A pulmonary embolism (PULL-mun-ary EM-bo-lizm), or
PE, is a sudden blockage in a lung artery. The blockage usually is due to a
blood clot that traveled to the lung from a vein in the leg.
A clot that forms in one part of the body and
travels in the bloodstream to another part of the body is called an embolus
(EM-bo-lus).
PE is a serious condition that can cause:
Permanent damage to part of your lung from lack
of blood flow to lung tissue
Low oxygen levels in your blood
Damage to other organs in your body from not
getting enough oxygen
If a blood clot is large, or if there are many
clots, PE can cause death.
Overview
In most cases, PE is a complication of a condition
called
deep
vein thrombosis (DVT). In DVT, blood clots form in the deep veins of the
body—most often in the legs. These clots can break free, travel through
the bloodstream to the lungs, and block an artery.
This is unlike clots in the veins close the skin's
surface, which remain in place and do not cause PE.
Outlook
At least 100,000 cases of PE occur each year in the
United States. PE is the third most common cause of death in hospitalized
patients. If left untreated, about 30 percent of patients who have PE will die.
Most of those who die do so within the first few hours of the event.
Other Names for Pulmonary Embolism
Venous thromboembolism (VTE). This term is used
for both pulmonary embolism and
deep
vein thrombosis.
What Causes Pulmonary Embolism?
Major Causes
In 9 out of 10 cases, pulmonary embolism (PE) begins
as a blood clot in the deep veins of the leg (a condition known as
deep
vein thrombosis). The clot breaks free from the vein and travels through
the bloodstream to the lungs, where it can block an artery.
The animation below shows how a blood clot from a
deep vein in the leg can travel to the lungs, causing pulmonary embolism. Click
the "start" button to play the animation. Written and spoken explanations are
provided with each frame. Use the buttons in the lower right corner to pause,
restart, or replay the animation, or use the scroll bar below the buttons to
move through the frames.
The animation shows how a clot in a
deep vein of the leg can break off, travel to the lungs, and block blood
flow.
Clots in the legs can form if blood flow is
restricted and slows down. This can happen when you don't move around for long
periods, such as:
After some types of surgeries
During a long trip in a car or on an
airplane
If you must stay in bed for an extended time
Veins damaged from surgery or injured in other ways
are more prone to blood clots.
Other Causes
Rarely, an air bubble, part of a tumor, or other
tissue travels to the lungs and causes PE. Also, when a large bone in the body
(such as the thigh bone) breaks, fat from the marrow inside the bone can travel
through the blood to the lungs and cause PE.
Who Is At Risk for Pulmonary Embolism?
Pulmonary embolism (PE) occurs equally in men and
women. Risk increases with age. For every 10 years after age 60, the risk of PE
doubles.
Certain inherited conditions, such as factor V
Leiden, increase the risk of blood clotting and, therefore, the risk of PE.
People who have been recently treated for cancer or
who have a central venous catheter are more likely to develop DVT. A central
venous catheter is a tube placed in a vein to allow easy access to the
bloodstream for medical treatment.
People who have been bedridden or have had surgery
or suffered a broken bone in the past few weeks also are at increased risk for
PE.
Other risk factors for DVT, which can lead to PE,
include sitting for long periods (such as on long car or airplane rides),
pregnancy and the 6-week period after pregnancy, and being
overweight
or obese. Women who take hormone therapy or birth control pills also are at
increased risk for DVT.
People who have more than one risk factor are at
higher risk for blood clots.
What Are the Signs and Symptoms of Pulmonary
Embolism?
Major Signs and Symptoms
Signs and symptoms of pulmonary embolism (PE)
include unexplained shortness of breath, problems breathing, chest pain,
coughing, or coughing up blood. An
arrhythmia
(an irregular heartbeat) also may indicate PE.
In some cases, the only signs and symptoms are
related to
deep
vein thrombosis (DVT). These include swelling of the leg or along the vein
in the leg, pain or tenderness in the leg, a feeling of increased warmth in the
area of the leg that's swollen or tender, and red or discolored skin on the
affected leg. See your doctor at once if you have any symptoms of PE or
DVT.
