Diabetic Foot Problems

December 31, 2006

When a patient with diabetes presentswith a foot wound, prompt and aggressiveintervention is required topromote healing and to prevent progressionthat could lead to a leg amputation.Fortunately, the majority ofdiabetic foot wounds heal rapidly withlittle difficulty.

When a patient with diabetes presentswith a foot wound, prompt and aggressiveintervention is required topromote healing and to prevent progressionthat could lead to a leg amputation.Fortunately, the majority ofdiabetic foot wounds heal rapidly withlittle difficulty.Healing can be complicated byadvanced peripheral vascular disease,deformities, uncontrolled infection(usually secondary to poor perfusion),or immunosuppression. Neuropathydoes not directly interferewith wound healing. In fact, in manysituations, it facilitates care because itallows dressings to be changed anddebridements to be done more effectivelyeffectivelyand without discomfort. Moreover,the neuropathic foot frequentlyhas increased circulation, as is oftenobserved in patients with Charcotarthropathy.In a previous article (CONSULTANT,November 2001, page 1693), Idiscussed the causes of diabetic footwounds and offered prevention strategies.Here, I present a wound evaluationsystem that provides a basis fortreatment decisions and also facilitatesassessment of healing. In addition,I describe the 4 chief aspects ofwound care.EVALUATION
Start by assessing the severity ofthe wound. A grading system can facilitatesuch evaluation. The Wagnersystem is one of the most common(Table 1).1 It is most useful for evaluatingforefoot wounds that requiresurgical management; the system isnot designed to assess improvement.In the Wagner system, Doppler bloodpressure measurements (ie, ankle/brachial indices) play a key role inthe treatment algorithms; however,these findings tend to be unreliablein patients with arteriosclerotic bloodvessels. I have designed an alternativewound grading system that is objectiveand easy to use (Table 2).2 It is similarto the Wagner system but includes additionalcriteria and can be used to assessprogress as well as the initial stateof the wound. The 'Strauss system'uses 5 criteria; each is rated 0, 1, or 2(with 0 the worst and 2 the best), andthe points for the 5 criteria are then totaled.The point total determines thewound score.A wound with a score in the 8-to-10 range is classified as a 'healthy'wound. In such a wound, almost anyintervention that does not injure thetissues will have good results. A scoreat the opposite end of the scale'from0 to 3'identifies a 'futile' wound. Fora futile wound, the chances of healingare slim and amputation is likely to berequired unless angioplasty or revarevascularization'possibly with adjunctivehyperbaric oxygen treatments'issuccessful. A score in the 4-to-7 range signifiesa 'problem' wound; in fact, theStrauss system provides an objective,quantitative definition of a problemwound. Comprehensive managementplays a critical role in the outcome ofproblem wounds. As healing progresses,improvement can be verified by improvedwound scoresTEAM THERAPY
There are 4 chief aspects to themanagement of problem diabetic footwounds: preparation of the woundbase, protection, dressing, and oxy-genation (Table 3); each of thesecomplements the others.3 Ninety percentof such wounds heal when acomprehensive strategy is employedthat addresses all 4 aspects of woundhealing.4 A team approach, in whicheach member of the team has expertisein a particular aspect of woundhealing, works best (Table 4). Youprovide overall management of thepatient's care; the wound care specialistsfocus on the problem footwound.PREPARATION OFWOUND BASE
The wound base needs to bemade as clean and healthy as possible.If the base is red (Figure 1), minimalintervention is needed and physiologicdressings are usually sufficient.If the wound base is white oryellow (Figure 2), debridement withenzymatic agents or a series of 'mini'debridements works well. Such minidebridements are most effective afterwhirlpool treatment or pulsatile lavage,which softens necrotic tissues.Surgical debridement can accomplishin a few minutes what may take daysto achieve with enzymatic agents.However, when the necrotic materialis thin and the underlying base poorlyvascularized, enzymatic agentscan be very helpful in preparing thewound base. If the wound base isblack (Figure 3)'and is coveredwith anything other than a very thineschar with sharply demarcated margins'it needs to be removed and theunderlying tissues debrided to a viablebase. This may require serial debridements.Contractures, deformities,and imbalances may also need tobe corrected as part of preparation ofthe wound.The preparation of the woundbase is primarily managed by woundcare specialists. If the patient has neuropathy,debridement can usually bedone in an office or clinic. When surgicalinterventions such as formal debridements,tenotomies, ostectomies,or partial amputations are required,select a surgeon with expertise andproven interest in foot problems.WOUNDPROTECTION
