Pulmonary embolism

Pulmonary embolism (PE) is when something blocks an artery in the lungs. This can happen when a substance moves from elsewhere in the body through the blood.

People with PE may feel shortness of breath or have chest pain when they breathe in. Sometimes, they might cough. Other signs can include low blood oxygen levels, rapid breathing, and a rapid heart rate.

Most often, PE happens when a blood clot from the leg travels to the lungs. This can be more likely with advanced age, cancer, long periods of bed rest, smoking, long travel, certain genetic conditions, pregnancy, or after some surgeries. Doctors can find out if someone has PE using tests like a D-dimer blood test, CT pulmonary angiography, or ultrasound of the legs.

To help prevent PE, it’s important to move around after surgery or while sitting for long periods. Sometimes, blood thinners are used. Treatment usually includes medicines such as heparin or warfarin to stop more clots from forming. In serious cases, special medicines or surgery might be needed.

Signs and symptoms

A pulmonary embolism can cause sudden symptoms like shortness of breath and chest pain that hurts more when you breathe in. In more serious cases, a person might feel very weak or have trouble with their blood flow.

Doctors might hear certain sounds when listening to the lungs or heart. Smaller blood clots in the lungs might cause pain but not other symptoms, while larger clots can cause low blood pressure and a fast heart rate.

Risk factors

Most blood clots that cause pulmonary embolism start in the legs. These clots can move to the lungs. Things that make these clots more likely include recent hip or knee surgery, certain cancers like pancreatic or colon cancer, pregnancy, and taking estrogen-containing medications.

Other risk factors include long periods without moving (such as during long flights), injury, obesity, and genetic conditions that affect blood clotting. Having varicose veins, high blood pressure in the lungs, diabetes, or breaking a hip and being unable to move can also increase the risk of a pulmonary embolism.

Diagnosis

To diagnose a pulmonary embolism, doctors look at signs and symptoms. If a person has low risk — like being under 50, having a heart rate under 100 beats per minute, oxygen levels above 94%, and no leg swelling, coughing up blood, recent surgery, or history of blood clots — they might not need more tests.

For those at higher risk, tests are needed. A CT pulmonary angiogram (CTPA) is the best way to diagnose a pulmonary embolism because it is easy and accurate. Other tests, like a compression ultrasound of the legs, can also help confirm the diagnosis. These tests check for blood clots in the legs, which can sometimes travel to the lungs.

The decision to do imaging tests depends on the person's medical history, symptoms, and physical examination. Doctors use special rules, like the Wells score, to help decide if a pulmonary embolism is likely.

Blood tests, like checking the level of D-dimer, can also help. A normal D-dimer level usually means there is no pulmonary embolism. Imaging tests such as CT pulmonary angiography are used to see the arteries in the lungs clearly. Another option is a ventilation/perfusion scan, which is useful for people who cannot have CT scans.

Prevention

Further information: Thrombosis prevention

Pulmonary embolism can often be prevented in people who have certain risk factors. For example, those staying in the hospital might be given special medicines such as low molecular weight heparin or fondaparinux, along with special stockings, to help stop blood clots from forming in the legs. These clots can sometimes travel to the lungs and cause a pulmonary embolism. After treatment to dissolve blood clots, taking aspirin regularly can help prevent another pulmonary embolism from happening.

Treatment

Anticoagulant therapy is the main way to treat pulmonary embolism. At first, people may need extra support like oxygen or pain relief, and they often stay in the hospital until they are better. For many years, doctors used medicines called vitamin K antagonists, but now there are newer options that are easier to use.

There are different medicines to stop blood clots, including some that can be taken at home. For people with cancer or during pregnancy, special treatments are used to keep them safe. Sometimes, if the blockage is very severe, doctors may use a special procedure to break up the clot directly. Surgery is rarely needed, but it can help in certain cases.

Prognosis

Pulmonary embolism (PE) can be serious, but many people get better with treatment. How well someone recovers depends on how much of their lung is affected and if they have other health problems. Blood flow often starts to get better within a few days after treatment.

Doctors use special tools to help figure out how serious a PE might be and how likely a person is to get better. These tools look at things like the person's symptoms and health history to decide which treatments work best.

Epidemiology

Every year, many people around the world experience pulmonary embolisms.

In the United States, these events can be very serious. The number of hospital visits for pulmonary embolisms has gone up from 1993 to 2012. But because of better medicine, fewer people die from this condition now.

Older people, especially those over 70, have a higher chance of getting pulmonary embolisms. This is often because they move less and have other health issues that come with age.