A pulmonary embolus is a blockage of an artery in the lungs by fat, air, a blood clot, or tumor cells.A.D.A.M.

Causes, incidence, and risk factors

A pulmonary embolus is most often caused by a blood clot in a vein, especially a vein in the leg or in the pelvis (hip area). The most common cause is a blood clot in one of the deep veins of the thighs. This type of clot is called a deep vein thrombosis (DVT). The blood clot breaks off and travels to the lungs.

Less common causes include air bubbles, fat droplets, amniotic fluid, or clumps of parasites or tumor cells, all of which may lead to a pulmonary embolus.

You are more likely to get this condition if you have a history of blood clots or certain clotting disorders.

Other risk factors for a pulmonary embolus include:

• Burns
• Cancer
• Childbirth
• Family history of blood clots
• Fractures of the hips or thigh bone
• Heart attack
• Heart surgery
• Long-term bed rest or staying in one position for a long time, such as a long plane or car ride
• Severe injury
• Stroke
• Surgery (especially orthopedic or neurological surgery)
• Use of birth control pills or estrogen therapy

Symptoms

• Chest pain

  • Under the breastbone or on one side
  • Most often feels sharp or stabbing
  • May also be described as a burning, aching, or dull, heavy sensation
  • Usually gets worse with deep breathing
  • You may bend over or hold your chest in response to the pain
• Sudden cough, possibly coughing up blood or bloody mucus
• Rapid breathing
• Rapid heart rate
• Shortness of breath that starts suddenly

Other symptoms that may occur:

• Anxiety
• Bluish skin discoloration (cyanosis)
• Clammy skin
• Dizziness
• Leg pain, redness, or swelling
• Lightheadedness or fainting
• Low blood pressure
• Sweating
• Wheezing

Signs and tests

The health care provider will perform a physical exam and ask questions about your symptoms and medical history.

The following lab tests may be done to see how well your lungs are working:

• Arterial blood gases
• Pulse oximetry

The following imaging tests can help determine where the blood clot is located:

• Chest x-ray
• CT angiogram of the chest
• Pulmonary ventilation/perfusion scan, also called a V/Q scan
• Pulmonary angiogram

Other tests that may be done include:

• Chest CT scan
• ECG
• D-dimer level
• Doppler ultrasound exam of the legs
• Echocardiogram

Treatment

A pulmonary embolus requires emergency treatment. You may need to stay in the hospital. You will receive oxygen if your oxygen level is low.

In cases of severe, life-threatening pulmonary embolism, treatment may involve dissolving the clot. This is called thrombolytic therapy. Clot-dissolving medications include:

• Streptokinase
• Tissue plasminogen activator (t-PA)

Blood thinners are given to prevent new clots. This is called anticoagulation therapy.

• The most common blood thinners are heparin and warfarin (Coumadin).
• Fondaparinux (Arixtra) is a newer blood thinner used under special circumstances.

Heparin or heparin-type drugs are almost always tried first. They can be given through a vein (by IV) or by injection under the skin.

Warfarin is usually start at the same time. It is a pill. When you first start taking warfarin, you will need frequent blood tests. This will help your doctor properly adjust your dose. You will likely need to take the warfarin for several months.

Patients who have reactions to heparin or related medications may need other medications.

Patients who cannot tolerate blood thinners or for whom they may be too risky may need a device called an inferior vena cava filter (IVC filter). This device is placed in the main vein in the belly area. It keeps large clots from traveling into the blood vessels of the lungs. Sometimes a temporary filter can be placed and removed later.

Expectations (prognosis)

How well a person recovers from a pulmonary embolus can be hard to predict. It often depends on what caused the problem in the first place. (For example, cancer, major surgery, or an injury.)

Death is possible in people with a severe pulmonary embolism.

Complications

• Coughing up blood
• Heart failure or shock
• Heart palpitations
• Pulmonary hypertension
• Severe breathing difficulty
• Severe bleeding (usually a complication of treatment)
• Sudden death

Calling your health care provider

Go to the emergency room or call the local emergency number (such as 911) if you have symptoms of pulmonary embolus.

Prevention

Doctors may prescribe blood thinners to help prevent DVT in people at high risk, or those who are undergoing high-risk surgery.

If you had a DVT, your doctor will prescribe pressure stockings. Wear them as instructed. They will improve blood flow in your legs and reduce your risk for blood clots.

Moving your legs often during long plane trips, car trips, and other situations in which you are sitting or lying down for long periods of time can also help prevent DVT. People at very high risk for blood clots may need heparin shots when they are on a flight that lasts longer than 4 hours.

Do not smoke. If you smoke, quit. Women who are taking estrogen must stop smoking. See: Smoking - tips on how to quit

References

1.  
2. Guyatt GH, Akl EA, Crowther M. et al. Executive Summary: AntithromboticTherapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines. Chest. 2012;141(2suppl):7s-47s. [PMC free article: PMC3278060] [PubMed: 22315257]
3. Righini M, Le Gal G, Aujesky D, et al. Diagnosis of pulmonary embolism by multidetector CT alone or combined with venous ultrasonography of the leg: a randomised non-inferiority trial. Lancet. 2008;371(9621):1343-1352. [PubMed: 18424324]
4. Weitz JI. Pulmonary embolism. In: Goldman L, Schafer AI,eds. Cecil Medicine. 24th ed. Philadelphia, PA: Saunders Elsevier; 2011:chap 98.

Review Date: 3/4/2012.

Reviewed by: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine. Yi-Bin Chen, MD, Leukemia/Bone Marrow Transplant Program, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M. Health Solutions, Ebix, Inc.