A pulmonary embolism is a blockage in the pulmonary artery - the blood supply to the lungs. It is one of the most common cardiovascular diseases in the United States.
Because the blockage (most commonly a blood clot) prevents oxygen from reaching the tissues of the lungs, it is a potentially life-threatening event.
The word "embolism" comes from the Greek émbolos, meaning "stopper" or "plug."
The term describes a condition where an object, called an embolus, is created in one part of the body, circulates throughout the blood supply, and then blocks blood flowing through a vessel in another part of the body.
Emboli (plural of embolus) are not to be confused with thrombi (plural of thrombus), which are clots that are formed and remain in one area of the body without being carried throughout the bloodstream.
This article will explain what a pulmonary embolism is, associated risk factors, symptoms, and how they are treated and prevented.
Contents of this article:
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 also 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 (most commonly a blood clot) blocks blood flowing through an artery that feeds the lungs.
Typically, a blood clot first forms in an arm or leg (deep venous thrombosis or DVT) and then eventually manages to break free.
The embolus then travels through the circulatory system towards the lungs; eventually, it is too large to pass through the small vessels of the lungs and forms a blockage.
This blockage prohibits blood from flowing into a part of the lung, causing the affected section of the lung to die through lack of oxygen.
It is also possible, though much more rare, for a pulmonary embolism to result from an embolus that is formed from fat droplets, amniotic fluid, or some other particle that enters the bloodstream.
Risk factors for pulmonary embolism
The risk of developing a pulmonary embolism increases with age. Also, people who have conditions or diseases that increase the risk of blood clotting are more likely to develop pulmonary embolisms.
In general, the risk of pulmonary embolism is high for individuals who have, or have had a blood clot in the leg or arm (DVT) and for those who have had a pulmonary embolism previously.
Long periods of bed rest or inactivity (such as a long airplane flight or car ride) substantially increase the risk of DVT and, therefore, increase the risk of pulmonary embolism.
This is because, when we are relatively motionless, our blood pools in the lower parts of our body. If blood is moving around less than normal, the formation of a blood clot becomes more likely.
Damaged blood vessels are another potential risk factor; this can occur through 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.
Other factors that put people at risk include certain cancers, inflammatory bowel disease, obesity, pacemakers, catheters in the veins, pregnancy, estrogen supplements, a family history of blood clots, and smoking.
Symptoms of embolism
Sharp, stabbing pains in the chest are a symptom of pulmonary embolism.
Symptoms of pulmonary embolism include:
- Chest pain - sharp, stabbing pain that might become worse when breathing in
- Increased or irregular heartbeat
- Difficulty catching breath - this could occur suddenly, or slowly develop over time
- Rapid breathing
- Cough - normally a dry cough but sometimes blood, or mucus containing blood, may be coughed up
If symptoms are severe, emergency medical assistance should be sought immediately.
Sometimes, more visible symptoms appear in the affected extremity, such as:
- Pain or tenderness
- Increased warmth
- Red, blue, or discolored skin
More severe pulmonary embolism cases may result in shock, passing out, cardiac arrest, and death.
Diagnosing pulmonary embolisms
Diagnosis of embolism depends on patient history, physical examinations, and a suspicion that a person's symptoms are due to an embolism. Diagnosis can be challenging because the symptoms are similar to a number of other conditions.
Tests that are frequently used to diagnose pulmonary embolism include:
- Electrocardiogram (EKG) - records the electrical activity of the heart
- Arterial blood gas study - measures oxygen, carbon dioxide, and other gases in the blood
- Chest X-rays - generates a picture of the heart, lungs, and other internal organs
- Pulmonary V/Q scan - two tests that analyze ventilation and structural properties of the lungs
- Computerized tomography (CT) scan (with and without contrast) - visualizes abnormalities in the chest, brain, and other organs
- Ultrasound of the legs - high-frequency sound waves that measure blood flow velocity and changes in blood flow
- d-Dimer test - blood test that can diagnose thrombosis
- Pulmonary angiogram - visualizes blood clots in the lungs
- Magnetic resonance imaging (MRI) - uses magnetic waves to develop detailed pictures of internal structures
Treatment for pulmonary embolisms
Exercise is one of the best ways to prevent pulmonary embolism.
Treatments for embolism are designed to stop the clot from getting bigger, prevent new clots from forming, or destroy/remove the embolus or clot if necessary. 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 administered to help thin the blood and prevent further clotting.
Clot-busting drugs called thrombolytics may also be administered, but they carry a high risk of excessive bleeding and are only normally used in the critically ill. Thrombolytics include Activase, Retavase, and Eminase.
In addition, very ill people with low blood pressure may receive medication such as dopamine to increase pressure.
Treatment typically requires taking medications regularly for an indefinite amount of time, usually for at least 3 months.
Preventing pulmonary embolism
High-risk patients may try various embolism prevention methods, such as taking the drugs heparin or warfarin (anti-coagulants) and wearing anti-embolism compression stockings. Patients may also use intermittent pneumatic compression of the legs - an inflatable jacket (sleeve, glove, or boot) that 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.
Additional ways to decrease the risk of pulmonary embolism include physical activity, regular exercise, a healthy diet, and giving up smoking tobacco.