Pulmonary Embolism

What is a pulmonary embolism?

A pulmonary embolism (PE) is a blood clot that develops in a blood vessel elsewhere in the body (most commonly from the leg), travels to an artery in the lung, and forms an occlusion (blockage) of the artery.

A blood clot (thrombus) that forms in a blood vessel in one area of the body, breaks off, and travels to another area of the body through the bloodstream is called an embolus. An embolus can lodge itself in a blood vessel, blocking the blood supply to a particular organ. This blockage of a blood vessel by an embolus is called an embolism.

An embolism to the lung may cause serious life-threatening consequences and, potentially, death. Most commonly, a PE is the result of a condition called deep vein thrombosis (blood clot in the deep veins of the leg).

Illustration of the circulatory system, arterial and venous

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The circulatory system:

The heart, arteries, capillaries, and veins make up the body's circulatory system. Blood is pumped with great force from the heart into the arteries, then into the capillaries (small blood vessels in the tissues) and returns to the heart through the veins. Much of the force of the heartbeat is lost when the blood enters the veins and results in the slowing down of the blood flow through the veins back to the heart. Under certain conditions, decreased blood flow may contribute to clot formation.

What causes a pulmonary embolism?

Blood clotting is a normal process that occurs in the body to prevent bleeding. The body makes blood clots and then breaks them down. Under certain circumstances, the body may be unable to break down a clot, which may result in a serious health condition.

Abnormal blood clotting in the veins is related to a combination of several problems such as "sluggish" blood flow through the veins, an over-increase in clot forming factors, and/or an injury to the blood vessel wall.

Blood clots can form in arteries and/or veins. Clots formed in veins are called venous clots. Veins of the legs can be classified as superficial veins (close to the surface of the skin) or deep veins (located near the bone and surrounded by muscle).

Illustration of the arteries of the legs

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Venous clots most often occur in the deep veins of the legs. This condition is called deep vein thrombosis (DVT), or deep vein clot. Once a clot has formed in the deep veins of the leg, there is a potential for part of the clot to break off and travel (embolize) through the bloodstream to another area of the body. Deep vein thrombosis is the most common cause of a pulmonary embolism. Therefore, the term venous thromboembolism (VTE) may refer to deep vein thrombosis and/or the complication, pulmonary embolism.

Other less frequent sources of pulmonary embolism are a fat embolus, amniotic fluid embolus, air bubbles, and a deep vein thrombosis in the upper body. Clots may also form on the end of an indwelling intravenous (IV) catheter, break off, and travel to the lungs.

What are the risk factors for pulmonary embolism?

Risk factors that are associated with the processes that may increase the risk of a venous thromboembolism include:

A risk factor is anything that may increase a person's chance of developing a disease. It may be an activity, such as smoking, diet, family history, or many other things. Different diseases have different risk factors.

Although these risk factors increase a person's risk, they do not necessarily cause the disease. Some people with one or more risk factors never develop the disease, while others develop disease and have no known risk factors. Knowing your risk factors to any disease can help to guide you into the appropriate actions, including changing behaviors and being clinically monitored for the disease.

What are the symptoms of a pulmonary embolism?

The following are the most common symptoms for pulmonary embolism. However, each individual may experience symptoms differently:

You may or may not have these symptoms should a pulmonary embolism occur. Usually, if a PE is suspected, the physician will check your legs for evidence of a deep vein thrombosis.

The type and extent of symptoms of a pulmonary embolism will depend on the size of the embolism and whether the person already has existing heart and/or lung problems.

The symptoms of a pulmonary embolism may resemble other medical conditions or problems. Always consult your physician for a diagnosis.

How is pulmonary embolism diagnosed?

Illustration of a pulmonary embolism

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Pulmonary embolism is often difficult to diagnose because the signs and symptoms of PE mimic those of many other conditions and diseases.

In addition to a complete medical history and physical examination, diagnostic procedures for a pulmonary embolism may include any, or a combination, of the following:

Treatment for pulmonary embolism:

Specific treatment will be determined by your physician based on:

Treatment options for pulmonary embolism include:

An important aspect of treatment of pulmonary embolism is prophylactic (preventative) treatment to prevent formation of additional embolisms.

Prevention of pulmonary embolism:

Because pulmonary embolism is caused by an embolus formed elsewhere in the body (generally in the legs), and because it is often difficult to detect presence of a venous embolus prior to the onset of complications such as a pulmonary embolism, the prevention of these emboli is necessary in the prevention of PE.

In order to prevent pulmonary embolism, the only effective way is to prevent deep vein thrombosis. Prophylactic treatment to prevent DVT includes:

Non-invasive mechanical measures:

Mechanical measures to prevent DVT include:

Medication: Anticoagulants are often given prophylactically to prevent DVT.

Many patients remain at risk for development of DVT for a period of time after they are either discharged from the hospital or transferred to a different type of care facility. It is important that prophylactic treatment for DVT continue until the risk for DVT development has been resolved.

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