Wound Care Update: A Plan for Battling Infection

• By Alan Braverman
• Oct 01, 2005

In order for a wound to heal normally, the following must be in place: early and appropriate intervention, a functioning immune system, adequate blood flow to the area, control of chronic diseases, an understanding of the expected healing time and, most importantly, control of bacterial bioburden. One of the major obstructions to wound healing remains bioburden, or an overgrowth of pathogens present in and around the chronic ulcer. Compromised or open skin and tissue provide a perfect environment for the growth of microorganisms. As organisms increase and set up residence in wounds, healing can be delayed and a real risk for clinical infection and possible sepsis can occur. Preparing the wound bed for healing, therefore, should include a plan for eradicating all "bugs" that can halt healing and eventual wound closure.

A successful plan involves many natural and manmade substances that have antimicrobial activity. Many of these compounds, however, not only kill the pathogens, but additionally pose a threat to the proliferating granulation tissue, fibroblasts and keratinocytes -- cells that help a wound heal. This issue has caused many a clinician to evaluate the appropriate antimicrobial treatment in chronic wounds. Gone are the days of using antiseptics like Betadine solution (povidone iodine), Dakin's solution (sodium hypochlorite), hydrogen peroxide or acetic acid. Another concern is bacterial resistance. Due mostly to antibiotic use, Methicillin-Resistant Staphylococcus Aureus (MRSA) has shown a five-fold increase from 1985 to 1995.

Silver's Long History

A safe, non-cytotoxic option is silver, which has been used for more than 3,000 years. In ancient history (before we had bottled water), silver vessels were used for preserving water and helped make it portable. Early pioneers carried pure silver coins in their canteens to prevent disease. In the late 1800s, silver nitrate and silver iodine solutions were applied to the eyes of newborns to prevent congenital blindness caused by gonorrhea. After that, the age of antibiotics emerged and silver wasn?t used as frequently, that is, until the 1960s when it re-emerged as an antimicrobial used to prevent infections in burn injuries.

The problem with silver nitrate solution is that it stained the skin and tissue and needed to be applied repeatedly throughout the day. Another form that gained popularity, a stabilized form with sulfadiazine, helped prevent staining but still needed to be applied frequently. The form we know as silver sulfadiazine, or Silvadene, was not very practical for advanced wound care.

In the past decade, silver has made a comeback as perhaps the safest and most effectively used antimicrobial in advanced wound care. The ionic form is safe and doesn't stain the skin. Many types have a sustained release, allowing silver to remain in place for up to a week while still being effective. Silver also kills a wide variety of bacteria, like MRSA and Vancomycin-Resistant Enterococcus (VRE), fungi and viruses.

Manufacturers offer most of the current dressings that we know and recognize with a silver component.

Silver and Its Chemistry

Silver is a naturally occurring element, a heavy metal with the atomic symbol Ag. It is shiny, lustrous and highly reflective, making it a popular choice for jewelry, silverware and other ornaments. Metallic silver is the most common state in which silver exists in nature. Silver metal is extremely stable but under certain conditions will undergo a transition to its ionic form (Ag+), which is highly reactive. In other words, the ionic form wants to bind with something that has a negative charge. When it reacts, a compound is formed. So, silver can exist in three states: as a metal, as a compound and as a free dissolved ionic form.

When in an aqueous medium, such as a wound fluid, a silver compound will typically dissociate into silver ions (Ag+) and its counterion, such as a chloride ion (Cl-). Some silver compounds, especially highly soluble ones like silver nitrate, will produce a huge and possibly toxic concentration of the silver ion upon dissolution in wound fluids or aqueous mediums. Others, such as the silver chloride compound, will form just the right concentration of silver ions in wound fluids or aqueous mediums, making this form suitable for a wound environment because it is non-toxic, yet lethal to microorganisms.

