to the editor: In the article “Peripheral Vascular Disease: Diagnosis and Treatment”1 in the June 1, 2006, issue of American Family Physician, Dr. Sontheimer indicated that if peripheral vascular disease is suspected, physicians should screen patients using the ankle-brachial index (ABI) in one or both extremities. In my experience, busy physicians rarely take the time to measure an ABI in the office, because this is usually not a reimbursed procedure. It is time consuming and expensive to refer a patient with suspected peripheral vascular disease to a hospital vascular laboratory for Doppler determination of ABI. Thus, many patients in the early stages of this disease may go undiagnosed and untreated.
A recent study demonstrated oscillometry to be a simpler and faster method for determining ABI in the office setting.2 Oscillometry is the automated method of measuring blood pressure that is utilized in most home blood pressure monitors. As the blood pressure cuff deflates, the oscillometer reports the greatest fluctuation in pulse-to-pulse pressure as the systolic pressure. The determination of ankle and brachial pressures by this method is a valid alternative to measuring ABI using Doppler.
The researchers in this study measured ABI by automated oscillometry and Doppler ultrasound in 201 patients, including 55 patients with peripheral arterial disease.2 They reported a correlation coefficient of 0.78 between methods in left and right legs; the mean ABI difference between methods was 0.04 ± 0.01 and 0.06 ± 0.01, respectively, in the left and right legs. They concluded that automated oscillometry is a reliable and easier way to measure ABI.2
I have tried this method in my own practice in patients whom I suspect have peripheral vascular disease. It only takes moments to move the arm cuff to the same-size part of the lower leg and push the button to automatically record the ankle systolic pressure. If the ankle pressure is equal to, or higher than, the brachial pressure determined by the same method, the ABI is normal. Conversely, an ankle-to-brachial pressure ratio significantly lower than 1 should prompt further diagnostic testing and referral.