Ankle brachial pressure index

It is a non invasive test to measure blood flow to your feet. The test compares blood flow in your arm (brachial), to your ankle, and gives an indication as to the possibility of peripheral vessel disease - that is damage, or narrowing of the blood vessels in the feet. Always more at risk if diabetes is present, or high blood pressure, for example.
Good that the referral to a vascular specialist has been made, so that you can have a more thorough examination, and further investigations may be organised.