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. 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 anticoagulant medications such as heparin, warfarin, or one of the direct-acting oral anticoagulants (DOACs). These are recommended to be taken for at least three months. However, treatment using low-molecular-weight heparin is not recommended for...