The Ankle-Brachial Index (ABI) is an indicator used to assess vascular health, particularly for diagnosing lower limb arteriosclerosis. It works by comparing the blood pressure in the lower and upper limbs to determine if there is vascular hardening.
Measuring Upper Limb Blood Pressure:
1. Measure the blood pressure in both upper arms, taking three readings on each side, with at least a one-minute interval between each measurement.
2. Select the side with the higher blood pressure as the reference for upper limb blood pressure.
Measuring Lower Limb Blood Pressure:
1. Measure the blood pressure 2-3 cm above the ankle joints on both sides, also taking three readings with at least a one-minute interval between each measurement.
2. The cuff should be placed at the pulse point of the posterior tibial artery, which is located just behind the inner ankle. This artery can usually be felt by hand.
3. Adjust the cuff according to the shape of the calf to ensure it fits snugly.
Normal Range:
The normal ABI range is 1.00-1.40. If the result is within this range, it indicates that the blood vessels are healthy with no signs of arteriosclerosis.
Borderline:
If the ABI is between 0.91 and 0.99, it is considered borderline. This suggests a potential risk of lower limb arteriosclerosis, and further tests like lower limb arterial ultrasound may be needed to clarify the diagnosis. In more severe cases, additional tests such as CT, MRI angiography, or digital subtraction angiography may be necessary.
Abnormal Range:
If the ABI is less than or equal to 0.90, it usually indicates ischemia in the lower limbs. In this case, prompt medical attention is required to take appropriate treatment measures.