Do you worry about the healing process of your surgical incision? Are you prone to wound infections? Or are you dealing with an infected cut?
A topical antimicrobial dressing applied to your surgical wound can help avoid problems as well as cure problematic wounds.
Silver wound dressings have been used for this purpose for a long time. Topical silver is a proven method that comes with pros and cons but is it your best option?
- What are the benefits of using silver in wound care?
- Should you use silver sulfadiazine, alginate, or nitrate, dressings on wounds?
- What is the recent controversy based on studies all about?
- Is topical silver an outdated health care practice?
- Are there better, more up to date solutions?
- And most importantly, when should you use silver wound dressings on your post surgery wound?
Here’s what you should know about topical silver for your surgical wound.
Why Silver? Facts on Silver in Wound Care
Silver has antiseptic, antimicrobial, anti-inflammatory properties and is a so called broad spectrum antibiotic ( acts against a wide range of disease-causing bacteria)
Because of its well known antibacterial properties, silver has been used for ages as a wound care product. In the form of silver wires placed in wounds, silver salt solutions, and nowadays, as a cream, (silver sulfadiazine cream (SSD cream)) and various dressings it was and still is used to prevent and cure infections.
The ancient Romans and Greeks already used silver to disinfect their food supplies and water. They inserted silver in jars to keep water and other beverages fresh. Some of us might remember our parents or grandparents putting silver coins in milk bottles to keep the milk fresh longer.
Also the saying born with a silver spoon in your mouth doesn’t come from nothing. Children were give a silver spoon to suck on. because silver is a natural antibiotic and anti viral mineral.
Apart from its antiseptic abilities silver is said to have additional benefits.
Hippocrates, commonly referred to as the “father of medicine” wrote that silver has beneficial healing and anti-disease properties.
Prior to the 1800s, silver foil was applied to surgical wounds in order to improve wound healing and reduce post operative infections.
In our modern times, silver coatings on urinary catheters and endotracheal breathing tubes in hospitals help prevent bacterial infections.
Silver has particularly been used in preventing and treating high risk wound infection, most commonly on chronic wounds and burns.
Silver sulfadiazine (SSD) is a widely-used silver-based antibacterial cream used on chronic wounds and burns.
The pros and cons of silver as a wound healing agent
Modern science demonstrates that silver ions are relatively effective in fighting off bacteria (germicidal effect) including antibiotic-resistant bacteria such as MRSA and VRE and even viruses, fungi, and parasites. Since post-operative surgical site infections occur a lot, having access to effective treatments is essential.
Silver ions seem to have certain advantages over regular antibiotics because the bacteria can’t develop resistance.
Some laboratory studies suggest that silver, next to its antibacterial properties, may have additional beneficial effects on wound healing. Silver nitrate, nanocrystalline silver, and some silver-containing dressings have demonstrated anti-inflammatory and blood vessel formation stimulating effects.
Various studies have found that silver dressings are linked to the following benefits:
- reduced time to wound healing
- shorter hospital stays
- reduced dressing change frequency
- less local pain during dressing change and thus reduced need for pain medication
- fewer MRSA blood infections caused by MRSA-infected wounds
On the other hand, there are studies and clinical trials showing side effects. Silver is toxic and prolonged used may cause detrimental effects such as skin irritation and even skin tissue damage.
Silver Wound Care Side Effects
Some researchers have concluded that silver has a negative effect on the migration and the shape of skin cells. There are examples where, after prolonged topical use, silver actually delayed the wound healing process.
More recently silver is thought to have so called cytotoxic activity. This means the body’s own skin cells (host cells) may be affected negatively.
Skin cells deformed and one particular source mentions that after 3 weeks keratinocytes and fibroblasts were all eliminated.
Silver dressings are known to occasionally cause local skin discoloration or staining. This side effect however, is harmless and usually reversible.
Is the topical use of silver toxic and harmful?
When addressing the possible toxic effects of topical silver we speak of cytotoxic. Cytotoxic means; toxic to living cells.
Study results are contradictory.
- Some in vitro studies demonstrate that some silver-containing dressings are cytotoxic to skin cells and delay wound healing in animal wound models.
- Other studies however show some silver preparations not to be toxic and promote healing.
In one study the researchers examined the cytotoxic effects of silver on keratinocytes (the predominant cell type (95%) in the epidermis which is the outer layer of the human skin,) and fibroblasts (play a critical role in wound healing and connective tissue).
“These results suggest that consideration of the cytotoxic effects of silver and silver-based products should be taken when deciding on dressings for specific wound care strategies.”
More on this study at PubMed.
Is silver present in the dressings absorbed by the body?
Most of the silver present in the dressing remains there. A small part is either allocated to fight off harmful bacteria or binds to proteins in the wound or wound debris. Only a very small amount is systemically absorbed.
Even if absorbed systemically, silver is excreted mainly via faeces or via urine. Studies show that silver is not absorbed into the central or peripheral nervous systems. (source: PubMed: Lansdown ABG. A pharmacological and toxicological profile of silver as an antimicrobial agent in medical devices.)
