A pulmonary embolism is a blockage of an artery in the
lungs. The embolism prevents blood and nourishment from
getting to a specific area of the lungs. This may lead
to the death of lung tissue in this area. Damage to the
lungs may make it difficult for the lungs to work
properly. In severe cases, a pulmonary embolism can lead
Pathway of Pulmonary Embolism
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An embolism is caused by a lump of material, called an
embolus, that is floating in the blood. An embolus, can
be a blood clot, air bubble, or a piece of fat, bone
marrow, or tumor tissue. The embolus travels from its
original location and passes through larger blood
vessels until it gets stuck in a smaller blood vessel.
In this case, the embolus is trapped in an artery of the
The embolus in a pulmonary embolism is usually a
blood clot. It most often starts in a vein in the legs
Factors that increase your chance of developing
pulmonary embolism include:
Blood clot in a deep vein of a leg or pelvis
Increased levels of clotting factors in the
Prolonged bed rest
Major surgery, especially after pelvic surgery,
knee replacement, or heart surgery
Injury to a vein in a leg or pelvis
Fractures of the hip or thigh bone (femur)
Certain blood disorders
Prolonged sitting, such as during a long trip
Pregnancy or postpartum period
Inflammatory bowel disease
Autoimmune disorder (eg, immune thrombocytopenic
purpura , polyarteritis nodosa , polymyositis )
Taking certain medicines, such as birth control
pills or antipsychotics
The symptoms of pulmonary embolism vary depending on the
size and location of the blockage. The area affected by
the lack of blood will also affect the symptoms. In
general symptoms may include:
Shortness of breath that starts suddenly for no
Chest pain, especially when breathing or
coughing (it can mimic a heart attack )
Feeling faint, lightheaded, dizzy
Cough, sometimes with bloody phlegm
Feeling of impending doom
The doctor will ask about your symptoms and medical
history. A physical exam will be done. Your doctor may
order the following tests:
Arterial blood gas study —a blood test to check
oxygen levels and lung function
Chest x-ray —picture of lungs to look for signs
of dead tissue; a pulmonary embolism cannot be
seen on the chest x-ray
Lung perfusion scan—a test that measures
breathing and circulation in all areas of the
lungs. An embolus will cause a mismatch in the
CT scan of the chest —detailed pictures of the
inside of the chest.
Pulmonary angiogram —a special dye can highlight
the areas of blockage in the lungs.
MR angiography (MRA)
Electrocardiogram (ECG, EKG)—a test to look for
abnormal rhythms in the heart like rapid heart
beats, may help in diagnosis
Echocardiography —a test to examine the size,
shape, and motion of the heart
D-Dimer (a clot dissolving substance) blood
test—Increased levels in the blood may suggest
the presence of a clot
If you have a family history of blood clots and
had blood clots in the past for no apparent
reason, your doctor may order additional blood
tests. The tests will look for possible
inherited defects in your clotting system such
Factor V Leiden mutation (seen
in up to 40% of cases)
Increased factor VIII
Additional tests may be done to check blood flow
or look for clots in the veins. Most likely done
If you are diagnosed with pulmonary embolism, follow
your doctor's instructions .
Treatment depends on the size and severity of the clot.
Emergency treatment and hospitalization may be needed.
The first step in treatment is a blood
thinner (anticoagulant medication).
After the initial period, the blood thinner
medication will be switched to a longer acting
anticoagulant. One example is warfarin .
Another type of medication may be needed to
dissolve the clot. These are called thrombolytic
medicines and include alteplase (Activase) and
urokinase (Kinlytic). This type of medication is
usually only used in patients with a very large
PE or a PE that is causing severe illness.
Thrombolytics will not be used if you have a
high risk of bleeding.
A surgery to remove the clot may be
needed if the blockage is very large.
The surgery is called an
Some may have repeated problems with
blood clots. In this case, a surgery
will be done to place a filter in the
main vein of the legs. This filter will
trap clots before they can travel to the
Prevention of pulmonary embolism means preventing clots
You can help prevent clots with a healthful lifestyle:
Eat a healthful diet, one that is low in
saturated fat and rich in whole grains, fruits,
Begin a safe exercise program with the advice of
Walk or move your legs to break up long periods
If you smoke, quit.
Unless you are on a fluid-restricted diet, be
sure to drink lots of water.
People at high risk of developing blood clots can do the
Take medicine, if your doctor recommends it.
Anticoagulant drugs are most commonly used.
Wear elastic stockings (also called support
hose) if suggested by your doctor. They can help
to improve circulation in your legs.
Walk or move your legs to break up long periods
of sitting. If your are traveling, get up and
walk every few hours.
American Lung Association http://www.lungusa.org
American Society of Hematology http://www.hematology.org/
Canadian Lung Association http://www.lung.ca/
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Reviewer: Brian Randall, MD
Review Date: 09/2012
Update Date: 00/93/2012