Keys To Diagnosing And Addressing PAD In Patients With Wounds

With increasing numbers of elderly patients and patients with diabetes, clinicians will encounter more and more patients with wounds and ischemic legs. In the United States, an estimated 8 million patients, or approximately 12 percent of the adult population, have peripheral arterial disease (PAD).1 Accordingly, our expert panelists discuss pertinent diagnostic tips, appropriate referrals and how to ensure adequate follow-up on these high-risk patients who often present to wound care centers.

Q:

What characteristics in patients with wounds make you suspect PAD?

A:

After implementing a strict, non-compromising pressure reduction plan (total contact cast or instant total contact cast), Nicholas Bevilacqua, DPM, notes a well perfused, uninfected wound should reduce in size by 50 percent after four weeks.

   When patients present with a non-healing wound, he says one must rule out underlying infection, ischemia and ensure an appropriate offloading plan. However, if the wound is properly offloaded and there are no clinical signs and symptoms of infection, Dr. Bevilacqua says physicians must suspect PAD. He says ischemic ulcers often appear on the distal aspect of the toes. The wound base with these ulcers is often fibrotic and may contain necrotic tissue, according to Dr. Bevilacqua.

   To Kazu Suzuki, DPM, CWS, it is “quite obvious” that if patients have dry, gangrenous toe wounds, they most likely have severe PAD. On the other hand, when it comes to ischemic legs, he notes the most typical physical exam findings — such as lack of hair growth, shiny and atrophic skin, or pulses that are difficult to palpate — are not accurate enough to rule in or rule out PAD.2 Therefore, Dr. Suzuki recommends a subsequent Doppler exam to help evaluate leg perfusion right after the physical exam and prior to wound debridement procedures.

   Desmond Bell, DPM, concurs, noting that a cursory Doppler exam can provide “extremely valuable” information in comparison to palpation of pedal pulses. He advocates regular non-invasive arterial screening for all patients with diabetes. Dr. Bell notes that any diabetic foot ulcer may have a component of arterial insufficiency as a contributing factor in addition to the structural deformities and reduced ability to heal that are inherent in patients with diabetes.

   Furthermore, Dr. Bell says ulcers previously diagnosed as being due to chronic venous insufficiency often have an arterial component, which physicians can easily overlook if they do not perform a thorough arterial assessment.

    “Just because it looks like a venous ulcer does not mean it is fully venous in etiology,” cautions Dr. Bell.

   One should also suspect PAD or critical limb ischemia when toe ulcers are accompanied by intense pain and other changes such as dependent rubor or cyanosis, according to Dr. Bell.

   Based on the American College of Cardiology/American Heart Association (ACC/ AHA) guidelines for the management of PAD, Dr. Suzuki assumes most of his patients over 70 years of age have some degree of PAD.3 He also assumes the presence of PAD in those over 50 years of age with known risk factors of diabetes; a history of smoking, hypertension and high cholesterol; or other cardiovascular diseases, coronary artery disease or stroke.

   For example, in the case of a 60-year-old male patient with palpable pulses, Dr. Suzuki would consider him at high risk for PAD if he has diabetes with a history of heart attack and coronary artery bypass graft (CABG). He says such a patient would probably have some degree of stenosis and plaques in his leg arteries in the same manner that he had stenosis in his coronary arteries.

   Dr. Suzuki also cautions that the probability of PAD increases as we age and 20 percent of 70-year-old Americans are known to have PAD.1 Given that he frequently sees new wound patients in their 80s and 90s, Dr. Suzuki would presume they would have some degree of PAD.

Q:

What kind of PAD workup do you do in your practice?

A:

From the patient interview and history, Dr. Suzuki can make an “educated guess” on the probability of PAD. Dr. Bevilacqua questions patients about common symptoms associated with PAD (claudication and/or rest pain).

   As for the physical exam, Drs. Bevilacqua and Suzuki palpate femoral, popliteal and pedal pulses. If Dr. Suzuki cannot palpate the pulses, he may use a handheld Doppler or utilize the skin perfusion pressure/pulse volume recording (SPP/PVR) test to determine the degree of leg ischemia. Dr. Bevilacqua assesses the ankle brachial index (ABI) in all patients with diabetes over the age of 50 or younger patients with multiple PAD risk factors.

   Since Dr. Bell’s practice specializes in treating patients with wounds and PAD, he says the issue is more in determining the degree of PAD. He does palpate pedal pulses but considers this test “very unreliable” when attempting to quantify the degree of PAD even when one can appreciate pulses. Using a simple Doppler allows Dr. Bell to hear the quality of blood flow and he notes the presence of turbulence is always a concern.

