WOUND DRESSING IN DIABETIC FOOT

Chapter XII WOUND DRESSING IN DIABETIC FOOT OVERVIEW OF DRESSINGS AND WOUNDS FUNCTIONS OF DRESSING TYPES OF DRESSING SELECTION OF DRESSING MATERIAL TOPICAL AGENTS AND ANTISEPTIC CLEANSERS NEWER OPTIONS IN THERAPY o PLATELET DERIVED GROWTH FACTOR o MAGGOTS o HYPERBARIC OXYGEN The management of wound and wound dressing is an important aspect of diabetic foot management, which is neglected many a time. Care of the wound involves management of the ulcer, care of the exudate and knowledge and rational use of myriad dressing materials available to provide a cost-effective, simple, and easy method of dressing tailored to each patient's needs. Proper dressing with cost effective dressing material, done with scientifically correct method can help in salvaging diabetic foot. It is necessary to keep in mind the basic physiological facts about wound healing when planning for the diabetic foot wound dressing. Management of the ulcer: It is aimed at achieving an ulcer bed that is clean, free from necrotic tissue, foreign matter and bacterial infection. This is accomplished by debridement. Debridement means the removal of dead tissue and the accompanying bacteria and foreign matter which may be present in the ulcer. Debridement can also be accomplished in an autolytic manner, meaning the wound itself is encouraged to do this task. In fact the job of the WBC's and macrophages is to debride the wound. In diabetic patients this may not be effective or sufficient. The doctor has to assist this natural process. Some of the measures are as follow. The advantages and disadvantages should be carefully understood and are by and large not recommended today. The wet to dry method of using saline gauze to debride, or the use of enzymes like Streptokinase as topical ointment is an effective but expensive method of debridement of ulcers. Ointments containing collagenase have also been tried with some benefit. Weak Hydrogen peroxide, Eusol, acetic acid have been shown to be harmful to the fragile regenerating epithelium and should therefore never be used. Surgical debridment is often necessary in large or refractory wounds. This involves the use of surgical blades or scissors to actively, quickly debride. Sometimes it is the only effective method to debride the wound. 81

Once the ulcer is clean, the decision to use the first dressing material on the wound is made. This layer has to be a non adherent layer to protect the granulating or the epithlialising layer from being damaged during the subsequent dressing. There are various ready made non adherent and non absorbing materials available. They all contain a mesh impregnated with paraffin, soframycin, povidone iodine or various by products of petroleum. Gauze impregnated with paraffin and autoclaved gives a cheap and effective non adherent layer. Thus remember that the first layer to be used is a non absorbent layer. Care of the exudates: The next layer to be applied over the non absorbent layer has to take care of the exudation from the wound. Contaminated and infected wounds pour out a large amount of exudate. This layer has to absorb and retain the exudates thus giving the twin advantage of not only keeping the wound moist but also prevent soiling the surroundings. Change of this layer is necessary whenever it gets soaked. Heavily soaked dressing can be detrimental to wound healing and also causes contamination of the bed, linen and becomes a source of infection to spread. Materials used for this include the commonly used Gamjee pads or much thicker rolls of absorbent cotton. Advanced wound healing compounds have much higher absorbent capacity and can be used in special circumstances where cost may not be a factor. The Third component in wound care is the use of various materials to keep the exudative layer in place and the advanced wound healing products. a. The retaining layer, which helps to retain the first two layers viz., the non adherent and the absorbent layer. This is in the form of adhesive tapes (Zinc oxide tapes, Micropore tapes, simple bandages, adhesive bandages, elastic bandages, Elastic woven synthetic elasticated bandages etc.) b. Advanced wound care products facilitate three basic functions - Debridement, absorption of unwanted material and retaining itself on the wound. All the three functions are carried out by chemical compounds produced in such a manner that a single sheet has the non adherent film which marks the first layer, chemical compounds which have high water absorbent capability or has the capability to evaporate the water thus capable of continuous display of the exudates away from the wound. A list of the available wound care products given below explains the merits of each. Choice of the appropriate material is made based on the requirements of the wound, cost and benefits of one over the other. In summary wound care involves Debridement, keeping wound moist and prevent further injury, which in diabetic foot means to keep weight off the foot. The other component involves good glycemic control, adequate and nutritious food, and good hydration. Fever, exudation, bleeding and vomiting if present can quickly cause dehydration thus impairing wound healing. 82

