What is Pulmonary Embolism?
Pulmonary embolism (PE) is obstruction of the pulmonary arterial tree by thrombus originating from the deep veins (usually lower limb), fat, amniotic fluid, or air. It ranges in severity from haemodynamically stable (submassive) to life-threatening (massive PE with haemodynamic compromise). PE is classified by ESC 2019 as high-risk (haemodynamic instability), intermediate-high, intermediate-low, or low risk based on clinical, imaging, and biomarker data.
Pathophysiology
Thrombus from deep veins migrates via the inferior vena cava to the right heart and pulmonary circulation. Large central emboli obstruct pulmonary blood flow, increase right ventricular afterload, and cause RV dilatation and failure. RV wall motion abnormality and elevated troponin/BNP indicate RV strain and higher mortality. Pulmonary infarction (with pleuritic chest pain and haemoptysis) occurs when peripheral emboli obstruct subsegmental arteries in patients without adequate bronchial collateral circulation.
Clinical Features & Symptoms
- Sudden dyspnoea (most common presenting symptom)
- Pleuritic chest pain (peripheral emboli)
- Haemoptysis (pulmonary infarction)
- Tachycardia (HR >100 bpm)
- Tachypnoea (>20 breaths/min)
- Hypoxia (SpO₂ <95%) and low PaO₂
- Syncope or near-syncope (massive PE)
- Signs of DVT in 30% of PE patients
Diagnosis
Wells PE score for pre-test probability. PERC rule (8 criteria) to exclude PE in very low-risk patients without further testing. Age-adjusted D-dimer (age × 10 µg/L for age >50) to rule out PE in low/intermediate probability. CT pulmonary angiography (CT-PA) is gold standard for diagnosis. VQ scan if CT-PA contraindicated. Echocardiography for RV assessment in haemodynamically unstable patients when CT-PA not immediately available.
Current Treatment Guidelines
Risk stratification
Class I, Level BHigh-risk PE (haemodynamic instability): immediate CT-PA or echo → systemic thrombolysis if confirmed. Intermediate-risk PE: CT-PA + RV assessment (echo, troponin, BNP) → anticoagulation + monitoring for deterioration. Low-risk PE: sPESI score 0 → home treatment with NOACs (HESTIA criteria).
Anticoagulation (NOACs first-line)
Class I, Level ARivaroxaban 15 mg BD × 21 days then 20 mg OD, or apixaban 10 mg BD × 7 days then 5 mg BD. Single-drug regimens, no initial LMWH. At least 3 months; extended for unprovoked PE based on risk-benefit reassessment.
Systemic thrombolysis (massive PE)
Class I, Level BAlteplase 100 mg IV over 2 hours for high-risk PE with haemodynamic compromise. Absolute contraindications: haemorrhagic stroke, recent surgery. Rescues RV failure — reduces mortality in cardiac arrest from PE.
Catheter-directed therapy / surgical embolectomy
Class IIa, Level CCatheter-directed thrombolysis or mechanical thrombectomy for intermediate-high risk PE or contraindication to systemic thrombolysis. Surgical embolectomy if thrombolysis fails or contraindicated in massive PE.
Home treatment (low-risk PE)
Class IIa, Level AsPESI score 0 or Hestia criteria met: safe discharge and treatment with NOACs as outpatient. OUTPUL and HOME-PE trials confirm safety. Reduces hospitalisation without compromising outcomes.
Monitoring & Treatment Targets
Serial oxygen saturation, HR, and BP in the first 24–48 hours for intermediate-risk PE. Troponin and BNP at 24 hours for RV strain monitoring. Repeat imaging at 3–6 months to evaluate chronic thromboembolic disease (rule out CTEPH). Reassess anticoagulation duration at 3 months.
Key Clinical Trials
External Resources
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Frequently Asked Questions
When is thrombolysis indicated for pulmonary embolism?
Systemic thrombolysis (alteplase 100 mg IV) is indicated in high-risk PE with haemodynamic instability (hypotension, cardiac arrest, or shock). It is NOT routinely recommended for intermediate-risk PE due to high intracranial haemorrhage risk (PEITHO trial). For intermediate-high-risk PE deteriorating on anticoagulation, rescue thrombolysis or catheter-directed therapy may be considered.
Can pulmonary embolism be treated at home?
Yes — low-risk PE (sPESI score 0, Hestia criteria met) can be safely treated at home with oral NOACs (apixaban or rivaroxaban). The HOME-PE trial confirmed non-inferiority of home treatment vs hospitalisation. Outpatient management requires adequate social support, stable haemodynamics, SpO₂ ≥90%, no contraindications to anticoagulation, and reliable follow-up.
Medical disclaimer: This content is intended for qualified healthcare professionals and does not constitute medical advice. Always apply clinical judgment and refer to current local guidelines and institutional protocols.