Turning Evidence Into Practice: A Guide To Treating Chronic Wounds In The Diabetic Foot

Author(s): 
By Barbara J. Aung, DPM, CWS

Lawrence Harkless, DPM, one of podiatry’s pioneers in the diabetic foot arena, has noted that an ulceration usually precedes an amputation in patients with diabetes. What available modalities do we have at our disposal to treat the ulcer before the patient requires an amputation?

When we perform surgery, we expect our incisions to heal in two to three weeks and we would normally remove sutures at this time. Then why do we commonly accept a wound, albeit one not caused by our hands, which has not healed in this almost standard timeframe? What treatments can we use when we see a wound that has not healed or made sufficient progress in two months?

Chronic wounds involve hyperactive tissues that do not heal due to a perpetual inflammatory process. In these situations, pro-inflammatory cytokines, proteases and cellular adhesion molecules overwhelm the wound bed.

Insights On Vascular Testing And Appropriate Referrals
Obviously, we work up these patients by obtaining a thorough medical history and doing a physical examination that is directed by the medical history. The American Diabetes Association and the Peripheral Arterial Disease (PAD) Coalition have published consensus statements, based on the evidence available in the current literature, which support the measurement of ankle-brachial indexes (ABI) and toe pressures for people with nonhealing wounds, especially people with diabetes, in order to assess for PAD.

One should also pursue noninvasive vascular testing for these patients. One may use a Doppler unit as long as the Doppler is bi-directional with a printout to record waveforms. This is acceptable under most insurance plan coverage policies. Physicians can also utilize the new systems available for obtaining pulse volume recordings (PVR). I use the Smart Dop 45 (Koven), which has a computer software model that I can link to my EHR (Medinotes).

If the results indicate there is vascular disease, I will refer the patient to a vascular surgeon or interventionalist colleague for further vascular assessment and possible endovascular intervention (such as the SilverHawk procedure by FoxHollow). Currently, there is four years’ worth of clinical documentation on the SilverHawk procedure.6

While this type of intervention may not ensure the affected blood vessel will remain open for the life of the patient, it may facilitate patency of the vessel long enough to heal the wound and salvage the limb. This procedure does not necessarily burn any bridges.

Should another SilverHawk procedure or an open bypass type procedure be required in the future, the surgeon can still accomplish the subsequent procedure.

What About Skin Substitutes?
Once the patient has restored blood flow in this area, I can proceed with further assessment for any infections (using appropriate oral antibiotics if necessary) and perform bone and soft tissue debridement as needed.

If no bone resection is necessary and one can move on to promoting wound healing, I consider the use of skin substitutes and there are many choices in this arena. However, only two products have the highest level of evidence via pivotal clinical trial data. Apligraf (Organogenesis) is a living human-derived, bilayered cell delivery system of keratinocytes and fibroblasts. These cells deliver the growth factors, allow the patient’s own cells to promote wound healing and allow the wound to emerge from the chronic inflammatory process it has been “stuck in.”

Apligraf is the only FDA-approved product for use with both venous and diabetic ulcers. There is Level 1 evidence to support efficacy in these instances. Apligraf provides both keratinocytes and fibroblasts as a bilayered cell delivery system. It provides the full range of growth factors and cytokines that the chronic wound may require in order to heal.

While Dermagraft (Advanced BioHealing) also has research behind it, the modality only recently came back on the market. Dermagraft provides fibroblasts alone, which may not be capable of producing all the cytokines and growth factors that our bodies are capable of producing. It is approved for diabetic foot ulcers only.

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