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34 Classication ofWound Infections
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tem and score in comparing outcome of foot ulcer management on three continents. Diabetes Care. 2008;31(5):964–7.
86. Lipsky BA, Polis AB, Lantz KC, Norquist JM, Abramson MA. The value of a wound score for diabetic foot infections in predicting treatment out­come: a prospective analysis from the SIDESTEP trial. Wound Repair Regen. 2009;17(5):671–7.
87. Cutting KF, Harding KG. Criteria for identifying wound infection. J Wound Care. 1994;3(4):198–201.
88. Gardner SE, Frantz RA, Troia C, Eastman S, MacDonald M, Buresh K, Healy D.A tool to assess clinical signs and symptoms of localized infection in chronic wounds: development and reliability. Ostomy Wound Manage. 2001;47(1):40–7.
89. Cutting KF, White R. Dened and rened: crite­ria for identifying wound infection revisited. Br J Community Nurs. 2004;9(3):S6–15.
90. European Wound Management Association. European wound management association position document: management of wound infection. London: European Wound Management Association; 2006.
91. International Wound Infection Institute (IWII). Wound infection in clinical practice. London: Wounds International; 2016. www.woundsinterna-
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92. Swanson T, Wolcott RD, Wallis H, Woodmansey EJ. Understanding biolm in practice: a global survey of health professionals. J Wound Care. 2017;26(8):426–40.
93. Caroline Dowsett AB, Carville K, Garten A, Woo K.A route to more effective infection management: the infection management pathway. Wound Int. 2020;11(3):50–7.
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99. Wang L, Pedersen PC, Agu E, Strong DM, Tulu B.Area determination of diabetic foot ulcer images using a cascaded two-stage SVM-based classica­tion. IEEE Trans Biomed Eng. 2017;64(9):2098–109.
100. Husers J, Hafer G, Heggemann J, Wiemeyer S, Przysucha M, Dissemond J, Moelleken M, Erfurt­Berge C, Hubner U. Automatic classication of diabetic foot ulcer images—a transfer-learning approach to detect wound maceration. Stud Health Technol Inform. 2022;289:301–4.
101. Guley O, Pati S, Bakas S. Classication of infec­tion and ischemia in diabetic foot ulcers using VGG architectures. Diabet Foot Ulcers Grand Chall. 2021;2022(13183):76–89.
102. Monteiro-Soares M, Russell D, Boyko EJ, Jeffcoate W, Mills JL, Morbach S, Game F, International Working Group on the Diabetic F.Guidelines on the classication of diabetic foot ulcers (IWGDF 2019). Diabetes Metab Res Rev. 2020;36(Suppl 1):e3273.
103. Bravo-Molina A, Linares-Palomino JP, Vera-Arroyo B, Salmeron-Febres LM, Ros-Die E.Inter-observer agreement of the Wagner, University of Texas and PEDIS classication systems for the diabetic foot syndrome. Foot Ankle Surg. 2018;24(1):60–4.
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106. Robinson WP, Loretz L, Hanesian C, Flahive J, Bostrom J, Lunig N, Schanzer A, Messina L.Society for Vascular Surgery Wound, ischemia, foot infec­tion (WIfI) score correlates with the intensity of multimodal limb treatment and patient-centered outcomes in patients with threatened limbs man­aged in a limb preservation center. J Vasc Surg. 2017;66(2):488–498 e482.
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TheDiabetic Foot
GiacomoClerici, FabrizioLosurdo, AndreaCasini, IuliaValeriaRusu, andRobertG.Frykberg
35
The expression “Diabetic Foot” (DF) is used to describe any infection, ulceration, or destruction of foot tissues occurring in a person with diabetes mellitus [1]. These conditions are usually associ­ated with peripheral neuropathy and/or lower extremity arterial disease.
DF represents one of the most common, com­plex, and costly diabetes complications [2]. It is estimated that between 9 and 25 million people with diabetes develop at least one foot ulcer per year worldwide [3] and that roughly one diabetic patient out of ve will experience at some point in his life a foot ulcer [4].