The transition of silver among the various forms has enabled wound care manufacturers to develop strategies for preserving silver in their products until the products are applied to patients. This is called the silver reservoir. Some manufacturers have chosen to use a metallic form of silver, thus relying on processes like oxidation to form the antimicrobial ionic form. Other manufacturers have developed a more sophisticated delivery system that employs unique compounds that are already in an ionic form and need only the fluid of a wound to release and become active. Some dressings that utilize metallic reservoirs deliver bolus doses of silver at extremely high concentrations compared to dressings that use carefully selected silver compounds. For example, dressings containing metallic reservoirs of the nanocrystalline variety release a bolus dose of very high levels of silver. These dressings, while effective in quickly killing microorganisms, have associated questions on toxicity, staining and reduction in the rate of healing. Silver compound reservoirs typically sustain the delivery of silver for longer periods of time while killing pathogens safely with a lower concentration of silver.

Silver has a very low potential for allergy or sensitivity problems. Many patients that have shown an allergy or reaction when using silver sulfadiazine cream actually had a reaction to the sulfa component of the product, not the silver. Allergies to silver jewelry are fairly common -- though it's not the silver that causes the problems, but rather a high nickel content. Many of today's silver dressings deliver small amounts of silver, so they're not likely to be locally toxic or cause systemic absorption.

How Silver Works

All silver products rely on moisture to mobilize delivery to the wound environment. Moisture in the air and in the wound fluid is sufficient for some dressings. A product specialist or sales representative can provide information on the delivery of various silver dressings, since some metallic varieties require the application of sterile water, which is labor intensive and often impractical. Very little silver is necessary to be considered effective, which is known as "oligodynamic" or active with few molecules.e safest silver dressings release 1-2 parts per million (ppm), killing pathogens without harming the tender granulation tissue. Any more than this can be toxic.

The beauty of silver is that bacteria and other pathogens can?t mutate and become resistant like they can with antibiotics and other antimicrobials. (Resistance to silver has been created in the laboratory, though it appears that any resistance developed is transient, unstable and difficult to propagate.)

Silver works better and more efficiently; it attacks many of the cell's vital structures and functions including the cell wall, the membrane transport, the RNA function, the DNA synthesis and the protein function. Silver has been used since antiquity and still has no known, clinically significant resistance. Because silver attacks a microorganism in a multitude of ways, a strain would have to develop mutations against a multitude of attack pathways--a clinically unlikely scenario. That's music to a clinician's ears. Some bacteria are only susceptible to certain, specific antibotics. Silver kills across a spectrum of bacteria (aerobic, anaerobic, gram-positive and gram-negative), viruses and fungi, and is more universally effective than antibiotics, more broadly effective than chlorine and provides a cost-effective, non-toxic alternative. Many dressings are offered over-the-counter (OTC), making them simple to acquire and cost-effective.

When to Recommend Silver

Silver dressings provide the perfect prophylactic environment against infection by reducing bioburden (bacterial population) in the wound-dressing interface in various types of wounds. Wounds that could be appropriate for silver dressings are chronic ulcerations, wounds that have high levels of exudate (wound fluid), wounds with odor, or wounds with possibly high or critical bacterial loads. Such wounds may also require local or systemic prescription drug treatment. Wounds that are marked by redness and/or swelling, wounds that are slow healing or stagnant, wounds with necrotic tissue and wounds associated with pain can all be addressed with dressings containing silver. Patients with diabetic wounds and patients with abnormal laboratory values might also benefit from the use of silver dressings. Silver, especially the ionic varieties, provides an anti-inflammatory action as well. Since most chronic wounds are stuck in the inflammatory stage, this is a huge benefit.

Dressing Caveats

Consider dressings that don't stick to the patient or wound bed when removed, thereby causing pain. Also, look for a variety of applications to address different wound needs. Search for "smart," safe, targeted silver that doesn't kill keratinocytes and fibroblasts, the building blocks of a healing wound. Seek dressings that don't stain and don't require any special delivery systems such as sterile water application.

Remember to always match the needs of the wound to the dressing. Is the wound wet or dry? Is the wound flat or does it have depth or an open space? Also, think about the change frequency, the location of the wound and where the patient resides. For example, a drier wound may need a silver hydrogel, whereas a wet wound requires a silver alginate/CMC combination or a silver hydrogel sheet. Wounds in difficult to dress areas may do well with a silver powder.

Now every wound can have a silver lining. Get in touch with a wound care product manufacturer, take a look at these versatile and effective dressings, and begin incorporating them into a care plan. State-of-the-art wound care is now at your fingertips!

This article originally appeared in the October 2005 issue of HME Business.