Leg ulceration and wound bed preparation – towards a more holistic framework August 2007 1.0 August 2007 Jackie Stephen-Haynes RGN, DN, DipH, BSc (Hons), ANP, PGDipR, PGDipEd, MSc Consultant Nurse and Senior Lecturer in Tissue Viability Worcestershire Primary Care Trusts and University of Worcester Stourport on Severn, Worcestershire. jackiesh@btopenworld.com leg ulcers chronic wounds frameworks acronyms wound bed preparation TIME holistic assessment. TIME 2. The concept of wound bed preparation and the TIME framework (Tissue management; Inflammation and infection control; Moisture balance; Epithelial (edge) advancement) offer a logical and systematic approach to the assessment and delivery of wound care for patients with leg ulceration. The TIME framework (Tissue management; Inflammation and infection control; Moisture balance; Epithelial (edge) advancement) focuses on the wound bed and could be developed to encompass a more holistic approach to care. Wound bed preparation and the TIME framework must be used as part of an integrated approach Development of an additional acronym could be considered alongside TIME to facilitate a broader approach to leg ulcer assessment, including differential diagnosis, and, prevention of recurrence and management of psychosocial issues. Future work needs to focus on evaluating the effectiveness of such frameworks and refining them to best suit the clinical environment. Significant advances have been made over the past two decades in the delivery of effective services for patients with leg ulceration. Treatment costs, however, remain high and the development of strategies to ensure future provision of effective care is important. Recent research into conditions at the wound bed has focused attention on the benefits of wound bed preparation and the use of the TIME framework to underpin care. Developed as a result of consensus meetings with key wound care opinion leaders, TIME offers a logical and systematic approach to the assessment and management of the wound bed, guiding practitioners in linking clinical observations and clinical outcomes. However, it is of limited value if clinicians fail to use it as part of an holistic approach. This paper explores additional factors that need to be considered alongside wound bed preparation and the TIME framework in order for care to be effective. A proposal for a second TIME acronym - TIME 2 – is presented, aimed at encouraging clinicians to focus not simply on conditions at the wound bed but also on identifying the ulcer aetiology and other factors that can impact on care and delay healing. Future work needs to focus on evaluating the effectiveness of such frameworks and refining them to best suit the clinical environment. The past 20 years have seen a significant shift towards the delivery of evidence-based leg ulcer care and improved healing rates for many patients. Recent interest in chronic wound healing has led to a clearer understanding of cellular and mollecular imbalances present in the wound bed that may contribute to delayed healing for some patients [1] [2]. Wound bed preparation – a concept aimed at assisting clinicians in wound bed assessment and the development of strategies to maximise healing potential – is now recognised as an important aspect of care. The associated development of the TIME framework (Tissue management; Inflammation and infection control; Moisture balance; Epithelial (edge) advancement) [3] offers clinicians a practical tool for translating wound bed preparation into practice. The success of the wound bed preparation framework and the TIME acronymframework in improving patient outcomes is dependent on their value in clinical practice. A holistic approach is central to effective care [3](3) . Other factors to consider alongside the wound bed include the skin, the limb, vascular supply, pain, and ulcer aetiology [4], as well as the patient’s health beliefs, level of understanding and concordan Leg ulceration is a common, difficult and expensive health problem, affecting 1-2% of the population [5] [6] [7], and representing a significant challenge to the health service. A third of patients develop their ulcer before the age of 50 [5] and 2% of those over 80 years of age is thought to suffer with this condition [8]. Recurrence rates are high: 26% after one year and 31% after 18 months of healing for venous ulcer patients [9]. The cost burden to the NHS has been estimated at around £400 million per annum [10] and numerous studies have identified the negative impact on patient quality of life [11] [12] [13]. Prevalence of leg ulceration and the associated demands on service provision are likely to remain a challenge, due not only to these high recurrence rates but also as a consequence of an ageing population and the rise in chronic conditions such as obesity and diabetes. Over recent decades service provision has become more rationalised and models of care have been developed. In the UK, most patients with leg ulceration are treated by nurses in the primary care setting, usually in their own homes [5]. It is important that primary care trusts (PCTs) are responsible for modelling services around the needs and profile of their patient groups. Moffatt et al [14] identified the benefits of leg ulcer clinics, where patients receive appropriate assessment and management and where a robust referral system to a member of the multi-professional team is in place. Clinics afford the adoption of leg ulcer guidelines and the opportunity to develop ‘one-stop’ assessment centres that incorporate investigations such as Duplex scanning and access to vascular surgeons [15]. The Lindsay Leg Club Model [12] recognises the importance of holistic care for patients with or at risk of leg ulceration and is based on a social model of ‘leg health’. Services are delivered in a non-medical setting with an emphasis on ‘drop-in’, social interaction, participation, empathy and peer support. The quest for effective frameworks of care continues. Service delivery and choice of setting