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Patient education: Pulmonary embolism (blood clot in the lungs) (The Basics)

Patient education: Pulmonary embolism (blood clot in the lungs) (The Basics)

What is a pulmonary embolism? — A pulmonary embolism (or "PE") is a blockage in 1 or more of the blood vessels that supply blood to the lungs. Most often these blockages are caused by blood clots that form somewhere else and then travel to the lungs. In rare cases, blockages can also be caused by air bubbles, tiny globs of fat, or pieces of tumor that travel to the lungs.

Why are blood clots dangerous? — If a blood clot forms or gets stuck inside a blood vessel, it can clog the vessel and keep blood from getting where it needs to go. When that happens in the lungs, the lungs can get damaged. Having blocked arteries in the lung can also make it hard to breathe and can even lead to death.

Most blood clots in the lungs actually form in the legs or pelvic area (where the legs connect to the body) and then travel to the lungs. Anyone who has had a blood clot in the lungs or who is at risk of a clot should know the symptoms of clots in these areas.

What are the symptoms of blood clots in the lungs? — Common symptoms include:

Panting, shortness of breath, or trouble breathing

Sharp, knife-like chest pain when you breathe in or strain

Coughing or coughing up blood

A rapid heartbeat

If you get any of these symptoms, especially if they happen over a short period of time (hours or days) or get worse quickly, call for an ambulance (in the US and Canada, call 9-1-1). At the hospital, doctors can run tests to find out if you do have a clot. Blood clots in the lungs can lead to death. That's why it's important to act fast and find out if there is a clot.

What are the symptoms of blood clots in the legs? — Blood clots in the legs cause different symptoms depending on whether the clots form in veins deep in the leg or in the veins near the surface of the skin.

Blood clots in the deep veins of the legs are the most dangerous (figure 1). This type of clot is also called "deep vein thrombosis" or "DVT." Clots in the deep veins can cause:

Swelling

Pain

Warmth and redness in the involved leg

Blood clots in the veins near the surface of the skin (called "superficial veins") are more painful, and can cause redness or infection. These clots sometimes also cause the veins to harden and bulge into ridges that look like cords. This is most common with the veins below the knee.

If you think you have a blood clot in your leg, call your doctor or nurse right away. Blood clots in the veins near the surface of the skin are less dangerous. But blood clots in the deep veins of the leg are more serious and are more likely to travel to the lungs. Your doctor or nurse can do tests to find out if you do have a clot and where it is.

Is there a test to find blood clots in the lungs? — Yes. There are several tests doctors can use to find out if a person has a blood clot in a lung. The most common tests include:

D-dimer blood test – D-dimer is a substance in the blood. The amount of D-dimer often goes up in people with a blood clot in a lung. This blood test is often done together with other tests.

CT pulmonary angiography (also called a "CT-PA") – A CT pulmonary angiogram is a special kind of X-ray that involves the use of computers. During this test, a dye is injected into 1 of your veins. The dye shows up on X-rays and can show if any blood vessels are blocked.

A ventilation/perfusion lung scan (also called a "V/Q scan") – For this test, you breathe in a small amount of a radioactive substance. You also have a radioactive dye injected into 1 of your veins. Then doctors look at how the different substances look on the scan. The scan can show if 1 of the arteries in the lung is blocked.

Less commonly, other tests are done, such as:

Pulmonary angiography – For this test, you have a small tube called a "catheter" inserted into 1 of the large veins in your body, usually in your leg. Then doctors gently push this tube up into the chest to where the major blood vessels of the lung are found. When the tube is in place, the doctors inject a dye that shows up on an X-ray.

MRI pulmonary angiography (also called "MRI-PA") – An MRI is an imaging test that uses a magnet to create pictures. During this test, a dye is injected into 1 of your veins. The dye shows up on X-rays and can show if any blood vessels are blocked.

How are blood clots in the lungs treated? — Blood clots in the lungs are treated with medicines that keep clots from getting bigger. These medicines are called "anticoagulants" or "blood thinners," although they do not actually thin the blood. Some come in shots and others come in pills. Most people being treated for a blood clot in the lung are treated first in the hospital.

