Chapter 9: Diabetic Foot Ulcers
- Dr. Laurie Parsons MD, FRCPC
- Tobi Mark BSc(Hon), DCh
- Review the problem of diabetic foot ulceration: background, pathophysiology and features
- Evaluate appropriate treatment for diabetic foot ulcers: local wound care and offloading considerations
Scope of the Problem
An increase in the incidence of diabetes globally is having major impacts on both health care systems and on the lives of persons with diabetes (PWD) (Hopkins et al., 2015). A recent Cochrane review found that diabetic foot ulcer (DFU) prevalence was 6.3% globally and highest in North America at 13% (95%CI: 10.0-15.9%), (Zhang et al., 2017). The annual cost associated with DFU in Canada has been calculated at $547.0M with an annual cost per patient of $21,371 (Hopkins et al., 2015). Another study found the average mean cost for DFU admission of $22,754, compared to the $10,169 for the top 5, most expensive, other medical conditions (Syed et al., 2020).
In statistics from the USA, 85% of lower leg amputations (LLA) are preceded by a DFU and being a PWD confers a 15-20 fold higher risk of a LLA (Pemayun et al., 2015). Walsh et al. (2017) examined the risk of dying as an independent factor for PWD and an amputation. Using a UK database, they examined the records of 20,737 patients and found that PWD and a new foot ulcer, had a 5% chance of dying within the first year and a 42% chance of death within 5 years. Even adjusting for other major comorbidities associated with diabetes, they still had significant correlation between DFU and death with a correlated hazard ratio of 2.48% (Walsh et al., 2016).
Armstrong et al. (2017) reports a lifetime risk of a PWD developing a DFU, to be as high as 19-34%. Unfortunately, the recidivism rate of DFU is even higher, with an estimate of 40% of patients will have a recurrence within one year and up to 60% within 3 years of healing a DFU.
This concept of high recidivism means that from a health economics point of view, we should consider allocating a significant proportion of health care resources to the prevention of DFU as a lower cost option than treating the complications of DFU; and to consider patients with DFU as having a chronic disease issue requiring ongoing and regular foot care and surveillance.
The journey from DFU to LLA begins with a small traumatic or surgical injury to the skin and is related to a complex interplay between peripheral neuropathy, poor glycemic control, foot deformity, peripheral vascular disease and limited joint mobility. Even PWD who do not have clinically demonstrable peripheral vascular disease will have local tissue ischemia secondary to microvascular changes. Approximately 60-80% of these ulcers will heal while 24% will lead to a LLA (Pemayun et al., 2015). A decreased immune response in PWD is a result of the negative effects of hyperglycemia on leukocyte function which increases the risk of a wound infection (Ogrin et al., 2015). Ulceration, secondary to neuropathy, poor local blood flow and decreased immune response, is due in large part to the metabolic effects of hyperglycemia, but also due to other risk factors such as smoking, dyslipidemia, obesity and hypertension (Syed et al., 2020). As well, ethnicity and associated genetic factors have been shown to be a risk factor for the development of neuropathy (Jhamb et al., 2016). Amputation is almost invariably a result of infection from a contiguous ulcer, leading to osteomyelitis (Berli et al., 2017; Volmer-Thole & Lobmann, 2016).
Healing a diabetic foot ulcer is complex. The following discussion will explore key aspects of the care of a diabetic foot ulcer in relation to the Wound Bed Preparation paradigm as depicted in Table 1.
Table 1 Wound Bed Preparation 2021 Ten Final Statements for patients with DFU
|1||Treatment of the cause||A. Determine if there is sufficient blood supply to heal/adequate perfusion.