It's possible to have a PE and not have any signs or
symptoms.
Other Signs and Symptoms
Sometimes people who have PE have feelings of
anxiety or dread, lightheadedness or fainting, rapid breathing, sweating, or an
increased heart rate.
How Is Pulmonary Embolism Diagnosed?
Your doctor will diagnose pulmonary embolism (PE)
based on your medical history, a physical exam, and the results from tests.
Specialists Involved
Doctors who treat patients in the emergency room
often are the ones to diagnose PE with the help of a radiologist. A radiologist
is a doctor who deals with x rays and other similar tests.
Medical History and Physical Exam
To diagnose PE, your doctor will ask about your
medical history and perform a physical exam to:
During the physical exam, the doctor will check your
legs for signs of DVT. He or she also will check your blood pressure and your
heart and lungs.
Diagnostic Tests
A number of tests can help diagnose PE. Which tests
you have will depend on how you feel when you get to the hospital, your risk
factors for PE, available testing options, and other conditions you possibly
have. You may have one or more of the following tests.
Ultrasound
Doctors use ultrasound to look for blood clots in
your legs. Ultrasound uses high-frequency sound waves to check the flow of
blood in your veins.
Gel is put on the skin of your leg. A hand-held
device called a transducer is placed on the leg and moved back and forth over
the affected area. The transducer gives off ultrasound waves and detects their
echoes after they bounce off the vein walls and blood cells.
A computer then turns the echoes into a picture on a
computer screen, allowing your doctor to see the blood flow in your leg. If
blood clots are found in the deep veins of your legs, your doctor will
recommend treatment.
DVT and PE are both treated with the same medicines.
Computed Tomography Scans
Doctors use computed tomography (to-MOG-rah-fee), or
CT, scans to look for blood clots in your lungs and in your legs.
Dye is injected into a vein in your arm. The dye
makes the blood vessels in your lungs and legs show up on an x-ray image. While
you lie on a table, an x-ray tube rotates around you, taking pictures from
different angles.
This test allows doctors to detect most cases of PE.
The test only takes a few minutes. Results are available shortly after the scan
is completed.
Lung Ventilation/Perfusion Scan
A
lung
ventilation/perfusion scan, or VQ scan, uses a radioactive substance to
show how well oxygen and blood are flowing to all areas of the lungs. This test
can help detect PE.
Pulmonary Angiography
Pulmonary angiography (an-jee-OG-ra-fee) is another
test used to diagnose PE. It's not available at all hospitals, and a trained
specialist must perform the test.
For this test, a flexible tube called a catheter is
threaded through the groin (upper thigh) or arm to the blood vessels in the
lungs. Dye is injected into the blood vessels through the catheter.
X-ray pictures are taken to show blood flowing
through the blood vessels in the lungs. If a blood clot is found, your doctor
may use the catheter to extract it or deliver medicine to dissolve it.
Blood Tests
Certain blood tests may help your doctor find out
whether you're likely to have PE.
A D-dimer test measures a substance in the blood
that's released when a clot breaks up. High levels of the substance may mean
there's a clot. If your test is normal and you have few risk factors, PE isn't
likely.
Other blood tests check for inherited disorders that
cause clots and measure the amount of oxygen and carbon dioxide in your blood.
A clot in a blood vessel in your lungs may lower the level of oxygen in your
blood.
Other Tests
To rule out other possible causes of your symptoms,
your doctor may use one or more of the following tests.
Echocardiogram.
This test uses sound waves to check heart function and to detect blood clots
inside the heart.
EKG
(electrocardiogram). An EKG measures the rate and regularity of your
heartbeat.
Chest
x ray. This test provides a picture of your lungs, heart, large arteries,
ribs, and diaphragm (the muscle below your lungs).
Chest
MRI (magnetic resonance imaging). This test uses radio waves and magnetic
fields to make pictures of organs and structures inside the body. In many
cases, an MRI can provide information that can't be seen on an x ray.
How Is Pulmonary Embolism Treated?
Pulmonary embolism (PE) is treated with medicines,
procedures, and other therapies. The main goals of treating PE are to stop the
blood clot from getting bigger and keep new clots from forming.