How does it work? What’s The Method of Action of Silver in Wound Care?
Let’s keep it simple by not delving into positive and negative isotopes and other technical aspects regarding silver’s method of action.
Simply put, silver impregnated wound dressings release silver ions at the wound surface which kill bacteria. Because of their antimicrobial properties infection is decreased and healing promoted.
Types of silver wound dressings
A wide variety of silver-containing dressings are now commonplace. These include hydrofiber dressings, polyurethane foams and gauzes.
In wound care, elemental silver or silver releasing compounds are utilized in several formulations such as silver sulfadiazine, alginate, and nitrate.
Silver nitrate is no longer widely used as a wound care methodology, but silver sulphadiazine (SSD) and silver releasing dressings remain popular.
Despite its declined use as a wound care agent silver nitrate applicators are still popular, used widely, and reviewed well. They especially seem to work well on mouth ulcers, mouth sores, and skin tag moles.
SSD cream still plays an important role in burn wound management.
Silver is biologically active when it is in soluble form ie, as Ag+ or Ag0 clusters. Ag+ is the ionic form present in silver nitrate, silversulfadiazine, or other ionic silver compounds. Ag0 is the uncharged form of metallic silver present in nanocrystalline silver. Source: PubMed.
Each type of wound has its own specific most appropriate wound dressing. The Mepilex dressing on the photo is often used on low to moderately exuding wounds such as ulcers and partial thickness burns as well as on skin graft wounds.
The controversy on topical silver efficacy and safety
More recent studies have led to a change in perception of this established wound treatment modality. There are two concerns regarding silver wound dressings.
- The question whether or not silver really is (cost) efficient.
- Questions about safety.
According to a recent Cochrane review, silver sulfadiazine may increase healing times – wounds may take longer to heal if treated with this drug and it is therefore not recommended. The study found that:
Although its us as a general wound healing commodity, there is little evidence to support silver sulfadiazine as an effective wound infection agent.
This conclusion however is disputed by other sources.
Other adverse effects due to using silver sulfadiazine dressings on your surgical incision are that silver may form clear fluid on the wound’s surface (aseptic exudate)
Also burning and painful sensations are known to occur although these generally aren’t long-lasting. Less than 1% of patients show hypersensitivity reactions like rashes or an inflammatory skin eruption called erythema multiforme.
The silver ions can lead to local discoloration of the skin, especially if the treated area is exposed to ultraviolet light. Generalized argyria with silver build-up in kidneys, liver and retina has been found in association with excessive long-term use, or repeated use on severe burns. Possible consequences of long term generalized argyria include kidney disorders and anemia.
Silver sulfadiazine (Ag-SD) prevents the growth of a wide array of bacteria, as well as yeast, on the damaged skin. It is a topical antibacterial historically used as a burn cream on second- and third-degree burns.
Opinions on this topical agent differ considerably. Some studies have found that it increased healing times and is therefore no longer recommended. (Source: silver sulfadiazine wiki.)
Other studies however demonstrated that silver sulfadiazine helped wounds heal far better than for example povidone-iodine and bacitracin. (Source: PubMed.)
Is it true that silver dressings do not improve healing rates?
The key to this discussion is appropriate use. Silver dressings are designed for short term use in order to;
- reduce bacteria count in a wound,
- treat local infection
- and prevent systemic spread.
Many silver dressings are not intended to promote wound healing from beginning to end stage. In other words, these dressings have potent properties but should be used sparsely.
Clinical guidelines recommend that silver dressings are used for wounds where infection is already established or an excessive wound bioburden is delaying healing (‘critical colonisation’ or ‘pre-infection’), and that they are used for short periods before re-evaluation.
Why silver should not be discarded as harmful or useless
Silver dressings, despite their potential side effects, should be perceived as an essential counterpart in the wound care mix. Especially due to increasing resistance to antibiotics and the dramatic fall in the number of antibiotics in development.
In case silver dressings are used appropriately, positive effects are confirmed by recent systematic reviews, meta-analyses, and clinicians.
Conclusion of a meta analysis conducted in 2009 was that there is efficacy but more research should be conducted.
“This meta-analysis confirms the effectiveness of silver dressings in wound healing and improving patients’ quality of life. However, it also highlights the need for additional well-designed randomized controlled trials to evaluate the effectiveness of silver-related dressings further.” Source:PubMed
When to use silver dressings
Antimicrobial silver dressings are commonly recommended when:
- there’s the need to reduce bioburden in acute or chronic wounds that are infected or are being prevented from healing by microorganisms. (bioburden: “the number of bacteria living on a surface that has not been sterilized”.)
- they can act as an antimicrobial barrier for acute or chronic wounds at high risk of infection or re-infection
Such wounds include surgical wounds, burns, wounds with exposed bone, or wounds in patients with a weakened immune system, poor circulation, unstable diabetes or neoplastic disease.
Concluding, are silver dressings a viable option when it comes to surgical wound care?
All advantages and disadvantages considered it can be concluded that silver can be a lifesaver in some circumstances. When other measures don’t work it can help treat presumably untreatable conditions.