The prognosis of patients affected by DF ulcers is generally not favorable. It has been esti­mated that roughly 1 in 5 will experience an amputation [5] of whom only 30% will survive
G. Clerici (*) · A. Casini Amputation Prevention Centre—Diabetic Foot Unit, Policlinico di Abano Terme and Clinica San Carlo Paderno Dugnano, Padua and Milan, Italy
F. Losurdo ASST Ovest Milanese - Diabetic Foot Unit - “C. Cantù” Hospital, Abbiategrasso, MI, Italy e-mail: fabrizio_losurdo@asst-bgovest.it
I. V. Rusu Manchester University NHS Foundation Trust (MFT), Manchester, UK
R. G. Frykberg Midwestern University, Glendale, AZ, USA e-mail: rgfdpm@diabeticfoot.net
© The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 M. Maruccia et al. (eds.), Pearls and Pitfalls in Skin Ulcer Management,
https://doi.org/10.1007/978-3-031-45453-0_35
after 5 years [6], a prognosis overlapping with many invasive cancers.
Nonetheless, the DF lesion management has been demonstrated to be highly time dependent. Delays in DF patients’ referral to specialized teams as well as delays in starting appropriate treatment have been demonstrated to be associ­ated with worse prognosis and a higher rate of more proximal amputations [7, 8].
These data highlight the importance of promptly diagnosing and appropriately manag­ing DF lesions.
The clinical picture of DF presentation is extremely variable ranging from aseptic shallow ulcers to severe life-threatening infections. The International Working Group on the Diabetic Foot (IWGDF) 2019 guideline suggests classify­ing diabetic DF lesions by taking into account both the ulcer characteristics and the perfusion status as well as the infective load [9]. Different classications have been proposed to achieve such a goal; however, a widely used classication among DF specialists is the WIfI system [10]. This scheme was originally developed by the Society for Vascular Surgery to stratify lower limb amputation risk and performs particularly well when applied to DF lesions (Table35.1).
The advantages offered by the WIfI classi­cation over previously used schemes include correlating well with limb salvage, amputation risk, and wound healing as well as to permit bet­ter identication of patients that may benet
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No gangrene
Gangrene limited to toes
Extensive gangrene
, TP
2
>100mmHg > 60mmHg
G. Clerici et al.
< 50mmHg < 30mmHg
Grade Description
1 Small, shallow ulcer on distal leg or foot; no exposed bone,
Unless limited to distal phalanx
ulcer, without calcaneal
Involvement
Full-thickness heel ulcer ± calcaneal involvement
0.80
2 Deeper ulcer with exposed bone, joint, or tendon; or shallow heel
3 Extensive, deep ulcer involving forefoot and/or midfoot; deep,
Grade ABI Ankle systolic pressure TcPO
1 0.60–0.79 70–100mmHg 40–59mmHg
2 0.40–0.59 50–70mmHg 30–39mmHg
0.39
3
Grade Clinical manifestation of infection
– Local swelling or induration
– Erythema >0.5 to 2cm around the ulcer
– Local tenderness or pain
– Local warmth
– Purulent discharge (thick, opaque to white, or sanguineous secretion)
1 Infection present, as dened by the presence of at least two of the following items:
2 Local infection involving only the skin and the subcutaneous tissue (without involvement of deeper
<32mmHg
2
Tissues and without systemic signs as described below)
Exclude other causes of an inammatory response of the skin (e.g., trauma, gout, acute Charcot
Neuro-osteoarthropathy, fracture, thrombosis, venous stasis)
Following:
– Temperature>38C or<36C
– Heart rate>90 beats/min
– Respiratory rate>20 breaths/min or Paco
– White blood cell count >12,000 or<4000 cells/mm3 or 10% immature (band) forms
3 Local infection (as described above) with the signs of SIRS, as manifested by two or more of the
Wound 0 No ulcer No gangrene
Table 35.1 Wound Ischemia foot Infection (WIfI) classication scheme [11]
Ischemia 0
Foot infection 0 No symptoms or signs of infection
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from limb revascularization. For these reasons, both the IWGDF and the Global Vascular Guidelines [11] suggest its use when character­izing DF lesions, particularly when infected or ischemic, as well as PAD related lesions. On the other hand, the main limit of the WIfI classica­tion is that it does not separately consider the loss of protective sensation (LoPS), a main pathogenetic factor of DF lesions. Also, for each of the three critical parameters (Wound, Ischemia, and foot Infection), four possible grades exist and must be ascertained to provide a nal WIfI score.
