How to Perform an Ankle Brachial Index Study (ABI)
The Ankle Brachial Index (ABI) exam is the most simple and common test currently used to diagnose Peripheral Arterial Disease (PAD). An Ankle Brachial Index (ABI) uses an ultrasound Doppler to assess the ratio of the highest systolic pressure at the arm to the systolic pressure at the ankle. Ankle Brachial Index studies are considered reimbursable when performed using a bidirectional Doppler with hard-copy output. Koven Technology non-invasive Doppler models Smartdop® 45, Smartdop® 30EX, Smartdop® 50EXF, and Bidop® 3 (when used with Smart-V-Link® Vascular Software) can be used to perform a reimbursable Ankle Brachial Index study.
Take a blood pressure reading at the arm
Place a blood pressure cuff around the patient's arm. Place ultrasound gel on the tip of the probe and apply the probe at a 45 to 60 degree angle over the brachial or radial artery.
Wait for Doppler sounds to become stable. If your Doppler has an LCD display, watch the waveform on the display until it becomes rhythmic and stable.
Inflate the cuff to 20 mmHg over pressure cessation. Then, slowly deflate the cuff until the first Doppler sound is heard.
Record the systolic pressure when the first sound is heard and repeat the test on the other arm. Use the highest arm pressure to calculate the ABI to rule out subclavean steal syndrome.
Take a systolic pressure at the ankle
Place a blood pressure cuff snugly above the patient's ankle. Place ultrasound gel on the probe tip and apply the probe at a 45 to 60 degree angle over the posterior tibial or dorsalis pedis artery.
Wait for Doppler sounds to become stable. If your Doppler has an LCD display, watch the waveform on the display until it becomes rhythmic and stable.
Print the waveform for documentation
Inflate the cuff to 20 mmHg over pressure cessation. Then, slowly deflate the cuff until the first Doppler sound is heard.
Record the systolic pressure when the first sound is heard and repeat the test on the other leg.
Interpreting the Results
Waveform Examples
To calculate the ABI, divide the ankle pressure by the highest arm pressure
Interpretation ¹
Greater than 1.30 = Noncompressible
0.91 - 1.30 = Normal
0.41 - 0.90 = Mild to Moderate PAD
0.00 - 0.40 = Severe PAD
¹ Hirsch AT, Haskal ZJ, Hertzer NR, Bakal CW, Creager MA, Halperin JL, Hiratzka LF, Murphy WRC, Olin JW, Puschett JB, Rosenfield KA, Sacks D, Stanley JC, Taylor LM Jr., White CJ, White J, White RA.ACC/AHA 2005 practice guidelines for the management of patients with peripheral arterial disease (lower extremity, renal, mesenteric, and abdominal aortic): a collaborative report from the American Association for Vascular Surgery / Society for Vascular Surgery, Society for Cardiovascular Angiography and Interventions, Society for Vascular Medicine and Biology, Society of Interventional Radiology, and the ACC/AHA Task Force on Practice Guidelines (Writing Committee to Develop Guidelines for the Management of Patients With Peripheral Arterial Disease). Circulation 2006;113:e463–e654. DOI:10.1161/CIRCULATIONAHA.106.174526.
The instructions provided above are intended as general guidelines. For specific instructions on performing an Ankle Brachial Index study using your Doppler, please refer to the operation manual and/or inservice video provided.
