Most types of foam dressings are made of polyurethane (PU) foam. PU is the same material many mattresses are made of. HOWEVER, the PU used in foam dressings contains other additives to give it better absorption properties. Most modern foam dressings have several layers. The inner layer is often made of non-adherent material like silicone which is gentle to granulation tissue. The core of the dressing is the PU layer with absorptive additives. The outer layer is usually made of a thin film which allows some evaporation but is usually impermeable for fluids and microbes from the outside.
It can be challenging to directly compare different types of foam dressings as they use different technologies. Producers will often claim that their unique technology is far superior to the products from competitors, and it can be confusing for us to decide which we find most suitable. Although PU foam dressings behave pretty similar, there are often considerable differences as to maximal absorption volumes, how well the dressing retains the absorbed exudate in the core of the dressing and how well they can absorb thick viscous exudate.
Foam dressings are among the most versatile dressings in wound care. They can be used on almost any type of wound with little to moderate amounts of exudate. They absorb quite well and maintain an optimal moisture balance beneath the dressing. There is very little you can do wrong with a foam dressing - it is a safe choice. In high exudate wounds, however, you should use a superabsorbent dressing. For wounds up to about 1 cm in-depth, they can be used as a primary dressing. For deeper wounds, you will need some sort of wound filler and then use the PU foam as the secondary dressing. Some PU foams do not have a film as the outer layer - i.e., they are permeable on both sides - and these can be used as wound fillers.
Foam dressings come in all shapes and sizes. There are special designs for certain anatomical regions like the sacrum or heel areas. They come with or without adhesive edges. Most modern foams use silicone adhesive technology, making removal at dressing change far more gentle.
Regular PU foam dressings do not transfer any substances into the wound. They simply absorb and retain exudate. Other PU foams contain antimicrobial substances like silver, PHMB, or iodine, for example. Some contain anti-inflammatory drugs like Ibumetin, which can help manage pain in wounds.
Foam dressings are also useful for preventing skin injuries from pressure- and shear forces. These can be applied to the skin in vulnerable areas in high-risk patients. The dressing can be lifted gently every day to inspect the skin, and the dressing can be applied again and used for about one week. Be aware that using a foam dressing in this way does not replace other off-loading practices like repositioning the patient every two hours and other interventions. In these situations, the foam dressings are merely a supplement to other standard preventive practices.
In summary, foam dressings have the following indications:
useful as general " all-round" wound dressings
Suitable for wounds with little - moderate amounts of exudate
In wounds up to 1 cm in-depth, they can be used as a primary dressing
In deeper wounds, they are used as a secondary dressing
Some foam dressings can be used as a wound filler for deeper wounds
Can be used to protect bony prominences and other anatomical regions at risk to pressure-and shear forces
Foam dressings containing Ibumetin can be tried in patients with painful ulcerations
Figure 1 Most producers have PU foam dressings that come in various shapes to conform to different anatomical regions. In addition, they come with and without adhesive borders. Sometimes, patients with very sensitive skin can react to adhesive materials, even with the gentlest silicone. Therefore it can be useful to have a stock of foams without adhesive material. The image above shows some of the products in Convatecs line of Aquacel PU foams. copyright: Convatec
Figure 2 Foam dressings are a versatile tool to prevent skin injuries from pressure- and shear forces. Smith& Nephew have made a useful poster showing how the heel dressing can be adapted to fit almost any anatomic region of the body. Click on the image above to get to a pdf visible at a higher resolution. You can print out the pdf and hang it up at your workplace! copyright: Smith& Nephew
Foam dressings without additives
Figure 4 With "foam dressings without additives," we mean PU foams that do not contain any active substances that influence the wound directly. These foam dressings simply absorb wound exudate and maintain an ideal moist wound environment. They represent one of the most common types of wound dressings used worldwide.
Foam dressings with silver technology
Figure 4 PU foams with silver coatings are useful in wounds with a high bacterial burden. Note that the image above only represents a small selection of these types of products available. The lower row shows products by Polymem. These foams differ from the others in that they also contain a surfactant in addition to silver. Surfactants are substances that aid in the cleansing process of wounds.
Foam dressings with other antimicrobial additives
Figure 5 Both Kendall AMD and Suprasorb X + PHMB use PHMB as the antimicrobial agent in the dressing. Iodofoam ( bottom left) contains iodine. Hydrofera Blue ( bottom right) contains two organic dyes - methylene blue and gentian violet- as antimicrobial agents.
Foam dressings with analgesic properties
Figure 6 As far as we know, Biatain Ibu is the only foam dressing that contains an active analgesic ingredient. It contains the substance Ibumetin, which is a non-steroidal anti-inflammatory analgesic. Paradoxically, many caregivers often forget that this alternative exists. It can be beneficial in, for example, painful venous ulcers. To work, it needs to be in contact with the wound bed. Therefore, it is only suitable for shallow ulcers up to about one centimeter in depth. From our own experiences with the product, we have seen that only about 30-40% of our patients have reported a significant improvement in pain. However, for those 30 - 40 %, it has been a game-changer. Our conclusion is: if you have a patient with a fairly shallow ulcer that is painful - give this dressing a try. Already within a few days, the patient should notice an improvement. If the patient does not experience any significant pain relief within 5-7 days, the product can be discontinued.
Foam dressings with surfactants
If you have read our chapter on wound cleansers, you will be familiar with the term " surfactant." A surfactant works like soap and disrupts the surface tension on water. Surfactants are seen as substances that can disrupt biofilm.
Polymem foam dressings are one of few foam dressings that contain a surfactant and glycerine. Combining these two substances appears to aid the cleansing process of a wound significantly. The surfactant breaks up necrotic tissue at the surface while the glycerine moistens the wound bed. Studies have shown that Polymem has anti-inflammatory properties and seems to have an analgesic effect too.
Polymem foam dressings were initially developed for burn care but can be applied to any type of wound. The products labeled " WIC" are permeable on both sides and can be used as wound fillers. The product range comes with and without adhesive borders and alternatives containing silver. They come in different sizes and rolls.
This type of foam dressing is marketed as a multi-functional foam dressing because it performs multiple functions simultaneously. At our clinic, we performed a trial where we only provided Polymem foam dressings at the hospital's outpatient clinic to manage all types of wounds for an entire year. Our goal was to show that when providing a simple wound dressing algorithm with one kind of dressing, most wounds can be managed adequately. In addition, the junior doctors and nurses with limited wound care experience felt confident in their choice of dressing.
Figure 7 Polymem is probably the most versatile foam dressing on the market. With a minimal stock of maybe three or four Polymem products, you can cover most of your needs in dressings. The so-called multifunctional foam dressings contain a cleansing agent ( surfactant) and glycerine to keep an ideal moisture level. The Max variant is a high absorption foam. Polymem WIC is a wound filler for deeper wounds. The product comes with and without silver and is available in different sizes and shapes.