Plethysmography

Alternative names
Arterial plethysmography

Definition

This test measures the systolic blood pressure (maximum pressure exerted when the heart contracts) of a leg compared to the arm. The test is usually performed to rule out blockages in the arms or legs (usually legs).

See also Blood flow studies.

How the test is performed

This test may be done in the health care provider’s office or in a hospital. You are placed in a partially propped-up position. Three blood pressure cuffs are wrapped snugly around the arm and leg. They are inflated to 65 mmHg (millimeters mercury), and a pulse volume recorder (plethysmograph) measures the pulse waves from each cuff.

Any differences between the pulse waves are noted. If there is a reduction in any of the waves compared with the others, it may indicate a blockage. When the test is complete, the blood pressure cuffs are removed.

How to prepare for the test
Refrain from Smoking at least 30 minutes before the test. Remove all clothing from the arm and legs.

Infants and children:
The preparation a parent can provide for this procedure depends on the child’s age, previous experiences, and level of trust. For specific information regarding how you can prepare your child, see the following:

How the test will feel
There should be minimal discomfort with this test. The pressure of the blood pressure cuff is all you should feel.

Why the test is performed
The test is done to help rule out arterial blockages in the arms or legs.

Normal Values

There should be less than 20 mmHg difference in the systolic blood pressure of the leg compared to the arm.

What abnormal results mean

Abnormal results may indicate arterial occlusive disease, trauma to the arteries, small vessel diabetic changes, Blood clots, and vascular diseases.

Additional conditions under which the test may be performed:

What the risks are

There are no risks associated with this test.

Special considerations

The test is not as accurate as an arteriography. This may be done for seriously ill patients who cannot be transported to the arteriography laboratory.

Johns Hopkins patient information

Last revised: December 5, 2012
by David A. Scott, M.D.

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