Pulmonary Embolism
Pulmonary embolism (PE) is a blockage of an artery in the lungs by a substance that has moved from elsewhere in the body through the bloodstream (embolism). Symptoms of a PE may include shortness of breath, chest pain particularly upon breathing in and coughing up blood.
Symptoms of a blood clot in the leg may also be present, such as a red, warm, swollen, and painful leg. Signs of a PE include low blood oxygen levels, rapid breathing, rapid heart rate, and sometimes a mild fever. Severe cases can lead to passing out, abnormally low blood pressure, and sudden death.
PE usually results from a blood clot in the leg that travels to the lung. The risk of blood clots is increased by cancer, prolonged bed rest, smoking, stroke, certain genetic conditions, estrogen-based medication, pregnancy, obesity, and after some types of surgery. A small proportion of cases are due to the embolization of air, fat, or amniotic fluid.
Diagnosis is based on signs and symptoms in combination with test results. If the risk is low, a blood test known as a D-dimer may rule out the condition. Otherwise, a CT pulmonary angiography, lung ventilation/perfusion scan, or ultrasound of the legs may confirm the diagnosis. Together, deep vein thrombosis and PE are known as venous thromboembolism (VTE).
Pulmonary Embolism Signs and symptoms
The most common symptoms of a pulmonary embolus are the acute onset of:
- Chest pain: The pain is often described as pleuritic, a sharp pain that worsens when taking a deep breath.
- Shortness of breath: The person may have difficulty catching his or her breath at rest, and the shortness of breath often worsens with activity.
- Hypoxia or hypoxemia: decreased oxygen concentration in the blood. (hypo=less + ox=oxygen + ia or emia= blood).
Vital signs (blood pressure, heart rate, respiratory rate, and oxygen saturation) may be normal or abnormal, depending upon the size of the embolus and how much lung tissue is affected. The larger the clot burden or load, the less stable the vital signs.
Abnormal vital signs may include:
- Tachycardia: elevated heart rate (tachy=fast + cardia=heart);
- Tachypnea: elevated respiratory (breathing) rate.(tachy=fast + pnea= breathing);
- Hypotension: decreased blood pressure (hypo=low + tension=blood pressure);
- Hypoxia: decreased SaO2. Oxygen saturation described how many hemoglobin molecules are carrying oxygen. Normal oxygen level is usually greater than 92%-93%.
The condition progresses as follows:
- The heart rate and respiratory rate may elevate as the body tries to compensate for the decreased oxygen transfer capabilities in the lung. This allows the oxygen that is available to be circulated more quickly, supplying the body’s organ and tissue needs as best as possible.
- This may lead to anxiety, weakness, and lightheadedness as the body’s organs are deprived of the necessary oxygen to function.
- If the clot burden is large enough, it may make it harder for the heart to pump blood through the blocked pulmonary arteries. This increases the work that the heart has to do, raising pressures inside the heart and straining the heart muscle itself.
Sudden death is the initial sign of the condition in up to 25% of cases. The person collapses, stops breathing, and his or her heart stops beating (cardiac arrest) without prior symptoms. Pulmonary embolus is the second leading cause of sudden death, behind coronary artery disease.
Pulmonary Embolism causes
Blood clots can form for a variety of reasons. Pulmonary embolisms are most often caused by deep vein thrombosis, a condition in which blood clots form in veins deep in the body. The blood clots that most often cause pulmonary embolisms to begin in the legs or pelvis.
Blood clots in the deep veins of the body can have several different causes, including:
- Injury or damage: Injuries like bone fractures or muscle tears can cause damage to blood vessels, leading to clots.
- Inactivity: During long periods of inactivity, gravity causes blood to stagnate in the lowest areas of your body, which may lead to a blood clot. This could occur if you’re sitting for a lengthy trip or if you’re lying in bed recovering from an illness.
- Medical conditions: Some health conditions cause blood to clot too easily, which can lead to pulmonary embolism. Treatments for medical conditions, such as surgery or chemotherapy for cancer, can also cause blood clots.
