Ankle-brachial pressure index (ABPI) is the ratio of systolic blood pressure (SBP) in the ankle (around the lower calf) compared with the systolic blood pressure in the arm. These readings are taken manually using a Doppler probe.
For example, an ankle SBP of 80 and an arm SBP of 100 gives a ratio of 0.8 (80/100).
Results:
- 0.9 – 1.3 is normal
- 0.6 – 0.9 indicates mild peripheral arterial disease
- 0.3 – 0.6 indicates moderate to severe peripheral arterial disease
- Less than 0.3 indicates severe disease to critical ischaemic
An ABPI above 1.3 can indicate calcification of the arteries, making them difficult to compress. This is more common in diabetic patients.