In the past, several other classications have been used to classify DF ulcers. Among all, it is important to mention some whose use may still be found in non-specialist settings.
– Wagner classication [12], divides DF
lesions into ve grades ranging from no
lesions to extensive gangrene. Its use is how-
ever limited because it does not consider
separately the presence/absence of ischemia
and/or infection.
– University of Texas Classication [13],
denes DF ulcers according to their depth,
the absence/presence of ischemia and the
absence/presence of infection. This classi-
cation scheme, when applied to DF patients,
resulted to be quite predictive of overall
amputation risk. However, its major limit
was to consider ischemia and infection as a
yes/no diagnosis.
– SINBAD classication [14], considers the
ulcer Site, presence/absence of Ischemia,
presence/absence of LOPS (Neuropathy),
Bacterial infection, wound Area and Depth.
It is a quite easy to use tool, as it does not
require use of any specialist equipment.
However, its simplicity’s drawback is a poor
denition of the degree of ischemia and
infection; thus resulting in limited use in
facilitating patient care. Its use should be
dedicated only for communications among
health professionals to optimize referral [9]
as suggested in the IWGDF guidelines.
35.1 Clinical Approach totheDiabetic Foot
35.1.1 The Multidisciplinary Diabetic Foot Team
The Diabetic Foot syndrome is characterized by an extremely variable array of clinical presenta­tions as well as clinico-pathological factors involved in its pathogenesis. As no single specialty could ever take over its management as a whole, the DF has been considered as the “Cinderella” among all diabetes complications. Furthermore, it has been associated with considerable healthcare costs, morbidity, and mortality. While for other diabetes complications affecting the eyes, kidneys, nerves, or heart, there are specialists (e.g., ophthal­mologists, nephrologists, neurologists, and cardi­ologists) with skills to assume the entirety of their care, this is not the case for DF syndrome. Rather, the diabetic foot and its complications requires the care of a combination of multiple medical and sur­gical branches. For these reasons, it has been pro­posed by several guidelines, as well as by experts in the eld, the multidisciplinary diabetic foot team (MDT) as the best clinical model to approach diabetic foot care [1517].
According to this view, the vast complexity of DF lesions can be safely and effectively managed in an economically sustainable way by a dedi­cated team including the following disciplines:
(a) Vascular Team, whose main focus is the
diagnosis and treatment of impaired blood supply to the affected foot. This team usually includes vascular surgeons with long stand­ing experience in peripheral ischemia treat­ment as well as interventional cardiologists or radiologists with extensive experience in peripheral endovascular revascularization procedures.
(b) Foot Surgery Team, whose main focus is the
surgical treatment of diabetic foot lesions, from drainage of acute suppurative infec­tions to reconstruction of deformed Charcot Foot to major amputations.
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(c) Medical Team, whose main focus is to cope
with the medical side of diabetic foot prob­lems (e.g., antibiotic therapy, adequate glu­cose control, hypertension and hyperlipidemia management etc.) as well as to deal with the wide range of medical co­morbidities that will invariably be encoun­tered when admitting to a hospital ward (e.g., acute renal failure, sepsis, heart failure, anti­coagulation management, etc.).
