
  • Length of anticoagulation treatment
    • Provoked PE = 3 months
    • Unprovoked PE = usually longer than 3 months depending on cause
    • Cancer-related PE = 6 months
    • Pregnancy = use heparin until delivery/end of pregnancy
  • Unprovoked PE needs further investigations to rule out occult malignancy
    • If age > 40 → consider CT chest-abdo-pelvis + mammogram for women
    • If family history +ve for thrombophilia → thrombophilia screen and antiphospholipid syndrome testing
  • Massive PE
    • Characterized by haemodynamic instability, e.g., hypotension → thrombolysis with tPA (e.g., alteplase 10 mg IV in 1 min then 90 mg IV infusion over 2 hour max 1.5 mg/kg)

Prevention
  • Heparin or LMWH to all immobilize patients
  • Stop HRT and stop combined hormonal contraceptive pills pre-operation

Reference: Oxford Handbook of Clinical Medicine (10th Edition)