Diabetic foot ulcer

Tackling one of the most serious complications of diabetes.

Diabetic foot ulcer is a common and serious complication of both type 1 and type 2 diabetes mellitus¹. Diabetes is associated with ischaemia, neuropathy and deformities that lead to a particularly high risk of developing foot ulcers and a low likelihood of ulcer healing.

Because of the reduced blood supply to the lower limb, diabetic foot ulcers are prone to necrosis, infection, and involvement of deep tissues, including bone². The age-adjusted rate of lower-limb amputation is estimated to be 15 times greater in individuals with diabetes than in the general population^{1 2 3}.

Approaches to the management of diabetic foot ulcer include debridement, protection from trauma, treatment of infection, control of exudate, and promotion of healing ⁴.

Patients with type 1 or type 2 diabetes mellitus have a lifetime risk of a foot ulcer of up to 25%^{2 3}. Infected or ischaemic diabetic foot ulcers account for approximately 25% of all hospital admissions for patients with diabetes^{3 4}. Diabetic foot ulcers account for almost two-thirds of all non-traumatic lower limb amputations performed in the Europe and the US^{1 4 5}.

These findings show how important it is to manage diabetic foot ulcer appropriately, quickly, and effectively⁶.

Aetiology

The causes of diabetic foot ulceration are a combination of chronic narrowing of small arterioles that supply oxygen to the tissues, diabetic arteriolosclerosis, which results in tissue ischaemia, and high venous pressure, resulting in tissue oedema and hypoxia².

Patients with diabetes develop specific risk factors that lead to foot ulcers, including loss of sensation due to diabetic neuropathy, prior skin damage or ulcers, foot deformity or other causes of pressure, external trauma, infection, and chronic ischaemia due to peripheral artery disease^{1 2}.

Clinical and economic burden

Globally, an estimated 422 million adults were living with diabetes in 2014, compared with 108 million in 1980 ¹. The global prevalence (age-standardised) of diabetes has nearly doubled since 1980, rising from 4.7% to 8.5% in the adult population, which reflects an increase in associated risk factors, mainly due to obesity. ¹

Rates of lower limb amputation, due to diabetic foot ulcer, are typically ten to 20 times those of non-diabetic populations ⁷. In the US, in 2010, approximately 73,000 non-traumatic lower-limb amputations were performed in adults aged 20 years or older with diabetes; 60% occurred in people with diabetes. ⁷

In the US, Medicare claims data showed that between 2006 and 2008, patients with a diabetic foot ulcer were seen by their outpatient healthcare provider about 14 times per year and were hospitalised about 1.5 times per year. The US claims data also showed that the cost of care for each claimant with a diabetic foot ulcer was about USD 33,000 for all Medicare services per year ⁸. Patients with a lower extremity amputation were seen by their outpatient healthcare provider about 12 times per year and were hospitalised about twice per year, with the total cost of care of USD 52,000 per year. ⁸

Effects on patient quality of life

Studies have shown that patients with diabetes who have a healed foot ulcer have a greater health-related quality of life (HRQoL) when compared with patients with chronic, non-healed diabetic foot ulcers when evaluated using standard questionnaires ⁹ . Also, for caregivers of diabetic patients with chronic, non-healing foot ulcers, there is a large emotional burden ⁹ .

Management

Successful treatment and diagnosis of patients with diabetic foot ulcers involves a holistic approach that includes the patients physical, psychological and social health and the status of the wound ¹⁰ .

The management of diabetic foot ulcer begins with assessment, grading, and classifying the ulcer based on clinical evaluation of the extent and depth of the ulcer and the presence of infection, which determine the nature and intensity of treatment ^{6 1}1 . The degree of ischaemia for patients with diabetic foot ulcers is assessed by ankle-brachial index (ABI) and toe pressure measurements ¹1 . To test the peripheral neuropathy there is two simple and effective tests used:

• 10 g Monofilament for testing the sensory neuropathy and should be applied at various sites along the plantar aspect of the foot.
• Tuning fork standard 128Hz is used to test the ability to feel vibrations, a biothesiometer is a device that also assess the perception of vibration ¹⁰

In patients with peripheral neuropathy, it is important to offload at risk areas of the foot in order to redistribute pressures evenly ¹² . Inadequate offloading leads to tissue damage and ulceration.

