A pulmonary embolism (PULL-mun-ary EM-bo-lizm), or
PE, is a sudden blockage in a lung artery, usually 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.
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 the 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 with 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 a blood clot in deep vein
thrombosis. 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 leg can form when blood flow is
restricted and slows down. This can happen when you don't move around for long
periods of time, 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?
Populations Affected
Pulmonary embolism (PE) occurs equally in men and
women. Risk increases with age: For each 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.
Major Risk Factors
People at high risk for a blood clot that travels to
the lungs are those who:
People who recently have been treated for cancer or
who have a central venous catheter (a tube placed in a vein to allow easy
access to the bloodstream for medical treatment) are more likely to develop
DVT. The same is true for people who have been bedridden or have had surgery or
suffered a broken bone in the past few weeks.
Other risk factors for DVT, which can lead to PE,
include sitting for long periods of time (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 with 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, difficulty breathing, chest pain,
coughing, or coughing up blood. An
arrhythmia
(a rapid or 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 of PE or DVT.
Other Signs and Symptoms
Sometimes people who have PE experience feelings of
anxiety or dread, lightheadedness or fainting, rapid breathing, sweating, or an
increased heart rate.
How Is Pulmonary Embolism Diagnosed?
Specialists Involved
Doctors who treat patients in the emergency room are
often the ones to diagnose pulmonary embolism (PE) with the help of a
radiologist (a doctor who deals with x rays and other similar tests).
Medical History and Physical Exam
To diagnose PE, the 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
There are many different tests that help the doctor
determine whether you have PE. The doctor's decision about which tests to use
and in which order depends on how you feel when you get to the hospital, your
risk factors for PE, available testing options, and other conditions you may
have.
You may have one of the following imaging tests:
Ultrasound. Doctors use this test to look for
blood clots in your legs. Ultrasound uses high-frequency sound waves to check
the flow of blood in your veins. A 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 of the ultrasound waves into a picture on a
computer screen, where your doctor can see the blood flow in your leg. If blood
clots are found in the deep veins of your legs, you will begin treatment. DVT
and PE are both treated with the same medicines.
Spiral CT scan or CT angiogram. Doctors use this
test to look for blood clots in your lungs and in your legs. Dye is injected
into a vein in your arm to make the blood vessels in your lungs and legs more
visible on the 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 PE in most patients. The test only takes a few minutes. Results are
available shortly after the scan is completed.
Ventilation-perfusion lung scan (VQ scan).
Doctors use this test to detect PE. The VQ scan uses a radioactive material to
show how well oxygen and blood are flowing to all areas of the lungs.
Pulmonary angiography is another test used to
diagnose PE. It's not available at all hospitals, and a trained specialist must
perform the 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
the blood flow through the blood vessels in the lungs. If a clot is discovered,
the doctor may use the catheter to extract it or deliver medicine to dissolve
it.
Certain blood tests may help the 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 mean there
may be 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 (arterial blood gas). A clot in a blood vessel in your lung may lower the
level of oxygen in your blood.
To rule out other possible causes of your symptoms,
the doctor may use one or more of the following tests.
Echocardiogram
uses sound waves to check heart function and to detect blood clots inside the
heart.
EKG
(electrocardiogram) measures the rate and regularity of your heartbeat.
Chest x ray provides a picture of the lungs,
heart, large arteries, ribs, and diaphragm.
Magnetic resonance imaging (MRI) 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?
Goals of Treatment
The main goals of treating pulmonary embolism (PE)
are to:
Stop the blood clot from getting bigger
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, the doctor
may give you medicine to dissolve the clot more quickly. Rarely, the doctor may
use surgery or another procedure to remove the clot.
Specific Types of Treatment
Medicines
Anticoagulants (AN-te-ko-AG-u-lants), which are
blood-thinning medicines, decrease your blood's ability to clot. They're used
to stop blood clots from getting bigger and to prevent clots from forming. They
don't break up blood clots that have already formed. (The body dissolves most
clots with time.)
Anticoagulants 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
will be stopped.
Pregnant women usually are treated with heparin
only, because warfarin is dangerous for the pregnancy.
If you have
deep
vein thrombosis, treatment with anticoagulants usually lasts for 3 to 6
months.
If you have 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 anticoagulants as long as risk factors for PE
are present.
The most common side effect of anticoagulants 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 anticoagulants usually receive regular blood tests.
These tests are called PT and PTT tests, and they measure the blood's ability
to clot. These tests also help the doctor make sure you're taking the right
amount of medicine. Call your doctor right away if you have easy bruising or
bleeding.
Thrombin inhibitors are a newer type of
anticoagulant medicine. They're used to treat some types of blood clots for
patients who can't take heparin.
Emergency Treatment
When PE is life threatening, doctors may use
treatments that remove or break up clots in the blood vessels of the lungs.
These treatments are given in the emergency room or in the hospital.
Thrombolytics are medicines given to 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
when you're taking blood thinners but continue to develop clots anyway, the
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 may occur after a blood clot has developed in a
leg. 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 it, these are steps you can take to decrease 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 directed by your doctor).
Follow up with your doctor.
If you already have had DVT or PE, you can take
additional steps to help keep new blood clots from forming:
Visit your doctor for regular checkups.
Use compression stockings to prevent chronic
swelling in your legs after DVT (as directed by your doctor).
Contact your doctor at once if you have any signs or
symptoms of DVT or PE.
Living With Pulmonary Embolism
Treatment for PE usually takes place in the
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 directed by your doctor.
Talk to your doctor before taking anticoagulants
with any other medicines, including over-the-counter medicines.
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 oil. 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 will not 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 have had PE (with or without
deep
vein thrombosis (DVT)), you have a greater chance of having another one.
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 at once.
Key Points
A pulmonary embolism (PE) is a blockage of an
artery in the lung, usually due to a blood clot that traveled in the
bloodstream to the lung from the leg. The clot blocks blood flow to part of the
lung. PE can be life threatening.
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 with PE will die.
Most of those who die do so within the first few hours of the event.
The greatest risk for PE occurs in people who
have DVT, have previously had DVT, or have previously had PE.
PE occurs equally in men and women.
Your risk for PE doubles every 10 years after age
60.
The most common signs and symptoms of PE are
unexplained shortness of breath, difficulty 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 of PE or DVT.
Your doctor will take your medical history and do
a physical exam and several diagnostic tests to decide whether you have PE.
The main goals in treating PE are to keep the
current blood clot from getting bigger and to stop new clots from forming.
Treatment varies depending on how severe your
symptoms are.
Treatment usually includes anticoagulant
medicines (blood-thinning medicines), such as warfarin
(Coumadin®) and heparin, which help prevent clots from forming
and help keep clots from getting larger.
Preventing PE begins with preventing DVT.
Contact your doctor at once if you have any signs
or symptoms of DVT or PE.
Links to Other Information About Pulmonary
Embolism
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Blood Diseases:
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