In 2018, Aderibigbe and Buyana reported that polymers in the form of hydrogels were able to absorb fluid, making them a suitable choice for minimally exudative wounds. However, in their distended state, the hydrogel subgroup of these products became unstable (perhaps making them a poor choice for extensively exudative wounds), tended to dehydrate, and often needed a secondary dressing, which could lead to wound maceration.22 Most commonly used for wounds with minimal exudate, these dressings shine when used in nominally exudative dry wounds to promote autolytic debridement and hydrate the wound that has formed an eschar.
Hydrocolloid dressings are another type of bioactive wound dressing. These dressings are composed of 2 layers: an inner hydrophilic layer and an outer vapor-permeable layer that promote a moist wound environment. Hydrocolloid dressings assist in hydrating dry eschar wounds and have slight absorbency for exudative wounds. These dressings are not designed to be changed daily and can remain in place for 3 to 6 days. In a 2008 extensive review article, Thomas compared the utility of these dressings in patients with superficial or partial thickness burns, donor sites, surgical wounds, and minor traumatic wounds with basic wound dressings. The results of the review suggested that hydrocolloid dressings conferred statistically significant advantages in measures of decreased pain, healing times (decreased in donor sites by 40%), mobility restriction, and number of dressing changes.27 Although more expensive than basic dressings, the longevity of the hydrocolloid dressing helps defray the original cost. Unfortunately, as these dressings remain in place and continue absorbing exudate, they can take on a very unpleasant odor.
A 2013 Cochrane database review comparing hydrocolloids with foams, alginate, basic wound dressing, and topical treatment found no statistical difference between hydrocolloids and basic wound dressings in patients with diabetes who have noncomplex foot ulcers.28 In 2014, Pott and colleagues suggested a slight superiority in the performance of polyurethane foam dressings over hydrocolloid dressings used in pressure ulcers in older adults.29 In a large pooled analysis in 2010, Davies compared foam to hydrocolloid dressings used in exudative wounds and reported that in 11 of 12 studies, foam dressings were superior to hydrocolloid in terms of exudate management, conformity to the wound, ease of use, decreased trauma and pain at dressing changes, and reduced odor of the wound.30
Foam dressings. These products are typically composed of silicone or polyurethane. Consisting of 2 to 3 layers with a hydrophilic surface, foams are cut to approximate the wound size and serve to wick the macerated wound products to a secondary dressing above the foam. The micropores in the foam matrix absorb exudate from the wound bed while maintaining moisture equilibrium in the wound by donating back moisture to the wound, creating an environment conducive to wound healing. Foam dressings can be combined with various antiseptics (silver, GV/MB, etc) and serve as a delivery vehicle of those products directly to the wound surface.
A 2011 review comparing 8 studies found no difference among foam products available at that time in the use for chronic wounds.31 However, newer products on the market today have produced intriguing results with chronic wounds.
In 2017, Woo and Heil observed that chronic wounds treated with foam products containing GV/MB produced significant improvement when measured at week 4 in the areas of mean wound surface area (42.5%), decrease in baseline Pressure Ulcer Scale for Healing scores (from 13.3 to 10.7), wound coverage by devitalized tissue reduced (from 52.6% to 11.4%), and mean upper and lower wound infection scores were reduced by 75%.32 Further, the researchers reported a moist wound bed was achieved at dressing changes with polyvinyl alcohol (PVA) foam dressing. This led to the presumption that adequate moisture balance and autolytic debridement were facilitated using GV/MB antibacterial PVA foam dressings.
Many foam products on the market today exert an antibacterial effect on the wound bed. Antibiotic properties of various foam dressings create a microenvironment hostile to bacterial growth.32 In addition, the antibacterial properties combined with foam products contribute to the following: autolytic debridement, absorptive qualities (which reduce the bioburden of the wound), and maintenance of moisture in the wound bed. These qualities contribute significantly to the effectiveness of foam products with antibacterial properties.32 The correct balance of moisture in the wound has been identified as a superior environment and perhaps the most important component in chronic wounds.4 Foam dressings are less painful to change, easier to change, and in this case report, contributed to faster wound healing than gauze alone. In 2016, a study by Lee and colleagues suggested that the makeup of the foam product, defined as smaller pore and uniform cell size (foam density), resulted in greater permeability and better moisture absorption and retention capacity, contributing to improved wound healing.33
In 2004, Sibbald and colleagues reported that in a 4-week study of nonhealing chronic wounds, foam wound dressing impregnated with sustained-release silver compared with foam dressing without silver resulted in a reduction in wound size (50% vs 30%, respectively), decreased fluid leakage (27% vs 44% respectively), and reduction in ulcer size measured from baseline (45% vs 25%, respectively).34
In a 2006 study, Varma and colleagues compared sterilized, saline-soaked, nonmedicated polyurethane industrial upholstery foam in nonhealing wounds used in patients with diabetes with conventional techniques using topical antibiotics, hydrocolloid or hydrogel dressings as necessary, and desloughing agents as controls. At the end of a 3-month follow-up period, 100% of the wounds of the foam group had healed compared with 29.2% of the control group. Additionally, the time to wound healing was less than half for the foam group (22.5 days) compared with the control group (52 days), and the time to granulation and epithelialization was faster in the foam group.35
In a 2012 meta-analysis, Aziz and colleagues reported that silver-impregnated dressings and topical silver were no better or worse than controls in preventing wound infection and promoting the healing of burn wounds.36 The authors also noted that the nonsilver dressing groups continuing povidone-iodine, ionic hydrogel, or silicone-coated dressing showed reduced healing time compared with the silver-containing group.36 This is intriguing because silver has long been used as a standard for the treatment of burn wounds.