Pulmonary Embolism

What is pulmonary embolism?

Some individuals are prone to developing blood clots in the legs. In most cases, these blood clots remain in the leg. However, in some cases, these blood clots can break off. Any time a blood clot breaks off from the vein and migrates to the lung, it is called a pulmonary embolism (PE). The lungs are important for oxygenation of blood and when the lung vessels are blocked, the blood can no longer be oxygenated. When the blood clots are small, the patient may recover with therapy. However, if the diagnosis is missed or if the blood clots are large, fatalities are common. Most physicians are aware of this preventable disorder and take all precautions against the formation of blood clots in the leg veins.

How common is pulmonary embolism?

It is estimated that close to 250,000 individuals in hospitals develop blood clots which migrate to the lungs. Of these more than 50,000 are fatal. These numbers are believed to be underestimates because many small cases of pulmonary embolism are not diagnosed.

Why do blood clots migrate to the lung?

All veins take blood back to the lungs where it can be oxygenated. Thus, if a clot forms in a vein and breaks off, it is more likely to migrate to the lungs.

How do I know if I have a PE?

PE is a very deceptive disorder with non specific signs and symptoms. If the embolus is small, many individuals will have no symptoms. The most common symptoms are:

- shortness of breath

- pleuritic chest pain (hurts when you take a deep breath)

- coughing with or without blood

- leg swelling and pain

- fast heart rate

- fast breathing rate

- fever

- nearly 50% of individuals have no symptoms

How does one make a diagnosis of PE?

Since most blood clots to the lung are from the leg, the physician will first order tests to make sure you do not have a blood clot in the leg. These tests may include:

Doppler ultrasound: This test can quickly determine if there is a clot in the leg. However, if the clot is located somewhere in the groin or abdomen, then another test may be required.

MRI: MRI can detect blood clots anywhere in the body. It is not the first test of choice and always is a complimentary test. It does not require the use of radiation and is more expensive.

Nuclear scans: This test requires the use of small amounts of radioactive material to determine the presence of blood clots. It is not always diagnostic and interpretation of the results is fraught with difficulties.

Venogram: This old test is rarely used today because of the availability of CT scan and MRI. It requires the use of dye and radiation.

CT scan: If a PE is suspected, then CT is an excellent technique. However, it does require the use of a dye and radiation exposure.

Echocardiography: This ultrasound based test is fast becoming a more important tool for evaluating patients with PE. Nearly 50% of stable patients who present with a PE will have poor contraction of the right sided of the heart, which is associated with an increase in mortality. This information can be helpful in determining whether a patient should immediately receive blood thinners or go for surgery.

Pulmonary angiogram: This is the gold standard for detection of PE. It requires the use of a dye injected in the lung vessels and radiation exposure. It is only used as a last resort when immediate surgical treatment is being considered.