CLINICAL
Overview
This topic is written based on recommendations provided by the Society for Vascular Surgery, American Podiatric Medical Association, Society for Vascular Medicine, Wound Healing Society and the International Working Group on the Diabetic Foot (IWGDF).[1][2][3] Goals of this topic are to guide clinicians in recognizing which patients with diabetic foot ulcers (DFUs) will benefit from surgical revascularization, which vascular imaging tests to order, and to provide an overview on preoperative imaging, and revascularization techniques.
For clinical guidelines and quality measures specific to DFU, see "Diabetic Foot Ulcers - Overview". For an introduction and assessment of diabetic foot ulcers (DFUs) including epidemiology, risk factors, etiology, pathophysiology, history, physical examination, diagnosis, differential diagnoses, documentation and ICD-10 coding, see " Diabetic Foot Ulcer - Introduction and Assessment". For management, see "Diabetic Foot Ulcer - Treatment". For prevention and a section for clinicians on patient education, see " Diabetic Foot Ulcer - Prevention" "Diabetic Foot Ulcers - Prevention". For more details on antibiotic therapy and management of DFU associated with infection, see topic "Diabetic Foot Ulcer Associated with infection - Management". For indications of surgical interventions including revascularization, see topic "Arterial Ulcer - Surgical Treatment".
Indications for Objective Vascular Evaluation
- People with diabetes with a DFU, signs or symptoms of vascular disease, absent pulses on screening foot examination or older than 50 years old need a more objective vascular evaluation with noninvasive arterial testing and consideration for a possible referral to a vascular specialist.[4] See section 'Peripheral Artery Disease (PAD) in patients with DFU' in "Diabetic Foot Ulcer - Introduction and Assessment"
Indications for Surgical Revascularization
Ischemic DFUs
- For patients with ischemic DFUs (DFUs associated with PAD), to promote DFU healing and prevent amputation, clinical guidelines recommend consideration for revascularization with either surgical bypass or endovascular therapy.[1][2][3]
- The framework below can guide decision making on which patients are likely to benefit from vascular imaging and revascularization.
Which patients need urgent vascular imaging and endovascular or surgical vascular intervention?
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The vascular exam findings below indicate high risk for limb ischemia in patients with DFU, and thus DFU is considered non-healable with conservative therapy only. If one or more findings are present, patients should be considered for urgent vascular imaging and revascularization [5][2][6][7]: - ABI <0.5*
- Continuous doppler wave ultrasound with monophasic flow
- Toe pressure < 30 mmHg
- TcPO2 < 25 mmHg
* Medial arterial calcification and non-compressive vessels may result in falsely elevated ABI in patients with diabetic neuropathy [5][4][8]. Thus, regardless of ABI values, to rule out PAD these patients should undergo TcPO2, continuous wave Doppler examination or TP/TBI.[5][2][9] |
Which patients need (non-urgent) vascular imaging and consideration for surgical revascularization?
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- For patients with DFU and PAD with exam findings different from the ones above, prediction of patients most likely to require and to benefit from revascularization can be based on the Society for Vascular Surgery (SVS) Wound, Ischemia, and foot Infection (WIfI) lower extremity threatened limb classification. See Table 1 for WIfI classification and Table 2 for likelihood of benefit/ requirement for revascularization below
- For all patients with DFU and PAD, irrespective of the results of bedside tests: if the ulcer does not improve within 6 weeks despite optimal management and have no other likely cause of poor wound healing, the IWGDF recommends vascular imaging and revascularization. PAD is not the only cause of reduced perfusion in a lower extremity; edema and infection should be ruled out and treated accordingly.[2][6][7]
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Which patients are not ideal candidates for revascularization?
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- For patients with DFU and PAD for whom, from the patient perspective, the risk-benefit ratio for the probability of success is unfavorable, the IWGDF recommends clinicians avoid revascularization.[2] Some examples are patients who:
- Are severely frail
- Have a short life expectancy
- Have poor functional status or are bed bound
- Have a large volume of tissue necrosis that renders the foot functionally unsalvageable
- For patients with DFU and PAD for whom, from the patient perspective, the risk-benefit ratio for the probability of success is unclear, revascularization may not be appropriate. In clinical decision-making, it should be taken into account that even severely ischemic ulcers can heal without a revascularization; as noted, two observational studies reported healing rates of about 50% (with or without minor amputations).[2][10][11]
- Patients who are not good candidates for revascularization may be treated with an approach for non-healable DFU (i.e. palliative wound care, mechanical offloading).[12] See topic "Diabetic Foot Ulcer - Treatment" If amputation is under consideration, transcutaneous oximetry is recommended to determine amputation level.[13] See topic "Transcutaneous Oximetry".