(d) Outpatient Team, whose main task is to man-
age patients before and after hospital admis­sion. This includes outpatient management of DFU not requiring hospitalization by per­forming a thorough evaluation and diagnosis of the present condition and by applying the principles of adequate wound care, ensuring adequate ofoading and follow-up when in remission. This team will often include podi­atrists, wound care specialist nurses, orthotic technician as well as medical doctors with a diabetic foot care background.
Such multidisciplinary teams should be con­nected with several other specialists that may be involved in diabetic foot care like the dialysis team, the emergency medicine team, the cardiol­ogy team, and the infectious disease specialists. Moreover, a complete multidisciplinary DF team should be nested in a hub-and-spoke model of clinical care, with the MDT being the hub and smaller peripheral centers the spokes with a fast­track connection to the hub center for more com­plex cases.
35.2 Diabetic Foot Pathogenetic
Factors
In order to clinically frame a newly discovered DF lesion, it is mandatory to appreciate its main pathogenetic factors: neuropathy, arterial disease, and infection. According to the main pathoge­netic factor, it is possible to divide DF lesions into four main classes:
(a) Neuropathic Foot, that includes DF patients
with ulcers associated with peripheral neu-
ropathy, deformities and LOPS in the absence of infection or critical ischemia.
(b) Ischemic Foot, that includes lesions whose
main cause is an insufcient blood supply to the affected area, mostly due to occlusive PAD, in the absence of active infection.
(c) Neuro-Ischemic Foot, which encompasses
both the characteristics of the neuropathic foot and those of the ischemic foot, in the absence of active infection.
(d) Infected Foot, a condition in which a DF
lesion is associated with any degree of active infection and may or may not be associated with some degree of ischemia.
The main task of the rst clinician approach­ing a patient with an active DF lesion is to under­stand in which of these categories the patient lies, as the subsequent steps in management and the specialists involved in treatment will be very dif­ferent according to the pathogenetic class.
35.3 Neuropathic Foot
Diabetic neuropathy typically affects peripheral nerve bers in a symmetrical distal-proximal way resulting in a gradual loss of sensation (both touch and pain), in motor decits and consequent abnormal postures. Neuropathic feet often develop deformities such as metatarsal head prominence with dislocation of plantar fat pads as well as claw toes, hallux valgus or tailor’s bun­ion. Such deformed feet, in turn, develop high pressure points mainly over the plantar surface as well as the dorsum of toes, thus inducing the overlying skin to thicken and become hyperkera­totic. This process, which in the short term repre­sents a compensation mechanism of skin tissues coping with elevated contact pressures, in the long term evolves to a failure pathway as the hyperkeratotic skin becomes a callus behaving as a foreign body pressing over underlying soft tis­sues. Repetitive mechanical stress, in the absence of protective pain sensation, leads to hemor­rhages under the callus and eventually development of a full thickness skin ulcer. Such ulcers can be dened “neuropathic” as their main
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pathogenetic factor is represented by foot defor­mities as well as by abnormalities in propriocep­tive and motor nerve bers and by the loss of protective pain sensation (LoPS).
A particularly extreme complication of peripheral diabetic neuropathy is Charcot Neuroarthropathy. In this condition, the severe damage to peripheral nerve bers results in deep tissues aseptic inammation leading to bone fractures and dislocations. Such feet, if not promptly immobilized in a total contact cast, will inevitably develop severe deformities and eventually ulceration. Unfortunately, in later stages, this complex situation often leads to major amputations.
Clinically, neuropathic foot ulcers, developed in high pressure areas, are usually surrounded by hyperkeratotic margins and, if not infected, show a healthy, viable ulcer bed. Foot pulses are often present and, even in those cases with a quite heavy arterial arteriosclerotic burden, distal per­fusion can be preserved. However, it is not uncommon to develop neuropathic ulcers in severe PAD.This condition will be addressed in the Neuro-Ischemic foot section.
