Current Insights On ABI And Diagnosing PAD
One obvious criticism of the ACCF/AHA guidelines is that patients younger than 50 do not get routine screenings unless they present with symptoms or the podiatrist has a high suspicion for PAD.14 Podiatrists should consider ABI screening tests in younger patients based on clinical physical exam findings (missing pulses, missing hair, dependent rubor, thin shiny skin, gangrenous changes, etc.) and clinical symptoms like leg pain that may support a diagnosis of PAD.
At Midwest Podiatry Centers, my fellow podiatrists and I utilize a questionnaire briefly explaining PAD and prompting patients to see if they have had the following symptoms:
• Slow healing wound or ulcers
• Missing pulses or poor circulation
• Injury to legs or extremity
• Exertional cramping or fatigue in extremity relieved by rest
• Resting pain in extremity that may disturb sleep
• Gangrenous black skin tissue
• Toes or feet that have become pale, discolored or bluish
Another criticism of the 2011 ACCF/AHA guidelines is that they do not include Doppler waveforms. Hard copy outputs of these waveforms are usually required for insurance reimbursement if one wishes to bill for services in addition to an office visit. Reporting the quality of waveforms as triphasic, biphasic, monophasic or inaudible can sometimes greatly assist with clinical decision making.
For instance, consider two patients presenting with a normal ABI value of 1.03. The first patient has normal triphasic waveforms but the second patient has barely audible monophasic waveforms. This second patient probably requires further workup like segmental pressures, toe brachial index or referral to primary care for risk factor reduction (smoking, dietary changes, statin drugs, blood sugar control). The second patient may also require referral to a vascular specialist depending on the history and clinical presentation.
Ankle brachial index screening is not appropriate for all patients. Generally, one should avoid screening for patients with active leg cellulitis, severe lymphedema, suspected deep vein thrombosis, severe obesity, overall poor health condition, end-stage renal dialysis, severe dementia and do-not-resuscitate status. I have observed that patients over the age of 90 years old seldom benefit from ABI testing but one must consider the overall clinical picture. Furthermore, ABI screening is not indicated for an asymptomatic 72-year-old male patient who has strong pedal pulses and recently completed a marathon race.
Screening for PAD adds value to your podiatry practice. Patients will appreciate your thoroughness and the extra time you spend with them. Primary care providers will appreciate the test results you send them along with an occasional phone call to discuss a high-risk patient with PAD. Vascular specialists will appreciate your timely referrals and the opportunity to avoid wounds or amputations.
Podiatrists are uniquely poised to help prevent limb loss and should take some time to critically consider using the ABI test to screen for PAD. Will your practice follow evidence-based systematic guidelines like the 2011 ACCF/AHA recommendations or will your practice only look for claudication, the tip of the Titanic-sized PAD iceberg, and ignore what lies underneath the water?
Dr. DeBrule is in private practice with Midwest Podiatry Centers in Richfield, Minnesota. He is board certified in wound care.