Pulmonary embolism
Pulmonary embolism (PE) is a blockage of an artery in the lungs by a substance that has moved from elsewhere in the body through the bloodstream (embolism). Symptoms of a PE may include shortness of breath, chest pain particularly upon breathing in, and coughing up blood. Symptoms of a blood clot in the leg may also be present, such as a red, warm, swollen, and painful leg. Signs of a PE include low blood oxygen levels, rapid breathing, rapid heart rate, and sometimes a mild fever. Severe cases can lead to passing out, abnormally low blood pressure, obstructive shock, and sudden death.
| Pulmonary embolism | |
|---|---|
| A lung illustration depicting a pulmonary embolism as a thrombus (blood clot) that has travelled from another region of the body, causes occlusion of the pulmonary bronchial artery, leading to arterial thrombosis of the superior and inferior lobes in the left lung | |
| Specialty | Hematology, cardiology, pulmonology |
| Symptoms | Shortness of breath, chest pain, coughing up blood |
| Complications | Passing out, abnormally low blood pressure, sudden death; chronic thromboembolic pulmonary hypertension (long-term complication) |
| Usual onset | Advanced age |
| Risk factors | Cancer, prolonged bed rest, blunt trauma, smoking, stroke, certain genetic conditions, estrogen-based medication, pregnancy, obesity, after surgery |
| Diagnostic method | Based on symptoms, D-dimer, CT pulmonary angiography, lung ventilation/perfusion scan |
| Treatment | Anticoagulants (heparin, warfarin, DOACs) |
| Frequency | ~450,000 per year (USA), 430,000 (Europe) |
| Deaths | >10–12,000 per year (US), >30–40,000 per year (Europe) |
PE usually results from a blood clot in the leg that travels to the lung. The risk of blood clots is increased by advanced age, cancer, prolonged bed rest and immobilization, smoking, stroke, long-haul travel over 4 hours, certain genetic conditions, estrogen-based medication, pregnancy, obesity, trauma or bone fracture, and after some types of surgery. A small proportion of cases are due to the embolization of air, fat, or amniotic fluid. Diagnosis is based on signs and symptoms in combination with test results. If the risk is low, a blood test known as a D-dimer may rule out the condition. Otherwise, a CT pulmonary angiography, lung ventilation/perfusion scan, or ultrasound of the legs may confirm the diagnosis. Together, deep vein thrombosis and PE are known as venous thromboembolism (VTE).
Efforts to prevent PE include beginning to move as soon as possible after surgery, lower leg exercises during periods of sitting, and the use of blood thinners after some types of surgery. Treatment is with anticoagulants such as heparin, warfarin or one of the direct-acting oral anticoagulants (DOACs). These are recommended for at least three months. However, treatment using anticoagulants is not recommended for those at high risk of bleeding, as well as those with renal failure. Severe cases may require thrombolysis using medication such as tissue plasminogen activator (tPA) given intravenously or through a catheter, and some may require surgery (a pulmonary thrombectomy). If blood thinners are not appropriate, a temporary vena cava filter may be used.
Pulmonary emboli affect about 430,000 people each year in Europe. In the United States, between 300,000 and 600,000 cases occur each year, which contribute to at least 40,000 deaths. Rates are similar in males and females. They become more common as people get older.