Octopedia ABI (Ankle-Brachial Index)
ABI is a method for measuring atrial calcification which is an indicator of heart attack and stroke risk. This is normally determined through various methods such as getting a CAC or calcium score (this method uses computer tomography to scan the blood vessels), stress tests, and various angiogram methods.
The ABI can be performed at home with no more than a good blood pressure monitor with a cuff long enough to be able to be used on the ankles and upper arms.
Formula
\[\displaylines{ \alpha = \frac{\frac{a_{1} + a_{2} + \cdots + a_{n}}{n}}{\frac{b_{1} + b_{2} + \cdots + b_{n}}{n}} }\]Where
\[\displaylines{ \begin{align*}b_{1} \cdots b_{n} &= \text{bicep measurements} \\ a_{1} \cdots a_{n} &= \text{ankle measurements} \\ n &= \text{number of samples} \end{align*} }\]| ABI Value | Interpretation | Recommendation |
|---|---|---|
| Greater than 1.4 | Calcification/Vessel Hardening | Refer to vascular specialist |
| 1.0 - 1.4 | Normal | |
| 0.9 - 1.0 | Acceptable | |
| 0.8 - 0.9 | Some Arterial Disease | Trest risk factors |
| 0.5 - 0.8 | Moderate Arterial Disease | Refer to vascular specialist |
| Less than 0.5 | Severe Arterial Disease | Refer to vascular specialist |
ABI Measurement Process
- Lay down comfortably on the bed. Stay there for 5 minutes.
- Measure your arm blood pressure. Make at least \(n\) measurements. Get the average systolic blood pressure (SBP).
- Measure your ankle blood pressure. Make at least \(n\) measurements. Get the average systolic blood pressure (SBP).
- A larger \(n\) (i.e. more measurements) gives you a more accurate reading.
- Calculate ABI by dividing your ankle blood pressure over your arm blood pressure.