SALSA’s Diabetic Foot Ulcer Flowchart to help #ActAgainstAmputation

We’ve had many people ask for our generalized flowchart for care. Here it is. As always, these are living documents that change over time. Feel free to improve and pay it forward!

Assessment of the Diabetic Foot: Wound, Ischemia and Foot Infection (WIFI)

Patient with Diabetic Foot Ulcer (A)

Of the 435 million people with diabetes, worldwide, up to 34% (148 million) will develop a diabetic foot ulcer in their lifetime.^{1, 2} Lower extremity complications of diabetes are a leading cause of infection and hospitalization and are now a major source of global disability.³ Optimal treatment in this population requires a team approach.Core participation of vascular and podiatric surgery along with physical therapy, diabetology, infectious disease and nursing appears to reduce time to treatment and therefore risk for high-level amputation.^4-6 When diabetic patients present with tissue loss, they should be assessed for overall limb threat. This should be done systematically using the Wound, Ischemia, and Foot Infection (WIfI) score. By assessing whether a wound, degree of ischemia, or infection is “None, Mild, Moderate or Severe” (0,1,2,3), one can rapidly communicate the degree of limb threat to the patient and other members of the interdisciplinary team (Table 1).^7,8

Table 1: Points Assigned by WifI Limb Threat Classification System²

Wound:
No ulcer and no gangrene
Small ulcer and no gangrene
Deep ulcer or gangrene limited to toes
Extensive ulcer or gangrene
Ischemia: toe pressure or TCPO2:
> 60 mmHg
40-59 mmHg
30-39 mm Hg
< 30 mm Hg
Infection:
No infection
Mild, < 2 cm cellulitis
Moderate, > 2 cm cellulitis / purulence
Severe, systemic response / sepsis

Physical Exam: Infection present? (B)

Diabetic patients presenting withfoot ulcers should undergo a comprehensive dermatologic, neurologic, musculoskeletal and vascular examination.⁹ The diagnosis of a diabetic foot infection is a clinical one. Importantly, bacteria in the wound is not a qualifier of active infection as all wounds have microorganism colonization. The examination should include an evaluation for soft tissue erythema, wound size, depth, associated drainage, and tissue/bone exposure. Infection can be identified by erythema, calor, drainage, and/or malodor, with inflammation and purulence identifying active infection. Because patients with diabetes have neuropathy, they may not have the painful feedback or other local/regional symptoms otherwise associated with inflammation.

Infections should be classified as mild (superficial and limited in size and depth), moderate (deeper or more extensive), or severe (accompanied by systemic signs or metabolic perturbations).⁹ Patients with active infection require specific management. The first examination should include an assessment of the degree of tissue loss, graded by the WifI system.⁸

Lab Tests/ Infection Grading (C)

Patients presenting with a diabetic foot infection require basic blood testing including a complete blood count, serum chemistries, and inflammatory markers (erythrocyte sedimentation rate and/ or C-reactive protein).¹⁰The overall grade of infection is scored by the Systemic Inflammatory Response Score (SIRS), with one point for each of the following potential findings:

• Temperature >38°C or <36°C

• Heart rate >90 beats/ min

• Respiratory rate >20 breaths/min or PaCO₂ <32 mm Hg

• White blood cell count >12 000 or <4000 cells/μL or ≥10% immature (band) form¹¹

Patients with SIRS score > 2 require more urgent resuscitation and IV antibiotics.

People diagnosed with SIRS and WIfI Foot Infection Grade 3 require more intensive medical and surgical intervention than those in lower infection grades. It is critical to also correct associated hyperglycemia and other electrolyte or metabolic disorders.