To ensure holistic assessment and treatment of diabetic foot ulcers, the wound should be classified according to a validated clinical tool. The University of Texas (UT) system was the first diabetic foot ulcer classification to be validated and consists of three grades of ulcer and four stages ¹³ .

The European Wound Management Association (EWMA) states that the emphasis in wound care for diabetic foot ulcers should be on radical and repeated debridement, bacterial control and frequent inspection and careful moisture balance to prevent maceration ¹⁴ . The patients vascular status must always be determined prior to sharp debridement. Patients needing revascularisation should not undergo extensive sharp debride ment because of the risk of trauma to vascularly compromised tissues ¹⁰ .

While it may seem logical that effective glucose control could promote healing of diabetic foot ulcers, there is no evidence in the published literature to support this assumption ¹⁵ . An explanation for this finding may be that small vessel diabetic arteriolosclerosis is irreversible and after a certain time, is not responsive to normoglycaemia ¹⁵

Risk of infection

Chronic non-healing ulcers of the foot are susceptible to infection, which can lead to serious complications, including osteomyelitis and septicaemia ^{16 17}.

When a diagnosis of ulcer infection is made, treatment is based on the clinical stage of infection, and X-ray imaging is usually performed to exclude or confirm osteomyelitis ¹⁷ . The most common infecting organisms include aerobic Gram-positive cocci, aerobic gram-negative bacilli, and anaerobic organisms in deep ulcers ^{16 17 18} .

According to the Infectious Disease Society of America (IDSA) guidelines, infection is present if there is obvious purulent drainage and/or the presence of two or more signs of inflammation (erythema, pain, tenderness, warmth, or induration ¹⁷ . The management and treatment of infection of a diabetic foot ulcer should include a multidisciplinary team of experts including surgeons, infectious disease specialists, diabetologists, microbiologist sand nursing staff ¹⁷.

The role of dressings in the management of diabetic foot ulcers

Following debridement, the diabetic foot ulcershould be kept clean and moist but free of excess exudate, with dressings selected based upon the ulcer characteristics, such as the extent of exudate, or necrotic tissue ¹⁹. Some dressings are also impregnated with antimicrobial agents to prevent infection and enhance ulcer healing ²⁰.

By using a dressing that create a moist wound healing a natural process to soften and remove devitalised tissue will occur, this process is called autolytic debridement. Care must be taken not to use a moisture donating dressing as this can predispose to maceration. In addition, the application of moisture-retentive dressings in the presence of ischaemia and/or dry gangrene is notrecommended ^{21 22}.

It is important to incorporate strategies to prevent trauma and minimise wound-related pain during dressing changes ²³. This may include the useof soft silicone dressings and avoiding unnecessary manipulation of the wound ²⁴. It is now acknowledged that many patients, even those with neuropathy or neuroischaemia, can feel pain due to their wound or a procedure ²⁴.

Other advanced treatments for diabetic foot ulcers

Adjunctive therapies may improve ulcer healing, such as negative pressure wound therapy (NPWT), the use of custom-fit semipermeable polymeric membrane dressings, cultured human dermal grafts, and application of growth factors ²⁵.

All ulcers subjected to sustained or frequent pressure and stress, including pressure-related heel ulcers or medial and lateral foot ulcersor repetitive moderate pressure (plantar foot ulcers) benefit from pressure reduction, which is accomplished with mechanical offloading. Offloading devices include total contact casts, cast walkers, shoe modifications, and other devices to assist in mobility ²⁵.

Patient education of self - care

Effective foot care should be a partnership between patients, carers and healthcare professionals. Educating patients about proper foot care and periodic foot examinations are effective interventions to prevent ulceration ²⁶.

'References'

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