Treatment may include medicines to thin the blood
and slow its ability to clot. If your symptoms are life threatening, your
doctor may give you medicine to dissolve the clot more quickly. Rarely, your
doctor may use surgery or another procedure to remove the clot.
Medicines
Anticoagulants (AN-te-ko-AG-u-lants), or blood
thinners, decrease your blood's ability to clot. They're used to stop blood
clots from getting bigger and to prevent clots from forming. Blood thinners
don't break up blood clots that have already formed. (The body dissolves most
clots with time.)
Blood thinners can be taken as either a pill, an
injection, or through a needle or tube inserted into a vein (called
intravenous, or IV, injection). Warfarin is given in a pill form.
(Coumadin® is a common brand name for warfarin.) Heparin is
given as an injection or through an IV tube.
Your doctor may treat you with both heparin and
warfarin at the same time. Heparin acts quickly. Warfarin takes 2 to 3 days
before it starts to work. Once warfarin starts to work, usually the heparin is
stopped.
Pregnant women usually are treated with heparin
only, because warfarin is dangerous for the pregnancy.
If you have
deep
vein thrombosis, treatment with blood thinners usually lasts for 3 to 6
months. If you've had blood clots before, you may need a longer period of
treatment. If you're being treated for another illness, such as cancer, you may
need to take blood thinners as long as risk factors for PE are present.
The most common side effect of blood thinners is
bleeding. This happens if the medicine thins your blood too much. This side
effect can be life threatening.
Sometimes, the bleeding can be internal. This is why
people treated with blood thinners usually have regular blood tests. These
tests are called PT and PTT tests, and they measure the blood's ability to
clot. These tests also help your doctor make sure you're taking the right
amount of medicine. Call your doctor right away if you're bruising or bleeding
easily.
Thrombin inhibitors are a newer type of
blood-thinning medicine. They're used to treat some types of blood clots in
people who can't take heparin.
Emergency Treatment
When PE is life threatening, doctors may use
treatments that remove or break up clots. These treatments are given in an
emergency room or hospital.
Thrombolytics are medicines that can quickly
dissolve a blood clot. They're used to treat large clots that cause severe
symptoms. Because thrombolytics can cause sudden bleeding, they're used only in
life-threatening situations.
In some cases, the doctor may use a catheter to
reach the blood clot. A catheter is a flexible tube placed in a vein to allow
easy access to the bloodstream for medical treatment.
The catheter is inserted into the groin (upper
thigh) or arm and threaded through a vein to the clot in the lung. The catheter
may be used to extract the clot or deliver medicine to dissolve it.
Rarely, surgery may be needed to remove the blood
clot.
Other Types of Treatment
When you can't take medicines to thin your blood or
your medicines don't work, your doctor may use a device called a vena cava
filter to keep clots from traveling to your lungs.
The filter is inserted inside a large vein called
the inferior vena cava (the vein that carries blood from the body back to the
heart). The filter catches clots before they travel to the lungs. This prevents
PE, but it doesn't stop other blood clots from forming.
Graduated compression stockings can reduce the
chronic (ongoing) swelling that a blood clot in the leg may cause. The leg
swelling is due to damage to the valves in the leg veins.
Graduated compression stockings are worn on the legs
from the arch of the foot to just above or below the knee. These stockings are
tight at the ankle and become looser as they go up the leg. This causes a
gentle compression (or pressure) up the leg. The pressure keeps blood from
pooling and clotting.
How Can Pulmonary Embolism Be Prevented?
Preventing pulmonary embolism (PE) begins with
preventing
deep
vein thrombosis (DVT). Knowing whether you're at risk for DVT and taking
steps to lower your risk are important.
If you've never had a deep vein clot but are at risk
for one, you can take steps to lower your risk.
Exercise your lower leg muscles during long car
trips and airplane rides.
Get out of bed and move around as soon as you're
able after having surgery or being ill. The sooner you move around, the lower
your chance of developing a clot.
Take medicines to prevent clots after some types
of surgery (as your doctor prescribes).
Follow up with your doctor.
