A pulmonary embolism (PE) is a blood clot in the lungs that happens when one or more of the blood vessels that supply blood to the lungs becomes blocked. Blood clots in the lungs usually form in the legs or pelvic area and then travel to the lungs.
When a blood clot forms or gets stuck inside a blood vessel, it can block the blood vessel and prevent blood from moving through the body. When a pulmonary embolism occurs, it may be difficult to breathe, the lungs can become damaged, and it can even lead to death.
If left untreated, acute pulmonary embolism is associated with a mortality rate as high as 30%. When diagnosed and treated promptly, the death rate of pulmonary embolism is 8%, however, up to 10% of patients with acute onset pulmonary embolism die suddenly.
What Are Symptoms of a Pulmonary Embolism?
A pulmonary embolism is a medical emergency that can be fatal if not treated promptly. If you experience any symptoms of a PE, especially over a short period of time such as hours or days, or symptoms worsen rapidly, call 9-1-1 and get to a hospital’s emergency department immediately. Do not drive yourself.
Symptoms of a pulmonary embolism include:
What Causes a Pulmonary Embolism?
There are many possible causes for a pulmonary embolism including:
- Loss of vein function (venous stasis)
- Prolonged bed rest
- Immobilization of a limb in a cast
- Long haul travel
- Surgery and trauma
- Oral contraceptives and estrogen replacement
- Conditions in which a person is more likely to develop blood clots (hypercoagulable states)
- Certain diseases
- Cancer (malignancy), especially:
- Hereditary factors
- Factor V Leiden (most common genetic risk factor for thrombophilia)
- Antithrombin III deficiency
- Protein C deficiency
- Protein S deficiency
- Plasminogen abnormality
- Plasminogen activator abnormality
- Fibrinogen abnormality
- Resistance to activated protein C
- AIDS (lupus anticoagulant)
- Behçet disease
- Congestive heart failure (CHF)
- Heart attack (myocardial infarction)
- Acute medical illness
- Increased red blood cell production (polycythemia)
- Systemic lupus erythematosus (SLE)
- Ulcerative colitis
Other risk factors for developing a pulmonary embolism include:
- Chronic obstructive pulmonary disease (COPD)
- Drug-induced lupus anticoagulant
- Heart failure
- Hemolytic anemias
- Heparin-associated thrombocytopenia
- History of thrombophlebitis
- Intravenous (IV) drug abuse
- Production of too many platelets (thrombocytosis)
- Varicose veins
- Venography (a type of X-ray that uses a special dye injected into the veins)
- Venous pacemakers
- Warfarin (first few days of therapy)
- Inflammatory bowel disease (IBD)
- Prior pulmonary embolism
- Sleep-disordered breathing
- Stroke, paresis, or paralysis
How Is a Pulmonary Embolism Diagnosed?
A pulmonary embolism is diagnosed with a patient history and physical examination. Tests used to help diagnose a pulmonary embolism include:
What Is the Treatment for a Pulmonary Embolism?
Pulmonary embolism is treated with medications called anticoagulants (blood thinners) to prevent blood clots from growing. A pulmonary embolism is usually initially treated in a hospital.
People who have a blood clot are at risk of developing another clot, especially in the first few months after diagnosis, so once a pulmonary embolism has been diagnosed medication is prescribed to reduce the risk of developing blood clots in the future. Medications are usually prescribed for at least three months or longer to give the body time to dissolve the old clot. Injection of a medication called heparin may be given first. Medications should be taken exactly as prescribed and patients will need to get regular blood tests to check how the blood is clotting.
Medications used to treat a pulmonary embolism and prevent new clots from forming include:
- Apixaban (Eliquis)
- Dabigatran (Pradaxa)
- Edoxaban (Lixiana, Savaysa)
- Rivaroxaban (Xarelto)
- Warfarin (Coumadin, Jantoven)
Patients unable to take medicines to prevent and treat blood clots, or patients who do not sufficiently benefit from the medicines may need an inferior vena cava filter (also called an IVC filter). This filter is placed inside the large vein that carries blood from the legs and the lower half of the body back up to the heart (the vena cava) to filter and trap large clots that form below the location of the filter. An IVC filter may be indicated for patients who:
- Cannot safely take medication for blood clots
- Form clots even while taking a medication for blood clots
- Have a serious bleeding problem while taking a medicine for blood clots
- Are very ill and another pulmonary embolism could be fatal
In severe cases, a clot in the lung can cause low blood pressure and even shock, and “clot-busting” medicine may be administered through a catheter. In other cases, surgery may be needed to remove the clot.
What Are Complications of a Pulmonary Embolism?
Complications of a pulmonary embolism include:
- Atrial or ventricular arrhythmias
- Blood clot in the veins, usually in the legs (thrombophlebitis)
- Cor pulmonale
- Death of lung tissue (lung infarction)
- Fluid around the lungs (pleural effusion)
- Heparin-induced low blood platelets (thrombocytopenia)
- Obstructive shock
- Paradoxical embolism
- Pulseless electrical activity (lack of a pulse that signals a type of heart rhythm that can result in cardiac arrest)
- Right-to-left intracardiac shunt
- Secondary pulmonary arterial hypertension
- Severely low levels of oxygen in the blood (hypoxemia)
- Sudden cardiac death
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