Culture, Antibiotics, Possible Debridement (D)

Patients with diabetes and an infected foot ulcer should have their wound cultured prior to or concomitant with the administration of antibiotics. Blood and deep tissue (obtained during debridement) cultures can help select appropriate antibiotics. While superficial cultures are often obtained in these patients, they have limited utility since most wounds have superficial skin flora contamination that does not necessarily identify the organism responsible for the infection. After cultures are obtained and diabetic infection is confirmed, empiric antibiotic therapy should be initiated and subsequently be narrowed as much as possible after bacterial speciation and drug sensitivities are available. Empiric treatment should be based on severity of infection the suspected organism, and detailed recommendations have been published by the Infectious Diseases Society of America ⁹ If infection is severe enough to require hospitalization, intravenous antibiotics are used. Undrained purulence or non-viable tissue should be surgically debrided in as expeditious manner as possible. Generally, advancing infection should take precedence over revascularization.¹³

[DGA1] [JC2]

Arterial Circulation Evaluation (E)

Because of the frequent association of ischemia with diabetic foot ulcers, all patients should undergo an evaluation of the arterial circulation to the foot, starting with pulse examination. Non-invasive vascular laboratory assessment should be performed in all patients with reduced pulses or exam findings of digital ischemia. Ankle-brachial indices (ABI) are obtained initially but may be falsely elevated in patients with diabetes due to arterial calcification (making tibial arteries non-compressible). ABI > 1.2 is considered falsely elevated, which can be confirmed by abnormal Doppler signals at the ankle. In this case, toe pressures are a more accurate assessment of arterial perfusion to the foot, and allow for better detection of peripheral arterial disease (PAD) and risk for limb loss.¹⁴ While there is no absolute threshold, ABI > 0.8 and toe-brachial indices (TBI) >0.6 or absolute toe pressure > 40 mm Hg is potentially adequate for ulcer healing, recognizing that the more extensive the tissue loss, the better the circulation must be to allow healing. Individual decision making is needed for each patient to determine whether arterial revascularization is needed to allow ulcer healing, and sometimes this is determined by the course of ulcer healing during the treatment program (See I.). If there is any doubt about the adequacy of arterial evaluation, further imaging is warranted to assess the potential for healing or the need for revascularization.

Arterial Imaging: Revascularization possible? (F)

Patients presenting with PAD and tissue loss have up to a 40% chance of progressing to major amputation within 6 months. Unfortunately, limb loss is far more likely if revascularization is not performed in patients with severe arterial disease. Duplex ultrasound (DUS), CTA or MRA can provide minimally invasive imaging to define the location and severity of arterial disease, and usually allow a decision to be made about whether revascularization is possible. In some cases, arteriography may be required to define detailed anatomy of distal arteries and may be done for surgical bypass planning or as part of an endovascular intervention. In most patients, endovascular or surgical revascularization is possible and should be attempted in all but the highest risk patients when arterial circulation is inadequate to allow ulcer healing.^15,16

Exam / Imaging Shows Osteomyelitis? (G)

Likelihood of bone infection is significantly increased if it is possible to probe to bone through the ulcer. This is especially true when performed in an inpatient setting when the pre-test probability is high.²⁰ Radiographs can also be helpful if they show obvious bone destruction. In equivocal cases, MRI can be utilized to confirm the diagnosis.²¹ It is important to determine if osteomyelitis is present because bone debridement and prolonged antibiotics will likely be required to allow wound healing, even in patients with adequate circulation.

Debridement/Foot-Sparing Amputation, Prolonged Antibiotics (H)

For patients with diabetic foot infection involving bone, definitive surgical treatment may be required to eradicate the infection.²²In this case, all devitalized tissue and bone should be surgically removed. In some cases, soft tissue and partial bone excision may be adequate, but in many cases, especially with forefoot osteomyelitis, trans-metatarsal amputation or pan-metatarsal head excision may be required. Recent data also suggests that for some patients, suppressive antimicrobial therapy may be clinically successful. ²³

Infection Improving? (I)

During the course of treatment, foot ulcers should be carefully monitored for new or worsening infection versus improvement of infection, and treatment altered if infection is not improving.

Augment Antibiotics, Debridement (J)

If patients have adequate circulation, and absence of underlying osteomyelitis, but do not respond to the initial treatment with oral antibiotics, the route or type of antimicrobial should be reconsidered. Repeat wound cultures of deep tissue and consultation with infectious disease colleagues may also be helpful at this stage. The ulcer should be carefully inspected for non-viable tissue, and additional local debridement performed at any stage where this is necessary.