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Ischemic and Infected DFUs
- Patients with DFU, PAD and foot infection are at particularly high risk for major limb amputation.
- If infection is severe, patient should be treated as a medical emergency with immediate drainage, debridement, culture, antibiotics and consideration for revascularization.[2]
- If infection is non-limb-threatening, the blood supply to the foot should be optimized before surgical debridement to ensure that potentially viable tissue is not unnecessarily removed.[2]
WIfI Classification System
Prediction of patients most likely to require and to benefit from revascularization can be based on the Society For Vascular Surgery (SVS) Wound, Ischemia, and foot Infection (WIfI) lower extremity threatened limb classification.[1][9] See Tables 1 and 2 below.
Table 1. The WIfI Classification System (a: W=Wound, b: I=Ischemia, c: fI=Infection) [9]
Table 1a: W=Wound. TMA: transmetatarsal amputation
| Grade | Ulcer | Gangrene | Clinical Description |
| 0 | No ulcer | No gangrene | Ischemic rest pain (requires typical symptoms of ischemia grade 3); no wound.
|
| 1 | Mild: Small, shallow ulcer(s) on distal leg
or foot; no exposed bone, unless limited to distal phalanx | No gangrene | Minor tissue loss. Salvageable with simple digital amputation (1 or 2 digits) or skin coverage
|
| 2 | Moderate: Deeper ulcer with exposed bone, joint or tendon; generally not involving the heel; shallow heel ulcer, without calcaneal involvement | Gangrenous changes limited to digits
| Major tissue loss salvageable with multiple (more than 3) digital amputations or standard TMA +/- skin coverage
|
| 3 | Severe: Extensive, deep ulcer involving forefoot and/or midfoot; deep, full thickness heel ulcer +/- calcaneal involvement | Extensive gangrene involving forefoot and /or midfoot; full thickness
heel necrosis +/- calcaneal involvement
| Extensive tissue loss salvageable only with a complex foot reconstruction or nontraditional TMA (Chopart or Lisfranc); flap coverage or complex wound management needed for large soft tissue defect |
Table 1b: I=Ischemia. ABI, Ankle-brachial index; PVR, pulse volume recording; SPP, skin perfusion pressure; TP, toe pressure; TcPO2, transcutaneous oximetry. Hemodynamics/perfusion: Measure TP or TcPO2 if ABI incompressible (>1.3). Patients with diabetes should have TP measurements. If arterial calcification precludes reliable ABI or TP measurements, ischemia should be documented by TcPO2, SPP, or PVR. If TP and ABI measurements result in different grades, TP will be the primary determinant of ischemia grade. Flat or minimally pulsatile forefoot PVR = grade 3.
| Grade | ABI | Ankle Systolic Pressure | TP, TcPO2 |
| 0 | > or =0.80
| >100 mmHg
| > or =60 mm Hg
|
| 1 | 0.6-0.79
| 70-100 mmHg
| 40-59 mmHg
|
| 2 | 0.4-0.59
| 50-70 mmHg
| 30-39 mmHg
|
| 3 | < or =0.39
| <50 mmHg
| <30 mmHg |
Table 1c: fI=Foot Infection. PaCO2, Partial pressure of arterial carbon dioxide; SIRS, systemic inflammatory response syndrome.
Ischemia may complicate and increase the severity of any infection. Systemic infection may sometimes manifest with other clinical findings, such as hypotension, confusion, vomiting, or evidence of metabolic disturbances, such as acidosis, severe hyperglycemia, new-onset azotemia. From Lipsky et al. [14]
SVS WIfi
| IDSA/PEDIS infection severity
| Clinical Manifestation of Infection |
| 0 | Uninfected | No symptoms or signs of infection Infection present, as defined by the presence of at least 2 of the following
items: - Local swelling or induration
- Erythema >0.5 to < or=2 cm around the ulcer d Local tenderness or pain
- Local warmth
- Purulent discharge (thick, opaque to white, or sanguineous secretion)
|
| 1 | Mild | Local infection involving only the skin and the subcutaneous tissue (without involvement of deeper tissues and without systemic signs as described below).
