Treatment of Pulmonary Embolism

Pulmonary embolism is treated by risk class. Haemodynamically unstable patients need reperfusion, and stable patients need anticoagulation, with oxygen and supportive care. Treat early: delay in anticoagulation raises mortality.

Risk class. High risk: systolic pressure under 90 mmHg for 15 minutes, or shock, or cardiac arrest. Intermediate risk: stable, with right ventricular dysfunction or raised troponin. Low risk: stable, normal right ventricle, a low simplified PESI score.

Initial steps. Oxygen if saturation is under 90%, cautious fluids (500 mL or less), noradrenaline for hypotension, and immediate anticoagulation if suspicion is high.

High-risk pulmonary embolism, with no contraindication:

• Alteplase 100 mg intravenously over 2 hours (10 mg bolus then 90 mg over 2 hours), or an accelerated 0.6 mg/kg over 15 minutes (maximum 50 mg). In cardiac arrest: 50 mg bolus.
• Tenecteplase weight-based single bolus (30 to 50 mg over 5 to 10 seconds) where used.
• Where alteplase is not available: streptokinase 250,000 units intravenously over 30 minutes, then 100,000 units/h for 12 to 24 hours.
• Give unfractionated heparin 80 units/kg bolus then 18 units/kg/h during and after thrombolysis, started once the infusion ends.

Absolute contraindications to thrombolysis: previous intracranial haemorrhage, ischaemic stroke within 6 months, central nervous system tumour, major trauma, surgery or head injury within 3 weeks, bleeding diathesis and active bleeding.

Intermediate and low risk:

• Apixaban 10 mg twice daily for 7 days, then 5 mg twice daily; or rivaroxaban 15 mg twice daily for 21 days, then 20 mg once daily with food; or dabigatran 150 mg twice daily or edoxaban 60 mg once daily after 5 days of parenteral therapy.
• Enoxaparin 1 mg/kg twice daily or 1.5 mg/kg once daily; warfarin with target INR 2.0 to 3.0 after overlap.
• Low-risk patients (simplified PESI 0, no right ventricular strain, good support at home) may be treated as outpatients.

Rescue. Failed thrombolysis or contraindication: surgical embolectomy or catheter-directed treatment by a specialist team.

Pregnancy. Weight-adjusted low molecular weight heparin. Thrombolysis only for life-threatening disease.

Kidney impairment. Unfractionated heparin or reduced-dose low molecular weight heparin if creatinine clearance is under 30 mL/min.

Cancer. Use apixaban, edoxaban, rivaroxaban or low molecular weight heparin, with caution in gastrointestinal tumours.

Special groups. In East Africa, pulmonary embolism in the setting of tuberculosis, HIV and postpartum states is common, and streptokinase is the usual affordable thrombolytic.

Monitoring. Monitor blood pressure, heart rate, oxygen saturation and urine output continuously in high-risk disease. After thrombolysis, check for bleeding and aPTT 6 hours after starting heparin.

Referral and escalation. Call the senior clinician and critical care for hypotension, rising lactate or deterioration. Seek haematology advice for recurrent embolism.

Stopping. Anticoagulate for at least 3 months. Review at 3 to 6 months for persistent dyspnoea (chronic thromboembolic disease), and stop only if a major transient trigger has resolved.