A pulmonary embolism (PE) is a blockage of a pulmonary artery by a blood clot, most often originating from the deep veins of the legs. Emboli can range from small, causing mild breathlessness, to massive, leading to sudden cardiovascular collapse. Prompt recognition and rapid transport are essential, as first-aid interventions are largely supportive and definitive treatment occurs in hospital.
Pulmonary embolism causes
- Blood collecting or “pooling” in a certain part of your body (usually an arm or leg). Blood usually pools after long periods of inactivity, like after surgery, bed rest or a long flight or plane ride.
- Injury to a vein, like from a fracture or surgery (especially in your pelvis, hip, knee or leg).
- Another medical condition, like cardiovascular disease (including congestive heart failure, atrial fibrillation, heart attack or stroke).
- An increase or decrease in your blood’s clotting factors. Elevated clotting factors can occur with some types of cancer or in some people taking hormone replacement therapy or birth control pills. Abnormal or low clotting factors may also happen as a result of blood clotting disorders.
Signs & Symptoms
- Sudden onset of difficulty breathing (dyspnoea)
- Rapid, shallow breathing (tachypnoea)
- Sharp, pleuritic chest pain, often worse on inspiration
- Rapid heart rate (tachycardia) and possible irregular pulse
- Cough, sometimes with blood-streaked sputum (haemoptysis)
- Light-headedness or fainting; distended neck veins in massive PE
When to Call Emergency Services
Activate EMS (e.g., 999/911) without delay if the person exhibits:
- Sudden severe breathlessness or chest pain
- Collapse, fainting, or signs of shock (pale, clammy skin; weak pulse)
- Coughing up blood or acute mental confusion
Rapid professional assessment is critical to reduce morbidity and mortality.
First Aid Steps for Pulmonary Embolism
- Call emergency services immediately, stating “suspected pulmonary embolism.”
- Help the person sit in a semi-upright position to ease breathing and reduce venous return to the heart.
- If trained and equipped, administer high-flow oxygen via mask or nasal cannula to maintain SpO₂ ≥ 94%.
- Monitor airway, breathing, and circulation (ABCs) every few minutes; be ready to begin CPR if the person becomes unresponsive.
- Reassure and keep them as still and calm as possible to minimize strain on the heart and lungs.
- Do not give any oral fluids, medications, or attempt to dissolve the clot these are managed in hospital.
Do’s and Don’ts
| Do | Don’t |
|---|---|
| Call EMS immediately and describe PE symptoms | Delay activating emergency services |
| Position the person semi-upright to improve respiration | Lay the person flat on their back |
| Administer oxygen if trained and equipment is available | Give oral anticoagulants or clot-dissolving drugs yourself |
| Monitor vital signs and be ready for CPR | Attempt invasive procedures or chest compressions unless trained |
| Keep the person calm and immobile until EMS arrives | Allow the person to walk or exert themselves |
Prevention
- Getting regular physical activity. If you can’t walk around, move your arms, legs and feet for a few minutes every hour. If you know you’ll need to sit or stand for long periods, wear compression stockings to encourage blood flow.
- Drinking plenty of fluids, but limiting alcohol and caffeine.
- Not using tobacco products.
- Avoiding crossing your legs.
- Not wearing tight-fitting clothing.
- Getting to a weight that’s healthy for you.
- Elevating your feet for 30 minutes twice a day.
- Talking to your provider about reducing your risk factors, especially if you or any of your family members have had a blood clot.
- Talking to your provider about a vena cava filter.
REFERENCES
- Vyas V, Sankari A, Goyal A. Acute Pulmonary Embolism. [Updated 2024 Dec 11]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK560551/
- Benjamin Wedro, Pulmonary Embolism (Blood Clot in the Lung), https://www.medicinenet.com/pulmonary_embolism/article.htm
- Streiff MB, Holmstrom B, et al. “NCCN Guidelines Insights: Cancer-Associated Venous Thromboembolic Disease, Version 2.” J Natl Compr Canc Netw. (2018) 16(11): 1289-1303.
- O’Brien CG, Barnett CF. Pulmonary Embolic Disease. In: Crawford MH, eds. Current Diagnosis & Treatment: Cardiology. 6th ed. McGraw-Hill Education; 2023.
- Tapson VF. Pulmonary Embolism. In: Fuster V, Narula J, Vaishnava P, Leon MB, Callans DJ, Rumsfeld J, Poppas A, eds. Fuster and Hurst’s The Heart. 15th ed. McGraw-Hill Education; 2022.
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