UConn Ankle Brachial Pressure Index Measurement (ABPI) Calculator

According to Gornik, et al, 2024, the ankle brachial index (ABI) is a simple, noninvasive physiological tests used to establish a diagnosis of peripheral arterial disease (PAD). The ABI is conducted after a history and physical examination identify patients at risk for PAD. Typically, physical examination symptoms or signs of PAD is present. There are limitations of conducting an ABI in the setting of diabetes and chronic kidney disease (CKD), which are associated with noncompressible vessels. Additionally, noncompressible vessels impact the assessment of chronic limb-threatening ischemia. 

The ABI may be performed in a vascular laboratory or in an office-based setting using a blood pressure cuff and a Doppler device. Continuous-wave Doppler waveforms or plethysmograph tracings (i.e., PVR) at the ankle are performed. Additional physiological testing is often performed in the evaluation of PAD to supplement the ABI, such as: 

• Exercise ABI testing
• Segmental pressures, leg pressures and (PVR and/or Doppler) waveforms
• Toe pressure/TBI
• Perfusion imaging
• Imaging studies (when further definition of anatomy is required, such as to plan revascularization)

The resting ABI is measured in each leg using a blood pressure cuff and a Doppler device to detect blood flow and pressure in the pedal and the brachial arteries. The ABI is the ratio of the higher

systolic pressure in the ipsilateral dorsalis pedis and posterior tibial arteries divided by the higher of the left and right brachial artery systolic pressures.  In patients with symptoms of PAD, the resting ABI has a sensitivity of 69% to 79% and a specificity of 83% to 99% compared with imaging studies showing significant arterial stenoses, although the sensitivity is reduced in the presence of diabetes. To learn how to conduct and ABI, watch the video created by Oklahoma State University.

Formula & Interpretation

ABPI = Highest ankle pressure (DP or PT) on the leg/ Highest SBP arm (right or left)

Acronyms

ABPI: Ankle brachial pressure index measurement 

DP: dorsalis pedis

PT: posterior tibial

SBP: systolic blood pressure

PAD: peripheral arterial disease

Revision Notes

Revision 5: You do not have the option to enter an already calculated ABPI.

Revision 6: You now have the option to either enter your calculated ABPI or have the app calculate the ABPI for you.