Think for example about hardly healing wounds that are infected by nasty MRSA bacteria. In some very severe cases amputations are necessary and even worse, life threatening situations may occur.
Especially hospitalized patients, due to their underlying disease or as a result of the surgery, often suffer from a suppressed immune system. This frequently results in wound healing problems, leaving the patient susceptible to wound infections. Due to their compromized immune system these wound infections spread easily and can cause secondary potentially life-threatening bloodstream infections.
With its side effects/ downsides kept in mind silver as a wound care agent should be used carefully, sporadically, and possibly, after weighing other options that may be less invasive.
Silver wound dressing alternatives
A widely used alternative are hydrocolloid dressings. These are occlusive, self-adhering dressings that contain gel-forming agents. One of the main benefits of these dressings is their adherance to both dry and moist wound beds. The wafer type dressing absorbs wound fluids and forms a gel.
Hydrocolloid dressings however, are not recommended for infected wounds, wounds with heavy exudate, and sinus tracts.
Another popular alternative to silver dressings are Medihoney dressings. Contrary to silver impregnated wound products these unique dressings can be used throughout all phases of wound healing.
What’s more, these dressings harness a “powerful and long-lasting antimicrobial activity – similar to that of ionic silver – but without the associated toxicity of ionic silver”.
When silver dressings are the choice of treatment they should be used with caution, only on short term and with evaluation at regular intervals.
Silver dressings should not be used on wounds where bioburden is not a problem, ie they
should be reserved for use in wounds with or at risk of high bioburden or local infection
Which silver dressings are best for surgical wounds?
First an explanation of the different types of occlusive dressings and their recommended uses.
- Alginates and hydrofibers are best for moderate to heavy exudate and help stop bleeding (hemostatic properties)
- Foams provide thermal insulation and are best for wounds with mild to moderate exudate
- Hydrocolloids and films protect the skin from friction and shearing. Designed to absorb light to heavy wound fluid (exudate)
- Hydrogel dressings (and cellulose) are best for dry and painful wounds since they provide moisture to the wound. (source: Beyond wet-to-dry: A rational approach to treating chronic wounds.)
The best silver wound dressings for post-surgery use are those that harness the power of ionic silver, releasing silver at a controlled level for broad spectrum antimicrobial action, without harming tissue cells.
Even when ionic silver is suspended in the dressing to control its release over a period several days it is still advised to use silver appropriately.
A wide range of randomized controlled trials (RCTs) have been done. Here are outcomes from studies done on surgical wounds.
A clinical trial comparing the healing process among colorectal patients treated with either a silver nylon dressing (Silverlon) versus gauze showed that:
The incidence of surgical site infection was significantly lower in the silver nylon group than
in the control group (p=0.011) (Krieger BR, et al. Dis Colon Rectum 2011; 54: 1014-19)
Another treatment comparison among the same type of patients (colorectal surgery) comparing Aquacel AG vs no dressing concluded that:
“The silver Hydrofiber dressing applied post-operatively for 7 days reduced bacterial colonisation at the surgical site in comparison with no dressing. The rates of surgical site infection between the silver dressing and no dressing groups were not statistically significantly different.” (Siah CJ, et al. J Wound Care 2011; 20(12): 561-68)
“Aquacel Ag® was shown to be an effective and safe dressing for a variety of wound types.” (Source: PubMed)
Patients recovering from open surgery and traumatic wounds treated either with Aquacel AG or Providone-iodine gauze experienced the following outcomes:
The silver dressing was significantly better than the iodine dressing for overall ability to manage pain, overall comfort, wound trauma on dressing removal, exudate handling and ease of use. Rates of complete healing between the two groups were not significantly different. (Jurczak F, et al. Int Wound J 2007; 4(1): 66-76)
Especially Convatec’s hydrofiber Aquacel AG dressings are very well-reviewed on Amazon.
A clinical trial among pilonidal sinus (a cyst or abces located at the cleft of the top of the buttocks) patients comparing Silver Hydrofiber with dry sponge dressing found that:
Number of dressings used and time to complete closure were significantly lower in the silver group than in the control group. (Koyuncu A, et al. EWMA Journal 2010; 10(3): 25-27)
Mepilex AG soft foam dressings by Molnlycke are bestsellers too. They are absorbent as well and the SafeTac technology ensures the dressings don’t stick to the wound bed.
Both brands are popular choices for those who are in the higher risk group for developing infections.
If you just want to make use of the benefits of silver as a wound healing agent but don’t want or need to shell out big bucks for dedicated antibacterial dressings, American Biotech Labs Silver Gel might be a better choice. The gel is affordable and very well reviewed. Just make sure to be cautious and not to over-use it.
What Do You Think About Silver in Wound Care?
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- Image Hippocrates: Wikimedia.
- Silver chemical symbol: Creative Commons.
- Product images copyright belongs to their respective owners.
- Much of the content in this article is based on a report by Wounds International. For more in-depth information read Appropriate Use of Silver Dressings in Wounds.