Dressings and the wound: The basic function of any dressing is to protect the wound from mechanical trauma, to create a moist environment and prevent exposure to infection. Simple gauze dressing applied properly can help in preventing and / or controlling infection. Pathogenic bacterial load of a colony count more than 105 is considered as infection. The diabetic wounds are often polybacterial. To distinguish the contamination from the multiple pathogens inhabiting the wound requires some sophistication of the way specimens are collected and the cultures are made and subcultures studied. However the contamination of the wound by the organisms can be minimized by mechanical cleaning during the dressing or by absorption of exudates by the dressing applied. This reduces the requirement for phagocytic and autolytic debridement and reduces the source for microbial growth. After major debridement of any diabetic foot infection the dressing regimen should avoid contamination, reduce the pain, reduce bacterial growth and absorb exudate. This can be achieved by applying to the wound any suitable anti bacterial ointment / cream and cover the wound with non-occlusive, absorbent simple dressing. This can be changed once / twice a day depending upon quantum of discharge. This should be continued till the wound is filled with healthy, well vascularised granulation tissue. In the second and third phase of the wound healing maintaining moist environment is vital for healing. Occlusive dressings, which maintain moist environment, are preferable. Functions of dressings: Isolation of wound from external environment. Promote haemostasis. Limit / reduce tissue edema. Reduce pain. Improve gas exchange between tissues & blood. Limit inflammation. Absorb exudate. Should not promote bacterial growth. Prevent desiccation and contamination: We describe below a recapitulation of the types and utilities of dressings. Primary and Secondary dressings: All the dressings can be classified as primary or secondary. Primary dressing is the one, which is in direct contact with the wound. Secondary dressing is of the material, which hold the primary dressing in place. It has function of compression, occlusion and additional protection. 83

Absorbent dressings: Flooding of the wound with wound exudate can have serious implication for the healing due to maceration. Therefore proper absorbent dressing can help in the wound healing. Cotton, wool, polyurethane foam, pectin, gelatin, alginate, karaya gum, carboxymethylcellulose, are the examples of absorbent dressings. Non-adherent dressings: Simple gauze impregnated with paraffin or petroleum jelly is routinely used as nonadherent dressing. Non-adherent dressings are either occlusive & semi-occlusive; they could be hydrophilic & hydrophobic consisting of hydrocolloid & hydrogel or bioabsorbables. Occlusive / Semi Occlusive dressings: These dressing provide moist environment for the wound healing and are very useful in minimally exudating wounds. Various types of adherent film dressings are examples of this type of dressings. These types of the dressings can promote bacterial growth and can cause maceration. The advantages of occlusive dressings are that it reduces pain, facilitates rapid healing, helps the process of autolytic debridement, helps increased granulation and reduces friction. The disadvantages of occlusive dressings are maceration, accumulation of pus, adherence to healthy tissue, increased number of bacteria in the wound and may promote anaerobic growth. Hydrocolloid dressings: These dressings combine the functions of occlusive and absorbent dressings. These dressings increase epithelialization by 30 to 36%. The examples are Intrasite Gel / Duoderm. Bio-absorbable materials: This includes gelatin, collagen and oxidised cellulose. Collagen granules and sheets have been used as biological dressing. Calcium alginate dressings from seaweeds have been used effectively. Medicated dressings: These are impregnated with chemotherapeutic agents, antibiotics or other sterilising solutions. Selection of the Dressing material: The dressing in diabetic foot wounds should be done with minimal damage to the wound and using available, cost effective dressing material. The selection of the dressing material will depend upon the type of the wound, cost of the dressing material, expected duration of the wound healing and the availability of the trained person. Any material which prevents bacterial contamination, enhances moist environment, reduces pain should be used. In diabetic foot infection it must be remembered that off loading of the affected foot is a very important adjuvant to the wound dressing. The following protocol can be followed for wound dressings in general terms: 84

