Module 205.4 20_b_en

Notes de l'éditeur

1. Peripheral neuropathy is the most common cause of diabetic foot ulcers. Peripheral vascular disease is the most important factor in the outcome of diabetic foot ulcers. Bone deformity may be a contributing factor to the development of ulcers and may complicate the healing process.
2. Lower-limb ulcers in people with diabetes can be classified as either neuropathic, ischaemic or neuroischaemic. For the purpose of this presentation, venous ulcers will not be discussed. Neuropathic ulcers are the most common of all diabetic foot ulcers, accounting for approximately 45% to 60% of all cases. Ischaemic ulcers that occur in the poorly perfused diabetic foot are rarely caused by the vascular disease itself; there is usually some precipitating trauma, such as knocking the foot. In addition to the purely neuropathic and ischaemic ulcers, there is a mixed group of neuroischaemic ulcers.
3. It is important to determine the type of wound you are dealing with as this will help you plan your management and to act as quickly as possible.
4. How can you differentiate between neuropathic, ischaemic or neuroischaemic foot ulcers? In most cases, the type of ulcer can be identified quickly by assessing the location, characteristics and clinical signs. Neuropathic ulcers are located in areas of pressure, such as tips of toes and bony metatarsal heads. As in the photograph, these areas are usually surrounded by callus – the body’s direct response to pressure. The ulcer’s base usually has granulating tissue. The level of exudate (pus) is low to moderate. These feet are well perfused, with bounding foot pulses, which indicate an ability to heal once pressure is reduced. Due to nerve damage resulting in loss of sensation, people with a neuropathic foot ulcer will not experience pain.
5. How do neuropathic ulcers develop? Neuropathic ulceration can occur due to intrinsic and extrinsic causes. An intrinsic cause is the change in foot mechanics that occurs due to peripheral and autonomic neuropathy, together with high foot pressures. Common foot deformities result, such as clawed toes and prominent metatarsal heads. These deformities lead to increases in pressure, resulting in callus formation and potential ulceration. Callus formation is dangerous on the insensate foot, is not protective, and should be debrided promptly and regularly – at least fortnightly (every two weeks).
6. People with severe neuropathy are susceptible to external injury. Heat-related injuries are common, especially in winter. People burn themselves by sitting too close to heaters (they should sit at least 3 m away), using a hot water bottle or immersing feet in hot water (see slide). Summer is also a time when burns occur; people walk barefoot on hot sand at the beach or on hot footpaths or roads.
7. The majority of external foot trauma is due to ill-fitting footwear. This man tied his shoelace so tight that the top of his shoe rubbed the skin, creating blisters and ulcerations. Foreign objects in people’s footwear, such as nails, screws and glass, also cause trauma and ulceration. People cannot feel these objects inside their shoe and continue walking, injuring their feet.
8. Additionally injury can result from chemical cures for corns, which can burn the skin of the insensate foot, creating an ulcer.
9. Before treatment of any foot ulcer, people must receive an explanation of their foot condition, its treatment and the rationale behind this. The treatment of infection is the first priority. Diabetic foot infection is generally under-diagnosed and under-treated. Treatment with antibiotics should be started empirically; infection can greatly increase the likelihood of amputation. The person with diabetes should continue on antibiotic therapy until the ulcer is close to healing. It is recommended not to wait for the results of a wound swab before starting antibiotic therapy. The reduction of pressure at the ulcer site is an essential component in healing foot ulceration. Evidence has shown that callus removal reduces pressure at the ulcer site by 26%. Reductions in pressure can also be achieved using an offloading device such as an airflow mattress, a bed cradle, a pillow, or special footwear, which we will look at shortly. It is important to evaluate footwear, which frequently is not conducive to wound healing – too small or narrow. People must be taken out of footwear that causes problems and placed in appropriate footwear, such as all-purpose boots. People with a foot ulcer must be advised to reduce their walking, weight bearing or sitting in one position for prolonged periods, which is enough to traumatise the ulcer and prevent healing. People should only do what is required to fulfill the basic activities of daily living. People with ulceration or a previous history of ulceration and/or amputation should not do any weight bearing exercise. Dressings are an adjunct to treatment and facilitate wound healing. It is best to become familiar with a small group of dressings for ulcers.
10. The removal of all visible callus and non-viable tissue at weekly intervals is crucial to breaking the vicious cycle of pressure generation. Also, debridement promotes healing by stimulating the chronic wound into an acute wound.
11. Felt with an adhesive backing is commonly used by podiatrists to reduce and deflect pressure from ulceration and bony prominences. Studies have shown that pressure can be reduced by 61%. The approach is simple to use and cheap. However, it needs to be replaced after one week. The felt can be placed on the skin or inside an all purpose shoe or a shoe with adequate depth. Felt is not to be used if the ulcer is highly exudative or the skin too fragile.
12. Pre-fabricated casts are an effective alternative to the total contact cast.Their rocker sole provides effective offloading for plantar ulcers. They are simple to apply and can be easily removed by the healthcare provider for monitoring and by the person with diabetes for foot inspection. However, pre-fabricated casts may hinder adherence, especially in those who choose to remove it. Because they are an “off-the-shelf” device, they will not fit all feet and are less effective in maintaining foot shape. The Aircast Diabetic System with an inflatable bladder is the most effective as it has the ability to be customized with use of the air-bladder. An advantage of a prefabricated cast is that it can be padded with custom-moulded insoles.
