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By Liza G. Ovington
Wound and Continence Management
Home Health Care Division, Southeast Florida
Columbia Healthcare Corp.
Fort Lauderdale, FL
(Editor’s Note: This is another in a continuing series on the various types of dressings available for wound care and their strengths and weaknesses.)
While transparent films are most suitable for lightly exuding wounds or as secondary dressings, and hydrocolloids are known primarily for their adhesive characteristics, foams are useful for absorbency. The wound care clinician will turn to this category of dressing to manage moderately or heavily exuding wounds.
As a category, foam dressings are the most variable from one brand to the next. In their simplest form they are sheets of foamed solutions of polymers. The most common polymer used is polyurethane. Foaming the polymer creates small open cells that can hold fluids. Cell size can be controlled during the foaming process. Foam products can also possess additional features such as film backings, adhesive coatings, island configurations, and different thicknesses. Combinations of foam thickness, film backings, and adhesive coatings are what leads to the diversity of foam dressings. (For a list of foam manufacturers, see chart above.)
Foams are available in traditional thickness versions and in extra thin versions. Foams may have a waterproof film covering on their top surface. Often this film covering is the same material as a transparent film dressing. The foams may also have an adhesive coating over the wound contact side or as a border on their perimeter. Foams also are available in island configurations. Most often, foams are in sheet form, but there are "cavity" versions of foams that consist of chopped foam pieces contained in a "bag" of permeable material that are designed to be placed into a deep wound. At least one brand of foam contains a surfactant within the foam to aid in its fluid handling properties.
Foams as a category (except for the extra thin versions) represent one of the most highly absorbent wound management materials. Foams are an appropriate choice for managing wounds with moderate to heavy drainage. The cellular structure of the foams allows them to absorb wound draining and pull it away from the wound bed, thereby decreasing maceration as compared to traditional absorbent gauze products. The fact that their physical bulk and softness provide a cushion and are often comforting and comfortable to the patient is an additional benefit.
Clinicians sometimes find that foam products are difficult to use in certain anatomical areas due to their "memory," or tendency to want to retain their shape rather than conform to the shape of the patient’s anatomy. It may be difficult to retain a foam sheet in a gluteal fold, for example.
There are several brands of extra thin foams available. These products have a top film coating that makes them waterproof and are coated on one side with a very mild adhesive. To the naked eye, they do not appear to be a foam but rather an opaque, thick film. However, they are foams, and they do have a modicum of absorbency. They are found to be well suited for skin tears and other minor wounds that have only slight drainage. These extra thin foams are especially resilient and conformable, making them a useful dressing on fingers and toes.