Key Considerations For Utilizing Silver Dressings
- Volume 19 - Issue 6 - May 2006
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What The Research Says About The Efficacy Of Silver
In deciding what specific topical silver to use in a particular clinical situation, one has to identify the differences in rate, amount and delivery of the silver cation to the wound bed. Unfortunately, most of the current literature demonstrates only the in vitro comparisons of silver dressings to specific organisms as opposed to comparisons in actual in vivo environments.2,4,6
Thomas and McCubbin compared antimicrobial effects of four silver-containing dressings on three organisms.4 In this study, they found Acticoat (Smith & Nephew) has a much more rapid onset of action and better performance than the other three products.4 Most of the other products tested still had antimicrobial effects. However, they did not have as a rapid of an effect as Acticoat.
Another study by Ovington examined the rate of silver cation release and whether a faster rate was more clinically significant than a slower rate of cation release.2 Of all the dressings tested, each achieved the same reduction in bacterial counts within two hours. This is still less than the typical timeframe between dressing changes.2
Other studies have discussed the amount of silver in dressings and whether too much silver in the wound bed would be harmful to wound healing. It seems that the amount of silver in a particular product is not as important as the amount and rate of silver cations released to the wound bed.
In wounds with low bacterial counts, Poon and Burd noted that high silver cation-releasing products can actually bind to the fibroblasts and epithelial host cells, causing delayed wound healing.7 Innes, et. al., studied the effects of silver on wounds with low bacterial counts and found a delay in epithelialized wounds such as skin graft donor sites.3 The authors compared Acticoat versus absorbent polyurethane foam on skin graft donor sites (a clean, superficial and epithelializing wound bed). These findings did not support the use of Acticoat as a skin graft donor site dressing.
Other Pertinent Pointers On Using Silver Products
Although some studies show the deleterious effects of silver on wounds, the impact of silver depends on not only the type of wound bed but also the amount of silver that is being released in the wound. For example, in an infected deep wound, one would need to utilize a silver product with a large amount of silver cation release compared to a clean superficial wound with fragile neo-epithelialization.
In regard to the delivery of silver in wounds, Thomas and McCubbin found that Contreet H (Coloplast) was effective after an extended period of time due to the fact that it is a hydrocolloid. This product contains an undisclosed silver complex that is activated by the uptake of wound fluid.4 This illustrates the importance of proper use of wound care products in specific wound types. The dressing vehicle is mainly dependent on the wound bed’s characteristics. For example, one should not use a silver impregnated alginate dressing on a dry, non-exudative wound. The dressing delivery mechanism will affect the overall performance of the product in terms of its ability to control moisture maintenance or exudate management in the wound.2
There are some important considerations when clinicians are looking to apply these silver dressings on wounds. For example, the product information guides for Acticoat and Silverlon (Argentum Medical) state that one should use sterile water (not saline) on their respective products. The chloride ion in normal saline reacts with the pure metallic silver coating of the Silverlon product to form silver chloride crystals, reducing the release of ionic silver (Ag+, the form necessary for the antimicrobial properties of silver).8
Smith and Nephew reinforces this same concept with Acticoat.9 In addition, the company also suggests not using papain-urea debriding agents, which tend to be inactivated by the silver salts of the Acticoat.10 Driver discusses these points in presenting the clinical role of silver dressings.1