If you have had a clot, your doctor will prescribe 1 of these medicines to lower your risk of getting more clots in the future. You will need to take the medicine for at least 3 months (and sometimes longer). Some people are first given a medicine that comes as a shot, called heparin. You might get this shot for a few days, or longer if for some reason you can't take pills.

The medicines do not dissolve existing blood clots, but they do keep them from getting bigger. They also help keep new blood clots from forming. Taking the medicine for a few months is important because it gives your body time to dissolve the old clot. It's also important because people who have a clot are at risk of developing another clot, especially in the first few months.

There are different oral medicines (pills) used to prevent and treat blood clots. They include apixaban (brand name: Eliquis), dabigatran (brand name: Pradaxa), edoxaban (brand names: Savaysa, Lixiana), rivaroxaban (brand name: Xarelto), and warfarin (brand name: Jantoven). Each medicine is different regarding the dose, how often you take it, the cost, and how your diet or other medicines might affect it (table 1). Your doctor can talk to you about your options and preferences.

If your doctor prescribes 1 of these medicines:

Take it exactly as your doctor tells you to – If you forget or miss a dose, call your doctor to find out what to do. When you start taking the medicine, you will need to have your blood tested. If you take warfarin, you will need regular blood tests to check how your blood is clotting. This is important to make sure you get the correct dose of warfarin for you.

Follow your doctor's instructions about diet and medicines – Depending on which medicine you take, you might need to pay special attention to what you eat. Also, certain other medicines can affect the way these medicines work.

Watch for signs of bleeding – Abnormal bleeding is a risk with any of the medicines used to prevent and treat blood clots. That's because while these medicines help prevent dangerous blood clots, they also make it harder for your body to control bleeding after an injury. So it's important to try to avoid getting injured, and to tell your doctor right away if you do have signs of bleeding.

People who cannot take medicines to prevent and treat clots, or who do not get enough benefit from the medicines, can get a different treatment. This is called an "inferior vena cava filter" (also called an "IVC filter"). The inferior vena cava is the large vein that carries blood from your legs and the lower half of your body back up to your heart. IVC filters go inside the inferior vena cava. They filter and trap any large clots that form below the location of the filter. Your doctor might suggest one of these filters for you if:

You cannot safely take a medicine for blood clots

You form clots even while taking a medicine for blood clots

You have a dangerous bleeding problem while taking a medicine for blood clots

You are so sick that another pulmonary embolism could kill you

In some cases, a person has a clot that is severe enough to cause low blood pressure and even shock. (Shock is when blood pressure gets too low, and not enough blood can get to the body's organs and tissues.) If this happens, doctors can give medicine to dissolve the clot. This is sometimes called "clot-busting" medicine, and is given through a catheter (a small tube inserted into the vein). In some cases, doctors will do surgery to remove the clot.

Can I do anything on my own to prevent blood clots? — Yes. People sometimes form clots because they have been sitting still for too long. People who travel on long airplane flights, for example, are at increased risk of blood clots. Here are some things you can do to help prevent a clot during a long flight:

Stand up and walk around at least once every hour

Do not smoke just before your trip

Wear loose, comfortable clothes

Shift your position while seated, and move your legs and feet often

Wear knee-high compression stockings

Avoid alcohol and medicines that make you sleepy, because they can impair your ability to move around

More on this topic

Patient education: Choosing a medicine for blood clots (The Basics)
Patient education: Taking medicines for blood clots (The Basics)
Patient education: Staying healthy when you travel (The Basics)
Patient education: What can go wrong after a heart attack? (The Basics)
Patient education: Factor V Leiden (The Basics)
Patient education: Deep vein thrombosis (blood clot in the legs) (The Basics)

Patient education: Lower extremity chronic venous disease (Beyond the Basics)
Patient education: Deep vein thrombosis (DVT) (Beyond the Basics)
Patient education: Pulmonary embolism (Beyond the Basics)
Patient education: Warfarin (Beyond the Basics)

This topic retrieved from UpToDate on: Jan 01, 2023.
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