best practice guidelines: wound management in diabetic foot ulcers

AETIOLOGY OFDFUsAetiology of DFUsThe underlying cause(s) of DFUs will have a significant bearing on the clinicalmanagement and must be determined before a care plan is put into placeIn most patients, peripheral neuropathy andperipheral arterial disease (PAD) (or both)play a central role and DFUs are thereforecommonly classified as (Table 1) 26 : Neuropathic Ischaemic Neuroischaemic (Figures 2–4).Neuroischaemia is the combined effectof diabetic neuropathy and ischaemia,whereby macrovascular disease and, insome instances, microvascular dysfunctionimpair perfusion in a diabetic foot 26,27 .is increasing and it is reported to be a contributoryfactor in the development of DFUsin up to 50% of patients 14,28,33 .It is important to remember that even in theabsence of a poor arterial supply, microangiopathy(small vessel dysfunction)contributes to poor ulcer healing in neuroischaemicDFUs 34 . Decreased perfusion inthe diabetic foot is a complex scenario andis characterised by various factors relatingto microvascular dysfunction in addition toPAD 34 .FIGURE 2: Neuropathic DFUPERIPHERAL NEUROPATHYPeripheral neuropathy may predispose thefoot to ulceration through its effects on thesensory, motor and autonomic nerves: The loss of protective sensation experiencedby patients with sensory neuropathyrenders them vulnerable to physical,chemical and thermal trauma Motor neuropathy can cause footdeformities (such as hammer toes andclaw foot), which may result in abnormalpressures over bony prominences Autonomic neuropathy is typicallyassociated with dry skin, which can resultin fissures, cracking and callus. Anotherfeature is bounding pulses, which isoften misinterpreted as indicating a goodcirculation 28 .Loss of protective sensation is a majorcomponent of nearly all DFUs 29,30 . It is associatedwith a seven–fold increase in riskof ulceration 6 .DFUs usually result from two or more riskfactors occurring together. Intrinsic elementssuch as neuropathy, PAD and foot deformity(resulting, for example, from neuropathicstructural changes), accompanied by anexternal trauma such as poorly fitting footwearor an injury to the foot can, over time,lead to a DFU 7 .TABLE 1: Typical features of DFUs according to aetiologyFeature Neuropathic Ischaemic NeuroischaemicSensation Sensory loss Painful Degree of sensorylossCallus/necrosisWound bedFoot temperatureand pulsesCallus present andoften thickPink and granulating,surrounded bycallusWarm with boundingpulsesNecrosis commonPale and sloughywith poorgranulationCool with absentpulsesFIGURE 3: Ischaemic DFUFIGURE 4: NeuroischaemicDFUMinimal callusProne to necrosisPoor granulationCool with absentpulsesPatients with a loss of sensation will havedecreased awareness of pain and othersymptoms of ulceration and infection 31 .PERIPHERAL ARTERIAL DISEASEPeople with diabetes are twice as likely tohave PAD as those without diabetes 32 . Itis also a key risk factor for lower extremityamputation 30 . The proportion of patientswith an ischaemic component to their DFUOtherTypical locationPrevalence(based on 35 )Dry skin andfissuringWeight-bearingareas of the foot,such as metatarsalheads, the heel andover the dorsum ofclawed toesDelayed healingTips of toes, nailedges and betweenthe toes and lateralborders of the foot35% 15% 50%High risk ofinfectionMargins of thefoot and toesBEST PRACTICE GUIDELINES: WOUND MANAGEMENT IN DIABETIC FOOT ULCERS 3