Plantar Ulcer? (K)

Autonomic neuropathy can lead to decreased capillary-bed perfusion and resultant dry and cracked skin. Disruption of the skin’s protective barrier can increase the risk for bacterial infection at this site. Motor neuropathy can result in claw-toe deformity, intrinsic muscle wasting and distortion of the foot’s normal weight-bearing surface which predisposes the foot pressure necrosis and ulceration. Sensory neuropathy impairs proprioception and decreases the foot’s ability to adapt to repetitive local stresses. This can result in injury or ulcerations that go unnoticed by the patient. Unfortunately, neuropathy sets the stage for ulcer recurrences, treatment failures and the Charcot foot. Neuropathic ulcers typically develop at areas of increased plantar pressure, especially under the metatarsal heads, on the plantar surface and on the distal and dorsal ends of deformed digits.^26.27 When a plantar ulcer is present, an offloading strategy at the site of the ulcer is needed.

Offloading: Non-Surgical and Surgical (L)

The gold standard for offloading remains the total contact cast (TCC).^26-28 This device works best for plantar wounds without uncontrolled infection or severe ischemia. Other offloading devices such as the removable cast walker, instant total contact cast, and depth inlay shoes, are also prescribed to relieve external foot pressure and enhance wound healing and may be used when the TCC is not.²⁹

Thepresence of structural foot deformities increases the risk for ulcerations because of the increased pressure to the area of deformity. While offloading and ultimately appropriate shoe gear is essential for wound healing in these patients, surgical reconstruction of the deformity may be required to prevent recurrent foot ulcerations This may involve an osteotomy/arthroplasty to allow a metatarsal or digit to be less prominent, an Achilles tendon lengthening to reduce plantar pressure in the forefoot or a midfoot or hindfoot reconstruction for people with Charcot arthropathy.^28,30,39.40

Specifically, for patients with severe foot deformities such as a rocker bottom foot resulting from Charcot neuropathy, if non-surgical means of offloading (Total Contact Casting Charcot Restraint Orthotic Walkers) are ineffective or inadequate to get a patient to a post-acute stage where they are shoe-able, then surgical reconstruction with external fixation can correct the foot deformity and allow the wounds to heal. A staged approach, with internal fixation, might also be utilized when ulcerations are in remission.

M: Wound Care, healing sandal

Choosing an appropriate offloading device or shoe is essential for ulcer healing and to prevent ulcer recurrence. Wounds that are not on the plantar aspect of the foot may require a less complex strategy such as a healing sandal that protects the margins or distal ends of digits.

Ulcer Improves During Follow-up? (N)

Ulcer size should ideally be measured at each visit to assess the healing trajectory. If an ulcer has healed by 50% at 4 weeks, it is likely to heal entirely over the subsequent 3-4 months. However, the converse is also true.^31-33 Wounds that do not progress should be reassessed for a) possible progression of ischemia, b) development of or persistence of occult infection or c) adequacy of debridement and offloading strategies, proceeding back to the appropriate step in the decision tree.

Surveillance (O)

After ulcer healing, 40% of patients will have a recurrence at one year and nearly two-thirds at three years. Recurrence is not only common, but likely. Therefore, when an ulcer is healed, the term “remission” should be used to communicate this to the patient and other members of the team.³⁴ Patients should be enrolled into a program designed around remission management including frequent (every 2-3 month) visits, shoe gear and insole modifications, and reconstructive surgery as necessary to treat deformities that progress or develop. Furthermore, this program can and should be synchronized for the patient with concomitant vascular non-invasive surveillance of endovascular or open vascular reconstruction as appropriate.^36-38

Lower Extremity Amputation vs. Wound Hospice (P)

Despite optimal care, some diabetic foot ulcers either ultimately require or are best treated with foot amputation.^17,18 Amputation is covered in detail in Chapter 48. In other patients where mobility is limited or where aggressive therapy is not ideal, the goals may change from wound healing to “wound hospice”. In other words, the goals may be to keep the wound uncomplicated and uninfected but to increase hospital-free days as much as possible.¹⁹

Table 2

Three Dynamic Rings of Risk- Wound, Ischemia, Foot Infection[JC3] [JC4]