There are additional risk factors that increase your odds of having the type of blood clot that can cause a pulmonary embolism.
Pulmonary Embolism Risk factors
Factors that increase your risk of developing deep vein thrombosis and pulmonary embolism include:
- cancer
- a family history of embolisms
- fractures of the leg or hip
- hypercoagulable states or genetic blood clotting disorders, including Factor V Leiden, prothrombin gene mutation, and elevated levels of homocysteine
- a history of heart attack or stroke
- major surgery
- obesity
- a sedentary lifestyle
- age over 60 years
- taking estrogen or testosterone
Pulmonary Embolism diagnosis
In some cases, a pulmonary embolism can be difficult to diagnose. This is especially true if you have an underlying lung or heart condition, such as emphysema or high blood pressure. When you visit your doctor for your symptoms, they’ll ask about your overall health and any pre-existing conditions you may have.
Your doctor will typically perform one or more of the following tests to discover the cause of your symptoms:
- Chest X-ray: This standard, noninvasive test allows doctors to see your heart and lungs in detail, as well as any problems with the bones around your lungs.
- Electrocardiography (ECG): This test measures your heart’s electrical activity.
- MRI: This scan uses radio waves and a magnetic field to produce detailed images.
- CT scan: This scan gives your doctor the ability to see cross-sectional images of your lungs. A special scan called a V/Q scan may be ordered.
- Pulmonary angiography: This test involves making a small incision so your doctor can guide specialized tools through your veins. Your doctor will inject a special dye so that the blood vessels of the lung can be seen.
- Duplex venous ultrasound: This test uses radio waves to visualize the flow of blood and to check for blood clots in your legs.
- Venography: This is a specialized X-ray of the veins of your legs.
- D-dimer test: A type of blood test.
Pulmonary Embolism treatment
- The best treatment for a pulmonary embolus is prevention. Minimizing the risk of deep vein thrombosis is key in preventing a potentially fatal illness.
- The treatment for PE is anticoagulation.
- Once the diagnosis of PE is made, it is important to know the severity of the illness and whether the patient needs to be hospitalized or whether treatment can occur at home.
- The Pulmonary Embolus Severity Index (PESI) can help risk-stratify who is stable and who may potentially be unstable. It takes the following factors into account:
- Age
- Sex
- History of cancer, heart disease, lung disease
- Vital signs
- Mental status
- All patients with abnormal vital signs (heart rate, respiratory rate, blood pressure, and oxygen saturation) need to be admitted to the hospital.
- Those who have unstable social situations, have difficulty obtaining medication or have difficulty understanding their medication may require observation prior to being discharged home.
When patients with a PE are admitted to the hospital, it is because they are unstable with abnormal vital signs, or there is concern that they will become unstable. The initial treatment of choice is unfractionated heparin, an injectable blood thinner that is continuously given intravenously.
If vital signs are not stable, other alternative treatments may be considered based on the clinical situation. Complications can include shock with hypotension (low blood pressure), confusion, coma, or heart failure.
Tissue plasminogen activator (tPA) or alteplase is an injectable clot-busting drug.
Thrombolytic therapy
- Peripheral thrombolysis (thrombo= clot + lysis= dissolve) is the use of a clot-busting drug injected into a vein, with the expectation that it will “dissolve” the blood clot in the pulmonary artery.
- Catheter-directed thrombolytic therapy is the use of a catheter threaded into the pulmonary artery where the clot is lodged and the clot-busting drug is injected directly into it.
Thrombectomy, embolectomy
- A catheter is inserted into the pulmonary artery and the clot is sucked out.
Once vital signs are stable, anticoagulation with oral medication will follow the intravenous heparin or tPA, and these will be maintained after discharge to home.
Anticoagulation
Anticoagulation, or blood-thinning, is the treatment of choice for both deep vein thrombosis and pulmonary embolism.
Anticoagulation prevents further blood clot formation and prevents the embolization of a clot to the lung from existing clots. Under normal conditions, the body will activate a system that will break down blood clots within 4 to 6 weeks.
