Pulmonary embolism is a condition that occurs when one or more arteries in your lungs become blocked. In most cases, pulmonary embolism is caused by blood clots that travel to your lungs from another part of your body — most commonly, your legs. Pulmonary embolism can occur in otherwise healthy people. Signs and symptoms can vary from person to person, but commonly include sudden and unexplained shortness of breath, chest pain and a cough that may bring up blood-tinged sputum. Pulmonary embolism can be life-threatening, but prompt treatment with anti-clotting medications can greatly reduce the risk of death. Taking measures to prevent blood clots in your legs also can help protect you against pulmonary embolism.
Complications of Pulmonary Embolism
Causes of Pulmonary Embolism
Pulmonary embolism occurs when a clump of material, most often a blood clot, gets wedged into an artery in your lungs. These blood clots most commonly originate in the deep veins of your legs, but they can also come from other parts of your body. This condition is known as deep vein thrombosis (DVT). Occasionally, other substances can form blockages within the blood vessels inside your lungs. Examples include:
It's rare to experience a solitary pulmonary embolism. In most cases, multiple clots are involved. The lung tissue served by each blocked artery is robbed of fuel and may die. This makes it more difficult for your lungs to provide oxygen to the rest of your body. Because pulmonary embolism almost always occurs in conjunction with deep vein thrombosis, some doctors refer to the two conditions together as venous thromboembolism (VTE).
Signs & Symptoms of Pulmonary Embolism
Pulmonary embolism symptoms can vary greatly, depending on how much of your lung is involved, the size of the clot and your overall health — especially the presence or absence of underlying lung disease or heart disease.
Common signs and symptoms include:
Other signs and symptoms that can occur with pulmonary embolism include:
Diagnosis of Pulmonary Embolism
Pulmonary embolism can be difficult to diagnose, especially in people who have underlying heart or lung disease. For that reason, your doctor may order a series of tests to help find the cause of your symptoms.
This noninvasive test shows images of your heart and lungs on film. Although X-rays can't diagnose pulmonary embolism and may even appear normal when pulmonary embolism exists, they can rule out conditions that mimic the disease.
This test, called a ventilation-perfusion scan (V/Q scan), uses small amounts of radioactive material to study airflow (ventilation) and blood flow (perfusion) in your lungs. For the first part of the test, you inhale a small amount of radioactive material while a camera that's able to detect radioactive substances takes pictures of the movement of air in your lungs. Then a small amount of radioactive material is injected into a vein in your arm, and pictures are taken of blood flow in the blood vessels of your lungs. Comparing the results of the two studies helps provide a more accurate diagnosis of pulmonary embolism than does either study alone.
Spiral (helical) computerized tomography (CT) scan
Regular CT scans take X-rays from many different angles and then combine them to form images showing two-dimensional "slices" of your internal structures. In a spiral or helical CT scan, the scanner rotates around your body in a spiral — like the stripe on a candy cane — to create three-dimensional images. This type of CT can detect abnormalities with much greater precision, and it's also much faster than are conventional CT scans.
This test provides a clear picture of the blood flow in the arteries of your lungs. It's the most accurate way to diagnose pulmonary embolism, but because it requires a high degree of skill to administer and carries potentially serious risks, it's usually performed when other tests fail to provide a definitive diagnosis. It also has the advantage of being able to measure the pressure in the right side of your heart. It would be unusual to have normal readings in the presence of pulmonary embolism. In a pulmonary angiogram, a flexible tube (catheter) is inserted into a large vein — usually in your groin — and threaded through your heart into the pulmonary arteries. A special dye is then injected into the catheter, and X-rays are taken as the dye travels along the arteries in your lungs. A risk of this procedure is a temporary change in your heart rhythm. In addition, the dye may cause kidney damage in people with decreased kidney function.
D-dimer blood test
Having high levels of the clot-dissolving substance D dimer in your blood may suggest an increased likelihood of blood clots, although D-dimer levels may be elevated by other factors, including recent surgery.
A noninvasive "sonar" test known as duplex venous ultrasonography (sometimes called duplex scan or compression ultrasonography) uses high-frequency sound waves to check for blood clots in your thigh veins. In this test, your doctor uses a wand-shaped device called a transducer to direct the sound waves to the veins being tested. These waves are then reflected back to the transducer and translated into a moving image by a computer. An echocardiogram of the heart can estimate the blood pressure in the right side of the heart.
Magnetic resonance imaging (MRI)
MRI scans use radio waves and a powerful magnetic field to produce detailed images of internal structures. Because MRI is expensive, it's usually reserved for pregnant women and people whose kidneys may be harmed by dyes used in other tests.
Treatments of Pulmonary Embolism
Prompt treatment of pulmonary embolism is essential to prevent serious complications or death.
Surgical and other procedures
Prevention of Pulmonary Embolism
Preventing clots in the deep veins in your legs (deep vein thrombosis) will help prevent pulmonary embolism. Some prevention measures are used in hospitals. Others are precautions you can take yourself.
Preventive steps in the hospital
Preventive steps while traveling
Sitting during a long flight or automobile ride increases your risk of developing blood clots in the veins of your legs. To help prevent a blood clot from forming:
When to seek Medical Advice
Pulmonary embolism can be life-threatening. Seek immediate medical attention if you experience unexplained shortness of breath, chest pain or a cough that produces bloody sputum.