A pulmonary embolism is a blockage in the pulmonary artery, which supplies the blood to the lungs. It is one of the most common cardiovascular diseases in the United States.
The blockage, usually a blood clot, prevents oxygen from reaching the tissues of the lungs. This means it can be life-threatening.
The word "embolism" comes from the Greek émbolos, meaning "stopper" or "plug."
In a pulmonary embolism, the embolus, forms in one part of the body, it circulates throughout the blood supply, and then it blocks the blood flowing through a vessel in another part of the body, namely the lungs.
An embolus is different from a thrombus, which forms and stays in one place.
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Fast facts on pulmonary embolism
Here are some key points about pulmonary embolism. More detail and supporting information is in the main article.
- The risk of pulmonary embolism increases with age
- Symptoms include chest pain, dizziness, and rapid breathing
- The risk of pulmonary embolism is high for individuals who have had a blood clot in the leg or arm
- In rare cases, a pulmonary embolism can be caused by amniotic fluid
What is a pulmonary embolism?
A blood clot typically forms in the arm or leg, eventually managing to break free, traveling through the circulatory system.
A pulmonary embolism occurs when an embolus, usually a blood clot, blocks the blood flowing through an artery that feeds the lungs.
A blood clot may start in an arm or leg, known as deep venous thrombosis (DVT).
After that, it breaks free and travels through the circulatory system towards the lungs. There, it is too large to pass through the small vessels, so it forms a blockage.
This blockage stops blood from flowing into a part of the lung. This causes the affected section of the lung to die through lack of oxygen.
Rarely, a pulmonary embolism can result from an embolus that is formed from fat droplets, amniotic fluid, or some other particle that enters the bloodstream.
The risk of developing a pulmonary embolism increases with age. People who have conditions or diseases that increase the risk of blood clotting are more likely to develop pulmonary embolisms.
A person has a higher risk of pulmonary embolism if they have, or have had a blood clot in the leg or arm (DVT), or if they have had a pulmonary embolism in the past.
Long periods of bed rest or inactivity increase the risk of DVT and, therefore, increase the risk of pulmonary embolism. This could be a long flight or car ride.
When we do not move much, our blood pools in the lower parts of our body. If blood is moving around less than normal, a blood clot is more likely to form.
Damaged blood vessels also increase the risk. This can occur because of injury or surgery. If a blood vessel is damaged, the inside of the blood vessel may become narrower, increasing the chances of a blood clot forming.
Symptoms and diagnosis
Sharp, stabbing pains in the chest may indicate pulmonary embolism.
Symptoms of pulmonary embolism include:
- Chest pain, a sharp, stabbing pain that might become worse when breathing in
- Increased or irregular heartbeat
- Difficulty catching breath, which may develop either suddenly or over time
- Rapid breathing
- Cough, normally dry but possibly with blood, or blood and mucus
Severe symptoms call for immediate emergency medical assistance.
More severe cases may result in shock, loss of consciousness, cardiac arrest, and death.
To reach a diagnosis, the doctor will look at the patient's history and consider whether an embolism is likely. They will carry out a physical examination. Diagnosis can be challenging because other conditions have similar symptoms.
Tests for diagnosing pulmonary embolism include:
- Electrocardiogram (EKG), to record the electrical activity of the heart
- Arterial blood gas study, to measure oxygen, carbon dioxide, and other gases in the blood
- Chest X-rays, to generate a picture of the heart, lungs, and other internal organs
- Pulmonary V/Q scan, two tests that analyze the ventilation and structural properties of the lungs
- Computerized tomography (CT) scan, which can reveal abnormalities in the chest, brain, and other organs
- Ultrasound of the legs, to measure the speed of blood flow velocity and any changes
- d-Dimer test, a blood test that can diagnose thrombosis
- Pulmonary angiogram, to reveal blood clots in the lungs
- Magnetic resonance imaging (MRI), to obtain detailed pictures of internal structures
Treatment and prevention
Exercise is one of the best ways to prevent pulmonary embolism.
Treatments for embolism aim to:
- stop the clot from growing
- prevent new clots from forming
- destroy or remove any existing clot
A first step in treating most embolisms is to treat shock and provide oxygen therapy.
Anticoagulant medications, such as heparin, enoxaparin, or warfarin are usually given to help thin the blood and prevent further clotting.
Clot-busting drugs called thrombolytics may also be administered. However, but these carry a high risk of excessive bleeding. Thrombolytics include Activase, Retavase, and Eminase.
If the patient has low blood pressure, dopamine may be given to increase pressure.
The patient will normally have to take medications regularly for an indefinite amount of time, usually at least 3 months.
Preventing pulmonary embolism
A number of measures can reduce the risk of a pulmonary embolism.
- A high-risk patient may use anticoagulant drugs such as heparin or warfarin.
- Compression of the legs is possible, using anti-embolism compression stockings or pneumatic compression. An inflatable sleeve, glove, or boot holds the affected area and increases pressure when required.
Compression methods prevent blood clots by forcing blood into deep veins and reducing the amount of pooled blood.
Other ways to decrease the risk include physical activity, regular exercise, a healthy diet, and giving up or avoiding smoking tobacco.