The American College of Chest Physicians has published guidelines regarding the choice of medications to anticoagulant a patient with VTE. The recommendations were based on a review of multiple clinical trials and meta-analyses (statistical evaluation) in the medical literature.
- In patients with VTE and no cancer, the drug of choice is a direct oral anticoagulant (DOAC) such as:
- apixaban (Eliquis)
- rivaroxiban (Xarelto)
- edoxiban (Sayvessa)
- dabigatran (Pradaxa)
- In patients with VTE and active cancer, the drug of choice is enoxaparin (Lovenox).
- The National Comprehensive Cancer Network suggests that DOACs may be an acceptable alternative to enoxaparin.
Apixaban and rivaroxiban are oral medications that have a relatively rapid onset of action and become effective within 3 to 4 days.
Edoxiban and dabigatran take long to become effective and, therefore, there is a two-step process in their use. Either intravenous heparin or subcutaneous enoxaparin needs to be used until the oral medications become effective.
Coumadin (warfarin) has historically been the medication of choice for the treatment of VTE. It takes many days to reach its therapeutic range in the body and, therefore, it too requires the use of heparin or enoxaparin until the medicine is effective.
Certain clinical situations also affect the choice of anticoagulation. Pregnancy, those who are breastfeeding, the presence of liver or kidney failure, and the presence of antiphospholipid syndrome may require specific anticoagulation medications. The health care professional needs to match the clinical situation with the appropriate medication.
The dosing of Coumadin is monitored by a blood test. INR (international normalized ratio) is used to guide the amount of Coumadin that is taken each day to keep the blood appropriately thinned. Certain foods and medications can interact with Coumadin and affect the dosing.
DOACs do not need blood tests to monitor their effectiveness or dosing. There are drug interactions that need to be considered when they are prescribed.
Duration of treatment
People usually take anticoagulation medications for a minimum of 3 to 6 months. At that time, the decision will be made based upon their risk of developing recurrent clots as to whether they should continue with long-term therapy.
Risk stratification may include whether the blood clot was provoked or unprovoked. An example of a provoked blood clot would be a patient who broke his or her leg, was placed in a cast, and was sedentary. Those who have VTE often undergo hypercoagulable evaluations looking for genetic or familial causes of blood clots.
If the health care professional, in consultation with the patient (shared decision-making), decides that lifelong therapy is required, that decision should be reviewed every year to determine if the risk of clotting still exists and whether the risk of clotting is greater than the risk of bleeding.
Can pulmonary embolism cause death?
Patient survival depends upon:
- the underlying health of the patient,
- the clot burden of the pulmonary embolus,
- the effect has on the heart and its ability to pump blood to the organs of the body,
- vital sign stability,
- the cause of the pulmonary embolus, and
- the ability for the diagnosis to be made and early initiation of treatment.
There are more than 900,000 cases of DVT and PE in the United States, and 60,000-100,000 people die each year from the condition. In addition, 25% of cases of PE cause sudden death, and 10%-30% of patients with PE will die within the first month of diagnosis.
Can pulmonary embolism be prevented?
Minimizing the risk of deep vein thrombosis minimizes the risk of pulmonary embolism. The embolism cannot occur without the initial DVT.
- In the hospital setting, the nursing staff works hard to minimize the potential for clot formation in immobilized patients.
- Compression stockings are routinely used.
- Surgery patients are out of bed walking (ambulatory) earlier.
- Low-dose heparin or enoxaparin is prescribed for deep vein thrombosis prevention.
- DVT in the legs may require the placement of vena cava filters to prevent clots in the legs from embolizing to the lung. The filter sits in the large vein that leads from the legs to the heart.
- Those who have had hip or knee replacements may be prescribed DOACs prevent DVTs.
- For long travel, getting up and walking or stretching every couple of hours may prevent clot formation.
- Compression stockings may be helpful in preventing recurrent DVT in people with a previous history of a clot.
- Those on hormone therapy, including birth control pills, should be counseled regarding the risk of DVT.
