Treating And Referring Patients With Wounds And PAD

The presence of peripheral arterial disease (PAD) can complicate the treatment of lower extremity wounds. These panelists explore the diagnosis and workup for PAD, and also share their insights on referring patients to other healthcare professionals.

Q:

When do you suspect PAD in patients with wounds?

A:

Michael DeBrule, DPM, suspects PAD in wounds located at the tips of toes and the lateral ankle, especially when black eschar is present. If there is a gangrenous change in toes (eschar at the toe tips, etc.), Kazu Suzuki, DPM, CWS, says the presence of lower extremity ischemia is obvious. That said, he cautions that ischemic changes, such as shiny skin and lack of digital hair, that physicians commonly believe to indicate PAD may not be reliable signs of PAD.

Dr. Suzuki also has a higher suspicion for PAD in older patients (over 65 in the latest guideline definition); those with diabetes or a smoking history; if the patient has a history of coronary artery disease or stroke; or less commonly, those with renal, carotid or mesenteric ischemia. Dr. DeBrule concurs with those risk factors, adding that PAD can also be present in patients with a history of claudication and in wounds that are slow to improve or do not bleed much during debridement.

“Any patient with a lower extremity wound needs to have an investigation for PAD,” stresses Lee C. Rogers, DPM. As he notes, the prevalence of PAD in those with diabetes and a foot complication is approximately 50 percent.¹  

Q:

What is your procedure for a PAD workup?

A:

Dr. Rogers implements protocols in his centers to perform non-invasive testing on all lower extremity wounds to avoid missing patients with poor perfusion. Then he will perform a PAD-focused history and physical. Dr. Rogers suggests asking about intermittent claudication. However, he cautions that people with neuropathy may not feel the typical pain of intermittent claudication and may instead describe their legs fatiguing and feeling like “jelly” or “giving out” after a certain distance of walking, which they get relief from with rest. Dr. Rogers suggests documenting any smoking history. His full PAD-focused H&P is below at right.  

Dr. DeBrule has patients of 65 to 89 years of age complete an annual PAD screening questionnaire. Then he reviews the risk factors and determines if a non-invasive vascular test should be the next step.

In his office, Dr. Suzuki utilizes a laser Doppler machine (PAD-IQ, SensiLase), which measures pulse volume recordings (PVR) and skin perfusion pressure (SPP) for most of his new patients with wounds as well as established patients in whom he suspects worsening ischemic disease.

Q:

What non-invasive tests do you perform for PAD?

A:

Besides PVR and SPP tests, Dr. Suzuki orders non-invasive arterial Doppler tests quite often to figure out the severity and morphology of the lower extremity PAD. By default, he notes the vascular technicians provide ABI but he does not rely on the number, saying it is often falsely elevated in some of his patients with calcified vessels.

Dr. Rogers concurs. While the ABI test is easy to perform and generally has good sensitivity and specificity for detecting PAD, he says it is not appropriate in those with diabetes. Skin perfusion pressure is most accurate for those with diabetes, is quick and easy to perform, and provides the clinician with a clear result, according to Dr. Rogers.

If patients have a venous leg ulcer and intend to use compression, Dr. Rogers says most compression devices are contraindicated when the ankle brachial index (ABI) is below 0.8 (or in some cases 0.6).

Dr. DeBrule formerly ordered ABIs and PADnet (BioMedix) segmental pressures (both with waveforms), but says these tests took too long, and it was difficult convincing his patients to come back another day. Recently, he notes Midwest Podiatry Centers switched to FloChec (Bard Peripheral Vascular), a blood volume plethysmography test that reports digital ABIs. Dr. DeBrule says his patients have been receptive to the new test, which takes three minutes and can occur on the same day in the office. He recommends FloChec for assessing for PAD, saying “it makes blood pressure cuffs seem old fashioned.”  

Dr. Rogers notes transcutaneous oximetry is operator-dependent, takes 20 minutes or more, and the presence of edema affects the readings. Furthermore, Dr. Rogers says arterial duplex testing is both anatomic and functional, but notes its accuracy depends highly upon having trained technicians assess the results.

Noting that there is no straightforward answer to the question, Dr. Rogers says the choice of test might depend on what is available in the clinic or hospital.

Q:

What are your criteria for referring patients with PAD to other medical doctors and vascular specialists?

A:

Dr. Rogers advocates that podiatrists have a very low threshold for ordering tests and referring to a vascular specialist.

“We are often the gatekeeper for the foot,” he explains. “Patients do not know they have vascular disease. It is incumbent upon us to make that diagnosis and get them to the appropriate specialist.”

To that end, Dr. Rogers suggests referring patients to either a vascular surgeon or an endovascular specialist like an interventional cardiologist or interventional radiologist. For patients without diabetes, he notes an ABI <0.9 or >1.2 should generate a referral while a SPP <50 mmHg is a good referring threshold for those with diabetes.

Dr. DeBrule previously referred patients with mild to moderate PAD back to their primary care physicians. He would send a letter with the ABI test results but stopped doing that “because too many PCPs didn’t care about PAD.

“Sadly, most PCPs did not even bother to discuss simple things: dietary changes, a walking program or smoking cessation,” says Dr. DeBrule. “So now, with few exceptions, I offer to send everybody with PAD (mild, moderate, severe) to a vascular specialist. It is best to hear it from the horse’s mouth.”

For a patient in the hospital with mild severity or worse PAD, Dr. Suzuki usually asks vascular specialists to be involved. “Since PAD is a progressive disease, I feel that we should have them involved as early as possible in the disease process,” he says.

For the outpatient clinic, Dr. Suzuki considers referring to a vascular specialist if his patient complains of intermittent claudication or rest pain. Alternatively, he refers to a vascular specialist if he has a patient with a wound and a SPP below 40 mmHg or a wound that does not respond to his best practice wound care over two to three weeks.

One aspect of PAD that Dr. Rogers says is often forgotten is the connection to mortality. In five years, he notes 32 percent of those with PAD will die.² If one diagnoses PAD, Dr. Rogers emphasizes that timely referral to an internist or a cardiologist for cardiovascular risk reduction with cardiovascular surveillance, statins, ACE inhibitors and aspirin can help reduce the five-year risk of mortality for these patients.

“You are truly saving your patient’s life,” says Dr. Rogers.

Dr. DeBrule is in private practice with Midwest Podiatry Centers in Richfield, Minnesota. He is board certified in wound care.

Dr. Rogers is the Executive Medical Director of the Amputation Prevention Center at Sherman Oaks Hospital in Los Angeles.

Dr. Suzuki is the Medical Director of the Tower Wound Care Center at the Cedars-Sinai Medical Towers. He is also on the medical staff of the Cedars-Sinai Medical Center in Los Angeles and is a Visiting Professor at the Tokyo Medical and Dental University in Tokyo. Dr. Suzuki can be reached via e-mail at Kazu.Suzuki@CSHS.org .

References
1.    Wukich DK, Shen W, Raspovic KM, et al. Noninvasive arterial testing in patients with diabetes: A guide for foot and ankle surgeons. Foot Ankle Int. 2015; epub July 20.
2.    Norgren L, Hiatt WR, Dormandy JA, et al. Inter-society consensus for the management of peripheral arterial disease (TASC II). J Vasc Surg. 2007; 45(Suppl1):S5-S67.