Wound Dressings

Wound dressings primarily contribute to the wound healing process by protecting the wound from microorganisms and infection. Ideal wound dressing materials are flexible, biodegradable, allow gas transmission, and possess protective properties. In addition, they must control the absorption of exudate from the injured area. While traditional dressings are effective in the initial phase of healing by preventing bleeding and shielding the wound from the environment, their sole use can cause them to dry out and adhere to the wound surface in exudative wounds. Today, natural polymers materials compatible with human tissue are used as common in wound treatment. The most common natural biopolymers applied for wound healing include cellulose, alginate, chitosan, heparin, hyaluronic acid like polysaccharides and collagen, gelatin, fibrin, keratin, and silk fibroin. In addition to their biodegradability, natural cellular interactions, and structural similarity to the extracellular matrix, biopolymers can respond to physiological signals and activate growth factors that support the natural healing mechanism.

Characteristics of an Ideal Wound Dressing

• Supports the transport of cells and various biochemical factors.
• Facilitates appropriate cell adhesion and migration, enabling cell interaction and attachment.
• Alters cell behavior by applying mechanical and biological stimuli.
• Mimics a three-dimensional microenvironment similar to the extracellular matrix.
• Removes exudate.
• Maintains moisture control.
• Allows gas transmission.
• Reduces wound surface necrosis.
• Can be easily removed and replaced.
• Biocompatible.
• Biodegradable.
• Elastic.
• Non-toxic.
• Reduces pain in the wound area.
• Low cost.

Wound Dressings According to Their Efficacy in Wound Healing

Passive Wound Dressings

Passive wound dressings protect the wound area from external factors and possess only a few of the ideal dressing characteristics. Gauze bandage and bandages are examples of passive wound dressings. When these dressings adhere to the wound site, removal and replacement become difficult and may cause trauma to the wound bed, so they are generally used as secondary covering in wound closure.

Interactive Wound Dressings

Interactive wound dressings maintain moisture, allow gas transmission, and have a transparent structure. They include polymeric film and foam-based dressings. Their ability to accelerate wound healing, prevent, and treat infection is limited.

Bioactive Wound Dressings

Bioactive wound dressings are also known as active wound dressings. They provide active support to wound healing through bioactive substances they deliver. These dressings are derived from polymers such as hydrocolloids, alginate, collagen, and chitosan.

Currently Used Wound Dressings

Gauze, Cotton Pad, Bandage

These materials are inadequate in maintaining a moist wound bed. Their use in the wound area results in adhesion to the wound bed after absorption of exudate. Removal or replacement may cause trauma to the wound bed. Their low cost and ease of production increase their usage.

Film Dressing

Film dressings allow observation of the wound healing process due to their transparent structure. They permit the exchange of O₂, CO₂, and water vapor between the wound and the environment. Their However impermeability to liquids limits their use by causing exudate accumulation.

Hydrocolloids

They consist of two layers. The outer layer acts as a barrier, while the hydrocolloid layer forms a gel upon contact with exudate by absorbing fluid, creating a moist environment for the wound bed and stimulating autolytic debridement.

Alginate

Alginate possesses a pharmacological property due to the presence of calcium ions. Upon contact with wound exudate, their high liquid absorption capacity forms a strong hydrophilic gel, maintaining the lesion at an ideal moisture and temperature level. Alginate dressings should not be used on dry wounds because they require moisture; otherwise, they may dehydrate the wound and negatively affect healing. If not removed at the appropriate time, they can cause tissue maceration and trauma.

Hydrogel

Hydrogel dressings are typically transparent or clear, allowing easy visualization of the wound surface without removal. When applied to dry wound surfaces, they hydrate the wound and create the moist environment necessary for healing. The degradation rate of hydrogels can also be adjusted, making them suitable for use as drug carriers and biologically active substance. On the other hand, due to their high water content, hydrogels tend to have low absorption capacity. This low absorption can facilitate exudate accumulation, leading to wound maceration and bacteria proliferation. They exhibit low adhesion to the wound bed, necessitating the use of a secondary dressing such as film or foam.

Foam

Foam dressings are based on polyurethane or silicone. They are semi-permeable and can be hydrophilic or hydrophobic with a bacterial barrier. They preserve wound moisture by providing thermal insulation and prevent wound damage during removal. Their insufficient ability to prevent bacterial contamination is a main factor that limits their use.