Pulmonary embolism (PE)

1. What Is Pulmonary Embolism?

Pulmonary embolism (PE) is a blood clot that develops in a blood vessel in the body (usually in the leg). It then travels to a pulmonary artery, where it suddenly blocks blood flow.

A blood clot that forms in a blood vessel in one part of the body, breaks off, and travels to another part of the body is called an embolus. An embolus can become lodged in a blood vessel. This can block the blood supply to a specific organ. The blockage of a blood vessel caused by an embolus is called an embolism.

The heart, arteries, capillaries, and veins make up the body's circulatory system. Blood is pumped in large amounts from the heart into the arteries. From there, blood flows into the capillaries (small blood vessels in the tissues). Blood returns to the heart through the veins. As it travels through the veins back to the heart, blood flow slows down. Sometimes, this slower blood flow can lead to the formation of blood clots.

2. What Causes Pulmonary Embolism?

Blood clotting is a normal process that prevents bleeding. The body forms blood clots and then breaks them down. Under certain circumstances, the body cannot break down a blood clot. This can lead to a serious health problem.

When blood clots in a vein, it may be due to slowed blood flow, abnormalities in the blood-clotting process, or injury to the blood vessel wall.

Blood clots can form in arteries and veins. Blood clots that form in veins are called venous blood clots. The veins in the legs may be superficial veins (located close to the skin's surface) or deep veins (located near the bones and surrounded by muscles).

Venous blood clots most commonly occur in the deep veins of the legs. This is called deep vein thrombosis (DVT). Once a blood clot has formed in the deep veins of the leg, part of the clot may break off and travel through the bloodstream to another area of the body, usually the lungs. DVT is the most common cause of pulmonary embolism.

Less common causes of pulmonary embolism include fat embolism (usually associated with major bone fractures), amniotic fluid embolism, air bubbles, and deep vein thrombosis in the upper body. Blood clots can also form at the end of an intravenous (IV) catheter, break off, and travel to the lungs.

3. Who Is at Risk of Pulmonary Embolism?

Risk factors for pulmonary embolism include:

Inherited conditions that increase the risk of blood clot formation
A family history of blood-clotting disorders
Surgery or trauma (especially involving the legs) or orthopedic surgery
Conditions that limit mobility, such as prolonged bed rest, long-distance flights or travel, or paralysis
A previous history of blood clots
Older age
Cancer and cancer treatment
Certain medical conditions, such as heart failure, chronic obstructive pulmonary disease (COPD), hypertension, stroke, and inflammatory bowel disease
Certain medications, such as oral contraceptives and estrogen replacement therapy
During and after pregnancy, including after cesarean delivery
Obesity
Varicose veins in the legs
Smoking

4. What Are the Symptoms of Pulmonary Embolism?

The following are the most common symptoms of pulmonary embolism (PE). However, each person may experience symptoms differently:

Sudden shortness of breath (most common)
Chest pain (often worse with breathing)
A feeling of anxiety
Dizziness, lightheadedness, or fainting
Irregular heartbeat
Palpitations (rapid heartbeat)
Cough and/or coughing up blood
Sweating
Low blood pressure

You may also have symptoms of deep vein thrombosis (DVT), such as:

Pain in the affected leg (which may occur only when standing or walking)
Leg swelling
Pain, tenderness, redness, and/or warmth in the affected leg(s)
Redness and/or skin discoloration

If your doctor suspects that you have a PE, they will examine your legs for signs of deep vein thrombosis.

The type and severity of PE symptoms will depend on the size of the embolus and whether you have heart and/or lung problems.

The symptoms of PE can resemble those of other conditions or diseases. Always talk with your doctor for a diagnosis.

5. How Is Pulmonary Embolism Diagnosed?

Pulmonary embolism (PE) can be difficult to diagnose because its symptoms are very similar to those of many other conditions and diseases.

Along with a complete medical history and physical examination, tests used to detect PE may include:

Chest X-ray. This imaging test is used to evaluate the lungs and heart. A chest X-ray provides information about the size, shape, contour, and anatomical location of the heart, lungs, bronchi (large airways), aorta and pulmonary arteries, and mediastinum (the area in the middle of the chest that separates the lungs).
Ventilation-perfusion scan (V/Q scan). For this nuclear imaging test, a small amount of radioactive material is used to help examine the lungs. The ventilation scan evaluates ventilation, or the movement of air into and out of the bronchi and bronchioles. The perfusion scan evaluates blood flow through the lungs.
Pulmonary angiography. This X-ray imaging of the blood vessels is used to evaluate various conditions, such as aneurysms (bulging of a blood vessel), stenosis (narrowing of a blood vessel), or blockage. Contrast material is injected through a thin, flexible tube inserted into an artery. This contrast material makes the blood vessels visible on X-rays.
Computed tomography (CT or CAT scan). This imaging test uses X-rays and a computer to produce detailed images of the body. CT scans show details of the bones, muscles, fat, and organs. Contrast-enhanced CT improves visualization of the blood vessels in the lungs. Contrast material is a dye-like substance injected into a vein that makes the organ or tissue being examined appear more clearly on the scan.
Magnetic resonance imaging (MRI). This imaging test uses a combination of magnetic fields, radiofrequency waves, and a computer to produce detailed images of organs and structures inside the body.
Duplex ultrasound (US). This is a type of vascular ultrasound performed to evaluate blood flow and the structure of blood vessels in the legs. (Blood clots from the legs often break off and travel to the lungs.) Ultrasound uses high-frequency sound waves and a computer to produce images of blood vessels, tissues, and organs.
Laboratory tests. Blood tests are used to evaluate blood clotting, including a test called the D-dimer level. Other blood tests may include testing for inherited disorders that can contribute to abnormal blood clotting. Arterial blood gases may be measured to determine the amount of oxygen in the blood.
Electrocardiogram (ECG). This is one of the simplest and fastest methods used to evaluate the heart. Electrodes (small adhesive patches) are placed at specific points on the chest, arms, and legs. The electrodes are connected to an ECG machine by wires. The heart's electrical activity is measured, interpreted, and printed.

