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  4. What tests are carried out to diagnose PAD?

PAD: Be Careful of Changes in Your LimbsWhat tests are carried out to diagnose PAD?

Diagnosis of obstructive arteriosclerosis - palpation method

A doctor will make a diagnosis after reviewing your medical history and carrying out a physical examination using palpation-touching the feet and legs with their hands to feel the temperature and to find the pulse.
Next, an exam called an ABPI will be conducted. This measures and compares the blood pressure in the ankles to the blood pressure in the upper arms. If blood flow to the feet/legs is poor, the blood pressure in the ankles will be much lower than the blood pressure in the upper arm. If PAD is suspected based on the outcome of this examination, further detailed tests such as ultrasound and angiogram will be performed after which a diagnosis will be made.

Stage 1: Pulse strength check

When PAD is suspected based on subjective symptoms, pulse strength is checked as a test for the first stage. This test is performed without equipment, causes no pain to the patient, and is very effective. The test involves directly feeling the pulse and listening with a stethoscope in the groin (inguinal region), behind the knees, and ankles to examine the condition of the blood flow. The pulse will be weak or difficult to find if there is an area where an artery has become narrowed or obstructed. If an artery has become narrowed, the doctor may also hear a vascular murmur.

Table 3: Symptoms of suspected PAD

Results of a pulse check Pathological changes
Cannot find the pulse in the groin Artery occlusion in the pelvis
Vascular murmur in groin Artery stenosis in the pelvis
Can find the pulse in the groin but not behind the knee Pathological change in the femoral artery
The pulse can be found, but there is a cold sensation and numbness Diabetic peripheral neuropathy or orthopedic disease

Initial simple tests used to diagnosis problems with blood flow in the lower limbs are the leg-elevation test and leg-drop test

Leg-elevation test

Lie on your back on a bed and raise your legs 60 degrees, bend and extend your knees for about 30 seconds to 1 minute. The foot with poor blood flow may become pale or feel painful.

Leg-drop test

Following the leg-elevation test, wake your upper body, turn to the edge of the bed and try lowering your feet towards the floor. When compared with the healthy foot, the foot with poor blood flow will take longer to turn red.

Stage 2: Blood flow test

If a blood flow disorder is suspected, the next step is to use a Doppler blood flow meter and a pulse wave detector to measure blood pressure in the ankle and upper arm, or the ankle brachial pressure index (ABPI), which is the systolic blood pressure of the ankle divided by that of the upper arm. This test is also painless and easy to perform. In a healthy person, blood pressure in the legs and arms is nearly the same. If, however, there is artery stenosis (narrowing) or occlusion (blockage) in the legs, the blood pressure in the legs will be lower. Blood flow disorders can be diagnosed and a judgment made about their severity by calculating the ABPI ratio of the blood pressure in the arms to the blood pressure in the legs. If the ABPI is 0.9 (90%) or less, the presence of some kind of occlusive disease will be suspected (Figure 2).

[Figure 2] How to calculate ABPI

Measuring skin perfusion pressure (SPP)

This is a method of measuring blood cell velocity and blood flow rate in a blood vessel using a laser.
This is used when it is thought that the blood flow failure in the lower limbs has advanced to a severe stage.

Stage 3: Whole body tests using medical equipment

Figure 3: Auscultation of blood flow in the arteries of the leg using a Doppler blood flow meter

Photo: Hiroshi Shigematsu

Further tests such as intravascular ultrasonography, thermography, CT scan, MR (MRI, MRA), angiography, and angioscopy may be used to identify which areas in the blood vessels have become narrow and where there are obstructions, and to examine the condition of the blood vessels and blood flow throughout the body.