This is a test to determine if there is Peripheral Artery Disease.
Your doctor will check a blood pressure at the arm (brachial artery) and ankle.
The formula is = Ankle Systolic Pressure
Brachial Systolic Pressure
The systolic pressure should be the same. That is, once the number are plugged in, it should equal 1
If the number is less than 1, it indicates that the pressure is lower in the ankle than the arm; The flow is less in the ankle.
Thus indicating Peripheral Artery Disease.