What Is Pulmonary Embolism?

Pulmonary embolism (PE) is the blockage of an artery in the lung, which prevents normal blood flow to a portion of the lung. The most common cause of PE is a blood clot that travels from the leg (deep vein thrombosis) and enters the pulmonary artery or one of its branches. Symptoms include shortness of breath, chest pain, and lightheadedness. 

Diagnostic tools such as imaging scans and blood tests are used to diagnose PE. Treatment may include medications to dissolve the clot or surgery to remove it. Pulmonary embolism can occur at any age but is most common in people ages 60 and older. In the U.S., an estimated 900,000 people are affected by PE.

This article provides an in-depth overview of pulmonary embolism, including types, symptoms, causes, diagnosis, treatment, and prevention. 

Pulmonary Embolism Symptoms 

Pulmonary embolism symptoms vary, depending on the size and location of the blockage and your overall health. Common symptoms of pulmonary embolism include shortness of breath, chest pain, rapid heart rate, cough, low blood pressure, and lightheadedness.

Shortness of Breath

Sudden shortness of breath is one of the most common symptoms of PE. Depending on the location and size of the blockage, this can range from mild to severe. This occurs because a partial or complete blockage of one of the blood vessels in the lungs prevents normal blood flow, reducing oxygen intake and making breathing more difficult.

Chest Pain

Chest pain occurs because the blood clot can cause damage to the lungs and surrounding tissues. The pain may be sharp or dull and feels worse when inhaling, coughing, bending, or leaning over. Some people may also feel pain in the back or neck.

Rapid Heart Rate

About 45% of people with pulmonary embolism experience rapid heart rate (tachycardia). This occurs because the body tries to compensate for the reduced blood flow to the lungs by increasing the heart rate.

Cough

Coughing, with or without blood, can occur in people with pulmonary embolism because the blockage can cause fluid to build up in the lungs (pulmonary edema). This is most common in people with more severe PE.

It is possible that a cough occurring during pulmonary embolism will be bloody or have blood-stained mucus in it. However, this is quite rare.

Low Blood Pressure

Low blood pressure can occur when a blockage is large enough to reduce blood flow (and oxygen) throughout the body and brain. It can cause dizziness and lightheadedness.

Be careful; having low blood pressure can cause you to faint. Fainting on its own is scary, but you can also sustain injuries such as hitting your head. Make sure to find a safe place to sit and call for assistance if you're feeling dizzy.

What Causes Pulmonary Embolism? 

Deep vein thrombosis (DVT) is the most common cause of pulmonary embolism. A blood clot (embolus) that forms in a deep vein in the body, usually the leg, can break away and travel to the pulmonary artery. The pulmonary artery is the main blood vessel in the lungs that carries blood from the heart to the lungs, where it picks up oxygen. The blockage from the blood clot obstructs the normal flow of oxygenated blood throughout the body. 

The formation of blood clots can occur for several reasons, the most common being:

• After surgery or severe injury 
• Long periods of inactivity (e.g., bedrest) 
• Cancer
• Pregnancy

Blood clots are not the only cause of pulmonary embolism. Other substances can also enter the pulmonary artery and cause a blockage, including:

• Fat: Fat can break away from bone marrow and enter the bloodstream. This can occur after a fracture, bone surgery, or even after procedures such as liposuction. 
• Amniotic fluid: Amniotic fluid (the fluid that surrounds a fetus during pregnancy) can enter the bloodstream during or up to 48 hours after a difficult childbirth.  
• Cancer cells: This occurs when a clump of cancer cells breaks away from a tumor and enters the bloodstream. 
• Air bubbles: Air bubbles can enter the bloodstream and become trapped in the pulmonary artery. Air embolisms are very rare and can occur during medical procedures or surgery. Physical trauma and deep-sea diving can also lead to air embolisms.

Risk Factors

Pulmonary embolism can happen to anyone, but certain risk factors can increase the likelihood of developing a blood clot that leads to pulmonary embolism:

• Prolonged bedrest, such as hospitalization after surgery or injury 
• Extended periods of inactivity, such as long car rides or flights
• Personal or family history of blood clots or pulmonary embolism 
• Smoking
• Obesity 
• Hormonal contraceptives (birth control pill) or hormone replacement therapy 
• History of cancer treatments such as chemotherapy or radiotherapy 
• Other medical conditions such as heart disease, COVID-19, or cancer 
• Pregnancy 
• Older age (60+)

How Is Pulmonary Embolism Diagnosed?  

Pulmonary embolism can be challenging to diagnose because other medical conditions can cause similar symptoms. If you have PE symptoms, see your healthcare provider immediately. To diagnose pulmonary embolism, your healthcare provider will ask about your symptoms, including how long you’ve had them and how severe they are. Your provider will perform a physical examination and ask about your medical history and lifestyle habits that may be potential risk factors. They may order blood tests and imaging scans to look for signs of obstruction in your pulmonary arteries. 

