Clinical Care  Treatment Protocols, Diabetic Foot Ulcer
Why is early treatment of diabetic foot ulcers important?
Diabetes is the most common disease process associated with lower limb amputation, accounting for nearly half of all non-traumatic amputations in North America and Europe. In the United States, 162,500 patients with diabetes are hospitalized for foot ulcers annually.5 Of the 50,000-60,000 diabetes-related lower-extremity amputations performed every year,6 84% are preceded by a foot ulcer.7 Equally important, once people with diabetes develop an open wound, they are furthered hampered both by impairments in wound healing and by an increased susceptibility for wound infection.
How many patients with diabetes develop a foot ulcer?
Two to three% of all patients with diabetes develop foot ulcers every year, and approximately 15% develop foot ulcers during their lifetime.8,9
How serious is a diabetic foot ulcer?
Not only is the risk for amputation increased in patients with diabetes, but the mortality rate is significantly higher among this population as well. The incidence of ischemic heart disease, arterial disease, and peripheral vascular disease is twice as high among this population. These complications have been shown to be the cause of the majority of mortalities associated with amputation. Patients with diabetes admitted to a nursing home with a pressure ulcer had an 88.1% greater death rate (<0.001) by one year than non-diabetics with similar foot wound infections.10
What is diabetic neuropathy?
Nerve damage in diabetes affects the motor, sensory, and autonomic fibers. Motor neuropathy causes muscle weakness, atrophy, and paresis. Sensory neuropathy leads to the loss of protective sensation to pain, pressure, and heat. Neuropathy of the autonomic nerves causes warm, overly dry feet that are prone to skin breakdown, as well as functional alterations in microvascular flow.5
How does loss of feeling affect the ulcer?
Diabetic peripheral neuropathy has several effects in the lower extremity. First, autonomic dysfunction (and denervation of dermal structures) causes decreased sweating and increased dryness, resulting in the loss of integrity of intact skin and providing an ideal site for microbial invasion.11 Secondly, somatic neuropathy results in sensory loss in the affected area, making it difficult for patients to notice or feel an ulcer. In such cases, the patient may not seek treatment until after the wound is already infected. Third, a combination of sensory and motor dysfunction can cause the patient to place abnormal stress on the foot, producing trauma and leading to infection.
What tests are essential for treating a diabetic foot ulcer?
It is important to assess the pulse of a person with diabetes and to verify if the person has ischemia. All patients with foot ulcers should have non-invasive vascular testing. In most vascular laboratories, lower extremity arterial pressures and the ankle/brachial index (ABI) are measured by calculating a ratio of pressure at the ankle to pressure in the arm. A normal ABI is 0.9 to 1.1. Claudication occurs as the ABI is reduced to approximately 0.7. Ischemic rest pain occurs at about 0.4, and tissue death occurs when the ABI falls to values between 0.1 and 0.3.6 A vascular consult should be obtained immediately after the first visit if the pulse volume is decreased and the ankle/brachial index is below 0.9.
Establishing glycoselated hemoglobin and determining whether glucose level is well controlled are important components for treatment. Although glucose levels must be maintained within normal limits, the reasons for complications in patients with diabetes are more complex than poor glucose control.
X-rays, bone scans, and magnetic resonance imaging (MRI) should be used to determine if infection has spread to the bone (osteomyelitis). Deep infection requires early, surgical debridement of all devitalized tissue, followed by antibiotic treatment which addresses the polymicrobial nature of the infection.
Do NIFs portray falsely elevated ABIs in patients with diabetes?
Non-invasive laboratory tests frequently underestimate the severity of the arterial disease in patients with diabetes, many of whom commonly have a falsely elevated ABI. In patients with diabetes, the atherosclerotic process leads to severe calcification of the arteries. When the arterial pressure is measured by Doppler echography using a blood pressure cuff, a portion of the squeeze of the cuff is used to overcome the rigidity of the vessel wall, which can result in leading to a falsely elevated value. A normal ABI with a markedly dampened waveform suggests calcified vessels and a falsely elevated ABI.6
What should be done if a person is ischemic?
Patients with ischemia will be referred for vascular intervention (e.g. bypass, arthrectomy, or stent). Ischemia must be assessed in all patients with extremity ulcers and any impairment in arterial flow.
Should every individual with a diabetic foot ulcer have offloading?
Yes. Pressure may increase the risk for developing ulcers and re-injury of the wound. Unrelieved pressure will certainly impair wound healing and will increase the risk of complications. Regardless of ulcer depth, without proper offloading and pressure reduction, ulcers will continually be traumatized so they cannot heal. Furthermore, patients with diabetes frequently present with peripheral neuropathy and loss of protective sensation. This lack of sensation of pain from poorly fitting footwear and unnecessary pressures will exacerbate the advent and progression of foot ulcers, possibly leading to amputations of the lower extremity.
