ABI values define normal, borderline, and PAD as which of the following?

• A. Normal 0.9–1.1; Borderline 0.6–0.89; PAD ≤0.95
• B. Normal 1.0–1.4; Borderline 0.91–0.99; PAD ≤0.90
• C. Normal 1.0–1.4; Borderline 0.50–0.89; PAD ≤0.49
• D. Normal 0.8–1.2; Borderline 0.75–0.95; PAD ≤0.85

Answer: (B)

Understanding the Ankle-Brachial Index (ABI) thresholds is key. The ABI is the ratio of ankle systolic blood pressure to arm systolic blood pressure. Normal values are about 1.0 to 1.4, which means the ankle pressure is essentially equal to or higher than the arm pressure, indicating no significant arterial blockage. A borderline range around 0.91 to 0.99 suggests mild flow limitation or early peripheral arterial disease, where symptoms or risk factors call for closer monitoring and possible further testing. An ABI of 0.90 or less indicates PAD, reflecting substantial arterial obstruction to the legs.

This set of thresholds aligns with standard interpretation, making the described ranges the best fit. The other options mix ranges in a way that doesn’t match how ABI values are typically categorized, or include unlikely combinations like very low or very high normal values.