Demand for Ankle-Brachial Index Increases
Edition: January 2005 - Vol 13 Number 01
Author: Laura Thill
The ankle-brachial index (ABI) is a simple noninvasive test designed to measure blood pressure at the ankle and in the arm, while the patient is at rest. The test is considered by some experts to be the gold standard for predicting peripheral arterial disease (PAD), which affects up to 12 million Americans annually, leaving them at risk for stroke or leg amputation. The Society of Interventional Radiology recommends that all patients being evaluated for PAD or peripheral vascular disease (PVD) have their ankle-brachial indexes measured.
The test requires cuffs and an aneroid - basic blood pressure equipment for measuring systolic pressure - and a Doppler, which listens to the blood flow and determines when it returns to the heart. (A stethoscope may not be used, because it is not as sensitive.) The Doppler relies on a transducer to emit high frequency sound waves into the patients veins and arteries. The result is a sound - along with digital read-outs - that informs the physician about how well blood is passing through the vessels.
During the ABI, the Doppler measures systolic pressure in the upper extremities (the arms) and the lower extremities (the legs), and calculates a ratio that can indicate the presence of PAD. The rationale behind this test is that plaque buildup often begins in the lower extremities, farthest away from the heart, since blood pressure is lowest there.
Experts say traditionally, ABI exams have not been as widely recognized as blood pressure and cholesterol measurements. But, awareness of peripheral arterial disease has increased in the last three or four years due to the efforts of the American Heart Association, the American Diabetes Association and the National Institute of Health. It was recently a front-page feature in The Wall Street Journal. As a result, the opportunities for ABI testing have grown. Today, Doppler is more sensitive and easier to use than earlier models, and it includes more features, such as wide-beam probes that stay on target more easily.
ABI tests are reimbursable under Medicare CPT Code 93922 at an average of $75. Basic Doppler units cost $500 or $600. But, in order to be reimbursed, physicians must use Doppler ultrasounds with a capacity for waveform printout of blood form. These models range in price from $2,000 (usually for single waveform performance) to as much as $6,000, depending on the manufacturer. However, manufacturers say the return on investment makes this equipment appealing to physician customers.
Physicians who have the greatest interest in performing ABI testing include those who work in primary care, internal medicine, podiatry (Diabetics with leg pain often visit podiatrists), cardiology and hospital settings. Essentially, any doctor who sees patients with hypertension or obesity, or patients who smoke, should require this test.
ABI testing can be performed in the doctors office in about 15 to 20 minutes. Although the physician need not actually be the one to perform the test, he must oversee testing in order to receive reimbursement. For patients exhibiting PVD symptoms, including pain with walking, the ABI test may be performed up to four times in one year.
The greatest challenge distributor reps may face when selling ABI equipment is lack of knowledge among physicians. Some doctors still may not be aware this test exists or can be performed in the office. This presents an opportunity for reps to educate customers, train them to use the equipment and show them how to file for reimbursement. Most manufacturers of Dopplers have the sales collateral needed to create opportunities with your physician customers. And its worth the call, since the demand for ABI tests will continue to grow with the continued onset of aging baby boomers.
The test involves several basic steps:
Apply cuff to arm
Record first Doppler sound as cuff is deflated
Record Doppler sound at the radial pulse
Repeat for other arm
Use the higher of the two arm pressures
Apply cuff to calf
Record first Doppler sound as cuff is deflated
Use Doppler ultrasound to record dorsalis pedis pressure and posterior tibial pressure
Repeat for other leg and use highest ankle
pressure for each leg
Calculate the ratio of each ankle to brachial pressure by dividing each ankle by the highest brachial pressure.
If the systolic pressure in the arms and legs are equal, it is probable that no blockage exists. If the ratio of the blood flow in the ankle to the flow in the arms is less than one, there is a significant possibility that peripheral arterial disease exists. The smaller the ratio, the more serious the condition. So, if the ABI is:
Less than 0.95 - significant narrowing of one or more blood vessels in the leg exists
Less than 0.8 patient may experience pain in the foot, leg or buttock during exercise
Less than 0.4 pain and symptoms of PAD may occur when the patient is at rest
At or below 0.25 severe limb-threatening PAD probably exists.