An obstruction or sudden blockage in the pulmonary
artery or one of its branches, usually due to a blood clot that traveled
to the lung from 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.
|Example of where a pulmonary embolism
Pulmonary embolism (PE) is a serious condition that can cause:
If a clot is large, or if there are many clots, pulmonary embolism can cause
- Permanent damage to part of your lung from lack of blood flow to lung
- Low oxygen levels in your blood
- Damage to other organs in your body from not getting enough oxygen
In most cases, pulmonary embolism 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 to the lung, and block an
More than 600,000 people in the United States have a pulmonary embolism
each year, and more than 60,000 of them die. Most of those who die do so
within 30 to 60 minutes after symptoms start. Pulmonary embolism is one
of the most common causes of death in hospitalized people who must remain
in bed for a long time.
Nine out of 10 cases of pulmonary embolism are caused by blood clots that
form in the legs (deep vein thrombosis) and then travel to the lungs.
Leg clots can form when blood flow is restricted and slows down. This happens
when you do not move around for long periods of time, such as:
Rarely, an air bubble, part of a tumor, or other tissue travels to the lung
and causes pulmonary embolism.
- 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.
Your doctor will take a health history and perform a physical exam in order
- Identify your risk factors for deep vein thrombosis (DVT) and pulmonary
- See how likely it is that you could have a pulmonary embolism
- Eliminate other possible causes for your symptoms
The physical exam will include:
- Checking your blood pressure,
heart rate, and breathing rate
- Listening to your lungs
- Listening to your heart
- Checking your legs for signs and symptoms of DVT
To help determine whether you have a pulmonary embolism or related disease
or condition, initial testing includes:
(EKG or ECG) to measure the rate and regularity of your heartbeat.
- Chest X-ray,
which takes a picture of the lungs, heart, large arteries, ribs, and
- Duplex ultrasound,
the most common test used to diagnose deep vein clots. It uses sound
waves to evaluate the flow of blood in your veins. A gel is put on the
skin of the leg. A hand-held device is placed on the leg and passed
back and forth over the affected area. This device sends sound waves
from the leg to an ultrasound machine. A computer then turns the sounds
into a picture. The picture is displayed on the computer screen, where
your doctor can see the blood flow in your leg. This is an indirect
way to diagnose a source of pulmonary embolism.
- Blood work:
- To check for inherited disorders that cause clots.
- To measure the amount of oxygen and carbon dioxide in the blood
(arterial blood gas).
A pulmonary embolism may change the levels of oxygen and carbon dioxide
in the blood.
Your doctor will order additional tests based on how likely it is that you
have a pulmonary embolism and which tests are available. Tests could include:
- Ventilation-perfusion lung scan (VQ scan), a test
that uses a radioactive material to see how well air and blood are flowing
to all areas of the lung.
- Pulmonary angiography,
an accurate, invasive test used to diagnose pulmonary embolism. A flexible
tube called a catheter is threaded through the upper thigh (groin) or
arm to the blood vessels in the lung. Dye is injected through the catheter
and then an X-ray picture is taken to show the blood flow through the
blood vessels in the lungs. This test is not available at all hospitals,
and a trained specialist is required to perform the test.
- Spiral computed tomography (CT) scan, a special type
of X-ray that takes pictures of structures inside the body. Dye is injected
into a vein, allowing the doctors to see the blood vessels in the lungs
on the X-ray picture. This is a very quick test and results are available
shortly after the scan is completed.
- Magnetic resonance
imaging (MRI), a test that takes pictures of organs and
structures inside the body. MRI uses radio waves to make the image.
In many cases, an MRI can provide information that would not show on
a test that uses sound waves to check for blood clots inside the heart
and to check heart function. It can also determine other possible causes
for your symptoms.
- D-dimer, a blood test that measures a substance in
the blood that is released when a clot breaks up. High levels may indicate
a clot. If your test is normal, a pulmonary embolism is not likely.
The primary goals in treating pulmonary embolism are to:
Treatment may include:
- Keep the blood clot or clots lodged in the lungs from getting bigger
- Stop the development of new clots
Treatment will vary depending on how severe your symptoms are. If your symptoms
are severe, you need immediate emergency treatment. If your symptoms are
mild, you can be treated as an outpatient.