The mainstay of neuropathic foot ulcer treat­ment is ofoading, thus removing the main trig­ger to the neuropathic foot ulcer pathway. The gold standard for ofoading non-infected purely neuropathic (i.e. non-ischemic) foot ulcers is still considered Total Contact Casting (TCC). This technique consists of applying plaster of Paris or berglass bandages covering the whole foot, ankle and most of the leg up to just below the knee. The TCC achieves a reduction in plantar pressures by reducing stride length, foot speed, and by immobilizing the ankle during the propul­sive phase of gait.
The main drawbacks of the TCC are that they can be time consuming to apply, poorly accepted by patients, and can be associated with an increased risk of falls and/or cast induced ulcers particularly when applied by operators with less experience in this technique. For these reasons, removable ankle-foot-orthoses have been devel­oped and their efcacy tested with randomized controlled trials versus TCC [18]. Most trials show that the healing rate in patients with foot
ulcers treated with TCC is overlapping with that of patients treated with a removable cast walker (RCW) even though the time-to-healing might be longer in the RCW treated group. The efcacy overlap is maximal when RCW are rendered irre­movable by application of a security lace that dis­courages patients from removing the walker at home. At the same time, the RCW allows for emergency checks of foot skin in case of dressing staining or should the patient develop other signs of concern. The RCW achieves ofoading by using custom made insoles applied in tall (i.e., knee high or mid-leg high) walkers with a rocker rigid sole, thus reducing both the peak plantar pressure and the time the ulcer bed is exposed to such pressure.
Besides ofoading, neuropathic foot ulcers’ treatment should be coupled to surgical debride­ment and appropriate wound care.
Surgical debridement aims to remove all non­viable and possibly infected tissue as well as to activate the wound bed that in turn switches from chronic to acute. This means that wound bed cells are induced by the mechanical trigger to switch their secretory prole and their gene expression from a quiet inert one typical of chronic wounds to a more active one, typical of acute wounds, and aiming at tissue restoration. Moreover, appropriate wound care must be ensured in order to control edema, balance moisture, facilitate margin proliferation, and hamper bacterial or fungal growth.
Nevertheless, when neuropathic foot ulcers do not resolve despite appropriate ofoading, debridement, and wound dressings it is necessary to re-consider the original diagnosis (i.e., are there any even subtle signs of infection that have been originally overlooked? Is there any isch­emia preventing tissues from receiving adequate blood supply to drive re-epithelization?). In those cases with a correct diagnosis and a neuropathic ulcer resistant to standard treatment, surgical ofoading might be considered. Surgery in this case aims at removing bony prominences or cor­recting foot deformities responsible for high pressure points.
Finally, it must be kept in mind that after a neuropathic foot ulcer undergoes re- epithelization
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there will still be a very high risk of re-ulceration. Therefore several guidelines [19] recommend that patients in secondary prevention use shoes with rocker or semi-rocker rigid soles and custom made total contact multilayer insoles. The cus­tomized insoles can achieve further ofoading using inserts of softer material like latex in areas of known higher plantar pressure.
The relationship between likelihood of devel­oping a neuropathic foot ulcer and risk factors can be described by the following formula L = (P × T)/S with L = lesion risk, P =Peak Pressure, T=time of pressure acting on foot tis­sues, and S= Surface of the area on which the weight force is acting. Therefore, the ideal pre­ventive shoe will have a total contact shape to redistribute forces through a wider plantar sur­face, an ofoading insole to reduce peak pres­sures on known high-risk areas, and a rocker sole to reduce the time that pressure acts on a specic foot area.
35.4 Ischemic Foot
A diabetic foot can be dened “ischemic” when there is evidence of insufcient arterial blood supply to allow for ulcer healing. While uncom­mon causes of poor arterial blood supply to the foot do exist (like peripheral embolization, arte­rial dissection, arterial trauma, vasculitis, etc.) the large majority of diabetic foot ischemic lesions are caused by Peripheral Artery Disease (PAD). This condition consists of the progressive occlusion of lower limb arteries stemming from a chronic arteriosclerotic disease. Classically, PAD has been considered a mainly atherosclerotic dis­ease. However, recent research has shown that while atheromas and typical atherosclerotic plaques represent the main pathologic feature of PAD affecting the suprainguinal and femoropop­liteal region, calcic arteriosclerosis represents a prominent pathologic feature of infrapopliteal disease particularly in diabetic patients and is associated with higher amputation risk [20].
