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Other Names:
PE, Venous thromboembolism, VTE
Pulmonary Embolism

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What Is Pulmonary Embolism?

A pulmonary embolism is a sudden blockage in a lung artery, usually due to a blood clot that traveled to the lung from the leg. A clot that forms in one part of the body and travels in the bloodstream to another part of the body is called an embolus.

Pulmonary embolism is a serious condition that can cause:

  • Permanent damage to part of your lung from lack of blood flow to lung tissue
  • Low oxygen levels in your blood
  • Damage to other organs in your body from not getting enough oxygen.

If a clot is large, or if there are many clots, pulmonary embolism can cause death.

In most cases, pulmonary embolism is a complication of a condition called deep vein thrombosis (DVT). In DVT, blood clots form in the deep veins of the body--most often in the legs. These clots can break free, travel to the lung, and block an artery.

More than 600,000 people in the United States have a pulmonary embolism each year, and more than 60,000 of them die. Most of those who die do so within 30 to 60 minutes after symptoms start. Pulmonary embolism is one of the most common causes of death in hospitalized people who must remain in bed for a long time.

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What Causes Pulmonary Embolism?

Nine out of 10 cases of pulmonary embolism are caused by blood clots that form in the legs and then travel to the lungs.

Leg clots can form when blood flow is restricted and slows down. This happens when you do not move around for long periods of time, such as:

  • After some types of surgeries
  • During a long trip in a car or on an airplane
  • If you must stay in bed for an extended time.

Veins damaged from surgery or injured in other ways are more prone to blood clots.

Rarely, an air bubble, part of a tumor, or other tissue travels to the lung and causes pulmonary embolism.

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Who Gets Pulmonary Embolism?

People at high risk for a blood clot that travels to the lung are those who:

  • Have DVT (a blood clot in the leg) or a history of DVT
  • Have had a pulmonary embolism before.

Pulmonary embolism occurs equally in men and women. As you age, your risk increases. Your risk of having a pulmonary embolism doubles for each 10 years after age 60.

Risk Factors for DVT

There are many factors that increase your risk for DVT. They include:

  • Inherited conditions that cause increased risk for blood clotting

  • Restricted or slow blood flow in a deep vein, due to injury, surgery, or having to stay in bed for a long time

  • Cancer and its treatment

  • Medical conditions such as varicose veins

  • Sitting for a long period of time, such as on long trips in a car or on an airplane

  • During pregnancy and in the 6 week period after delivery

  • Being over age 60 (although DVT can occur at any age)

  • Being overweight or obese

  • Taking birth control or hormone replacement pills

  • Having a medical condition that requires a central venous catheter. A central venous catheter is a tube placed in a vein to allow easy access to your bloodstream for medical treatment.

The more risk factors you have, the greater your chance for developing DVT and pulmonary embolism.

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What Are the Signs and Symptoms of Pulmonary Embolism?

Common Signs and Symptoms

Pulmonary embolism usually occurs suddenly, causing the onset of new symptoms.

The most common signs and symptoms of pulmonary embolism are:

  • Unexplained shortness of breath
  • Chest pain that gets worse with a deep breath, coughing, or chest movement
  • Coughing up blood.

Sometimes, small pulmonary emboli can occur over time. These emboli may cause a more gradual onset of symptoms.

Other Signs and Symptoms

General, less-specific signs and symptoms may occur, including:

  • Anxiety or feelings of dread
  • Lightheadedness
  • Fainting
  • Rapid breathing
  • Increased heart rate
  • Sweating.

Signs and Symptoms of DVT (Deep Vein Thrombosis)

Some people with pulmonary embolism only have signs and symptoms of DVT. These include:

  • Swelling of the leg or swelling along the vein in the leg.

  • Pain or tenderness in the leg. The pain is usually only in one leg. You might only have pain when standing or walking.

  • Feeling of increased warmth in the area of the leg that is swollen or that hurts.

  • Red or discolored skin on the affected leg.

