Pulmonary Embolism

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What is a pulmonary embolism?

A pulmonary embolism is a blockage in one of the arteries of the lungs. It is caused when a piece of a blood clot located elsewhere in the body breaks off (thromboembolism) and travels through the bloodstream and lodges in one of the arteries that supply the lungs. A pulmonary embolism may be serious and life threatening. Each year, more than 100,000 cases of pulmonary embolism occur in the United States (Source: NHLBI).

Deep vein thrombosis is the primary cause of pulmonary embolism. In deep vein thrombosis, blood clots form in the large veins of the legs. A blood clot may break free in a leg vein and travel through the bloodstream to the lungs, where it can cause symptoms by blocking an artery.

Symptoms of pulmonary embolism vary greatly, depending on the severity of the embolism. Some individuals with pulmonary embolism have no symptoms, or they experience only symptoms associated with deep vein thrombosis in the legs.

Treatment of pulmonary embolism aims to dissolve, remove or limit the growth of the blood clot. This may be achieved through medication, minimally invasive procedures, or, rarely, surgery.

In some cases, a pulmonary embolism may be life threatening. Seek immediate medical care (call 911) for serious symptoms, such as chest pain, sweating, or severe difficulty breathing, which may be combined with leg pain or swelling and sharp pain in the lungs.

What are the symptoms of pulmonary embolism?

Many of the symptoms of pulmonary embolism are the result of difficulty breathing or deep vein thrombosis. At times, any of these pulmonary embolism symptoms can be severe. It is possible to have a pulmonary embolism without any symptoms.

Symptoms caused by deep vein thrombosis

Deep vein thrombosis is one of the primary causes of a pulmonary embolism. In some cases, the only symptoms of pulmonary embolism are those associated with deep vein thrombosis in the legs. In other cases of pulmonary embolism, symptoms of deep vein thrombosis may be accompanied by more serious symptoms. Symptoms of pulmonary embolism caused by deep vein thrombosis include:

  • Leg pain and swelling
  • Red or discolored skin on the leg
  • Tenderness or warmth in the leg
  • Visible collateral veins

Serious symptoms that might indicate a life-threatening condition

In some cases, pulmonary embolism can be life threatening. Seek immediate medical care (call 911) if you, or someone you are with, have any of these life-threatening symptoms including:

  • Chest pain or pressure
  • Coughing up blood (hemoptysis)
  • Difficulty breathing
  • Fainting or change in level of consciousness or lethargy
  • Rapid breathing (tachypnea) or shortness of breath (dyspnea)
  • Rapid heart rate (tachycardia)
  • Sharp pain in the lungs or chest that occurs with breathing
  • Sweating

What causes pulmonary embolism?

A pulmonary embolism is a blockage in one of the arteries of the lungs. The blockage is usually caused by a blood clot, but other, less common causes exist. Blockage of an artery in the lung restricts blood flow to a portion of the lung.

Common cause of pulmonary embolism

The primary cause of pulmonary embolism is deep vein thrombosis. Deep vein thrombosis is a condition in which blood clots form in the large veins of the lower extremities, such as the leg or thigh. If a blood clot breaks free from the wall of the vein, it can travel through the bloodstream and cause a pulmonary embolism by blocking an artery in the lungs.

Other causes of pulmonary embolism

At times, substances other than blood clots may travel through the bloodstream and eventually lodge in a branch of a pulmonary artery, causing a blockage. Less common causes of pulmonary embolism include:

  • Air bubbles
  • Body tissue
  • Fat from bone marrow (from a bone fracture)
  • Portion of a tumor

What are the risk factors for pulmonary embolism?

A number of factors increase the risk of developing pulmonary embolism. Not all people with risk factors will get pulmonary embolism. Risk factors for pulmonary embolism include:

  • Advanced age

  • Cancer

  • Central venous catheters (tubing placed in a large vein, usually for long-term delivery of medications, fluids or nutrients)

  • Deep vein thrombosis (blood clot in the leg that can break loose from the leg and cause a pulmonary embolism in the lung, a heart attack, or stroke)

  • Long periods of immobility, such as bed rest or prolonged travel

  • Obesity

  • Oral contraceptives or hormone therapy

  • Pregnancy

  • Previous heart attack, pulmonary embolism, or stroke

  • Recent surgery or broken bone

How is pulmonary embolism treated?

Treatment of pulmonary embolism varies greatly depending on the severity of the embolism. Medications are used to control the formation and growth of blood clots and restore blood flow to the lungs. Oxygen may be administered through a face mask, prongs (tiny plastic tubes) in the nostrils, or a breathing tube. More invasive procedures may be required in severe or life-threatening cases of pulmonary embolism, or if the blood clot is very large.

Medications used to treat pulmonary embolism

Depending on the underlying cause and severity of your pulmonary embolism, your doctor may prescribe:

  • Anticoagulants such as warfarin (Coumadin), heparin, or thrombin inhibitors, which thin the blood and prevent the formation or growth of blood clots

  • Sedatives and pain medications, which can make you more comfortable

  • Thrombolytics, which quickly dissolve large blood clots in severe or life-threatening cases of pulmonary embolism

Other treatments for pulmonary embolism

A catheter, or flexible tube, may be used to access the blood clot. In this procedure, a catheter is inserted into a vein in the upper thigh or arm and is guided though the veins to reach the blood clot. The catheter may then be used to remove the clot or deliver medications to dissolve it. Less commonly, surgery may be needed to access the clot.

When medications or other treatments are unsuccessful, a vena cava filter may be surgically inserted into the vena cava (large vein that carries blood back to the heart) to prevent blood clots from the lower extremities from reaching the lungs.

What are the potential complications of a pulmonary embolism?

Complications of an untreated or poorly controlled pulmonary embolism can be serious, even life threatening in some cases. You can help minimize your risk of serious complications by following the treatment plan you and your health care professional design specifically for you. Complications of pulmonary embolism include:

  • Adverse effects of treatment
  • Hypoxia (low levels of oxygen in the blood)
  • Permanent lung damage
  • Pulmonary hypertension
  • Organ failure or dysfunction
  • Recurrent thrombolic events
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Medical Reviewer: William C. Lloyd III, MD, FACS
Last Review Date: 2021 Jan 18
THIS TOOL DOES NOT PROVIDE MEDICAL ADVICE. It is intended for informational purposes only. It is not a substitute for professional medical advice, diagnosis or treatment. Never ignore professional medical advice in seeking treatment because of something you have read on the site. If you think you may have a medical emergency, immediately call your doctor or dial 911.
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