13. Alginate and hydro-fibres should be cut to wound size. Gel applied to weight-bearing ulcers must be used sparingly to avoid maceration of the area surrounding the wound. Hydrogel-impregnated products, which assist in keeping gel within the wound, are ideal. Occlusive dressings may mask infection, retain wound exudate, macerate and retard healing, and precipitate the breakdown of the surrounding skin. These are contraindicated in the presence of exposed bone/tendon. Peri-pads and crepe bandages increase pressure and overheat the ulcer; avoid over-wrapping the wound.
14. Ischaemic ulcers are relatively rare compared with neuropathic ulcers but it is most important that we able to identify them as their treatment is different. These ulcers present on feet with impalpable or weak pulses. They are found on the borders of feet or the tips of toes, or in between the toes. Ischaemic ulcers may present with dry eschar (dead tissue) or have a sloughy ulcer base, and are usually irregular and non-exudative. These ulcers are usually painful.
15. Again, it is important to explain the nature of the problem, the treatment required and, in this case, the prognosis. These ulcers usually take a long time to heal; vascular intervention is often required. A more cautious approach to managing ischaemic ulcers is essential as their ability to heal is impaired. Check the ulcerated foot for signs of infection. Remember that inflammatory signs (redness and heat) may be absent due to the lack of blood supply. Reviewing infection status regularly is essential. Pain management should be considered in people with ischaemic ulcers. Do not use sharp debridement or dressings that debride the wound until you have information regarding blood supply or have permission from the person’s vascular specialist. Protect the area with black eschar with a non-stick dressing. If the ulcer base is sloughy and exudative, a dressing is required to absorb the pus. Do not use compression stockings or bandages unless advised by a vascular specialist as they may further reduce blood flow.
16. Controlling infection, improving blood supply and optimising the wound healing environment are essential in achieving effective wound healing. However, it is extremely important to protect the foot/ischaemic ulcer to reduce the risk of trauma-related injuries. Assess footwear for suitability. Post-operative shoes or sheepskin boots are good alternatives. Protecting heels in bed also needs consideration.
17. The neuro-ischaemic ulcer has a combination of neuropathic and ischaemic characteristics. In order to determine the more dominant process, a thorough neurological and vascular assessment is essential. Treatment will depend on these results.
18. Debridement and use of gel is contraindicated when pulses are not palpable, the Ankle Brachial Index (ABI) is not known or below 0.5. These may enlarge the wound and macerate the surrounding ulcer area when there is inadequate blood supply to support healing. The skin of ischaemic feet tends to be dry and fragile. Tapes may therefore cause tearing.
19. As stated previously foot infection is under-recognised and under-treated. When assessing infection it is important to compare both feet and lower limbs for differences (noting swelling, redness and heat). When the wound is dirty or smelly, suspect the presence of anaerobic infection. This can be treated with appropriate antibiotics. When an ulcer is highly exudative it may indicate the presence of a sinus (deep tract). Sinus need probing to determine their depth. People most susceptible to infection are those who have poorly controlled diabetes (HbA1c >10%) and those who live in hot, humid climates. Remember the person may not feel pain due to the neuropathy and therefore may not complain of any discomfort.
20. A broad spectrum antibiotic should be used because 89% of these ulcers have mixed flora and a lot of cases will require antibiotics via intravenous.
21. Infection alone in the diabetic foot increases the risk of amputation. However, in the presence of an ulcer there is always the risk of infection spreading to deeper tissues and into bone with rapidity – causing osteomyelitis. Infection in the bone has been shown to be present in more than 60% of infected diabetic foot ulcers and is associated with significant morbidity and amputation.
22. While you may not be the person prescribing the antibiotics it is essential you know what the person needs and help ensure they remain on antibiotic therapy until the infection has healed. A repeat x-ray or scan should be performed to check for resolution of the osteomyelitis. If surgical removal of bone is necessary the person should remain on antibiotics until after the surgery.
23. Preventing diabetic foot disease requires a multidisciplinary approach. Although there are no clinical trials indicating specific methods to prevent foot complications, we know that achieving good glycaemic control can maintain nerve function; smoking cessation can reduce the risk of peripheral vascular disease. Prevention also requires the identification of high-risk feet and the delivery of foot education and podiatry for these people. It is important for people to know when and where to refer if ulceration/infection occurs.
24. In summary, key foot care messages are: Assessment is essential Once done, it will help in determining the aetiology of the condition Knowing the aetiology will guide arrangements for appropriate wound management, if possible, by a skilled multidisciplinary team.
25. Ask participants to work in pairs to evaluate the case history illustrated in the following slides. Provide feedback to the whole group.
26. Known risks are Age Duration of diabetes Smoking Inappropriate education and lack of awareness Further information needed to assess other risks: Diabetes control Presence of other complications Hypertension or prior history of wounds Type of footwear and socks 2. Check for: Pedal pulse Reflexes Ankle Brachial Index Biothesiometer Monofilament Doppler studies/nerve conduction studies X-ray Culture studies 3. Depending on the responses to the previous slide the following can be discussed Antibiotic therapy Adequate /correct wound treatment and dressing Off loading There was an ulcer on the first metaphalangeal joint or in other words under the ball of the foot. There was also an ulcer on the great right toe but following bypass surgery blood flow improved as indicated by the normal Ankle Brachial Index of 1. 4. Controlling DM and complications (diet+exercise+treatment) Correct footwear/socks Foot care habits (skin/nail) Stop smoking Check feet daily and seek help when problem is minor Regular check with HCP
27. There was an ulcer on the first metaphalangeal joint or in other words under the ball of the foot. There was also an ulcer on the great right toe but following bypass surgery blood flow improved as indicated by the normal Ankle Brachial Index of 1.