Micro-contouring in Clinical Practice: the Impact on Infection

One of the key challenges in wound management is infection prevention. This can be achieved through control of the superficial bioburden — ie, wound microbial colonization. One consideration in infection prevention is that antimicrobial effectiveness may be a factor of the different physical properties of dressings.¹ The ability of a dressing to conform to the wound surface appears to be a factor in the prevention of wound infection as a result of the antimicrobial protection provided at the wound-dressing interface.² However, the choice of the optimal dressing for skin ulcers, diabetic lesions, or surgical wounds remains controversial.³Previous studies have demonstrated that the physical properties of hydrofiber interact with exudate components,⁴ modulating inflammatory cells and permitting a higher number of macrophages to populate the wound lesion.⁵ It is also known that hydrofiber dressings promote and maintain a moist wound interface, a key factor for an optimal healing process,⁶ due to the conformability of their cohesive gel.   In our experience, use of this hydrofiber dressing, both with and without silver, facilitates the formation of a “biological wall,” micro-contouring at the wound edge (see Figure 1). This wall forms as the result of the interaction between the re-keratinization of the lesion margin and the hydrofiber in the dressing, and provides both a barrier for the residual exudate and a protective barrier.   Observation with digital microscopy shows that the biological wall is located at the external border of the wound, sealing the lesion margins and acting as a natural barrier to prevent bacterial contamination (from the wound periphery toward the wound bed). Removal of the biological wall reveals an already active wound-margin of newly forming keratinocytes moving towards the center of the wound during the re-epithelialization process (see Figure 2).   Histological examination of the biological wall found it to contain approximately 80% keratin (corneocytes with ortho- and parakeratosis), with sparse amorphous, oval, slightly eosinophilic structures. Following the dressing change, the formation of a new protective micro-contouring biological wall adjacent to the new line of developing keratinocytes wall is observed. (see Figure 3).   We hypothesize that the structure formation induced only by the silver-containing hydrofiber dressing drives the centripetal direction of the wound repair process and keratynocite migration, preserving lesion border from exudate cytolytic activity— that is, micro-contouring seems to promote the ongoing process of wound healing by inducing natural wound sealing through a specific conformability mechanism, ensuring the ideal conditions for wound repair via optimal moisture balance. In addition, the histological barrier induced by the interaction between silver-containing hydrofiber and lesion border prevents infection from possible pathogens on periwound skin. The specific wound healing-mechanism induced by this dressing may be a predictive factor for the effectiveness of the dressing.   To explore the healing potential of this hydrofiber dressing, a 62-patient study was conducted. Patients with venous leg ulcers, posttraumatic wounds, vasculitis, and mixed ulcers were treated using this dressing and etiologically appropriate care. They were followed-up once weekly for a mean period of 12 weeks. Results suggest that the properties of a specific hydrofiber dressing (Aquacel®, ConvaTec, Skillman, NJ) — the only hydrofiber dressing currently available in our geographic area — may induce healing. These preliminary observations support the need for further investigation, via controlled studies, to address the possible correlation between the formation of a biological wall on the lesion border and an accelerated healing process. A difference may exist in healing mechanism between core and border lesions.

References

1. Parsons D, Bowler P, Myles V, Jones S. Silver antimicrobial dressings in wound management: a comparison of antibacterial, physical and chemical characteristics. WOUNDS. 2005;17:222–232. 2. Jones S, Bowler P, Walker M. Antimicrobial activity of silver-containing dressings is influenced by dressing conformability with a wound surface. WOUNDS. 2005;17:263–270. 3. Chaby G, Senet P, Vaneau M, Martel P, Guillaume JC, Meaume S, et al. Dressings for acute and chronic wounds. Arch Dermatol. 2007;143:1297–1304. 4. Coutts P, Sibbald G. The effect of a silver-containing hydrofiber dressing on superficial wound bed and bacterial balance of chronic wounds. Int Wound J. 2005;2:348–356. 5. Hoekstra MJ, Hermans MH, Richters CD, Dutrieux RP. A histological comparison of acute inflammatory responses with a hydrofiber or tulle gauze dressing. J Wound Care. 2002;11:113–117. 6. Richters CD, du Pont JS, Mayen I, Kamperdijk EWA, Dutrieux RP, Kreis RW, et al. Effects of a hydrofiber dressing on inflammatory cells in rat partial-thickness wounds. WOUNDS. 2004;16:63–70.

Dr. Greco is a dermatologist and Chief of the Centre of Specialization for Treatment and Prevention of Cutaneous Ulcers, Frosinone ASL, Italy; email: firstauthor-greco@yahoo.com. 

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