   Dr. Bell will refer the patient to a vascular specialist if he discovers trophic changes such as rubor, cyanosis, decreased hair growth and delayed capillary refill along with other risk factors for significant PAD. He also works closely with interventional cardiologists.

Q:

What kind of non-invasive tests for PAD do you do in your practice?

A:

Dr. Suzuki mainly uses a SPP laser Doppler (SensiLase, Vasamed), which can measure both SPP and PVR. He has found the combination of SPP/PVR is adequate enough to make an accurate diagnosis of PAD and refers the patient appropriately based on the test results. Dr. Suzuki no longer uses transcutaneous oximetry (TcPO2) as it takes over 30 minutes and is often inaccurate in his patient demographics.

   Although he acknowledges the ABI is a useful tool for screening for PAD in the general population, Dr. Suzuki often finds he cannot measure ABI due to the rigid leg arteries that occur in elderly patients and patients with diabetes. Dr. Bell also expresses concern with ABI testing. Since most of his patients have diabetes, Dr. Bell says their non-compressible arteries make the test results unreliable in a number of cases.

   Although the ABI is the initial step in non-invasive evaluation, Dr. Bevilacqua says the toe brachial index (TBI) may be a better assessment of peripheral pressure. He notes the smaller vessels in the toes are generally spared from calcification. When it comes to patients presenting with an ulcer, Dr. Bevilacqua says one can assess the periwound perfusion with a laser Doppler, which may aid in predicting healing.

   Dr. Bell will make a referral when he is strongly suspicious of PAD.

    “Getting patients to a specialist who not only determines the extent of PAD through invasive or non-invasive testing, but can then improve blood flow and, as a result, wound healing outcomes, is more expeditious,” asserts Dr. Bell.

Q:

What kind of precautions do you take on following up with your patients who had recent vascular intervention or bypass surgery?

A:

The key is close monitoring, according to Dr. Bell. He often treats patients who have undergone recent bypass or cardiovascular intervention. Dr. Bell notes that he frequently sees such patients more often during the critical post-op time period than the surgeon or interventionalists who performed the procedure.

    “We become the other set of eyes. If symptoms of ischemia return or if a complication is observed, we make immediate contact with that specialist,” says Dr. Bell.
Dr. Bell emphasizes the importance of patient education. Reminding patients not to ignore symptoms or encouraging them to speak up “when something just doesn’t seen right” helps reduce post-procedure complications.

   Dr. Suzuki first ensures that patients are following up with their appointments with vascular specialists. Although it can be easy for patients to forget appointments, he emphasizes the importance of routinely scheduled “surveillance” of the bypass graft or stented arteries with arterial Doppler machines to ensure adequate blood flow and detect restenosis as early as possible.

   Dr. Suzuki also notes that re-opened blood vessels or bypass grafts may close down over time. He emphasizes vigilant monitoring for the signs and symptoms of leg ischemia by asking about the patient’s pain level and ability to walk, and checking the wound and skin status.

   Dr. Bevilacqua supports “aggressive management” of lower extremity wounds in patients after bypass surgery. He adds that one must debride wounds of all non-viable tissue and prefers an aggressive approach to closure.

   Dr. Suzuki says the conventional thinking is that surgeons should not use a tourniquet during foot and ankle surgeries (such as toe or foot amputations) after revascularization procedures. He notes that the tourniquet, especially with prolonged use, may facilitate new occlusions in the leg arteries or possibly disrupt the bypass conduit, especially if the leg bypass procedure was recent.

    “Some of my colleagues disagree with me on this point but I take a ‘better to be safe than sorry’ approach with this particular topic,” says Dr. Suzuki.

   Dr. Bell is a board certified wound specialist of the American Academy of Wound Management and a Fellow of the American College of Certified Wound Specialists. He is the founder of the “Save a Leg, Save a Life” Foundation, a multidisciplinary, non-profit organization dedicated to the reduction of lower extremity amputations and improving wound healing outcomes through evidence-based methodology and community outreach.

   Dr. Bevilacqua is a foot and ankle surgeon at North Jersey Orthopaedic Specialists in Teaneck, NJ. He is a Fellow of the American College of Foot and Ankle Surgeons.

   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, Japan.

References
1. Olin JW, Allie DE, Belkin M, et al. 2010 Performance measures for adults with peripheral arterial disease. J Am Coll Cardiol. 2010; 56(25):2147-2181.
2. Khan NA, Rahim SA, Anand SS, et al. Does the clinical examination predict lower extremity peripheral arterial disease? JAMA. 2006; 295(5):536-546.
3. Hirsch AT, Haskal ZJ, Hertzer NR, et al. ACC/AHA guidelines for the management of patients with peripheral arterial disease. J Am Coll. Cardiol. 2006; 47(6):239-312.