First, a decision regarding modality of the treatment i.e. whether conservative or operative should be made. If the ulcer / wounds do not require debridement then: 1. There should be appropriate strategy to off load the affected foot. 2. The wound / ulcer needs to be dressed with any dressing material, which can keep the wound environment moist. The simplest and cheapest is Metronidazole gel. Other antibacterial creams as per the culture and sensitivity report of the wound can be used. If sophisticated occlusive materials like Hydrogel, Kaltostat, Collagen sheets, Collagen Granules are available, and affordable they can be used. 3. The frequency of the dressing will depend on the quantum of the discharge. In the initial phases the quantum is more, necessitating every day dressing. 4. The dressing should be done till the wound fully epithelializes. If the wound requires debridement then after total / complete debridement based on anatomical principles, the wound dressing should be done as follows: A. On the operation table, simple paraffin gauze soaked in either very dilute 1 to 2% Povidone Iodine should be used to gently pack / cover the wound. B. This dressing should be opened after 24 to 48 hours. It should be irrigated with saline. An antibacterial ointment as per the culture and sensitivity report should be used. C. This should be continued till the early granulation is seen. This usually takes 7 to 10 days. You can put anything on the wound except the patient's weight. Off load, off load, off load!!!!!!!!!! For proper wound healing following factors are of paramount importance: Total Debridement preferably at the first time Adequate Blood Supply Total off Loading of the Affected Foot Colonisation of bacteria less than 105/gm of tissue where body defenses control the spread. Infection: Colonisation by bacteria more than 105 pathogens/gm of tissue where body defenses are unable to control the spread. If the wound does not show proper healing then re assessment for above mentioned factors should be done. This method of wound treatment was followed in All India Institute of Diabetes in Mumbai from Jan 1986. 4129 cases of complicated diabetic foot infections have been treated from Jan 1986 to Jan 1999 by the abovementioned method of dressing. The foot salvage rate of 91.2% was achieved in this institute, by Bal et al. Topical Agents and Antiseptic Cleansers: Many of the traditionally used agents of this type have been shown to be harmful to the wound healing. The cleaning of the wound is best achieved by saline or sterile 85

water. Vigorous mechanical cleaning should be avoided. Eusol / hydrogen peroxide, acetic acid etc., should not be used in the diabetic foot wounds. These agents can damage the delicate granulation tissue. The table below may be perused to see the availability of the dressing materials. Agents That Delay Wound Healing Relative Rate of Agent Healing Synthetic or fluorinated Corticosteroids 34 Nitrofurazons 30 Liquid detergent 28 Neomycin sulphate 5 Chlorhoxidlno 2% 7 Povidone-Iodine solution (10%) 10 Dakin's solution (0.25%) 15 Acetic acid solution (0.25%) 12 Hydrogen peroxide (3%) 8 Note: The comparisons were carried on with untreated, air-exposed control wounds. Data obtained from swine studies conducted on partial thickness wounds. Relative rate of healing was calculated as HT 50 untreated x HT50 exp HT 50 this ratio is multiplied by 100 erimental HT 50 is healing time in which 50% of wounds are completely healed. Newer, Innovative Therapies for Wound Healing: Platelet Derived Growth Factor: The new addition to the dressing material is useful but the imported gels are prohibitively costly. The indigenous PDGF is much less so in comparison to the imported product. The PDGF helps in epithelialization of the wounds. There is evidence to show that the wound closure occurs earlier even in wounds of fair sizes. It is felt that PDGF will make larger wounds more graftable with partial or full thickness grafts earlier than other methods Maggot: Sterile maggots are commercially available in several countries. In wounds with lot of exudation and dead tissue, maggots can be placed on the wounds and left lightly covered for a day or two. They eat away all the dead tissue, exudates and leave the 86

