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What are silver dressings?
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Silver has been used as a topical antimicrobial agent for millennia in wound care and is currently available in a variety of wound dressings. In modern medicine, silver is found in the form of silver oxide, silver sulphadiazine, silver nitrate, ionic silver and nano silver, used in the prevention and treatment of infection in both acute and chronic wounds.
It is available in a range of formulations including creams, ointments and dressings impregnated with elemental silver or silver-releasing compounds. However, silver dressings differ considerably in the nature of their silver content and in their physical and chemical properties.
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What are the types of silver dressing available?
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A variety of silver dressings are available, including foams, hydrogels, alginates, hydrofiber, hydrocolloids, and polymeric films. These may be classed into four types:
- Nanocrystalline silver dressings that release silver into the wound
- Dressings that release a silver compound rather than silver ions
- Dressings that absorb wound fluid and bacteria into the dressing where antibacterial action takes place, and
- Dressings that release silver while simultaneously absorbing wound fluid and bacteria
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How do silver dressings work?
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The silver ion (Ag+) is the active antimicrobial agent in silver dressings. In dressings, silver:
- Provides bactericidal action due to the Ag+ ion
- Inhibits the bacterial DNA replication process
- Reduces the wall strength of bacteria
- Increases the permeability of the bacterial cytoplasmic membrane and inhibits the respiratory enzymes, causing asphyxia of the bacteria.
Not all silver products are the same and the manufacturer's instructions should be considered when treating different types of wound. It is also important to consider the amount of fluid (exudate) present.
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How to select an appropriate silver dressing?
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Selection of a silver dressing should be guided by:
- Volume of exudate
- Condition of skin
- Location of wound
- Use under compression
- Presence of infection
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What precautions should be followed while using silver dressings?
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Wound care specialists should ensure that the patient is not sensitive to any additives or agents in silver. Most silver products come with a precaution warning and should be avoided before magnetic resonance imaging (MRI) scans or with electronic measurement procedures.
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What can be the performance indicators for silver dressings?
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- Fluid-handling capacity
- Film backing in some silver products
- Secondary dressing may be required
- Self-adherent/non-adherent
- Antimicrobial
- Can be used under compression
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Why some silver dressings have film backing?
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Some silver dressings have a film-backing which prevents fluid leaking out of the back, which could prevent bandages or other dressings used to fix them in place from becoming wet.
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What is adherent and non-adherent silver dressing?
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There is a wide variety of adherent and non-adherent silver dressings on the market. Non-adherent silver dressings do not stick to the skin and therefore, need to be secured in place by another dressing such as a tape or light retention bandages. These dressings are suitable for use on fragile or damaged skin, whereas adhesive dressings may result in skin damage.
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Is the use of dressings with silver sulfate an issue with sulpha allergies?
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Some people are allergic to a family of drugs called the sulfonamides, or sulfa drugs. These are completely different from the silver sulfate molecule found in Restore Contact Layer Dressing, Silver and Restore Foam Dressing, Silver Non-Adhesive. Sulfate has nothing to do with the sulfonamide molecule, other than the two names sound somewhat similar.
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How does silver affect bacteria?
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Ionic Silver (Ag+) can affect bacteria in a number of ways:
• The silver ion (Ag+) alters the bacterial cell membrane structures, leading to a loss of the cell contents
• The silver ion (Ag+) disrupts the function of the intracellular enzyme systems and alters bacterial respiration and nutritional metabolism of the bacterium
• The silver ion (Ag+) binds to the base of the bacterial DNA chains and blocks DNA replication
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What is the PPM (parts per million) of silver that is effective?
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Research suggests that 5-50 PPM of silver is toxic to most bacteria.
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What is the difference between bactericidal and bacteriostatic and why is this important?
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The term bacteriostatic refers to the inhibition of growth and reproduction of bacteria. All Restore dressings with silver deliver bactericidal levels of silver, meaning they kill the bacteria. According to many wound articles and experts, "In antimicrobial activity testing, an active such as silver may be considered bactericidal if it achieves log10 reductions of 3 log10 or greater".
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