If you've already had DVT or PE, you can take
additional steps to prevent new blood clots from forming. Visit your doctor for
regular checkups. Also, use compression stockings to prevent chronic swelling
in your legs after DVT (as your doctor advises).
Contact your doctor right away if you have any signs
or symptoms of DVT or PE.
Living With Pulmonary Embolism
Pulmonary embolism (PE) usually is treated in a
hospital. After leaving the hospital, you may need to take medicine at home for
6 months or longer. It's important to:
Take medicines as prescribed.
Have blood tests done as your doctor
advises.
Talk to your doctor before taking blood-thinning
medicines with any other medicine, including over-the-counter products.
Over-the-counter aspirin, for example, can thin your blood. Taking two
medicines that thin your blood (even if one is over-the-counter) may increase
your risk for bleeding.
Ask your doctor about your diet. Foods that
contain vitamin K can affect how well warfarin (Coumadin®)
works. Vitamin K is found in green leafy vegetables and some oils, such as
canola and soybean oils. It's best to eat a well-balanced, healthy diet.
Discuss with your doctor what amount of alcohol
is safe for you to drink if you're taking medicine.
Medicines used to treat PE can thin your blood too
much. This can cause bleeding in the digestive system or the brain. If you have
signs or symptoms of bleeding in the digestive system or the brain, get
treatment at once.
Signs and symptoms of bleeding in the digestive
system include:
Bright red vomit or vomit that looks like coffee
grounds
Bright red blood in your stool or black, tarry
stools
Pain in your abdomen
Signs and symptoms of bleeding in the brain
include:
Severe pain in your head
Sudden changes in your vision
Sudden loss of movement in your legs or arms
Memory loss or confusion
Excessive bleeding from a fall or injury also may
mean that your PE medicines have thinned your blood too much. Excessive
bleeding is bleeding that won't stop after you apply pressure to a wound for 10
minutes. If you have excessive bleeding from a fall or injury, get treatment at
once.
Once you've had PE (with or without
deep
vein thrombosis (DVT)), you have a greater chance of having it again.
During treatment and after, continue to take steps to prevent DVT.
Check your legs for any signs or symptoms of DVT,
such as swollen areas, pain or tenderness, increased warmth in swollen or
painful areas, or red or discolored skin.
If you think that you have DVT or are having
symptoms of PE, contact your doctor right away.
Key Points
A pulmonary embolism (PE) is a sudden blockage in
a lung artery. The blockage usually is due to a blood clot that traveled to the
lung from a vein in the leg. The clot blocks blood flow to part of the lung. If
a blood clot is large, or if there are many clots, PE can cause death.
In most cases, PE is a complication of a
condition called
deep
vein thrombosis (DVT). In DVT, blood clots form in the deep veins of the
body—most often in the legs. These clots can break free, travel through
the bloodstream to the lungs, and block an artery.
At least 100,000 cases of PE occur each year in
the United States. PE is the third most common cause of death in hospitalized
patients. If left untreated, about 30 percent of patients who have PE will die.
The greatest risk for PE occurs in people who
have DVT or a history of it, or who have had PE before. PE occurs equally in
men and women. Your risk for PE doubles every 10 years after age 60.
Signs and symptoms of PE include unexplained
shortness of breath, problems breathing, chest pain, coughing, or coughing up
blood. Other symptoms may be linked to DVT, such as swelling of the leg. It's
possible to have PE and not have any signs or symptoms.
Your doctor will diagnose PE based on your
medical history, a physical exam, and the results from tests.
PE is treated with medicines, procedures, and
other therapies. The main goals of treating PE are to stop the blood clot from
getting bigger and keep new clots from forming. Treatment varies depending on
how severe your symptoms are.
Preventing PE begins with preventing DVT. Knowing
whether you're at risk for DVT and taking steps to lower your risk are
important. Contact your doctor right away if you have any signs or symptoms of
PE or DVT.
PE usually is treated in a hospital. After
leaving the hospital, you may need to take medicine at home for 6 months or
longer. It's important to take your medicines as prescribed, get ongoing care,
and contact your doctor if you have signs or symptoms of bleeding (a side
effect of some medicines for PE) or another PE.
Links to Other Information About Pulmonary
Embolism
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