B. Identify the cause(s) as specifically as possible or make appropriate referrals
C. Review cofactors/comorbidities: Bony deformities (amputations, bunions, calluses), signs of potential osteomyelitis (exposed bone, probe to bone, purulent discharge), callus and evidence of previously healed ulcers)
D. Choose appropriate offloading device
|2||Patient-centered concerns||A. Manage pain (diagnosis and treatment)
B. Evaluate activities of daily living through the lens of wearing an offloading device, mobility/exercise, eating habits, psychological wellbeing (mental health), and support system (patient circle of care, access to care, and financial constraints), ability to drive
C. Evaluate habits: smoking, alcohol, substance use, personal hygiene
D. Empower patients with education and support to increase treatment adherence (coherence)
|3||Determine healability (status may change)||A. Healable: adequate blood supply to heal and treated the cause
B. Maintenance: adequate blood supply to heal where the patient either cannot or will not adhere to the plan of care/healthcare system does not have appropriate resources
C. Non healable: inadequate blood supply and/or a cause that cannot be corrected (e.g., terminal cancer, negative protein balance)
|4||Local wound care: monitor wound history and clinical examination||A. Document wound(s): location, longest length × widest width at right angles, wound shape, wound bed, exudate, margin, undermining, tunneling, surrounding skin condition and photoimaging when available
B. Cleansing: gently with water, saline, or low-toxicity antiseptic agents
C. Reassess and document wounds at appropriate, regular intervals
D. Assess callusing regularly (weekly)
|5||When appropriate, debride wounds with adequate pain control.||A. Consider sharp surgical debridement (to bleeding tissue) for healable wounds and conservative surgical debridement for maintenance/nonhealable wounds
B. Evaluate the need for alternative debridement modalities: autolytic with dressings, enzymatic, mechanical, or biologic
C. Callus care
|6||Assess and treat wounds for infection/inflammation||A. Treat local infection (three or more NERDS criteria) with topical antimicrobials (silver, iodine, PHMB/chlorhexidine, methylene blue/gentian violet, surfactants)
B. Consider treating deep and surrounding infection (three or more STONEES criteria) with systemic antimicrobials
C. Evaluate and alleviate persistent inflammation including consideration of anti-inflammatory agents (topical dressings, systemic medication)
As per the University of Texas Wound Classification system (Lavery et al. 1996): daily dressings with a thin dressing choice may be more appropriate as bulky dressings may increase local pressure on the wound and surrounding tissues
|A. Healable, moisture balance, and autolytic debridement: alginates, hydrogels, hydrocolloids, acrylics, films
B. Moisture balance alone: super absorbents, foams, calcium alginates, hydrofibers, hydrocolloids, films, hydrogels
C. Non healable and maintenance wounds and moisture reduction: if antibacterial needed, low toxicity topical anesthetics: chlorhexidine/PHMB, iodine, acetic acid
D. Wound packing: saline wet (donate moisture) or dry (absorb moisture) but not antibacterial; PHMB gauze: antibacterial, non-release above the wound (stays in the gauze) only not in the wound surface; povidone iodine or other antiseptic soaked gauze: antibacterial above and on wound surface
|8||Evaluate the rate of healing- a healable wound should be 20%-40% smaller by week 4 to heal by week 12||A. Stalled (healable) wounds should be re-evaluated for alternate diagnoses; consider wound biopsy, further investigation, and/or referral to an interprofessional assessment team to optimize treatment|
|9||Edge effect: use active therapies for stalled but healable wounds||A. Some active modalities have weak to mixed evidence and should be only used after interprofessional assessment of the patient and with regular re-evaluations
B. Skin grafts have variable but positive evidence, and cellular and/or tissue-based products may or may not be cost effective at this time
C. Evidence for using NPWT as an adjunctive therapy for stalled healable wounds
|10||Organizational support||A. Organizational support may include a culture conducive to interprofessional education and patient-centered care, standardized evidence-informed protocols, adequate staffing, and established quality improvement programs that may include audits, prevalence and incidence studies, patient navigation|
Abbreviations: NERDS, Non-healing, Exudate increase, Red friable granulation, Debris or dead cells, and Smell; PHMB, polyhexamethylenebiguanide; STONEES, Size enlargement, Temperature increase of ≥3° F versus the opposite limb mirror image temperature, Os (bone exposed or direct probing), New areas of break down on the wound margin, Exudate increase, Erythema and/or Edema, and Smell.