What is the most important part of healing a diabetic foot ulcer?
The most important steps in the promotion of healing in a diabetic ulcer are offloading and debridement.12 The foundation for comprehensive care of diabetic foot ulcers is the removal of all non-viable, infected tissue and bone from open wounds, as well as any surrounding calluses, until a new border of healthy, bleeding soft tissue and uninfected bone are formed. Debridement is helpful not only in removing abnormal tissue (i.e., hyperkeratotic epidermis) and significant amounts of bacteria. In addition, debridement results in the release of growth factors that begin the healing process.6
Should calluses be debrided?
Removal of the callus results in lowered plantar pressures.13 All patients should thus be examined for callus formation with serious consideration for excision.
What therapies has the US Food and Drug Administration approved to accelerate the closure of non-healing ulcers based on efficacy?
- Apligraf®, which contains fibroblasts and keratinocytes.
- Regrenex, pgf-bb, a growth factor that comes in a gel form
When should cellular therapy be used?
If proper wound bed preparation and offloading does not promptly result in accelerated closure within three weeks, consideration should be given to treatment with Apligraf® or Regranex®, which have been shown to result in rapid closure.
What type of wound dressings should be used after debridement?
Although foot ulceration is one of the most common complications in diabetes mellitus, much controversy exists over the proper dressing care of the diabetic ulcer. As a result, standards of care have yet to be defined. There are many questions regarding the best dressing and how often it should be changed.
Since cells cannot survive in a dry environment, preservation of a moist setting in a wound is imperative for healing. Following debridement, tissues should be kept moist to prevent the formation of devitalized tissue and subsequent deepening of the wound. Benefits of moisture include:
- Facilitating more rapid migration of epidermal cells across the wound bed
- Promoting angiogenesis and connective tissue synthesis
In the past decade, the technology of dressing has developed significantly. Several new products, which reflect greater knowledge of tissue repair physiology, have been produced and successfully used for the management of various types of chronic ulcers. Some newer agents, such as hydrogels, hydrocolloids, and polymers, not only protect the wound against dehydration, but may also play a role in the treatment of these ulcers by retaining cells needed to phagocytose bacteria and facilitate repair. In addition, some of these dressings have been shown to provide a barrier against environmental contamination, bacteria, and some viruses.13
Should treatment and dressing regimens be changed frequently?
Dressing indications and contraindications are determined by wound location, depth, amount of eschar or slough present, amount of exudates, condition of the wound margins, presence of infection, and conformability of the dressing. Since the wound is constantly changing during treatment, dressing selection should be periodically re-evaluated.12 We suggest making a change in the wound treatment plan every two weeks if the wound is not healing.
Should fungal toenails be treated?
Thickened fungal toenails are a common occurrence in patients with diabetic foot ulcers. The toenails must always be treated, since they impair the ability to fight any type of infection. Treatment must include appropriate cutting of nails by a trained specialist. Possible topical antifungal and systemic oral antifungal treatments may be necessary.
Should a patient with a diabetic foot ulcer stop smoking?
Yes. Thickened fungal toenails are a common occurrence in patients with diabetic foot ulcers. The toenails must always be treated, since they impair the ability to fight any type of infection. Treatment may include removal of the nail bed. Possible topical antifungal and systemic oral antifungal treatments may be necessary.12
What should be done to treat infection?
A bacterial culture should be performed as soon as a patient presents with a diabetic foot ulcer. Infections in patients with diabetic foot ulcers are commonly polymicrobial, with both aerobic and anaerobic bacteria involved.12 The polymicrobial nature of the infection complicates the fight against it and its related morbidities, such as cellulitis, abscesses, sepsis, and osteomyelitis.
Specifically, parenteral antibiotics should be used when treating serious infections in order to achieve higher concentrations of antibiotics in the peripheral tissues. Due to poor vascularization, oral antibiotics and outpatient management may not be successful.
How can sepsis be prevented?
Sepsis, a major contributor to heightened morbidity and mortality, often originates in a diabetic foot ulcer, which acts as a portal of entry for infection.12 Since patients with diabetes frequently have impaired immune function17 (in addition to ischemia and neuropathy), they are at higher risk of developing foot infections than non-diabetic patients. Furthermore, a foot ulcer is a wound that has high concentrations of bacteria (e.g., Streptococcus group B, Pseudomonas aeruginosa, Enterococcus), and so remains a source of sepsis even in the absence of clinical infection.
Ultimately, because the immune system of a person with diabetes is impaired, the body is unable to prevent sepsis caused by the local bacterial contamination that is always present in the undebrided wound. Thus, debridement and antibiotic therapy must be initiated as early as possible. If growth factors are used for therapy, it is important to control infection for the therapy to be effective.
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