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Pulmonary Embolism

Pulmonary Embolism (PE) Overview

A pulmonary embolism (PE) is a blood clot in the lung. The clot usually forms in smaller vessels in the leg, pelvis, arms, or heart, but occasionally the clot can be large. When a clot forms in the large veins of the legs or arms, it is referred to as a deep venous thrombosis (DVT). The pulmonary embolism occurs when part or all of the DVT breaks away and travels through the blood in the veins and lodges in the lungs.

The clot travels through the vessels of the lung continuing to reach smaller vessels until it becomes wedged in a vessel that is too small to allow it to continue further. The clot blocks all or some of the blood from traveling to that section of the lung. These blockages result in areas in the lung were the disruption of blood flow does no allow the carbon dioxide waste to be delivered to the air sacs for removal (ventilation). Similarly, since blood is blocked to certain portions of the lung, oxygen can not be extracted from these same air sacs (perfusion). The process of matching the lungs ventilation with the blood flow through the lungs is disrupted, resulting in ventilation-perfusion inequalities. In other words, areas in the lung are ventilated (get air) but get no blood to exchange the waste product carbon dioxide with oxygen.

If the pulmonary embolism is large, it may be capable of such a large mismatch, the patient cannot get enough oxygen into the blood and can be become acutely short of breath. In some instances, clots are so large that blood flow is blocked from the right side of the heart entering the lungs. This can result in instantaneous death. In other patients, the mismatch is not so profound, but still causes symptoms, especially when oxygen demand increases (for example, during exercise). Pulmonary infarction (death of lung tissue due to arterial blockage) is unusual because of collateral circulation.

Medically Reviewed by a Doctor on 11/3/2014

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Patient Comments & Reviews

The eMedicineHealth doctors ask about Pulmonary Embolism:

Pulmonary Embolism - Experience

Please describe your experience with pulmonary embolism.

Pulmonary Embolism (Blood Clot In The Lung) - Symptoms

Please describe your symptoms of pulmonary embolism (blood clot in the lung).

Pulmonary Embolism (Blood Clot In The Lung) - Treatments

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Living With Pulmonary Embolism

Pulmonary embolism (PE) usually is treated in a hospital. After leaving the hospital, you may need to take medicine at home for 6 months or longer. It's important to:

  • Take all medicines as prescribed, and have blood tests done as your doctor advises.
  • Talk with your doctor before taking blood-thinning medicines with any other medicines, including over-the-counter products. Over-the-counter aspirin, for example, can thin your blood. Taking two medicines that thin your blood may increase your risk of bleeding.
  • Ask your doctor about your diet. Foods that contain vitamin K can affect how well warfarin (Coumadin) works. Vitamin K is found in green leafy vegetables and some oils, such as canola and soybean oils. It's best to eat a well-balanced, healthy diet.
  • Discuss with your doctor what amount of alcohol is safe for you to drink if you're taking medicine.

Medicines used to treat PE can thin your blood too much. This can cause bleeding in the digestive system or the brain. If you have signs or symptoms of bleeding in the digestive system or the brain, get treatment at once.

Signs and symptoms of bleeding in the digestive system include:

  • Bright red vomit or vomit that looks like coffee grounds
  • Bright red blood in your stool or black, tarry stools
  • Pain in your abdomen

Signs and symptoms of bleeding in the brain include:

  • Severe pain in your head
  • Sudden changes in your vision
  • Sudden loss of movement in your legs or arms
  • Memory loss or confusion

Excessive bleeding from a fall or injury also may mean that your PE medicines have thinned your blood too much. Excessive bleeding is bleeding that won't stop after you apply pressure to a wound for 10 minutes. If you have excessive bleeding from a fall or injury, get treatment at once.

Once you've had PE (with or without deep vein thrombosis (DVT)), you're at higher risk of having the condition again. During treatment and after, continue to take steps to prevent DVT.

Check your legs for any signs or symptoms of DVT, such as swollen areas, pain or tenderness, increased warmth in swollen or painful areas, or red or discolored skin.

If you think that you have DVT or are having symptoms of PE, contact your doctor right away.

National Heart Lung and Blood Institute. Living With Pulmonary Embolism.

Atrial Fibrillation Slideshow

Read What Your Physician is Reading on Medscape

Pulmonary Embolism »

Pulmonary embolism (PE) is a common and potentially lethal disease; unfortunately, the diagnosis is often missed because patients with PE present with nonspecific signs and symptoms.

Read More on Medscape Reference »

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