Diagnostic tools commonly used to diagnose pulmonary embolism include:

• D-dimer test: A blood test that measures the levels of a protein fragment produced when a blood clot dissolves in the body. If levels of D-dimer are elevated, it may indicate the presence of a blood clot.
• Computed tomography (CT) scan: An imaging scan that creates detailed images of the lungs so your healthcare provider can look for a blockage in the pulmonary arteries and determine its size and location. 
• Ventilation/perfusion (V/Q) scan: Radioactive dye (a tracer) is inserted into a vein, which collects in the blood vessels in the lungs. A scanner takes pictures of the lungs to measure blood flow in the lungs. If a pulmonary artery is partially blocked, the affected area of the lung will receive less of the tracer, which is visible on images produced by the scanner. 

Pulmonary Embolism Classification 

Pulmonary embolism is classified based on the location of the clot and the severity of symptoms. PE types based on the severity of symptoms and how well the lungs are functioning include:

• Low-risk PE: The blood clot is small and causes only mild symptoms. People with low-risk pulmonary embolisms are usually stable and do not require hospitalization but may still require treatment to prevent the blood clot from growing or causing more serious complications.
• Intermediate risk PE: The blood clot is larger and causes more severe symptoms. People with moderate-risk pulmonary embolism may require hospitalization for observation and treatment and may need more aggressive treatments to dissolve the blood clot and prevent further lung damage.
• High-risk PE: The blood clot is large and causes more severe symptoms. People with high-risk pulmonary embolisms are at significant risk of death and require immediate hospitalization and aggressive treatment. 

Pulmonary embolism can also be classified based on the location of the blockage: 

• Saddle PE: Occurs in the main pulmonary artery, the largest blood vessel in the lungs.
• Lobar PE: Occurs in one of the larger branches of the pulmonary artery.
• Distal PE: Occurs in one of the smaller pulmonary artery branches.

Treatments for Pulmonary Embolism 

Treatment begins immediately following a diagnosis of pulmonary embolism. Treatment aims to prevent the blood clot from getting bigger and reduce the likelihood of new clots forming. The treatment recommended depends on the type and severity of the PE and your overall health. 

Pulmonary embolism treatments include:

• Anticoagulants: Also known as blood thinners, anticoagulants are medications that prevent blood from clotting. Anticoagulants help prevent the blood clot from getting bigger and reduce the risk of future clots. Anticoagulants do not dissolve the blood clot, but the body often dissolves clots over time, so they give your body time to do that.
• Thrombolytics: Thrombolytics are medications that dissolve blood clots. They are usually only used in severe cases of pulmonary embolism with a high risk of death or when anticoagulants are ineffective. 
• Inferior vena cava filter: A vein filter may be recommended if anticoagulants are ineffective or can’t be used. In this procedure, a filter is placed in the inferior vena cava (the largest vein in the body) to prevent clots from entering the lungs. 
• Surgery: In some cases, surgery may be recommended when more conservative therapies are ineffective or if the embolism is large and life-threatening. The most common surgical procedure is embolectomy. During the procedure, a surgeon accesses the affected blood vessel through an incision or a catheter and removes the clot. 

How to Prevent Pulmonary Embolism

Healthy lifestyle habits are the best way to prevent blood clots and pulmonary embolisms.

• Quit smoking 
• Exercise regularly 
• Maintain a healthy weight 
• Eat a balanced, nutritious diet 
• Avoid long periods of inactivity.
• Get up and move around regularly during long flights or make pit stops on road trips to stretch your body. 
• Take medications as prescribed. If you have a history of blood clots, your healthcare provider may prescribe blood thinners to prevent the formation of clots and lower the risk of PE. 
• Be proactive. If you are recovering from a surgical procedure or traumatic injury, talk to your healthcare provider about ways to lower the risk of PE. This may include taking blood thinners, wearing compression stockings, and regularly engaging in physical activity.

Awareness of the symptoms of pulmonary embolism can help you identify the signs in yourself or a loved one. If you have symptoms of PE, seek medical attention immediately to reduce the risk of serious complications. 

Comorbid Conditions   

Certain health conditions can increase your risk of developing a pulmonary embolism:

• Deep vein thrombosis 
• Heart diseases, such as high blood pressure and heart failure 
• Vascular diseases, such as atherosclerosis (buildup in the arteries) and stroke 
• Cancer
• Inflammatory bowel diseases, such as Crohn’s disease and ulcerative colitis 

Living With Pulmonary Embolism

Living with and recovering from pulmonary embolism can be challenging, but it is possible to live well by making healthy lifestyle choices and following your treatment regimen. Staying physically active and eating a healthy diet can help you recover and lower your risk of future embolisms. 

When caught and treated early, most people can expect to make a full recovery. Be vigilant about symptoms and seek prompt medical attention if your symptoms return or worsen. Regular follow-ups with your healthcare provider are essential for monitoring your condition and making necessary adjustments to your treatment.