Exclude other causes of an inflammatory response of the skin (eg, trauma, gout, acute Charcot neuro-osteoarthropathy, fracture, thrombosis, venous stasis)
|
| 2 | Moderate | Local infection (as described above) with erythema >2 cm, or involving structures deeper than skin and subcutaneous tissues (eg, abscess, osteomyelitis, septic arthritis, fasciitis), and No systemic inflammatory response signs |
| 3 | Severe | Superficial or deep infection associated with systemic inflammatory signs as manifested by at least 2 of the items below: - Temperature > 38 °C or < 36 °C
- Heart rate > 90 beats/min
- Respiratory rate > 20 breaths/min or PaCO2 < 4.3 kPa (32 mmHg)
- White blood cell count > 12 000/mm3 or < 4000/mm3,or > 10% immature (band) forms
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Table 2. Estimating likelihood of benefit of/ requirement for revascularization (assuming infection can be controlled) [9]. W=Wound, I = Ischemia, fI = foot Infection. VL = Very low benefit, clinical stage 1; L = Low benefit, clinical stage 2; M = Moderate benefit, clinical stage 3; H = High benefit, clinical stage 4; clinical stage 5 would signify an unsalvageable foot.
| Ischemia - 0 | Ischemia - 1 | Ischemia - 2 | Ischemia - 3 |
| W-0 | VL | VL
| VL
| VL
| VL
| L | L | M | L
| L
| M | M | M | H
| H
| H
|
| W-1 | VL
| VL
| VL
| VL
| L
| M | M | M | M
| H | H
| H
| H
| H
| H
| H
|
| W-2 | VL
| VL
| VL
| VL
| M | M | H | H | H
| H
| H
| H
| H
| H
| H
| H
|
| W-3 | VL
| VL
| VL
| VL
| M | M | M | H | H
| H
| H
| H
| H
| H
| H
| H
|
| fI-0 | fI-1
| fI-2
| fI-3
| fI-0
| fI-1
| fI-2
| fI-3
| fI-0
| fI-1
| fI-2
| fI-3
| fI-0
| fI-1
| fI-2
| fI-3
|
Premises related to Table 2 are listed below [9]:
- Increase in wound class increases risk of amputation (based on PEDIS, UT and other classification systems). See section 'Diabetic Foot Ulcer and Infection Classification Systems' in "Diabetic Foot Ulcers - Introduction and Assessment"
- PAD and infection are synergistic [15]; infected wound and PAD increases likelihood of revascularization will be needed to heal wound
- Infection 3 category (systemic/metabolic instability): moderate to high-risk of amputation regardless of other factors [16]
Preoperative Imaging for Revascularization Candidates
- When considering revascularization, the IWGDF recommends obtaining imaging exams to assess anatomy. The entire lower extremity arterial circulation should be evaluated, with detailed visualization of below-the-knee and pedal arteries, in an anteroposterior and lateral plane.[2] The following exams may be ordered:
-
- Color duplex ultrasound
- Computed tomography
- Angiography
- Magnetic resonance angiography or
- Intra-arterial digital subtraction angiography
Surgical Revascularization Techniques
- The aim of revascularization is to restore direct flow to at least one of the foot arteries, preferably the artery that supplies the anatomical region of the wound.[2] The IWGDF recommends achieving a minimum skin perfusion pressure = 40 mmHg, a toe pressure = 30 mmHg or a TcPO2 = 25 mmHg to increase the likelihood of healing. [2]
- There is insufficient evidence to establish which revascularization technique is superior.[1][2] Thus, clinical guidelines [1][2] recommend that decisions be made by a multidisciplinary team and factors such as morphological distribution of PAD, availability of autogenous vein, wound and infection extent patient comorbidities and local expertise be considered. According to the Society for Vascular Surgery and the American Podiatric Medical Association[1]:
- In functional patients with long-segment occlusive disease and a good autologous conduit, bypass is likely to be preferable.
- In the setting of tissue loss and diabetes, prosthetic bypass is inferior to bypass with vein conduit.
- After a revascularization procedure in a DFU patient, the patient should be treated by a multidisciplinary team as part of a comprehensive care plan.[1][2]
- For more details on surgical interventions including revascularization, see topic "Arterial Ulcer - Surgical Treatment".
Risk factors for Endovascular Limb Salvage failure
- In an Asian population of 809 patients, independent predictors of endovascular limb salvage failure included end-stage renal failure, toe pressures < 50 mm Hg, infrainguinal TASC II patterns C or D, and indirect angiosome revascularization.[17]