Signs and symptoms of pulmonary emboli vary depending on the amount of blood flow blocked in the lung by clots. Large clots or many clots are life threatening and cause more severe symptoms. Smaller clots cause fewer symptoms or no symptoms at all. It is important that you see your doctor immediately if you have any symptoms of pulmonary embolism or DVT.

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How Is Pulmonary Embolism Diagnosed?

Your doctor will take a health history and perform a physical exam in order to:

  • Identify your risk factors for DVT and pulmonary embolism
  • See how likely it is that you could have a pulmonary embolism
  • Eliminate other possible causes for your symptoms.

Physical Exam

The physical exam will include:

  • Checking your blood pressure, heart rate, and breathing rate
  • Listening to your lungs
  • Listening to your heart
  • Checking your legs for signs and symptoms of DVT.

Tests

To help determine if you have a pulmonary embolism or related disease or condition, initial testing includes:

  • EKG or ECG (electrocardiogram) to measure the rate and regularity of your heartbeat.

  • Chest x-ray, which takes a picture of the lungs, heart, large arteries, ribs, and the diaphragm.

  • Duplex ultrasound, the most common test used to diagnose deep vein clots. It uses sound waves to evaluate the flow of blood in your veins. A gel is put on the skin of the leg. A handheld device is placed on the leg and passed back and forth over the affected area. This device sends sound waves from the leg to an ultrasound machine. A computer then turns the sounds into a picture. The picture is displayed on the computer screen where your doctor can see the blood flow in your leg. This is an indirect way to diagnose a source of pulmonary embolism.

  • Blood work
    • To check for inherited disorders that cause clots.
    • To measure the amount of oxygen and carbon dioxide in the blood (arterial blood gas). A pulmonary embolism may change the levels of oxygen and carbon dioxide in the blood.

Your doctor will order additional tests based on how likely it is that you have a pulmonary embolism and which tests are available. Tests could include:

  • Ventilation-perfusion lung scan (VQ scan), a test that uses a radioactive material to see how well air and blood are flowing to all areas of the lung.

  • Pulmonary angiography, an accurate, invasive test used to diagnose pulmonary embolism. A flexible tube called a catheter is threaded through the groin or arm to the blood vessels in the lung. Dye is injected to take a picture of the blood flow through the blood vessels in the lungs. This test is not available at all hospitals, and a trained specialist is required to perform the test.

  • Spiral computed tomography (CT) scan, a special type of x-ray that takes pictures of structures inside the body. Dye is injected into a vein, allowing the doctors to see the blood vessels in the lungs. This is a very quick test and results are available shortly after the scan is completed.

  • Magnetic resonance imaging (MRI), a test that shows pictures of organs and structures inside the body. MRI uses radio waves to make the image. In many cases, an MRI can provide information that would not show on an x-ray.

  • Echocardiogram, a test that uses sound waves to check for blood clots inside the heart and to check heart function. It can also determine other possible causes for your symptoms.

  • D-dimer, a blood test that measures a substance in the blood that is released when a clot breaks up. High levels may indicate a clot. If your test is normal, a pulmonary embolism is not likely.

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How Is Pulmonary Embolism Treated?

The primary goals in treating pulmonary embolism are to:

  • Keep the blood clot or clots lodged in the lungs from getting bigger
  • Stop the development of new clots.

Treatment may include:

  • Medications
  • Emergency treatment to dissolve a clot
  • Other treatments.

Treatment will vary depending on how severe your symptoms are. If your symptoms are severe, you need immediate emergency treatment. If your symptoms are mild, you can be treated as an outpatient.

Medications

Anticoagulants (blood thinners) decrease your blood's ability to clot. They are used to stop clots from getting bigger and to prevent blood clots from forming. Anticoagulants do not break up blood clots that have already formed. Your body's natural system will dissolve the clot. Anticoagulants can be given:

  • As a pill (warfarin)
  • As an injection or shot (heparin)
  • In a vein (intravenous or IV) (heparin).

