Technology and product reviews References


16. Tennvall GR, Hjelmgren J, Oien R. The costs of treating hard-to- heal venous leg ulcers: results


from a Swedish survey. World Wide Wounds, 2006. Available at: http://


www.worldwidewounds.com/2006/ november/Tennvall/Cost–of–


treating–hard–to–heal–venous– leg–ulcers.html


17. Bowler PG. The 10(5) bacterial growth guideline: reassessing its


clinical relevance in wound healing. Ostomy Wound Manage 2003; 49(1): 44–53.


18. Falanga V, Brem H, Ennis WJ, et al. Maintenance debridement in


the treatment of difficult–to–heal chronic wounds. Ostomy Wound Manage 2008; (Suppl) 2–13.


19. EWMA. Position Document:


Wound bed preparation in practice. London MEP Ltd, 2004.


20. Price P, Fogh K, Glynn, C et al.


Managing painful chronic wounds: the Wound Pain Management


Model. Int Wound J 2007; 4(Supp 1): 4–15.


21. White RJ, Cutting KF. Critical colonization: the concept under


scrutiny. Ostomy Wound Manage 2006; 52(11): 50–6.


22. Cooper RA. Understanding wound infection. In: EWMA.


Position Document: Identifying criteria for wound infection. London: MEP, 2005.


23. Harker J. The effect of bacteria on leg ulcer healing.


Br J Community Nurs 2001; 6(3): 126–34.


24. Phillips PL, Wolcott RD, Fletcher J, Schultz GS. Biofilms made easy.


Wounds Int 2010; 1(3). Available at: http://www.woundsinternational. com/article.php?issueid=303


25. Tamuzzer RW, Schultz GS.


Biochemical analysis of acute and chronic wound environments.


Wound Repair Regen 1996; 4(3): 321–5.


26. Falanga V, Grinnell F, Gilchrest B, et al. Workshop on the


pathogenesis of chronic wounds. J Invest Dermatol 1994; 102(1): 125–7.


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article.php?issueid=1&contentid= 123&articleid=21


bacteria, wound dressings containing topical antibacterials such as silver, iodine, honey or polyhexamethylene biguanide (PHMB) are popular choices, irrespective of the quality of the in vivo efficacy data, since they have a broad theoretical spectrum of antibacterial activity[35,36,37]


. However, a lack of knowledge regarding the


appropriate and timely use of these products could put patients at risk of delayed closure, while untreated local infection can lead to systemic sepsis [38]


. Using antibacterial dressings to stop


local infection spreading may avoid unnecessary complications and costs, such as extended hospitalisation and, therefore, it is important to recognise and accurately identify the signs and symptoms of at-risk wounds[39]


.


THE ROLE OF SILVER DRESSINGS When the antibacterial properties of silver are used in wound-care products, it is the silver ions rather than the atoms that exert their effect. The theory is that on contact with wound fluid, silver atoms are slowly released from the dressing as positively charged ionic silver (Ag+)[40]


. These silver ions kill pathogens


in a variety of ways: n Binding to the bacterial cell wall,


weakening it and causing leakage from the cell and death of the bacteria[41]


n Binding to bacterial cell oxidative enzymes, inhibiting their activity[42]


n Binding to bacterial cell DNA to interfere with cell division and replication[43]


.


How far a dressing’s antibacterial effect is influenced by the amount of silver contained in a dressing and the rate of release of Ag+ remains unclear[36,44]


.


One Cochrane review reported on three studies (n=847) using absorbent sustained- release silver dressings in venous leg ulcers, but failed to show faster closure rates at four weeks[36]


. Similarly, the VULCAN study did


not show a difference in closure rates over 12 weeks for venous leg ulcers treated with a silver dressing when compared with an absorptive dressing[45]


. However, the goal of using a silver dressing


is not to close the wound, but rather to help reduce the bioburden and thus prepare the wound bed for closure. Therefore, large studies into the ability of a dressing that is intended to kill bacteria being used to close wounds, many of which may not have significant bacterial burden, would appear to be inappropriate.


31 Wounds International Vol 2 | Issue 4 | ©Wounds International 2011


Indeed, very few studies report on bioburden, with the exception of one that examined a 0.9% cadexomer iodine dressing (Iodosorb™, Smith & Nephew), which was found to significantly reduce S. aureus levels over a six- week period in venous leg ulcers[35]


. Other factors such as the dressing's capacity


to manage exudate, promote autolytic debridement or maintain an optimum wound environment also need to be considered when selecting a silver dressing[44]


.


Infected wounds are more painful and may be associated with high exudate levels[46]


.


This can lead to malodour and periwound maceration and leakage, requiring more frequent dressing changes. Treatment of the wound infection, by reducing bacterial load and reducing the inflammatory stimulus to the nervous system, should also result in a reduction in pain, malodour and exudate[46]


. ALLEVYNTM AG


ALLEVYN Ag (Smith & Nephew) is described as a highly absorbent antibacterial foam dressing range that has been designed to manage exudate and provide an effective bacterial barrier[40]


. It comprises a triple-layered


structure of hydrocellular foam containing silver sulfadiazine, a perforated wound contact layer and an outer highly breathable top layer. Silver sulfadiazine (SSD) is a silver compound


that was first developed in 1968and is effective against a variety of pathogens[47]


. It has been


used by clinicians as a topical antibacterial agent for burns and other wound types, including venous leg ulcers[48,49,50]


. As exudate


is absorbed into the dressing and away from the wound, the SSD within the central layer is released as positively charged ions at a bactericidal concentration for up to seven days[51]


. In vitro, ALLEVYN Ag has been shown to


have a broad spectrum of bactericidal activity against Gram-positive and Gram-negative bacteria, antibiotic-resistant strains, anaerobes, fungi and yeast[52,53]


.


Clinical evidence for ALLEVYN Ag In an international study, Kotz et al[2]


reported


on data generated from 24 participating centres in the USA and Europe. The performance of a number of dressings, ALLEVYN Ag Adhesive, ALLEVYN Ag Non-Adhesive and ALLEVYN Ag Sacrum (Smith & Nephew), was studied for up to six dressing changes in patients with wounds of various aetiologies (median duration 8.7


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