Plethysmography is a simple, painless, noninvasive test that measures blood flow within blood vessels (arteries) in the legs or arms.
The measurements obtained from plethysmography are used in combination with other tests such as segmental pressure measurements, to help locate blockages in the arteries.
If plethysmography suggests that a patient has a blockage in one or more arteries, a physician may order additional tests, such as an arteriogram, CT angiography, and magnetic resonance angiography (MRA) to confirm a diagnosis of peripheral arterial disease and design a treatment plan.
Plethysmography, also known as pulse volume recording, is a noninvasive test that measures blood flow within the blood vessels, or arteries. Its purpose is to help locate blockages in the arteries. Physicians usually perform plethysmography on the legs to help diagnose leg artery disease. However, plethysmography may also be used in patients with suspected arm artery disease, thoracic outlet syndrome, or spasms of the finger arteries (Raynaud's disease).
The patient should not smoke for at least 30 minutes before the test. Immediately before the test, the patient will be instructed to remove clothing from the area to be tested and change into a hospital gown.
WHAT TO EXPECT
For this procedure, the patient will lie in a semi-recumbent (propped-up) position. A nurse or vascular technologist will place 3 or 4 blood pressure cuffs on the patient's extremities, for example, on the thighs, calves, and ankles. The cuffs are connected to a machine known as a pulse volume recorder, and the pulses appear as waveforms (peaks and valleys) on a chart. The shape of these waveforms helps the physician diagnose possible blockages.
During the procedure, the technologist or nurse will also take readings known as segmental blood pressures or compare the blood pressure in the arms with the blood pressure in the ankles.
Finally, the technologist may ask the patient to walk on a treadmill or rise up on his or her toes repetitively in an effort to duplicate the walking discomfort often experienced by patients with leg artery disease. This symptom is known as intermittent claudication.
The plethysmography procedure lasts about 30 minutes. Results of the test are usually available in a few hours and are interpreted by a physician.