9. Pulmonary Embolism

📄Definition

Pulmonary embolism is a blockage of a pulmonary artery (or one of its branches) by a thrombus, usually originating from a deep vein thrombosis (DVT).

🛡️ Risk Factors

🧠 Mnemonic:
THROMBOSIS

  • Trauma (esp. long bone fractures)

  • Hospitalisation or immobility

  • Recent surgery

  • Oestrogen (pregnancy, OCP, HRT)

  • Malignancy

  • Blood disorders (thrombophilia, antiphospholipid syndrome)

  • Obesity

  • Smoking

  • Infection/inflammation

  • Stasis (e.g. long flights)

📋Clinical features 

🧠 Mnemonic:

PHD DADS

  • Pleuritic chest pain

  • Haemoptysis

  • Dyspnoea (sudden onset)

  • DVT signs (leg swelling/pain)

  • Anxiety (sense of doom)

  • Dizziness/syncope

  • Sinus tachycardia

Additional: low-grade fever, cyanosis, hypotension (if massive PE)

📊Diagnosis

  • Clinical Risk Stratification:

    • Wells Score → PE likely/unlikely

    • PERC rule (in low-risk patients)

  • D-dimer:

    • If PE unlikely, negative D-dimer excludes PE

  • Imaging:

    • CTPA: 1st line if stable & not pregnant

    • V/Q scan: preferred in pregnancy/renal impairment

    • Leg Doppler USS: if DVT suspected

  • ECG: sinus tachycardia, S1Q3T3 (rare), RBBB

  • CXR: usually normal; may show wedge infarct or effusion

  • ABG: may show hypoxia, low PaCO2

Management –  Mnemonic: ABCDE + ACUTE PE

🔎 Initial (ABCDE approach):

  • Airway: ensure patency

  • Breathing: oxygen if hypoxic

  • Circulation: IV access, fluids if hypotensive

  • Disability: assess GCS

  • Exposure: leg exam for DVT, signs of bleeding

🔊 Definitive:

  • Anticoagulation: LMWH or DOAC (e.g. apixaban)

  • CTPA confirmation

  • Unfractionated heparin if high bleeding risk or renal failure

  • Thrombolysis: only for massive PE with haemodynamic instability

  • Echo: RV strain in severe cases

❗Complications

  • Death

  • Pulmonary infarction

  • Chronic thromboembolic pulmonary hypertension (CTEPH)

  • Right heart failure

🧐 Differentials 

  • ACS (MI)

  • Pericarditis

  • Pneumothorax

  • Pneumonia

  • Anxiety/panic attack

🩺 Monitoring

  • Anticoagulation for 3+ months (longer if unprovoked or thrombophilia)

  • Monitor for bleeding, INR if warfarin used

  • Review for CTEPH symptoms

NICE NG158 (Venous thromboembolic diseases) – Last Updated: March 2020

Last reviewed: July 2025
PASSMAP ensures all content is NICE-aligned and reviewed for Physician Associate Registration Assessment (PARA) success.

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