wounds clean for further dressing and healing. They should be pulled out of the wound area after two or three days. Hyperbaric Oxygen Therapy: Hyperbaric Oxygen Therapy (HBO) involves intermittent inhalation of 100% Oxygen under a pressure exceeding that of the atmosphere. O2 is delivered to the tissues in dissolved form. During HBO Therapy, quantum of dissolved Oxygen in plasma increases. At rest, the tissues extract 6ml of O2 per 100ml blood. On air at 1 atmospheric pressure there is 0.3ml of O2 per 100ml blood. At 2ATA on 100% O2 there is 4.3ml per 100ml blood dissolved in the plasma. At 3ATA on 100% O2 there is 6.5ml per 100ml blood dissolved in the plasma. Thus HBO arterialises the venous blood. The therapy is delivered in Monoplace Chambers which admit one patient at a time with the entire chamber pressurized with Oxygen. It is less expensive but can't take serious patients. Standard precautions should be observed about preparing the patients for it. The therapy session lasts for about 60 to 90 minutes. Addition of Hyperbaric Oxygen results in significant cost savings due to lesser stay in hospital and shorter course of illness. How does it work? When tissue Oxygen tension drops to less than 30 mm Hg, healing by cellular division is significantly reduced and may even stop. Fibroblasts, angioblasts, and leucocytes are not capable of functioning in this environment. These wounds usually develop in compromised hosts. Multiple local and systemic factors may contribute to inhibition of tissue repair. Adequate supply of dissolved oxygen helps these mechanisms for the wounds to heal. It is the larger wounds in the compromised patient where the demand for oxygen exceeds the supply that the non-healing chronic wound develops. In these patients adjunctive HBO is beneficial. Hyperbaric oxygen plays no role in enhancing wound healing in the normal host, unless there is evidence of compromise of vascular flow in the local wound area. Patients with Class 3, 4, or 5 Wagner lesions are considered for treatment based upon blood flow assessment. TcPO 2 is a reliable and useful noninvasive method for perfusion evaluation. Periwound TcPO 2 greater than 30-40 mmhg on room air is sufficient for the wound to heal without intervention. TcPO 2 of less than 20 mm Hg on room air indicates poor prognosis. If the TcPO 2 increase to 40 mmhg on 100% O 2 in hyperbaric chamber at 1 ATA indicates perfusion enough for HBO Thearpy to benefit. HBO treatments in diabetic foot are performed at 2-2.5 ATA for 60-90 minutes of Oxygen breathing. If presence of limb threatening infection or compromised surgical flaps the treatment is given twice daily. Once the infection comes under control and soft tissue envelope improves, the treatment schedule is changed to once daily. Utilization review is usually after 30 treatments and 10 treatments post grafting. 87

Brief outline of how to deal with ulcers: 1. Assess ulcer (general wound parameters) Anatomic considerations and measure wound discussed before 2. Address underlying pathologic conditions by 3. Doing sharp debridement reaching up to healthy bleeding tissue. Eliminate undermining and assure hemostasis. 4. Apply topical antibiotic ointment (Silver Sulfadiazine. Polymyxin and Bacitracin, Zinc, Mupuricin 2%.)once daily for 2 weeks. 5. Select non-adherent, non-occlusive absorbent dressing (dressing change once daily) 6. As soon as wound is granulated and well vascularized occlude with synthetic dressing that keeps would moist. Make sure dressing is changed at least once daily, and patient follows up is once weekly. Advise patient to notify if they notice the clinical signs of infection. 88