Limb plethysmography is a test that compares blood pressure in the legs and arms.
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 health care 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 - 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.
There should be less than a 20 - 30 mmHg 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:
- 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:
If you have an abnormal result, you may need to have more testing to find the exact site of the narrowing.
There are no risks.
This test is not as accurate as an arteriography. Plethysmography may be done for very ill patients 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.
Fowler GC, Reddy B. Noninvasive venous and arterial studies of the lower extremities. In: Pfenninger JL, Fowler GC, eds. Pfenninger & Fowler's Procedures for Primary Care. 3rd ed. Philadelphia, PA: Elsevier Mosby; 2011:chap 88.
Gerhard-Herman M, Gardin JM, Jaff M, et al. Guidelines for noninvasive vascular laboratory testing: a report from the American Society of Echocardiography and the Society of Vascular Medicine and Biology. J Am Soc Echocardiogr. 2006;19(8):955-972.