varies across the UK and even within individual PCTs. Factors that may influence future developments include the increase in the number of older people as the population ages, as well as growing financial constraints within the health service. It is important that directors within health service organisations engage with the needs of patients with leg ulceration, and that clinicians are well educated, utilise local and national guidelines and continue to network in the quest for delivery of a high-quality, systematic and effective approach to care. Wound bed preparation and the TIME framework Wound bed preparation is a rapidly emerging concept [16] that has recently gained popularity among practitioners. It represents a model of care for the management of chronic wounds based on the observation that cellular and molecular imbalances at the wound bed may contribute to delayed healing [3]. The TIME acronym – inspired by Falanga’s original work and further developed by EWMA (European Wound Management Association) following consensus meetings with key opinion leaders [3] – comprises the four components of wound bed preparation and offers a logical and systematic framework (see Table 1). It guides clinicians to consider each of these key clinical areas in monitoring the wound, decision making and use of targeted interventions. Table 1: The TIME Acronym. The TIME acronym, as originally developed by the International Wound Bed Preparation Advisory Board [3]: T = Tissue, non-viable or deficient I = Infection or inflammation M = Moisture imbalance E = Edge of wound, non-advancing or undermined. Terms proposed by the EWMA Wound Bed Preparation Editorial Advisory Board in order to maximise its value across different disciplines and languages [3]: T = Tissue management I = Inflammation and infection control M = Moisture balance E = Epithelial (edge) advancement. It has always been stressed that the original concept of wound bed prepartionpreparation must be part of an ongoing , holistic wound management starratergy ([3)]. It could, however, be argued that in some areas of practice clinicaians focus mainly on the wound and less attention is paid to assessment, underlying aetiology and the management of psycosocial issues. The importance of the ability of a dressing to perform adequately when partially compressed cannot be over emphasised. A key part of the management of venous leg ulcers, for example, is the application of significant levels of compression, often as high as 40mmHg. Similarly, in the management of pressure ulcers, dressings are frequently required to function adequately when at least some part of the patient's body weight is bearing down upon them. Simple foams, like bath sponges, initially take up large volumes of fluid, but a large amount of the retained liquid is lost if the sponge is gently compressed. If allowed to stand in one position, fluid will drain away under the effect of gravity. Much research has therefore been devoted to maximising the performance of foam dressings by casting the foam from hydrophilic polymers and/or the inclusion of super-absorbents within the porous structure of the foam itself. These developments have resulted in the formation of a family of products that are among the most absorbent and widely used dressings available. A fundamental requirement for any company involved in developing new or improved absorbent dressings or any organisation that performs in vitro testing to obtain comparative results to facilitate dressing selection is a suitable test system that mimics, as closely as possible, the conditions that are encountered in normal clinical practice. Key design criteria for a new wound model have been described in an earlier publication, as followsref1: Fluid should be provided to the test sample by some form of pump or other suitable positive flow device, which more closely simulates the clinical situation. A passive uptake technique is not acceptable The fluid should not be presented to the test sample under excessive pressure. Previous test systems have, in effect, injected fluid into the dressing under pressure, although there is no evidence that this occurs in wounds There must be some suitable method for controlling the temperature of the system for the duration of the test, to reproduce the environmental conditions in the wound The test should provide some indication of the dynamic performance of the dressing, measuring its fluid handling capacity profile over time, and not just a single total absorbency figure The equipment should be capable of delivering test solution at a range of different flow rates, so that the effect of different rates of exudate can be examined The apparatus should indicate when either vertical or lateral strike-through has occurred The apparatus should be suitable for testing a wide range of different types of dressings to permit direct comparison of the results. Previous methods were frequently dedicated to one type of technology, such as alginates The equipment should be compatible with a range of different test solutions Where appropriate, the apparatus should permit the application of varying loads to the test samples in order to determine the effect of external pressure The apparatus should permit the measurement of moisture vapour transmission by the dressing as an integral part of the test The test should be easy to perform and provide results that can be reproduced within and between laboratories The equipment should not be excessively expensive to produce The test should, ideally, provide an indication of the wear time of a dressing in normal clinical use. The development of a prototype test rig (see Figure 1 and Figure 2) that was believed to meet most, if not all, of these requirements, was similarly described in the earlier publicationref1. A new version of this rig has been developed over recent years through collaboration with academia and industry through the Woundcare Research for Appropriate Products (WRAP) project (details available at: www.kcl.ac.uk/wrap).