References

Armstrong DG, Boulton AJM, Bus SA. Diabetic Foot Ulcers and Their Recurrence. N Engl J Med. 2017;376(24):2367-2375.
Lazzarini PA, Pacella RE, Armstrong DG, van Netten JJ. Diabetes-related lower-extremity complications are a leading cause of the global burden of disability. Diabet Med. 2018 May 23. doi: 10.1111/dme.13680. [Epub ahead of print]
Lazzarini PA, Pacella RE, Armstrong DG, van Netten JJ. Diabetes-related lower-extremity complications are a leading cause of the global burden of disability. Diabet Med. 2018 May 23. doi: 10.1111/dme.13680. [Epub ahead of print]
Rogers LC, Andros G, Caporusso J, Harkless LB, Mills JL Sr, Armstrong DG. Toe and flow: essential components and structure of the amputation prevention team. J Vasc Surg. 2010 Sep;52(3 Suppl):23S-27S.
Skrepnek GH, Mills JL, Armstrong DG. Foot-in-wallet disease: tripped up by “cost-saving” reductions? Diabetes Care. 2014 Sep;37(9):e196-7. doi: 10.2337/dc14-0079.
Driver VR1, Fabbi M, Lavery LA, Gibbons G. The costs of diabetic foot: the economic case for the limb salvage team. J Vasc Surg. 2010 Sep;52(3 Suppl):17S-22S.
Armstrong DG, Mills JL. Juggling risk to reduce amputations: The three-ring circus of infection, ischemia and tissue loss-dominant conditions. Wound Medicine. 2013;1:13-14.

8. Mills JL Sr, Conte MS, Armstrong DG, et al. The Society for Vascular Surgery Lower Extremity Threatened Limb Classification System: risk stratification based on wound, ischemia, and foot infection (WIfI). J Vasc Surg. 2014;59(1):220-234.e1-e2.

9. Lipsky BA, Berendt AR, Cornia PB, et al. 2012 Infectious Diseases Society of America clinical practice guideline for the diagnosis and treatment of diabetic foot infections. Clin Infect Dis. 2012;54(12):1679-1684.

10. [JC5] Wukich DK, Armstrong DG, Attinger CE, et al. Inpatient management of diabetic foot disorders: a clinical guide. Diabetes Care. 2013;36(9):2862-2871.

11. Lipsky BA, Silverman MH, Joseph WS. A Proposed New Classification of Skin and Soft Tissue Infections Modeled on the Subset of Diabetic Foot Infection. Open Forum Infect Dis. 2017;4(1):ofw255.

12. Malone M, Bowling FL, Gannass A, Jude EB, Boulton AJM. Deep wound cultures correlate well with bone biopsy culture in diabetic foot osteomyelitis. Diabetes Metab Res Rev. 2013;29(7):546-550.

13. Fisher TK, Scimeca CL, Bharara M, Mills JL Sr, Armstrong DG. A step-wise approach for surgical management of diabetic foot infections. J Vasc Surg. 2010;52(3 Suppl):72S – 75S.

14. Tehan PE, Bray A, Chuter VH. Non-invasive vascular assessment in the foot with diabetes: sensitivity and specificity of the ankle brachial index, toe brachial index and continuous wave Doppler for detecting peripheral arterial disease. J Diabetes Complications. 2016;30(1):155-160.

15. Woo K, Palmer OP, Weaver FA, Rowe VL, Society for Vascular Surgery Vascular Quality Initiative. Outcomes of completion imaging for lower extremity bypass in the Vascular Quality Initiative. J Vasc Surg. 2015;62(2):412-416.

16. El-Sayed HF. Bypass Surgery For Lower Extremity Limb Salvage: Vein Bypass. Methodist Debakey Cardiovasc J. 2012;8(4):37-42.

17. Armstrong DG, Fiorito JL, Leykum BJ, Mills JL. Clinical efficacy of the pan metatarsal head resection as a curative procedure in patients with diabetes mellitus and neuropathic forefoot wounds. Foot Ankle Spec. 2012;5(4):235-240.

18. Fiorito J, Trinidad-Hernadez M, Leykum B, Smith D, Mills JL, Armstrong DG. A tale of two soles: sociomechanical and biomechanical considerations in diabetic limb salvage and amputation decision-making in the worst of times. Diabet Foot Ankle. 2012;3. doi:10.3402/dfa.v3i0.18633

19. Mills JL, Armstrong DG. The concept and proposed definition of “wound simplification.” Wound Medicine. 2013;2-3:9-10.