PVR tests, namely the ankle brachial index (ABI), are a series of measures of the degree of arterial blood flow in legs.
In other words, the ABI allows one to identify how complete the blood supply to the lower extremities is.
In order to determine the ABI, the doctor has to measure the patient’s blood pressure at the feet (at ankle level) and at the hands (at shoulder level).
The mathematical ratio of these two values gives the PVR index: ABI = BP (at ankle level) / BP (at shoulder level).
What is a PVR test aim?
ABI helps objectively assess the severity of leg artery disease.
In some cases, PVR tests can be used to monitor the progression of the illness, as well as to evaluate the performed surgical treatment.
ABI is the gold standard for the screening and diagnosis of PAD (peripheral arterial disease).
How is ABI measured?
PVR test for legs is measured in approximately the same way as a standard blood pressure (BP) measurement, with the only difference – in addition to measuring pressure on the arms, BP on the legs is also determined.
To identify the ABI, a special ultrasound device is used – a doppler or duplex scanner, which records blood flow in the arteries of the extremities with high accuracy.
Measurement of blood pressure is performed in the supine position.
When the shin or shoulder cuff is compressed, blood flow through the arteries stops.
With a slow deflation of the cuff at the time of the passage of the first pulse wave through the arteries, systolic blood pressure is recorded.
The results are used in subsequent PVR tests calculations.
Some patients may experience discomfort or soreness in the arm or leg under the cuff during the procedure.
However, due to the short duration of the study (from five to fifteen minutes), these complaints are short-lived.
By the way, for today, no harmful effects of ultrasound on the body of an adult have been identified.
Using ultrasonic waves to determine the PVRis completely harmless.
Can an accurate diagnosis be made by measuring the ABI?
Determining what is a PVR test for the patient helps obtain an objective assessment of blood flow in the lower extremities.
However, it doesn’t allow identifying the exact location of vascular lesions and their prevalence.
ABI measurement is not a substitute for diagnostics such as duplex scanning and angiography.
Therefore, it is impossible to establish an actual diagnosis of the illness using only one PVR test.
Despite the high information content of this research method, while planning surgical treatment, the patient may need to perform additional studies, such as:
- duplex scanning;
- radiopaque angiography;
- computed or magnetic resonance imaging of the vessels.
What ABI index is normal?
The ABI of a healthy person ranges from 0.9 to 1.2.
In patients with arterial disease of the lower extremities, the ABI index decreases and is under 0.9.
The critical PVR level at which limb viability is threatened is under 0.4.
People suffering from diabetes can have higher results than significant values (due to increased wall rigidity and difficult compressibility of the leg arteries).
Therefore, PVR test for legs is not an objective criterion for assessing the disease in this category of patients.