Pulmonary Embolism

Definition

Pulmonary embolism is the blockage of a pulmonary artery in the lung by a blood clot (thrombus) or other emboli (fragment of material) such as air, fat, bone marrow, or amniotic fluid that travels through the bloodstream via the heart and into the lungs.

Description

Blood clots generally form in leg veins when blood pools in the thighs, calves, and ankles. This pooling causes platelets and other blood components to stick together and adhere to the wall of the vein. This pooling of blood leads to clot formation and inflammation of the vein (thrombophlebitis).

These blood clots are soft and prone to detachment from the venous wall during injury, sudden muscle action or a change in blood flow to the arms and legs. The lungs then respond to this blockage by releasing chemicals that cause the blood vessels to spasm. The heart has more difficulty pumping blood through the lungs causing labored breathing and chest pains. Pulmonary embolism may cause sudden death.

Causes

Pulmonary embolism is associated with as many as 250,000 hospitalizations and about 50,000 deaths each year in the U.S. About 10 percent of victims die within the first hour. More than 90 percent of pulmonary emboli begin as clots in the deep veins of the legs.

Physiological risk factors include venous stasis (stagnant blood in the veins), venous injury, and having a condition that predisposes to clotting (cancer, certain blood protein deficiencies, oral contraceptives).

Clinical risk factors include prolonged bed rest or inactivity, surgery, childbirth, stroke, heart attack, congestive heart failure, obesity, and fractures of the hip or femur (leg bone).

Symptoms

There may be no obvious warning signs and if there are symptoms, they often mimic those of other cardiopulmonary disorders. The symptoms and signs may include:

• Shortness of breath
• Rapid respiratory rate
• Chest pain
• Coughing, including coughing up blood
• Rapid heart rate
• Sweating
• Slight fever
• Fainting
• Dizziness
• Leg swelling and pain
• Bluish skin
• Swollen neck veins

Diagnosis

Pulmonary embolism can be extremely difficult to diagnose. Since many symptoms mirror other cardiopulmonary disorders, an accurate diagnosis includes a battery of tests with a thorough examination of a person's medical history. Doctors review a person's medical history for risk factors that would predispose them to pulmonary embolism. The risk factors include:

• Long term immobility (bedridden)
• Chronic pulmonary disease
• Congestive heart failure
• Atrial fibrillation
• Thrombophlebitis (inflamed veins)
• Sickle cell anemia
• Varicose veins
• Recent surgery
• Advanced age
• Pregnancy
• Leg or foot fractures or surgery
• Burns
• Obesity
• Blood vessel injury
• Cancer
• Use of oral contraceptives
• An abnormally high platelet count
• An increased number of red blood cells and bone marrow elements

After review of the person's medical history, as well as a physical exam, the doctors will perform a battery of diagnostic tests, including blood tests to evaluate clotting and evidence of pulmonary embolism.

• A chest x-ray helps rule out other respiratory diseases.
• An electrocardiogram (EKG) monitors the heart's electrical activity and helps distinguish pulmonary embolism from other cardiopulmonary conditions.
• The arterial blood gas test measures the amount of oxygen in the blood that is being pumped from the heart to the rest of the body. People with a pulmonary embolus may have abnormally low oxygen levels.
• A lung scan (V-Q scan) consists of inserting radioactive tracer particles through an intravenous line. In a normal lung, all parts of the organ light up from the radioactive tracer. When scanned, the area of the lung that is supplied by the blocked artery tends to have little or no detectable radioactivity.
• The positive identification of deep venous thrombosis (DVT; a clot in the vein) helps confirm the diagnosis of pulmonary embolism. A Doppler ultrasound study of the legs may be done to detect the clot.
• In pulmonary angiogram, a thin tube (catheter) is inserted into a vein and through the right side of the heart and into the pulmonary artery. A special dye visible on an x-ray is then injected into the vessel and the obstructive clots are detected.

Treatment

Treatment depends on the size and severity of the embolus. Current treatments include anticoagulant ('blood thinner') and oxygen therapy, thrombolysis, or a vena cava filter. If surgery is required, procedures include traditional pulmonary embolectomy or catheter-directed pulmonary embolectomy:

• Anticoagulant / oxygen therapy: Patients with stable acute pulmonary embolism are hospitalized immediately so that a blood thinning agent (anticoagulant) can be given and oxygen administered. Anticoagulants prevent further traveling of a blood clot and reduce the threat of another embolus. The most widely used intravenous anticoagulant is heparin. This drug acts quickly and can stop blood-clot formation almost immediately. In addition to heparin, patients are treated with warfarin (coumadin). This pill acts more slowly and in a different way from heparin. Warfarin takes about five days to take effect so intravenous heparin is given until warfarin can take effect.
• Thrombolysis or reperfusion therapy: Involves injecting a thrombolytic (clot-dissolving) agent into the pulmonary artery to dissolve the blood clot and restore blood flow. Unlike heparin, thrombolytic agents can dissolve an existing clot in both the deep venous system and the pulmonary circulation.
• Vena Cava Filter: If the patient cannot tolerate the anticoagulant therapy or has other conditions that might lead to excessive bleeding, a filter device can be introduced through a catheter and positioned within the vena cava (the large vein leading to the heart) to trapping large clots before they reach the pulmonary circulation.
• Pulmonary embolectomy (surgical removal of the emboli): An embolectomy may be useful for unstable pulmonary emboli when other treatments fail. Catheter-directed pulmonary embolectomy involves inserting a catheter via the femoral or internal jugular vein and using fluoroscopic guidance to navigate into the pulmonary artery. Emboli are then extracted from the pulmonary bed using a cup device and syringe suction.

Prevention

Ordinarily, the leg muscles keep blood flowing by compressing the walls of the veins every time you move. This action provides enough energy for the veins to defy gravity and propel the blood back to the heart. When you are immobile for long periods of time the blood begins to pool. Your doctor may suggest the following ways to improve circulation:

• Exercise daily.
• Start a weight reduction plan.
• Do not stand or sit in one position for more than 15 minutes at a time; move your legs frequently; contract and release your buttock and leg muscles often.
• When you sit or lie down, use a stool or pillows to raise your legs.
• Use graduated compression stockings. These stockings help blood move from the legs to the heart by exerting gentle and consistent pressure.
• Use intermittent pneumatic compression boots. The boots inflate and deflate air-filled cuffs around the legs in slow cycles throughout the day.

Questions to Ask Your Doctor

• What type of treatment do you recommend?
• If surgery is recommended, what are the risks?
• Can pulmonary embolism recur?
• Is the pulmonary embolism attributed to another medical condition? If so, what can be done to reduce or eliminate the other condition?
• Are there any preventive measures you recommend?

Learn more about Pulmonary Embolism, consult an EliteHealth physician today.