Heparin and warfarin may be given at the same time. Heparin acts quickly, while warfarin takes 2 to 3 days before it starts to work. Once warfarin is working, the heparin will be stopped. Pregnant women cannot take warfarin and are treated with heparin only.

If you have DVT, treatment with anticoagulants usually lasts for 3 to 6 months. However, the length of treatment may vary if:

  • Your blood clot occurred after a short-term risk such as surgery. In this case, your treatment may be shorter.

  • You have had clots before. You will need longer treatment.

  • You are being treated for another illness (such as cancer). You will take anticoagulants for as long as those risk factors are present.

The most common side effect of anticoagulants is bleeding. You need to have regular blood tests to check how well the medicine is working. You should call your doctor right away if you have easy bruising or bleeding.

Thrombin inhibitors are new medications that interfere with the clotting process. They are used to treat some types of clots and for patients who cannot take heparin.

Emergency Treatment

When pulmonary embolism is life threatening, doctors may use treatments to remove or break up clots in the lungs. These treatments are given in the emergency room or in the hospital and include:

  • Medications called thrombolytics to quickly dissolve the blood clot. Thrombolytics are used to treat large clots causing severe symptoms.

  • Surgery to remove the blood clot.

  • A new procedure that uses a catheter to reach the clots. The catheter is inserted into the groin or arm and threaded to the clot in the lung. The catheter may be used to extract the clot or deliver medication to dissolve it.

Additional Considerations

Vena cava filters are used when you cannot take medications to thin your blood, or if you are taking blood thinners and continue to develop clots. The filter is inserted inside a large vein called the inferior vena cava (the vein that carries blood from the body back to the heart). It can catch the clots as they try to move through the body to the lungs. This treatment can prevent a clot from traveling to the lungs. It cannot stop other clots from forming.

Graduated compression stockings are worn on the legs from the arch of the foot to just above or below the knee. These stockings are tight at the feet and become looser as they go up the leg. This causes a gentle compression (or pressure) up your leg. The stockings provide support and reduce the chronic swelling that can occur in the leg after a blood clot has occurred.

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Summary

  • A pulmonary embolism is a blockage of an artery in the lung, usually due to a blood clot that traveled to the lung from the leg.

  • In most cases, pulmonary embolism is a complication of a condition called deep vein thrombosis (DVT). In DVT, blood clots form in the deep veins of the body--most often in the legs. These clots can break free, travel to the lung, and block an artery.

  • A pulmonary embolism blocks blood flow to part of the lung. It can be a life-threatening condition.

  • Each year, more than 600,000 people in the United States have a pulmonary embolism, and more than 60,000 of them die. Most of those who die do so within 30 to 60 minutes after symptoms start.

  • Pulmonary embolism is one of the most common causes of death in hospitalized people who must remain in bed for a long time.

  • The greatest risk for pulmonary embolism occurs in people who:
    • Have or have previously had DVT
    • Have previously had a pulmonary embolism.

  • Pulmonary embolism occurs equally in men and women.

  • Your risk for pulmonary embolism doubles every 10 years after age 60.

  • More than half of people with pulmonary embolism do not have symptoms. Some have symptoms that could be due to other conditions.

  • When present, the most common symptoms of pulmonary embolism are:
    • Unexplained shortness of breath
    • Chest pain that gets worse with a deep breath, coughing, or chest movement
    • Coughing up blood.

  • Your doctor will do a physical exam and several tests to decide if you have a pulmonary embolism.

  • The primary goals in treating pulmonary embolism are to keep the current clot or clots from getting bigger and to stop the development of new clots.

  • Treatment varies depending on how severe your symptoms are. Some people need immediate emergency treatment, while others can be treated as an outpatient.

  • Treatment usually includes anticoagulant medications (blood thinners), such as warfarin and heparin, which help prevent clots from forming and help keep clots from getting larger.

  • Preventing pulmonary embolism begins with preventing DVT.

  • If you think that you have DVT or are having symptoms of a pulmonary embolism, contact your doctor immediately.

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Pulmonary Embolism