The clinical approach to follow when facing a suspected ischemic foot is well described in the recently developed Global Vascular Guidelines. This document focused on the management of
critical limb-threatening ischemia (CLTI) in gen­eral but that adapts very well to the subpopula­tion of diabetic CLTI patients that, nowadays, represents the vast majority.
The diagnostic pathway starts with a clinical exam performed because of a patient reported sign/symptom or as part of the periodic screening for diabetic foot complications that diabetic patients should undergo according to interna­tional consensuses[21, 22]., Patients with an ischemic foot may access medical care because of distal skin ulcers, mostly located at the toe-tip or on the heel area, or because of foot pain with ischemic clinical features (i.e., worse with limb elevation or with exercise, particularly at night, and improving with a dependent position). These conditions may be associated with skin gangrene, a condition of tissue necrosis associated with blackened discoloration of affected tissues and that may be dry (i.e., non-infected) or wet (i.e., infected).
The clinical examination of the suspected ischemic foot aims at answering the following question:” Is the arterial blood ow to this foot enough to allow for ulcer healing and to avoid ischemic pain or does it need to be improved?”
Answering this question is not always an easy task; however, in addition to pedal pulse palpa­tion, in most cases, it can be done starting with a quantication of the degree of arterial disease with simple bedside tests. These include Ankle­Brachial- Index (ABI) measurement and/or sys­tolic Ankle Pressure (AP) measuring and/or Trans-cutaneous Oxygen partial pressure (TcPO2) and/or systolic Toe Pressure (TP). Cut­off values for any of these parameters are pro­vided in the GVG guideline and allow for establishing the degree of ischemia a patient is affected by. It has to be kept in mind, however, that medial arterial calcications (MAC) are very frequent in patients with long standing diabetes as well as renal failure. MAC may falsify ABI, AP, and TP measurements as a higher pressure needs to be generated to compress the rigid arterial vessel, thus providing a falsely elevated pressure reading. On the other hand, an ABI, AP, or TP in the CLTI range is to be considered valid until proven otherwise as calcication will only give falsely high readings. Caution must be
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advised when interpreting ostensibly normal pressure readings, however, since MAC in the ischemic limb can actually elevate arterial pres­sures to what would ostensibly be considered normal levels. Hence, it is always recommended to obtain several different measures of arterial perfusion to corroborate the validity of ankle or toe pressures.
The clinical evaluation is usually completed by an imaging test, particularly if a revasculariza­tion strategy is considered. This is usually repre­sented initially by a color-Doppler ultrasound imaging as it allows for safe, inexpensive and quick anatomic and velocimetric evaluation of the whole lower limb arterial tree. If further imaging is needed, MRA or CTA may be consid­ered. However, if an endovascular revasculariza­tion will be attempted, imaging might be completed with the diagnostic angiography that precedes the angioplasty attempt.
If the complete clinical evaluation shows that the arterial blood ow to the affected foot is insufcient, a diagnosis of Critical Limb Threatening Ischemia (CLTI) is done and the next step in management consists in deciding if a revascularization procedure is to be attempted and with which strategy.
The GVG guideline suggest a clinical approach based on the acronym PLAn that stands for P=Patient risk estimation, L=Limb staging, and An=Anatomic pattern of disease.
are achieving ulcer healing, pain control, and functional limb salvage. However, revasculariza­tion procedures are associated with periproce­dural risks that must be balanced with the likelihood of achieving the revascularization goals. If periprocedural risks turn out to outweigh the potential benets, patients may be better served with palliative medical care or with a pri­mary major amputation. A model for estimating procedural risks and expected life-expectancy has been proposed by the Vascular Quality Initiative (VQI) that evaluated a cohort of more than 38,000 patients undergoing infra-inguinal revascularization procedures [23]. There are also available free online calculators that allow clini­cians to quickly estimate these risks [24].