- Emergency treatment to dissolve a clot
- Other treatments
Anticoagulants (blood thinners) decrease
your blood's ability to clot. They are used to stop clots from getting bigger
and to prevent blood clots from forming. Anticoagulants do not break up
blood clots that have already formed. Your body's natural system will dissolve
the clot. Anticoagulants can be given:
Heparin and warfarin may be given at the same time. Heparin acts quickly,
whereas warfarin takes 2 to 3 days before it starts to work. Once warfarin
is working, the heparin will be stopped. Pregnant women cannot take warfarin
and are treated with heparin only.
- As a pill (warfarin)
- As an injection or shot (heparin)
- In a vein (intravenous or IV) (heparin)
If you have deep vein thrombosis, treatment with anticoagulants usually
lasts for 3 to 6 months. However, the length of treatment may vary if:
The most common side effect of anticoagulants is bleeding. You need to have
regular blood tests to check how well the medicine is working. You should
call your doctor right away if you have easy bruising or bleeding.
- Your blood clot occurred after a short-term risk, such as surgery.
In this case, your treatment may be shorter.
- You have had clots before. You will need longer treatment.
- You are being treated for another illness (such as cancer). You will
take anticoagulants for as long as those risk factors are present.
Thrombin inhibitors are new medicines that interfere with the clotting process.
They are used to treat some types of clots for patients who cannot take
When pulmonary embolism is life threatening, doctors may use treatments
to remove or break up clots in the lungs. These treatments are given in
the emergency room or in the hospital and include:
- Medicines called thrombolytics to quickly dissolve the blood clot.
Thrombolytics are used to treat large clots causing severe symptoms.
- Surgery to remove the blood clot.
- A new procedure that uses a catheter to reach the clots. The catheter
is inserted into the upper thigh (groin) or arm and threaded to the
clot in the lung. The catheter may be used to extract the clot or deliver
medicine to dissolve it.
Vena cava filters are used when you cannot take medicines to thin your blood,
or if you are taking blood thinners and continue to develop clots. 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).
It can catch the clots as they try to move through the body to the lungs.
This treatment can prevent a clot from traveling to the lungs. It cannot
stop other clots from forming.
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 feet
and become looser as they go up the leg. This causes a gentle compression
(or pressure) up your leg. The stockings provide support and reduce the
chronic swelling that can occur in the leg after a blood clot has occurred.
Preventing pulmonary embolism begins with preventing deep vein thrombosis
(DVT). It is important to know whether you are at risk for DVT and to take
steps to lower your risk.
If you have never had a deep vein clot, but are in a situation that may
increase your risk, be sure to:
If you already have had DVT or a pulmonary embolism, you need to prevent
further clots from developing by:
- Exercise your lower leg muscles during long car trips and plane rides.
- Get out of bed and move around as soon as you are able after having
surgery or being ill. The sooner you move around, the lower the chance
you have of developing a clot.
- Take medicines to prevent clots after some types of surgery as directed
by your doctor. Follow up with your doctor.
- Seeing your doctor for regular checkups
- Taking your medicines to prevent or treat blood clots as prescribed
by your doctor
- Using compression stockings as directed to prevent chronic swelling
in your legs after a DVT, if prescribed by your doctor
Contacting your doctor immediately if you have any signs or symptoms of
DVT or pulmonary embolism
Life after pulmonary embolism
Once you have had a pulmonary embolism (with or without deep vein thrombosis
(DVT)), you have a greater chance of having another one. After treatment
has begun and you are feeling better, your treatment will continue at home.
At home, you will continue taking blood-thinning medicines. It is important
Medicines used to treat pulmonary embolism can thin your blood too much.
This can cause:
- Take medicines as prescribed.
- Check with your doctor before taking any other medicines, including
over-the-counter medicines, vitamins, or herbal treatments.
- Continue to have regular blood tests as directed by your doctor.
- Check with your doctor before changing your diet or taking any supplements.
- Wear your compression stockings as directed, if prescribed by your
- Bleeding in the digestive system. Get immediate treatment if you:
- Vomit bright red blood or material that looks like coffee grounds
- Pass bright red blood in your stool or have black tarry stools
- Develop pain in your abdomen
- Excessive bleeding from a fall or injury. Get immediate treatment
if you cannot stop any bleeding after applying pressure for 10 minutes.
- Bleeding in the brain. Get immediate treatment if you:
- Develop a severe headache
- Have any sudden changes in your vision
- Have sudden loss of movement of your legs or arms
- Have sudden memory loss or confusion
Treatment for pulmonary embolism usually lasts up to 6 months. During treatment
and after, you should continue to:
- Prevent DVT
- Check your legs for any signs or symptoms of DVT
Source: U.S. National
Heart, Lung and Blood Institute