Pulmonary embolus Health Article

Definition

A pulmonary embolus is a blockage of an artery in the lungs by fat, air, blood clot, or tumor cells.

Alternative Names

Venous thrombo-embolism; Lung blood clot; Blood clot - lung; Embolus; Tumor embolus

Causes, incidence, and risk factors

Pulmonary emboli are most often caused by blood clots in the veins, especially veins in the legs or in the pelvis (hips). More rarely, air bubbles, fat droplets, amniotic fluid, or clumps of parasites or tumor cells may obstruct the pulmonary vessels.

The most common cause of a pulmonary embolism is a blood clot in the veins of the legs, called a deep vein thrombosis (DVT). Many clear up on their own, though some may cause severe illness or even death.

Risk factors for a pulmonary embolus include:

• Prolonged bed rest or inactivity (including long trips in planes, cars, or trains)
• Oral contraceptive use
• Surgery (especially pelvic surgery)
• Childbirth
• Massive trauma
• Burns
• Cancer
• Stroke
• Heart attack
• Heart surgery
• Fractures of the hips or femur

Persons with certain clotting disorders may also have a higher risk.

Symptoms

Symptoms of pulmonary embolism may be vague, or they may resemble symptoms associated with other diseases. Symptoms can include:

• Cough
  • Begins suddenly
  • May produce bloody sputum (significant amounts of visible blood or lightly blood streaked sputum)
• Sudden onset of shortness of breath at rest or with exertion
• Splinting of ribs with breathing (bending over or holding the chest)
• Chest pain
  • Under the breastbone or on one side
  • Especially sharp or stabbing; also may be burning, aching or dull, heavy sensation
  • May be worsened by breathing deeply, coughing, eating, bending, or stooping
• Rapid breathing
• Rapid heart rate (tachycardia)

• Wheezing
• Clammy skin
• Bluish skin discoloration
• Nasal flaring
• Pelvis pain
• Leg pain in one or both legs
• Swelling in the legs (lower extremities)
• Lump associated with a vein near the surface of the body (superficial vein), may be painful
• Low blood pressure
• Weak or absent pulse
• Lightheadedness or fainting
• Dizziness
• Sweating
• Anxiety

Signs and tests

Tests to evaluate the function of the lungs:

• Arterial blood gases
• Pulse oximetry

Tests to detect the location and extent of embolism:

• Chest x-ray
• Pulmonary ventilation/perfusion scan
• Pulmonary angiogram
• CT angiogram of the chest

Tests to detect DVT:

• Doppler ultrasound exam of an extremity blood flow studies
• Venography of the legs
• Plethysmography of the legs

An ECG may show abnormalities caused by strain on the heart.

This disease may also alter the results of the following tests:

• Echocardiogram
• D-dimer level
• Chest CT scan
• Chest MRI scan

Treatment

Emergency treatment and hospitalization may be necessary. In cases of severe, life-threatening pulmonary embolism, definitive treatment may consist of dissolving the clot with thrombolytic therapy. Anticoagulant therapy prevents the formation of more clots and allows the body to re-absorb the existing clots faster.

Clot-dissolving medication (thrombolytic therapy) includes streptokinase, urokinase, or t-PA. Clot-preventing medication (anticoagulation therapy) consists of heparin by intravenous infusion initially, then oral warfarin (Coumadin). Subcutaneous low-molecular weight heparin is substituted for intravenous heparin in many circumstances. Patients who have reactions to heparin or related medications may need other medications.

Patients who cannot tolerate anticoagulation therapy may need an inferior vena cava filter (IVC filter). This device, placed in the main central vein in the abdomen, is designed to block large clots from traveling into the pulmonary vessels. Oxygen therapy may be required to maintain normal oxygen concentrations.

Surgery is sometimes needed in patients at great risk for recurrent embolism.

Expectations (prognosis)

It is difficult to predict how the patient will do in the future. Often, the outlook is related to the disease that puts the person at risk for pulmonary embolism (for example, cancer, major surgery, trauma). In cases of severe pulmonary embolism, where shock and heart failure occur, the death rate may be greater than 50%.

Complications

• Heart palpitations
• Heart failure or shock
• Severe breathing difficulty
• Sudden death
• Hemorrhage (usually a complication of thrombolytic or anticoagulation therapy)
• Pulmonary hypertension with recurrent pulmonary embolism