Overview 

Hydrocolloids are interactive as they use wound fluid to form a moist gel at the wound interface. They consist of carboxymethyl cellulose, gelatins and pectins which form the hydrocolloid base which is secured onto a backing of polyurethane film or foam. Hydrocolloids have a low moisture transmission rate of less than 300 g/m2/24 hours. They can promote wound debridement and angiogenesis, reduce pain through keeping the nerve endings moist and absorb excess exudate. Depending on the level of exudate, the dressing can stay in situ for up to 6 days. Odour on dressing removal is worst with heavily exuding or infected wounds (8). Examples: Comfeel, Granuflex, Tegaderm Hydrocolloid. Indications: mild-moderate burns, small abrasions, wounds with low to moderate exudate. Pros: Waterproof, conforms well to wound, gel formation provides moist wound environment. Cons: Gel can be mistaken for infection, moderate to heavy exudate will overwhelm dressing, impermeable to oxygen so use with caution in wounds with suspected anaerobic infection. Notes: Should be avoided on dirty and infected wounds, wounds where muscle, tendon or bone is exposed and if the wound requires frequent dressing changes (8). Patients should be warned that initially, the wound may smell and appear larger (8).

 

Description of System

It’s usually a multi-layered structure, consisting of an outer layer to provide protection and a supporting material, present in form of a film, foam or fibre. Onto this supporting material, is a laminated composite consisting of an adhesive through which hydrophilic particles are distributed. The typical supporting materials are nonwoven polyester fibres and semipermeable polyurethane films while the hydrophilic component of the adhesive may contain several components such as synthetic polymers including gelatin and cellulose derivatives (8).

 

Mechanisms Involved

Hydrocolloid dressings form and maintain a moist wound environment that supports wound healing. Moisture under occlusive dressings such as hydrocolloids can help promote angiogenesis, increase the number of dermal fibroblasts, stimulate the production of granulation tissue, and increase the amount of collagen synthesised. In the presence of wound exudate the hydrocolloid forms a hydrophilic gel that facilitates autolytic debridement of the wound by softening and rehydrating necrotic tissue and slough (8).

 

Some dressings form a cohesive gel mostly contained within the adhesive matrix; others form more mobile, less viscous gels that are not retained within the structure. As gelation occurs, the dressing becomes more permeable, resulting in the loss of water vapour through the dressing and increaseing the ability of the product to absorb exudate (57). The dressing needs to be changed when the gel leaks out. To avoid frequent changes, the dressing should have a diameter at least 2cm bigger than the wound. They can be used in the presence of necrotic material but tend to have problems with overwhelming exudates and in anaerobic bacteria colonisation (8). Tegasorb combines moisture vapour permeability with absorbency and comfortability. It’s also transparent, allowing for wound observation (8).

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Costs and Evidence

Hydrocolloids may provide a cost-effective option in patients with pressure ulcers and venous leg ulcers vs gauze. This may be due to a decrease in the number of clinic visits required during treatment and faster healing times (57). They are relatively inexpensive. An example by Coloplast Ltd includes Comfeel Plus Transparent, its prices ranging from £0.66 - £3.42 (54). A systematic review and meta-analysis performed by Palfreyman et al (2007) examined healing rates of dressings in venous leg ulcer management. The author concluded that there was insufficient evidence of effectiveness to recommend one type of dressing over another and stated that, wherever possible, simple non-adherent dressings should be applied under compression. An earlier cost-effectiveness study by Harding et al (2000) measured the cost per healed wound using published clinical trial data. They concluded that hydrocolloid dressings were more cost-effective than gauze in the treatment of venous leg ulceration (57).