35.4.2 Limb Staging
Limb evaluation aiming to dene the disease severity is crucial in deciding whether a revascu­larization procedure could be benecial or not. The GVG suggests the use of WIfI classication (Table35.2) derived matrixes to relate the isch­emia degree with infection severity and wound extension. Generally speaking, the worse the ischemia grade and the WIfI stage the greater are the benets of a revascularization attempt.
35.4.3 Anatomic Pattern ofDisease
35.4.1 Patient Risk Estimation
Patients with a diabetic ischemic foot are usually frail, with advanced age and affected by multiple comorbidities. The main goals of CLTI treatment
Table 35.2 Staging and Grading of limb ischemia according to the Global Vascular Guidelines and corresponding expected clinical benet from a limb revascularization [11]
WIfI Ischemia Grade
3 N/A High benet High benet High benet 2 N/A Low benet Moderate benet High benet 1 Very Low
0 Very Low
The denition of the anatomic pattern of disease is to be done based upon angiographic data, best sup­ported by pre-angiographic imaging with color­Doppler ultrasound scanning as well as any other imaging technique used in the pre-op evaluation.
Low benet Moderate benet Moderate benet
benet
Very Low
benet 1 2 3 4 WIfI stage
benet
Very Low benet Very Low benet
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The GVG suggests defining the anatomic pattern and the possible revascularization strategy using a standardized staging system like the Global Limb Anatomic Staging System whose main advantage is to define a Target Arterial Path, i.e., the optimal anatomic route that might be followed to restore blood supply to the foot, thus allowing evaluation of its feasibility.
The above clinical pathway is suggested by the GVG for evaluation and treatment of any patient with a foot lesion associated with CLTI.However, it has to be kept in mind that any time a diabetic patient is to undergo any kind of foot surgery, it is good clinical practice to ensure adequate vascularity to the foot. In cases of arte­rial insufciency, preliminary restoration of pedal blood ow can better ensure healing of the operative site.
35.5 Neuro-Ischemic Foot
A neuro-ischemic foot is the result of a combina­tion of neuropathic and ischemic features. They represent roughly 25–30% [25] of all diabetic foot lesions and are characterized by a very vari­able clinical appearance with attributes of both neuropathic as well as ischemic appearing lesions.
It is crucial to correctly detect neuro-ischemic feet as they will not heal if only one of the two concomitant pathogenetic factors is addressed. Therefore, a patient with a neuro-ischemic foot ulcer that correctly utilizes the appropriate cast walker device will not see a relevant clinical improvement unless revascularization of the limb occurs as well. At the same time, neuro-ischemic patients with digital or calcaneal necrosis that receive adequate restoration of blood ow to the affected foot area will not heal unless adequate ofoading is ensured.
In consideration of all this, the IWGDF guidelines recommend thorough vascular evalu­ation also in DFU with a typical neuropathic appearance as well as ensuring adequate ofoad­ing also in lesions with a typical ischemic appearance.
35.6 Infected Foot
Diabetic Foot Infections (DFI) result from the invasion and proliferation of bacteria or fungi within foot tissues causing an inammatory response by the host as well as tissues break­down. Clinically, DFI manifests with the typical signs and symptoms of inammation whose detection is used as the main diagnostic criteria. As the vast majority of DFI develop in skin ulcers or open wounds, they are to be considered colo­nized by bacteria until proven otherwise. The diagnosis of DFI therefore cannot be done on iso­lated culture data, as cultures will be positive in most cases of simple wound colonization. Hence, the diagnosis of infection is based primarily on clinical signs and symptoms [26]. Moreover, it has to be kept in mind that peripheral neuropathy as well as PAD may increase the risk of develop­ing DFI while, at the same time, mask the appear­ance of clinical signs of inammation. For example, an infected ischemic foot will hardly appear hot or hyperaemic as the arterial blood impairment will not allow an increase in blood ow to the affected area.
