Microvascular complications: Foot care

Foot ulceration and limb amputation are among the major drivers of disability and healthcare costs in people with diabetes. Foot ulceration is a leading cause of hospitalisation for people with diabetes,¹ and in 2012–13, 3570 people with diabetes had a lower limb amputation in Australia.³

A foot protection program that includes prevention, patient education, multidisciplinary care, and close monitoring and treatment of foot ulcers can substantially reduce amputation rates.

Patient education and support

Foot care education should be provided to all people with diabetes to assist with prevention of foot complications.

• emphasising the importance of appropriate footwear and foot care (improper footwear and tinea infection are associated with increased problems)
• establishing a regular self-monitoring schedule (including visual checks)
• developing an action plan to respond to early problems (eg skin breakdown).

Regular podiatric review should be considered.

Assessing risk of foot complications

A careful foot assessment should be performed to stratify the risk of developing foot complications. Stratification is dependent on four risk factors:¹

• peripheral arterial disease (PAD) – which can be assessed by dorsalis pedis and tibialis anterior pulses or hand-held Doppler. If problems are suspected, consider ankle-brachial pressure index (ABI) testing, toe brachial index (TBI) testing or absolute toe pressure
• peripheral neuropathy – which can be assessed using a neuropathy disability score or a 10 g monofilament
• deformities
• previous amputation or ulceration.

The following factors might also increase the risk of foot complications:¹

• visual impairment
• kidney disease
• sub-optimal glucose control
• ill-fitting footwear
• socioeconomic disadvantage.

Table 1 shows risk stratification and corresponding foot care. People at intermediate and high risk should be assessed by a diabetic high-risk foot service. The intensity of monitoring and review increases according to the level of risk.

Table 1

 Guidance on risk categorisation for complications, and elements to consider  during foot assessment¹
 

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Refer to the section ‘Microvascular complications – Diabetes-related neuropathy’ for practice-based tools for assessing circulation and foot deformity.

Indications for immediate referral to a multidisciplinary foot care clinic include active foot disease:

• foot ulcer, with or without local Infection
• suspected Charcot neuroarthropathy (eg unilateral, red, hot, swollen, possibly aching foot).

Any patients presenting with acute limb ischaemia should be referred immediately to an emergency department.

Patients with chronic, limb-threatening ischaemia require urgent referral to a vascular specialist.

Foot ulceration

A foot ulcer is a serious condition and needs to be managed immediately.

Assessment

Several wound classifications have been developed to provide objective assessment of severity of foot ulcers.

• The International Working Group on Diabetic Foot (IWGDF) guidelines recommend using IWGDF/Infectious Diseases Society of America (IDSA) classification criteria to assess infection severity.⁴
• The wound, ischaemia, foot infection (WIfI) system is recommended for use in people with PAD to stratify amputation risk and revascularisation benefit.⁴
• The SINBAD system – Site, Ischaemia, Neuropathy, Bacterial infection, Area, Depth – is recommended for communication between health professionals (Table 2).⁵

If arterial insufficiency is suspected, assessment and management of the peripheral vasculature is mandatory before debridement.

Referral to a vascular surgeon, high-risk foot clinic and/or multidisciplinary team is suggested in this situation.

Table 2.

The SINBAD wound classification system⁵
 

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Wound management

Patient ability to understand and undertake management should always be a factor in choosing a treatment and in counselling the patient regarding the treatment plan.

Debridement

Local sharp debridement of non-ischaemic wounds improves healing. Other methods of debridement that might be appropriate in certain cases include larval therapy, hydrosurgical debridement and autolytic debridement.⁶

The priority of debriding wound tissue is to prepare the surface and edges of a wound to facilitate healing. Debridement also reduces pressure on the wound, allows for full inspection of tissue underneath the debrided tissue and helps drain secretions or pus.⁶

Wound dressings

Currently, there is insufficient evidence to demonstrate the superiority of any one type of wound dressing over another in the management of ulcers. Dressings should therefore be tailored to the specific characteristics of the wound.

• In non-ischaemic ulcers, create a moist wound environment.
• Appropriate management of wound exudate levels should be a guiding principle in dressing selection and frequency of dressing change.
• In ischaemic ulcers, maintain a dry wound environment using a dry, non-adherent dressing until someone with experience in PAD has reviewed the wound.

A full list of considerations for dressing choice can be found on page 15 of Wounds International’s Best practice guidelines: Wound management in diabetic foot ulcers.

Off-loading devices

Ongoing weight bearing on an insensate foot causes continued trauma and results in poor wound healing.

Pressure on the wound should be off-loaded, using padding or other off-loading devices such as total-contact casts and removable prefabricated devices (eg controlled ankle-movement walkers, half-shoes, therapeutic shoes).

Ulcers are often caused by patients’ footwear; if this is the case, advise the patient not to continue wearing the same shoes.

Guidelines on footwear for people with diabetes can be found in an article by van Netten et al.

Infection

The need for antibiotics should be determined on clinical grounds.

It is appropriate for cultures to be collected for identification of microbiological organisms and antibiotic sensitivities. The most appropriate tissue samples for microbiological evaluation are either deep tissue swabs after debridement or tissue/bone biopsies.

There is no need to culture clinically uninfected ulcers, as colonising organisms will always be detected.

Infected ulcers should be treated with antimicrobial therapy according to published antibiotic guidelines.

The duration of therapy may need to be for extended periods.

Diabetic Foot Australia has resources for health professionals and people with diabetes.
Wounds International’s guidelines for management of diabetic foot ulcers provide detailed and practical information.