Hydrocolloid dressings gain in popularity

Question: Our facility uses hydrocolloid dressings a great deal for our patients with chronic wounds. What are some of the advantages and disadvantages of hydrocolloids over other types of dressings, and under what circumstances do they work best?

(Editor's note: This month's answer is provided by Liza Ovington, PhD, CWS, president, Ovington & Associates, Fort Lauderdale, FL.)

Answer: Hydrocolloid dressings have steadily grown in popularity and are now one of the most widely used wound dressings. There are some clear reasons why: They are relatively easy to use, last several days between changes, do not cause trauma when removed, stay in place very well, and can adhere even when the skin is moist. Hydrocolloids were the first occlusive dressings that were able to handle wound exudate. This contrasts with films (the very first occlusive dressings). They also are "uniform" dressings, meaning you can cut off a piece of any size or shape you choose (trim the edges, cut out a hole, etc.) and it will still work as designed. You can't say that about other dressing types.

The most effective use of hydrocolloid dressings seems to be for non-necrotic, granulating superficial wounds that produce low to medium amounts of exudate. High levels of exudate may overwhelm hydrocolloid dressings. They also provide effective occlusion and can have a hydrating effect on dry wounds. Some evidence suggests that their occlusive nature prevents the spread of bacteria.

The rise to prominence of hydrocolloids, however, has not necessarily been paralleled by a commensurate increase in knowledge about the dressing's properties and its advantages and disadvantages compared with other types of dressings. There are also notable differences among the many brands on the market. Let's start with a quick overview of hydrocolloid dressings.

The most distinctive feature of hydrocolloid dressings is their ingredients. One such ingredient is sodium carboxymethylcellulose (NaCMC) mixed with gelatin. These are fixed to a carrier such as polyurethane foam or film. When the dressing contacts wound exudate, the absorptive reaction results in a viscous gel, and ultimately an absorbent, self-adhesive, waterproof dressing. The exact properties of the gel vary depending on the exact formulation, but the following is true for most hydrocolloid dressings:

· Initially, hydrocolloid dressings are impermeable to water vapor. As more gel forms, their permeability increases. This characteristic allows the dressing to handle exudate without being overwhelmed, up to a point.

· Hydrocolloids adhere to moist and dry skin. This versatility is another factor that has made them popular.

· Hydrocolloid dressings can be changed every three to five days, which is considered a relatively long time and is considered another one of their advantages. Typically, removal does not cause pain because the dressings don't stick to the wound or surrounding tissue. If changed daily, however, they can cause skin stripping.

· Side effects such as contact dermatitis have been associated with hydrocolloids, but documented reports are rare.

· Various brands of hydrocolloids look pretty much the same, but their performance varies considerably when it comes to permeability and ability to absorb wound exudate. In the May 1998 issue of Wound Care, we reported on a United Kingdom study showing that the differences in fluid-handling capacity among 12 different hydrocolloid dressings varied from 0.5 gm to more than 7.5 gm (adjusted for size and thickness of the dressing). Those results were attained in a lab, so performance in clinical practice may be different. Another lab study was performed in the United States and published in the January 1998 issue of Ostomy Wound Management. This study showed that in 15 different hydrocolloid dressings, fluid-handling capacity varied from 75% to 647% of a dressing's weight. Absorption also varied depending on whether the fluid was water, saline, or actual wound exudate.

Hydrocolloids, of course, are not the most suitable choice for all chronic wounds. Heavily exuding and very deep wounds may not respond well to them. There's also some controversy over whether or not they should be used for diabetic foot ulcers. But hydrocolloids have remained popular because most product newcomers have not demonstrated markedly better performance or cost-effectiveness. One of the newer dressings, polyurethane foam, is promoted as an alternative to hydrocolloids, and a clinical study did show that the foam surpassed the hydrocolloid in terms of dressing leakage and odor protection. However, it didn't seem to improve wound healing itself.

Many studies have shown that hydrocolloids outperform wet-to-dry gauze dressings (i.e., faster healing times, less pain). And despite the gradually declining costs of hydrocolloids, many health care professionals still opt for materials and methods that are now considered obsolete.

Another advantage of hydrocolloid dressings is that because the dressing does not require frequent changes, nursing care devoted to this activity is reduced significantly, as are the costs of material. Studies also have shown that hydrocolloid dressings caused less pain during removal than did other materials, such as paraffin gauze, when applied to skin graft donor sites. The hydrocolloids also appeared to facilitate faster healing of these sites.

In other research, patients with lacerations, abrasions, and minor operation incisions experienced less pain, needed less pain medication, and handled daily activities better with hydrocolloid dressings than with nonadherent, nonocclusive dressings. Showering and bathing did not affect the benefits of the hydrocolloid because it remains adherent even when wet. How or why hydrocolloids reduce pain is not fully understood, and it's not certain whether this observed effect is indeed real. One theory holds that the occluded environment leads to reduced production of arachidonic acid metabolites, which are thought to play a role in pain.

Hydrocolloids also are useful for diabetic foot ulcers under certain circumstances, but they may not always be the best choice. Foot ulcers often are deep, which alone can preclude their use, though hydrocolloids may be a good choice as a secondary dressing in these instances. In addition, diabetic patients are more prone to infections than non-diabetic patients - a consequence of the underlying disease. For this reason, some wound care professionals have been afraid to totally occlude these wounds. Traditionally, hydrocolloids have been one of the most occlusive types of dressings available.

Despite findings showing that occlusive dressings may foment necrosis in diabetic foot wounds, many health care professionals still prefer hydrocolloids for the protection of these ulcers once necrotic tissue has been removed. As one researcher said, "the best advice would seem to be to use caution in patients with diabetes."

The ability of hydrocolloids to aid in infection control also has been researched. Any occlusive dressing that promote a moist environment will enable endogenous phagocytes to fight infection. The physical barrier of the dressing will keep out exogenous bacteria. Some data show there are fewer airborne bacteria dispersed when you change a moist dressing as compared with a dry dressing.

In one study, 30 patients with lower-extremity ulcers of varying etiologies were treated with an occlusive hydrocolloid dressing twice a week for a maximum period of 12 weeks. No antibacterial chemotherapy was utilized. A culture was taken of the exudate of the ulcer before commencement of treatment and weekly or biweekly thereafter.

The results showed a mixed flora with prevalence of Staphylococcus aureus. Subsequent bacterial cultures showed a persistence of the original flora, but there was no correlation between the type of flora present and clinical evidence of infection or between the type of flora present and the rate of healing of the ulcer.

In another study, the bacterial flora of chronic venous ulcers treated with an occlusive hydrocolloid dressing were studied over eight weeks. The flora were generally stable. Once a species was present, it remained, with the exception of Pseudomonas, which appeared to be inhibited by the dressing. Twelve out of 20 ulcers contained anaerobic bacteria, and healing did not appear to be impaired by the presence of any particular species of bacteria.