Continuing on in our discussion of wound dressings, let’s turn our attention to hydrogels and semipermeable foams.
Hydrogels are water- or glycerin-based wound dressings that come in sheets, gels or impregnated gauzes. Hydrogels swell and are able to absorb small amounts of fluids. They are also able to add moisture to dry wounds. They are permeable to water and gas, which makes them less effective at repelling bacteria than hydrocolloids or semipermeable films. Water-based hydrogels may dry easily. Hydrogels can decrease wound pain due to their cooling effect upon application. Most hydrogels are nonadhesive and require a secondary dressing.
Sheet hydrogels can only be used for minimally or moderately draining wounds. They may be used on superficial and partial-thickness wounds, including abrasions, blisters, donor sites, thermal burns, diabetic ulcers, surgery sites, and skin tears. Sheet hydrogels can also be used to provide padding within total contact casts and splints to decrease shear forces and pressure. Amorphous hydrogels are used on dry wounds to create a moist wound environment and are available in spray bottles or tubes. Hydrogels are very effective softening hardened eschar to facilitate the process of autolytic debridement.
Hydrogels are incapable of absorbing large amounts of fluid and should not be used on wounds that are highly exudative. Because they absorb fluid slowly they should not be used on wounds that are actively bleeding. They should also not be used on infected wounds. A skin sealant should be used to protect the skin surrounding the wound from maceration- trimming the sheet hydrogel to the exact size of the wound can reduce the potential of maceration of the periwound area.
Semipermeable foam dressings have two sides-a hydrophilic wound side and a hydrophobic outside. There are composed of polyurethane foam. They are permeable to gas but do not allow bacteria to enter. These dressings are able to transmit moisture vapour at a high rate; however, some of these dressings have a film backing that decreases the amount of moisture vapour that can escape, therefore increasing moisture retention. Semipermeable foam dressings may be thin, while others are thicker to provide absorption and cushioning. They come in both nonadhesive and adhesive forms. The adhesive used in these dressings is not likely to cause damage to frail skin. These dressings should be secured to intact skin. Nonadhesive semipermeable foam dressings will require a secondary dressing to keep them in place. These dressings are easy to apply and easy to remove. As such, these dressings are often used on pressure ulcers.
Semipermeable foam dressings can be used on wounds with light to heavy drainage. They are indicated for use on wound beds that have granulation tissue present or slough covered partial- to full-thickness wounds. They may be used on burns, diabetic ulcers, donor sites, venous insufficiency ulcers and ostomy sites. If these dressings are used on infected ulcers, they should be changed on a daily basis.
Semipermeable foam dressings should not be used on dry or eschar-covered wounds, such as arterial insufficiency ulcers. Nonadhesive foams are ideal for patients with fragile skin. These dressings often roll in areas of high friction, therefore they are often not suitable for heel ulcers in bedbound patients. A skin sealant should be used to protect the periwound from excess moisture.
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Meyers, B (2008). Wound Management: Principles and Practice. 2nd edition. Pearson Prentice Hall. Upper Saddle River, New Jersey. pg. 128-130.
Wound dressings- acute traumatic wounds. The Royal Children’s Hospital Melbourne. http://www.rch.org.au/clinicalguide/guideline_index/Wound_dressings_acute_traumatic_wounds/