Limb plethysmography

Definition

Limb plethysmography is a test that compares blood pressure in the legs and arms.

Alternative Names

Plethysmography - limb

How the Test is Performed

This test may be done in the health care provider's office or in a hospital. You will be asked to lie with the upper part of your body slightly raised.

Three or four blood pressure cuffs are wrapped snugly around your arm and leg. The provider inflates the cuffs, and a machine called a plethysmograph measures the pulses from each cuff. The test records the maximum pressure produced when the heart contracts (systolic blood pressure).

Differences between the pulses are noted. If there is a decrease in the pulse between the arm and leg, it may indicate a blockage.

When the test is complete, the blood pressure cuffs are removed.

How to Prepare for the Test

Do not smoke for at least 30 minutes before the test. You will be asked to remove all clothing from the arm and leg being tested.

How the Test will Feel

You should not have much discomfort with this test. You should only feel the pressure of the blood pressure cuff. The test often takes less than 20 to 30 minutes to perform.

Why the Test is Performed

This test is most often done to check for narrowing or blockages of blood vessels (arteries) in the arms or legs.

Normal Results

There should be less than a 20 to 30 mm Hg difference in the systolic blood pressure of the leg compared with that of the arm.

What Abnormal Results Mean

Abnormal results may be due to:

• Arterial occlusive disease
• Blood clots
• Blood vessel changes due to diabetes
• Injury to an artery
• Other blood vessel disease (vascular disease)

Other conditions for which the test may be performed:

• Deep venous thrombosis

If you have an abnormal result, you may need to have more testing to find the exact site of the narrowing.

Risks

There are no risks.

Considerations

This test is not as accurate as an arteriography. Plethysmography may be done for very ill people who cannot travel to the arteriography lab. This test can be used to screen for vascular disease or to follow up earlier abnormal tests.

The test is noninvasive, and it does not use x-rays or injection of dye. It is also less expensive than an angiogram.

References

Creager MA, Libby P. Peripheral artery diseases. In: Mann DL, Zipes DP, Libby P, Bonow RO, Braunwald E, eds. Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine. 10th ed. Philadelphia, PA: Elsevier Saunders; 2015:chap 58.

Tang GL, Kohler TR. Vascular laboratory: arterial physiologic assessment. In: Sidawy AN, Perler BA, eds. Rutherford's Vascular Surgery and Endovascular Therapy. 9th ed. Philadelphia, PA: Elsevier; 2019:chap 20.