Ankle-brachial pressure index





Introduction

The ankle-brachial pressure index (ABPI) is the ratio of the systolic blood pressure in the lower leg to that in the arms. Lower blood pressure in the legs (result in a ABPI < 1) is an indicator of peripheral arterial disease (PAD).

Indications

ABPI is useful in evaluating patients with suspected PAD, for example a male smoker who presents with intermittent claudication.

It is also important to determine the ABPI in patients with leg ulcers. Venous ulcers are often treated with compression bandaging. Doing this in a patient with PAD could however be harmful as it would further restrict the blood supply to the foot. ABPIs should therefore always be measured in patients with leg ulcers.

Interpretation

Interpretation of ABPI
  • > 1.2: may indicate calcified, stiff arteries. This may be seen with advanced age or PAD
  • 1.0 - 1.2: normal
  • 0.9 - 1.0: acceptable
  • < 0.9: likely PAD. Values < 0.5 indicate severe disease which should be referred urgently

The ABPI is a good test, values less than 0.90 have been shown to have a sensitivity of 90% and a specificity of 98%* for PAD.

Compression bandaging is generally considered acceptable if the ABPI >= 0.8.


*Yao ST, Hobbs JT, Irvine WT. Ankle systolic pressure measurements in arterial disease affecting the lower extremities. Br J Surg. Sep 1969;56(9):676-9.