Hydrogel dressings consist of 90% water suspended in a gel made of insoluble hydrophilic polymers that swell up on contact with water, which are typically synthetic molecule polymers such as polyvinylpyrrolidine and polymethacrylate combined with alginate dressings, that control fluid exchange on wound-bandage interface with sodium and/or other molecules in wound discharge being exchanged for hydrogel compounds.
Hydrogel provides moisture to enable painless debridement of infected and necrotic tissues, promoting granulation while encouraging complete healing. Hydrogel dressings have high water content which makes them not completely absorbent and appropriate only for wounds with light to moderate exudation. Skin maceration and/or multiplication of microbes can result from water accumulation which can lead to foul smelling infected wounds. The cooling hydrogels can alleviate some pain, which flatten out the wound surface contours and prevent dead space from getting infected, while providing support for surface healing.
Hydrogel sheets are polymeric cross linked molecules capable of absorbing some water helping to prevent wounds with light exudation from becoming to wet with semipermeable polymer film backings. Evaporation is regulated with the backing and keeps wounds from drying out. Sheets can be cut to shape and size, and may be used as secondary or primary dressings.
Amorphous hydrogels are primary dressings that flow freely and enter all of the wound crevices regardless of size and depth, that must be typically covered by gauze to keep in place, frequent dressing changes are required.
Impregnated hydrogels are a primary dressing which is formed by dispersing the gel into sponge/gauze pad/strips to apply over wound areas, or pack deep wounds, which are then typically covered by a secondary dressing to seal the wound.
These types of dressings are in many respects the ideal dressing. Applied to dry skin wounds they keep them clean by promoting removal of necrotic or infected tissues via autolysis. They keep wounds closed, warm, and moist. Hydrogels will not adhere to wound surfaces which allows metabolites to pass freely, while providing a cooling effect on the wound, making them pleasant to the patient. Wound reepithelialization is promoted as they mimic skin structure and encourage new growth. Drugs can be incorporated into them to enhance wound healing.
Hydrogel dressings are suitable to be used on all stages and types of wounds, with exception to presence of heavy exudate, painful wounds, radiation wounds, minor burns, dry wounds, as well as partial and full thickness wounds. These types of dressings cannot absorb large amounts of fluids and are not suitable for wet wounds which could become infected and macerated. These types of dressings are easy to tear and difficult for patients to change their own dressing due to low mechanical strength.
Use of hydrogel dressings for most wounds is supported by all current research, due to the ability of hydration and loosening of necrotic tissue, debridement and autolysis promotion, and absorbing moderate amounts of exudate and sloughing discharge.