As a multi-national panel of experts in the eld of DF care, the International Working Group on the Diabetic Foot (IWGDF) has developed solid guidelines on the management DFI based on a systematic review of the available literature [27].
The diagnostic criteria recommended by the IWGDF (Table35.3) for DFI have been validated by at least 2 large prospective cohort studies and have subsequently been included in the Society for Vascular Surgery WIfI classication for the foot infection (fI) component.
While approaching a DF lesion for the rst time, it is essential to evaluate the infective status according to the aforementioned diagnostic crite­ria as well as the vascular status and the presence/ absence of neuropathy or deformities.
Patients with severe infections must be hospi­talized as soon as possible for emergent surgical drainage. While some national guidelines, as the English NICE Guidance [28], report a 24-h time limit within which a patient with a DFI should be referred to the multidisciplinary foot care team,
35 Infected Wound Bed Management: TheDiabetic Foot
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Table 35.3 Classication of foot infections according to the International Working Group on Diabetic Foot [27]
Clinical denition/classication of infection IWGDF grade
Uninfected No systemic or local signs of
infection Infected Presence of at least 2 of the following
criteria: – Local swelling or induration – Erythema >0.5cma around the
wound – Local tenderness or pain – Local increased warmth – Purulent discharge No other possible explanations are present for the detected inammatory changes (e.g., trauma, gout, acute Charcot neuro-osteoarthropathy, fracture, thrombosis or venous stasis)
Absence of systemic manifestations (see below) but presence of both the following criteria: – Involvement of only skin or
subcutaneous tissue (not any deeper
tissues), – Erythema does not extend >2cma
around the wound Absence of systemic manifestations
(see below) but presence of at least one of the following criteria: – Erythema extending>2cma from
the wound margin, – Tissue deeper than skin and
subcutaneous tissues (e.g., tendon,
muscle, joint, bone) Any DFI associated to manifestations
of systemic inammatory response syndrome (SIRS), and thus with at least 2 of the following criteria: – Temperature>38°C o<36°C – Heart rate>90bpm – Respiratory rate>20/min or
PaCO2<32mmHg – Leucocytes >12.000/mm3
o<4.000/mm3 o immature
forms>10% Infection involving bone
a
Inammatory changes can be present in any foot area, not
necessarily contiguous to the skin ulcer
b
If osteomyelitis is demonstrated in the absence of≥2 signs/symptoms of local or systemic inammation, clas­sify as either grade 3(O) (if <2 SIRS criteria) or grade 4(O) if2 SIRS criteria as osteomyelitis is per se an infec­tion deeper than subcutaneous tissues and therefore can­not be classied as grade 1 or 2
b
1 (uninfected)
2 (mild infection)
3 (moderate infection or limb threatening)
4 (severe infection or life threatening)
Add “O” after grade 3 or 4
several other reports have shown that purulent collections, particularly when associated with rapid systemic deterioration or signs of elevated compartmental pressure, necessitate an urgent drainage, typically within a few hours from rst access to medical care [7, 8, 29, 30]. This “as­soon- as-possible” approach, based on a rapid multidisciplinary diabetic foot team referral, has been demonstrated to perform particularly well also for DFI of moderate and mild severity both in terms of nal outcomes [31] and in terms of costs [32] . The expression “time is tissue” has been proposed to emphasize the importance of time management in determining the nal fate of the limb [33].
35.7 Diabetic Foot Life- or Limb­Threatening Infections
Several pathologic entities may be responsible of an infective life or limb threatening condition. We report herein the most common causes of moderate to severe DFI.
35.7.1 Deep Suppurative Infections
This category includes mainly foot abscesses (Fig.35.1) and phlegmons (Fig.35.2). The for­mer are dened as purulent collections localized within a cavity that has formed de-novo from destruction or mechanical dissection of surround-
Fig. 35.1 Foot abscess