A pulmonary embolism is a blockage of an artery in the lungs. The embolism prevents blood and nourishment from getting to a specific area of the lungs. This may lead to the death of lung tissue in this area. Damage to the lungs may make it difficult for the lungs to work properly. In severe cases, a pulmonary embolism can lead to death.
Pathway of Pulmonary Embolism
An embolism is caused by a lump of material, called an embolus, that is floating in the blood. An embolus can be a blood clot, air bubble, a piece of fat, bone marrow, or tumor tissue. The embolus travels from its original location and passes through larger blood vessels until it gets stuck in a smaller blood vessel. In this case, the embolus is trapped in an artery of the lungs.
The embolus in a pulmonary embolism is usually a blood clot. It most often starts in a vein in the legs or pelvis.
Factors that may increase your chance of a pulmonary embolism include:
- Blood clot in a deep vein of a leg or the pelvis
- Increased levels of clotting factors in the blood
- Prolonged bed rest
- Major surgery, especially after pelvic surgery, knee replacement, or heart surgery
- Injury to a vein in a leg or the pelvis
- Fractures of the hip or thigh bone
- Certain blood disorders
- Prolonged sitting, such as during a long trip
- Pregnancy or postpartum period
- Inflammatory bowel disease
- Autoimmune disorder, such as immune thrombocytopenic purpura, polyarteritis nodosa, or polymyositis
- Taking certain medications, such as birth control pills or antipsychotics
The symptoms of a pulmonary embolism vary depending on the size and location of the blockage. The area of lung affected by the lack of blood will also affect the symptoms. Pulmonary embolism may cause:
Your doctor will ask about your symptoms and medical history. A physical exam will be done. Your doctor may order the following tests:
- Arterial blood gas study—to check oxygen levels and lung function
- Electrocardiogram (EKG)—to assess the electrical activity of the heart
- D-Dimer blood test—to detect the presence of a clot
If you have a family history of blood clots, and had blood clots in the past for no apparent reason, your doctor may do additional blood tests. The tests will look for possible inherited defects in your clotting system, such as:
- Factor V Leiden mutation (seen in up to 40% of cases)
- Increased factor VIII
Imaging tests evaluate the lungs and surrounding structures. These may include:
Treatment depends on the size and severity of the clot. Emergency treatment and hospitalization may be needed.
Emergency treatment for shock may include IV fluids, medications, and oxygen therapy.
Treatment includes medication, and in some cases, surgery.
Medications are used to break up and control the clot. After the initial period, the blood thinner will be switched to a longer-acting anticoagulants.
Another type of medication may be needed to dissolve the clot. These are called thrombolytics. This type of medication is usually only used in people with a pulmonary embolism that is very large or is causing severe illness. Thrombolytics will not be used if you have a high risk of bleeding.
Surgery to remove the clot may be needed if the blockage is very large, not responding to treatment, or the person is in shock. The surgery is called an embolectomy.
To reduce your chance of a pulmonary embolism:
- Eat a healthful diet that is low in saturated fat and rich in whole grains, fruits, and vegetables.
- Begin a safe exercise program with the advice of your doctor.
- Walk or move your legs to break up long periods of sitting.
- If you smoke, talk with your doctor on ways you can quit.
- Unless you are on a fluid-restricted diet, be sure to drink lots of water.
People at high risk of developing blood clots can do the following:
- Take medication if your doctor recommends it. Anticoagulant drugs are most commonly used.
- Wear elastic stockings if suggested by your doctor. They can help improve circulation in your legs.
- Walk or move your legs to break up long periods of sitting. If you are traveling, get up and walk every few hours.
American Lung Association
American Society of Hematology
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Last reviewed August 2014 by Michael Woods, MD
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.