- Smoking cessation reduces the risk of a clot.
- In those who are overweight, weight loss may decrease the risk of clot formation.
Frequently Asked Questions About Pulmonary Embolism
What is a pulmonary embolism?
The lungs are a pair of organs in the chest that are primarily responsible for the exchange of oxygen and carbon dioxide between the air we breathe and blood. The lung is composed of clusters of small air sacs (alveoli) divided by thin, elastic walls (membranes). Capillaries, the tiniest of blood vessels, run within these membranes between the alveoli and allow blood and air to come near each other. The distance between the air in the lungs and the blood in the capillaries are very small and allows molecules of oxygen and carbon dioxide to transfer across the membranes.
What is the treatment for pulmonary embolism?
Prevention is the best treatment for a pulmonary embolus. Minimizing the risk of deep vein thrombosis is key in preventing a potentially fatal illness.
The initial decision is whether the patient requires hospitalization. Those patients with a small pulmonary embolus, who are hemodynamic, stable (normal vital signs) and who can be compliant with treatment, may be treated at home with close outpatient care.
Those who are unstable need to be admitted to the hospital.
Thrombolytic therapy
Pulmonary embolism can be fatal, especially if involves a large amount of clot. When the patient is unconscious, has low or no blood pressure or is not breathing, clot-busting or thrombolytic therapy using medications like TPA (tissue plasminogen activator) may be considered. It is also often considered when signs of right heart strain are present. Some physicians argue that thrombolytic therapy should be used more often since the source clot is also dissolved as well as the pulmonary embolus. This therapy is associated with a slightly greater risk of bleeding and is contraindicated if recent surgery or significant trauma has occurred.
What is the prospect for pulmonary embolism?
Patient survival depends upon:
- size of the pulmonary embolus,
- the cause of the pulmonary embolus
- the ability for a diagnosis to be made and treatment initiated, and
- The underlying health of the patient.
Usually, the mortality risk is much less in most patients. In older patients, the higher incidence of death occurs, have other underlying illnesses, or have a delay in diagnosis. Racial differences may also exist, but probably are due more to access to quality care than a specific genetic difference.
How can pulmonary embolism be prevented?
Minimizing the risk of deep vein thrombosis is key in preventing a potentially lethal illness.
- For those who travel, it is recommended that they get up and walk every couple of hours during a long trip.
- Compression stockings may be helpful in preventing future deep vein thrombus formation in patients with a previous history of a clot.
- In the hospital setting, the staff works hard to minimize the potential for clot formation in immobilized patients. Compression stockings are routinely used. Surgery patients are out of bed walking (ambulatory) earlier and low dose heparin or enoxaparin is being used for deep vein thrombosis prophylaxis (measures are taken to prevent deep vein thrombosis).
Who is at risk of PE?
Anyone can develop a blood clot that turns into PE. However, there are certain conditions that may put a person at greater risk, such as those suffering from heart disease, cancer or those with a family history of clotting disorders. In addition, recent surgery or long periods of immobility can heighten the risk of clots. Some other behaviors that may put a person at risk include smoking, supplemental estrogen (like birth control pills or hormone replacement), pregnancy and obesity.
What are the signs of PE?
Pulmonary embolism can have different signs and symptoms related to embolism or DVT. Some signs may include the following:
- Difficulty breathing (including shortness of breath)
- Coughing (including coughing up blood)
- Chest pain, or an irregular heartbeat
- Swelling, pain or tenderness in the leg
- Red or discolored skin and/or warmth in the leg where swollen
Some people may also experience rapid breathing, sweating, light-headedness, loss of consciousness or anxiety.
What treatment options are available for PE?
Typically, blood thinners (anticoagulants) are used first to stop the clot from getting larger and to prevent new clots from forming. The blood thinners may be taken orally or intravenously (or both) and the length of treatment may vary. In life-threatening situations, thrombolytics may be used to dissolve the blood clot or it may be removed surgically in very serious situations. A vein filter may also be used to stop clots from traveling to the lungs.