6. How Is Pulmonary Embolism Treated?

Treatment options for pulmonary embolism (PE) include:

Anticoagulants. Also described as blood thinners, these medications reduce the blood's ability to clot. This helps prevent an existing blood clot from becoming larger and prevents new blood clots from forming. Examples include warfarin and heparin.
Thrombolytic therapy. Also known as clot-busting medications, these drugs are injected into a vein (IV or intravenously) to break up blood clots. These medications are used only in life-threatening cases.
Inferior vena cava filter. A small metal device placed in the vena cava (a large blood vessel that carries blood from the body back to the heart) may be used to prevent blood clots from traveling to the lungs. These filters are generally used when you cannot receive anticoagulant treatment, develop additional blood clots despite anticoagulant treatment, or experience bleeding problems caused by anticoagulant medications.
Pulmonary embolectomy. Rarely used, this is a surgical procedure performed to remove a PE. It is generally performed only in severe cases when the PE is very large, you cannot receive anticoagulant and/or thrombolytic treatment because you do not respond well to these treatments, or your condition is unstable.
Percutaneous thrombectomy. A long, thin, hollow tube (catheter) can be guided through a blood vessel to the site of the embolus using X-ray imaging. Once the catheter is properly positioned, it is used to break up the embolus, remove it, or dissolve it using thrombolytic medication.

An important aspect of PE treatment is preventive therapy to prevent the formation of additional emboli.

7. What Are the Complications of Pulmonary Embolism?

Pulmonary embolism (PE) can reduce blood flow, leading to damage to lung tissue. It can cause low blood oxygen levels and may damage other organs in the body.

PE, particularly a large PE or multiple blood clots, can rapidly cause serious, life-threatening problems and even death.

Treatment for PE often involves anticoagulants or blood thinners. These medications can increase your risk of significant bleeding if they thin the blood too much. Excessive bleeding is bleeding that does not stop after applying pressure for 10 minutes. Other signs of bleeding to watch for include:

Signs of bleeding in the digestive system:
Bright red vomit or vomit that looks like coffee grounds
Bright red blood in the stool or black, tarry stools
Abdominal pain
Signs of bleeding in the brain:
Severe headache
Sudden changes in vision
Sudden loss of movement or sensation in a leg or arm
Memory loss or confusion

If you experience these symptoms, you need to seek medical treatment immediately.

8. Can Pulmonary Embolism Be Prevented?

Because pulmonary embolism (PE) is often caused by a blood clot that initially forms in the leg, and because DVT can be difficult to detect before problems begin, preventing DVT is key to preventing PE. A healthy lifestyle is one of the keys to preventing PE. This includes:

Regular exercise
Maintaining a healthy weight
Eating a balanced diet
Taking medications as prescribed
Not smoking

Treatment to Prevent DVT Includes:

Noninvasive mechanical measures
Ways to prevent DVT without medication include:
Compression stockings (elastic stockings that compress the veins and prevent blood from flowing backward)
Pneumatic compression devices (leg sleeves connected to a machine that applies alternating pressure to the legs to keep blood moving)
Getting up and moving as soon as possible after surgery or illness. Movement can help prevent blood clots from forming by stimulating blood circulation.

Medications

Anticoagulants and aspirin are commonly given to help prevent DVT.

Many people remain at risk of developing DVT for some time after they are discharged from the hospital. It is important to continue treatment to prevent DVT until the risk has resolved, usually for about 3 to 6 months.

9. Key Points About Pulmonary Embolism

Pulmonary embolism (PE) is a blood clot that develops in a blood vessel elsewhere in the body (usually the leg), travels to an artery in the lungs, and suddenly causes an arterial blockage.

Abnormal blood clots can form due to problems such as sluggish blood flow through the veins, abnormalities in clotting factors, and/or injury to the blood vessel wall.

Many conditions and risk factors are associated with PE.

Sudden shortness of breath is the most common symptom of PE.

PE can be difficult to diagnose because its signs and symptoms are very similar to those of many other conditions and diseases. Imaging tests and blood tests are used to detect PE.

An important aspect of PE treatment is preventing additional blood clots. Medications, filters to prevent blood clots from entering the lungs, and surgery are used to treat PE.

PE, particularly a large PE or multiple blood clots, can rapidly cause serious, life-threatening consequences and death.

The information above is for reference purposes only and is not intended as medical advice. Please contact your doctor for detailed medical consultation.