Essentially it consists of a two-part stainless steel plate (the 'wound bed'), mounted on a Perspex table, with an electronically controlled heating mat that enables the test plate and sample under examination to be maintained within a narrow temperature band. The central section contains a recess into which a 15mm-long channel has been milled, joining a 3mm inlet hole with a 7mm outlet hole. The centre section is milled from block stainless steel, and includes two ports that permit the introduction and unimpaired exit of the test solution. The diameter and depth of the recess is sufficient to accommodate two absorbent pads that ensure the effective transfer of liquid from the channel to the dressing above. Test fluid, fed through one of the ports by means of a syringe pump, travels along the narrow channel and out through the second port, falling vertically down through a short, wide-bore tube. This tube discharges into a receiver placed on the pan of an electronic balance. The liquid in the receiver is covered with a layer of oil to prevent loss by evaporation. The balance is connected to an electronic data capture device that records changes in the balance reading at predetermined intervals throughout the period of the test. The test fluid usually used for absorbency testing consists of a solution of sodium/calcium chloride with an ionic composition similar to that of serum, although others are possible. The new test rig is currently being evaluated by a multidisciplinary group comprising representatives from most European dressings companies, in addition to others with an interest in dressing design or performance. This group, which was originally funded by a research grant from the Engineering and Physical Sciences Research Council (EPSRC), is concerned with the development and validation of methodologies for medical device evaluationref2. A dressing sample typically measuring 10cm x 10cm (total area of 100cm2) is secured on to the 'wound bed'. During use, as test fluid is applied to the test rig and passes along the open channel, some will be taken up by the dressing. Any unabsorbed fluid will continue to pass along the channel until it falls through the outflow pipe into the receiver, causing a change in the balance reading. The amount of fluid that accumulates in this way is inversely proportional to the absorbency of the dressing. A highly absorbent dressing may take up all the liquid that is applied to it, while less absorbent products will absorb only for a short time or take a little while to reach maximum absorbency. During a test, therefore, the maximum weight of fluid that can be taken up by a dressing is determined by the flow rate of the syringe pump. When performing laboratory-based tests to assess or compare the performance of medical devices, it is clearly important to ensure that the test conditions employed are as clinically relevant as possible. In the context of this investigation, this means ensuring that the flow rate of the simulated wound exudate is comparable with the volume of exudate produced by a heavily exuding wound. According to the literature, this is typically around 5ml per 10cm2 per 24 hoursref3, but in the presence of infection this value can easily doubleref4. For this reason, the syringe pump is normally set to deliver a nominal 1ml per hour as this value provides a reasonable compromise between clinical relevance and a need to keep testing times to a minimum for practical reasons. In order to simulate levels of compression encountered clinically, each sample is typically loaded with a total mass of 5kg distributed over 100cm2, equivalent to 36.8mmHg. This pressure is chosen as it approximates to the maximum value that is usually used therapeutically. In the treatment of leg ulcers caused by venous insufficiency 40mmHg is widely quoted in the literature as the target pressure for compression bandaging systems such as the Charing Cross four-layer system. The aim of the present study was to use this equipment to compare the performance of two commonly used foam dressings (identified as Products A and B) in order to demonstrate the important effects of externally applied pressure on dressing performance. For the purposes of this investigation, each dressing was tested in the compressed and uncompressed state, to determine whether they performed differently under compression. The products were tested in duplicate, giving a total of eight runs (two dressings, in duplicate, with and without compression) and each test lasted approximately 20 hours. During the course of the test, both dressings (Product A and Product B) absorbed all of the fluid supplied to them in the uncompressed state. In Figure 3, the plot contains 8 different data sets. However only 3 are visible due to the superimposition of some data sets on top of others. These data sets are superimposed on each other due to the fact that the absorption rate of each dressing was greater than the fluid delivery rate, and therefore the absorption rate equals the flow rate of the pump, giving a straight line. In the presence of compression, however, although Product B was still able to absorb the total volume of fluid applied (straight line in Figure 3), the absorbency of Product A was considerably reduced, capable of only absorbing about 25% of the volume of fluid taken up by the comparator product under the same conditions (the two lower lines, orange and green, in Figure 3).

In the clinical situation, when treating heavily exuding wounds such as venous leg ulcers, it may be appropriate to select a product for exudate management that has been shown to perform well when subjected to clinically relevant levels of compression. When measuring or comparing the absorbent capacity of dressings in the laboratory, it is therefore essential to take account of the effects of compression if the results of the investigation are to have any clinical relevance. The test system described in the present study clearly facilitates such comparisons, and appears to be able to detect significant differences in performance under compression. This investigation was designed purely to assess the effect of compression on absorbance. Evaporative loss was prevented by the occlusive nature of the weighted pressure plate and this would undoubtedly have reduced the total fluid handling capacity of both products. This parameter can be accounted for by a modification to the test equipment if required, which is the addition of a chamber filled with silica gel, used to simulate a humidity gradient across the dressing. 2001 Thomas S S Fram P P http://www.worldwidewounds.com/2001/december/Thomas/absorbency-wound-dressings.html February 8, 2006 Grocott P P http://www.hesmagazine.com/story.asp?sectionCode=21&storyCode=2034370 3 1977 159-65 Lamke L O LO Nilsson G E GE Reithner H L HL 8 5 1996 145-50 Thomas S S Fear M M Humphreys J J Disley L L Waring M MJ