Dressing (medical)

A dressing can have a number of purposes, depending on the type, severity and position of the wound, although all purposes are focused towards promoting recovery and protecting from further harm. Key purposes of a dressing are:

• Stem bleeding – to help to seal the wound to expedite the clotting process;
• Protection from infection – to defend the wound against germs and mechanical damage;
• Absorb exudate – to soak up blood, plasma, and other fluids exuded from the wound, containing it/them in one place and preventing maceration;
• Ease pain – either by a medicated analgesic effect, compression or simply preventing pain from further trauma;
• Debride the wound – to remove slough and foreign objects from the wound to expedite healing;
• Reduce psychological stress – to obscure a healing wound from the view of the patient and others.

Ultimately, the aim of a dressing is to promote healing of the wound by providing a sterile, breathable and moist environment that facilitates granulation and epithelialization. This will then reduce the risk of infection, help the wound heal more quickly, and reduce scarring.[2]

Two packages of gauze. One 10 cm by 4.1 m. The other 5 by 5 cm.

Three types of gauze

Depiction of a dressing on a face from a painting from 1490

Historically, dressings were made of a piece of material, usually a cloth, but the use of cobwebs, dung, leaves and honey have also been described.

However, modern dressings[3] include dry or impregnated gauze, plastic films, gels, foams, hydrocolloids, alginates, hydrogels, and polysaccharide pastes, granules and beads. They all provide different physical environments suited to different wounds:

• Absorption of exudate, to regulate the moisture level surrounding the wound- for example, dry gauzes absorb exudate strongly, drying the wound, hydrocolloids maintain a moist environment and film dressings do not absorb exudate;
• Gas permeability and exchange, especially with regard to oxygen and water vapour;
• Maintaining the optimum temperature to encourage healing;
• Mechanically debriding a wound to remove slough.
• Pressure dressings are commonly used to treat burns and after skin grafts. They apply pressure and prevent fluids from collecting in the tissue.[4]

Dressings can also regulate the chemical environment of a wound, usually with the aim of preventing infection by the impregnation of topical antiseptic chemicals. Commonly used antiseptics include povidone-iodine, boracic lint dressings or historically castor oil.[5] Antibiotics are also often used with dressings to prevent bacterial infection. Medical grade honey is another antiseptic option, and there is moderate evidence that honey dressings are more effective than common antiseptic and gauze for healing infected post-operative wounds.[6] Bioelectric dressings can be effective in attacking certain antibiotic-resistant bacteria[7] and speeding up the healing process.[8]

Dressings are also often impregnated with analgesics to reduce pain.

The physical features of a dressing can impact the efficacy of such topical medications. Occlusive dressings, made from substances impervious to moisture such as plastic or latex, can be used to increase their rate of absorption into the skin.

Dressings are usually secured with adhesive tape and/or a bandage. Many dressings today are produced as an "island" surrounded by an adhesive backing, ready for immediate application – these are known as island dressings.

[9]Modern Wound Dressings:Main characteristic of maintaining the moisture level is the foremost advantage of modern dressings. They also become a part of drug delivery for the healing of the wound

Hydrocolloid Dressings: Due to the gel forming nature, hydrocolloids are widely used modern dressings with inherent wound healing properties. Gelatin, pectin, and carboxymethylcellulose are the gel forming agents and can be formulated as films and sheets They are used in healing of moderately exuding wounds like pressure sores, traumatic injuries, and minor burns. Due to their absorbent nature, their water vapor permeability also gets increased while forming gels. These dressings are held by an occlusive outer cover which is preventing water vapor exchange.

Alginate Dressings: Alginate dressings are prepared in the form of foams or fibrous sheets. Due to their higher absorbency, alginate forms gels when it is in contact with exudates. This characteristic feature makes alginate dressing minimize bacterial contamination . The calcium ions present forms a cross linked polymeric gel when in contact with fluid. When it is compared with hydrocolloid dressings, alginate dressings last longer on the wound surface . Human macrophages are activated to produce TNFa and, so the inflammatory signals are initiated . The calcium ions released, also aids in clotting mechanism. Moderate to heavily exuding wounds can use alginate dressings. These dressings are not suitable for dry wounds covered with necrotic tissue

Hydrogel Dressings: Hydrogels are hydrophilic materials, swellable and insoluble dressings. They are prepared from synthetic polymers. The form of the hydrogel dressings may be gel, film or solid sheet [15,16]. Significant amount of water is entrapped or absorbed by the hydrogels and retained. Hydrogel dressings are suitable for light to moderately exuding wounds. They can be used as primary or secondary wound dressings. Due to their low mechanical strength, handling becomes a tedious when it is used alone

Semi-Permeable Adhesive Film Dressings: These semipermeable dressings were initially prepared from nylon derivatives with an adhesive polyethylene support. Due to nylon, the ability of absorbing water is limited. They tend to wrinkle and become difficult to apply on the wound site. Due to their flexibility, the conformity is good, and the films are transparent.Extensibility, water vapor permeability and conformability differ with the material used.

Film Dressings: Films are semi-occlusive dressings, which can be used directly on the wound or used as a secondary dressing for a nonadhesive dressing. Hence, the exchange of water and oxygen between the outside environment and wound bed is permitted. Film dressings can be used for moderately exuding wounds to avoid fluid trapping.

Foam Dressings: Porous polyurethane foam or film forms foam dressings. They provide thermal insulation and maintain a moist environment. Foam dressings are highly absorbent and have a high moisture vapor transmission rate. The absorbency of foam dressings can be controlled by foam properties. They are suitable for light to moderately exuding wounds.

Biological Dressings: Biological dressings are prepared from biomaterials and also called as bioactive dressings. They are biodegradable and help in new tissue formation. These dressings can be incorporated with antimicrobial compounds and growth factors to be delivered at the wound site. Chitosan, collagen and hyaluronic acid are also used as dressing for the delivery of drugs to the wound site.

Application of paraffin gauze on the cellulitis wound on the leg.

Applying a dressing is a first aid skill, although many people undertake the practice with no training – especially on minor wounds. Modern dressings will almost all come in a prepackaged sterile wrapping, date coded to ensure sterility. Sterility is necessary to prevent infection from pathogens resident within the dressing.

Historically, and still the case in many less developed areas and in an emergency, dressings are often improvised as needed. This can consist of anything, including clothing or spare material, which will fulfill some of the basic tenets of a dressing – usually stemming bleeding and absorbing exudate.

Applying and changing dressings is one common task in nursing.

• History of wound care#Wound-site dressing
• Hydrocolloid dressing
• Hydrogel dressing
• Field dressing (bandage)