Wounds heal best if they arekept at 'rest.'Soft bandaging, splints,orthoses, casts, and fixation devices(both external and internal) can all beused. Fixation devices are generallyemployed only in special circumstancesand are contraindicated if thewound is infected. Casts effectivelyimmobilize wounds, and with appropriatewindowing, they allow accessto the wound so that it can be properlycared for. Total contact casts can effectivelyheal problem wounds, but they requirefrequent cast changes'usuallyover weeks or months'and specialexpertise in application. Also, if theunderlying deformity is not corrected,a wound healed with contact castingmay soon recur after the casting isstopped.A wound can be immobilized bytemporary placement of pins across ajoint. This technique is particularlyuseful in large foot wounds, in whichcasting would interfere with woundcare, and in short foot amputations, inwhich a cast would be unable to preventthe development of equinus contracturesof the ankle. To prevent pintract infections, weight bearing is absolutelyproscribed for any joint thathas a pin across it.DRESSINGS
Saline is the standard dressingagent; however, hundreds of othersare available. Selection of the bestagent for a particular wound dependson the goals you are trying to achieve.A nurse practitioner who specializes inwound care can be very helpful in thisaspect of a patient's care.Dressing agents can be dividedinto 4 major typesSaline and similar agents.Gauze moistened with saline or salinewith an additive such as acetic acidcan be used for wounds of almost anytype and size. The advantage of thesedressings is their low cost. The disadvantageis that such dressings need tobe changed 2 or 3 times a day. Also,some expertise is required to keepthe moist dressing from touching theskin and causing maceration.Occlusive and semi-occlusivecovering agents. A second group ofagents are recommended for clean,vascular-based, nonexudative wounds.Impregnated, impermeable or semipermeablemembrane-type coveringsmaintain a moist, physiologic environment.They need to be changed onlyoccasionally.Absorbent agents. For highly exudativewounds, select an agent thatabsorbs secretions, such as a seaweedpreparation, a sponge-like material, ora hydrophilic agent. A wound vacuumis very effective for large, exudativewounds that are difficult to manage.Agents with special additives.Ointments, salves, and creams cantarget particular problems (eg, continuinginflammation, absence ofgranulation tissue, ongoing infection,dryness). These agents have specialadditives such as moisturizers,growth factors, antibiotics, anti-inflammatoryagents, or naturopathicsubstances.OXYGENATION
An adequate oxygen supply iscrucial to the healing of problemwounds. Although revascularizationand angioplasty may improve perfusion,patients with problem diabeticfoot wounds frequently are not candidatesfor such surgery. Moreover, becauseof diffuse and/or distal arterialblood vessel involvement, those measuresmay not improve flow to thelevel required for wound healing.Other interventions can improveoxygenation of the wound; you and/oran appropriate consultant can usuallyinstitute these strategies. Optimizingthe patient's cardiac and renal functionimproves cardiac output and fluidbalances. Removal of edema fluidfrom the wound area decreases theoxygen diffusion distance (the distanceoxygen must travel from the capillaries,through tissue fluids, to thehealing tissues). Hyperbaric oxygenincreases tissue oxygen tensions 10-fold and increases the ability of oxygento travel through tissue fluids and edema3-fold.5,6 Juxtawound transcutaneousoxygen measurements with hyperbaricoxygen can help predict whichwounds will heal, regardless of whatthe transcutaneous oxygen measurementsare in room air.7Medications that can improvewound oxygenation by improvingblood flow include local and systemicvasodilators, red blood cell deformingagents, and anticoagulants (Figure 4).Vascular surgeons frequently orderanticoagulants to maintain perfusionafter revascularizations, especially ifthe flow is tenuous. I have observedimproved juxtawound tissue oxygentensions following the administrationof a calcium channel blocker.PATIENT FACTORS
Before undertaking care of a diabeticfoot wound, assess the patient'sability and desire to help with the healingprocess. The patient's motivationto avoid amputation, comprehension ofthe problem, compliance with physicianrecommendations, family support,and capacity for self-care can each berated from 0 (worst) to 2 (best) andthese ratings totaled to yield an overallscore of 0 to 10 (Table 5).If this score is low, the best decisionin the case of a problem or futilewound is a major amputation, becauseit is likely the problem will recur or anew problem will develop after the patientleaves the controlled environmentof the hospital or skilled nursing facility.In patients who have good or highscores, limb salvage is cost-effective reregardlessof the wound type (unless thejuxtawound tissues are totally avascular).Amputation is costly; one studyshowed that when revascularizationfailed to prevent amputation, the totalcosts for hospitalization, revascularizationsurgery, amputation, prostheticfitting, and rehabilitation approached$50,000.8 Although limb salvage is notinexpensive (in the United States, $5billion a year is spent on wound careproducts9), it has the added intangiblebenefit of preserving independence forpatients who'because of generalizedweakness, balance problems, or earlieramputations'would be placed in anassisted care facility if they underwentamputation.