What should you know about pulmonary embolism syncope?

Syncope is a brief loss of consciousness caused by temporarily reduced blood flow to the brain. In pulmonary embolism, a clot can obstruct circulation in the lungs and place strain on the heart. This may reduce the amount of blood the heart can move forward, causing sudden light-headedness, collapse, or a feeling that you are about to pass out.

A pulmonary embolism can also present with sudden breathlessness, chest pain that may worsen with breathing, a fast heartbeat, coughing, or coughing up blood. Symptoms vary, and fainting may happen with or without obvious warning. Fainting has many possible causes, so it cannot identify a pulmonary embolism on its own; the combination of symptoms and clinical assessment matters.

If fainting occurs with sudden breathing difficulty, chest discomfort, a racing heartbeat, coughing blood, severe weakness, or new confusion, treat it as an emergency. Keep the person lying down, avoid giving food or drink while they are drowsy, and call emergency services. Do not drive yourself if you feel faint or short of breath.

Clinicians may check oxygen levels, heart rhythm, blood pressure, and signs of strain on the heart, then decide whether scans or other tests are needed. Tell them when the episode began, how long recovery took, whether there was injury, and any recent surgery, prolonged immobility, pregnancy, or previous clot.

Call emergency services immediately for fainting with breathlessness, chest pain, blue or grey lips, coughing blood, a very fast or irregular heartbeat, severe dizziness, or collapse that does not resolve promptly. Emergency assessment is also needed when these symptoms appear after a long period of limited movement or alongside one-sided leg swelling and pain.

If the episode has passed but the cause is unexplained, arrange prompt medical review. Until assessed, avoid strenuous activity and do not start, stop, or change blood-thinning medicine without medical advice.

Ask what findings could explain the fainting, whether testing is needed to check for a clot or another heart and circulation problem, and which symptoms should prompt an immediate return to emergency care. If treatment is prescribed, ask how to take it safely, what bleeding symptoms to report, and when follow-up should occur.