Pulmonary Embolism

Pulmonary Embolism (Blood Clot in the Lungs)

Cardiovascular

Written by the doctors and editors at UpToDate
What is a pulmonary embolism? — 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 elsewhere 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, dial 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 (also called "DVT") are the most dangerous (figure 1). 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 angiogram (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.
Pulmonary angiography – For this test, you have a small tube called a "catheter" inserted into 1 of the large veins in your body, usually 1 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.
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 put on a medicine that comes as a shot, called heparin. This might be 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: Coumadin). Each medicine is different in terms of 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 one 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 in order 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 1 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 every 1 to 2 hours
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
All topics are updated as new evidence becomes available and our peer review process is complete.
This topic retrieved from UpToDate on: Mar 30, 2020.
Topic 16922 Version 16.0
Release: 28.2.2 - C28.105
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