28.5 Wound Care and Dressing

Common Lower Leg Ulcer

Common chronic ulcers of the lower extremities may appear similar but require vastly different treatment approaches, as demonstrated in Table 28.4. To determine the appropriate treatment, it is important to understand the origin and pathophysiology of the wound. For example, venous leg ulcers (VLU) most often occur on the medial lower leg, are irregularly shaped, and present with extensive drainage (Figure 12.34). Skin can appear scaly, brown, red, or edematous. Treatment focuses on compression and wound management. VLUs involve changes to tissue as a complication of chronic venous insufficiency. A VLU can develop after a minor injury if the patient’s lower extremity circulation is compromised.

Arterial ulcers, although also caused by impaired perfusion, commonly occur on the ankle or toes of the patient (see Figure 12.35). These ulcers can be very painful, and the pain can increase at night. Wounds appear punched out or circular and are typically dry. Arterial wound treatment focuses on moist wound healing. Due to the compromised circulation, compression is contraindicated unless the appropriate studies, such as an ankle-brachial index (ABI), have been performed.

Diabetic foot ulcers (DFUs) are often located on the plantar, or bottom portion, of the foot and are caused by angiopathy and neuropathy (Figure 28.11). DFUs typically have a round, punched-out appearance with a callus surrounding the wound. DFUs are managed with off-loading devices and debridement of the devitalized tissue.

Figure 28.11 Diabetic foot ulcers have a punched-out appearance and have a thick callous surrounding the wound. (credit: modification of “Diabetic Foot Ulcer” by StatPearls/National Center for Biotechnology Information, CC BY 4.0)

Cleansing Agents

Wound bed preparation begins with cleansing the wound. The goal in cleaning the wound is to remove as much devitalized tissue, bacterial burden, and exudate as possible without damaging proliferative cells. Appropriate noncytotoxic solutions include saline, commercial wound cleansers, and potable tap water. Cleansing of a dirty or infected wound requires 4 to 15 psi irrigating force and may involve antiseptics. Antiseptic solutions are generally preferred if the goal is to kill bacteria in an infected wound or one with abundant necrosis. Common examples of cytotoxic antiseptic solutions include Dakin’s solution (sodium hypochlorite) and acetic acid, both of which provide temporary cleansing until the wound bed is clean.

Foam Dressings

Foam dressings are very versatile dressings that can be used for almost any wound with exudate. Foam dressings are available in a variety of shapes and sizes, with or without borders; they may be adhesive or nonadhesive and may or may not have antimicrobial agents. Foam dressings can be used as either primary or secondary dressings. They are appropriate for low- to moderate-exudating wounds, as well as heavily draining wounds. Foam dressings help maintain a moist wound environment through absorption capacity while allowing enough moisture to remain in the wound bed to facilitate healing. The frequency of dressing change is dependent on the amount of exudate and the absorptive capacity of the dressing. Manufacturer guidelines commonly indicate the absorptive capacity of the dressing and the recommended timetable for changing the dressing.

Hydrocolloid

Hydrocolloid dressings are occlusive, wafer-like dressings made of gelatin materials. They are self-adhesive. Some hydrocolloids have a thin border around the dressing. Because the dressing is occlusive, water vapor cannot escape, and the dressing must absorb the moisture secreted by the skin together with the wound exudate. The dressing interacts with wound exudate, which allows for atraumatic removal. Hydrocolloids are appropriate for low-exudating, shallow wounds; because they are occlusive dressings, they are contraindicated in infected wounds. Wear time varies from three to seven days depending on the volume of exudate.

Alginates and Hydrofibers

Alginate dressings are often referred to as calcium alginate or seaweed dressings. These dressings are nonwoven and composed of polysaccharide fibers derived from seaweed. The dressings are available in ropes or sheets. Some alginates are impregnated with antimicrobial agents, such as silver. Alginate dressings absorb a moderate amount of exudate; some form a gel as they absorb the exudate, which allows for atraumatic removal. The frequency of dressing changes depends on the exudate amount but on average ranges from daily to every three days. Typically, alginates are reserved for moderately to highly draining wounds; they are not appropriate as the primary dressing choice for wounds with exposed tendons or bone.

Hydrofiber dressings are similar to alginates; however, hydrofibers are composed of sodium carboxymethylcellulose, making them highly absorptive. Similar to alginates, when the hydrofiber absorbs exudate, it forms a gel. Hydrofibers are available in ribbon or sheet form and can be plain or antimicrobial in design. Hydrofibers are also nonadherent, which means that a secondary dressing or cover dressing is always required. The frequency of dressing changes depends on the exudate amount but on average ranges from daily to every three days. Hydrofibers are indicated for moderately to heavily draining wounds and contraindicated in dry wounds, wounds with eschar, and third-degree burns.

Hydrogels

Hydrogels are designed to hydrate wounds through donation of water. There are two types of hydrogels: amorphous and solid gel dressings. Amorphous hydrogels are a combination of water and polymers, which can be applied directly to the wound bed or to another dressing such as gauze. Amorphous hydrogels are available as viscous liquids and impregnated dressings, such as gauze, ropes, and strips. This type of hydrogel is typically used in wounds with depth or tunnels and for wounds with minimal exudate. Solid gel sheets are available with and without borders. They can absorb varying amounts of exudate and offer a cooling effect. Hydrogel dressings are ideal for any wound with minimal to no exudate. The frequency of dressing changes depends on the wound and dressing selected but on average changes occur about every three days.

Contact Layers

Contact layers are dressings placed in direct contact with the wound bed to help maintain a moist and protective environment. Contact layers are porous, allowing exudate to pass through for absorption by a secondary dressing while protecting the wound base from trauma. Typically, a contact layer is a single layer of nonadherent dressing material impregnated with petroleum derivatives; it may also be silicone-based. Contact layers are most appropriate for surface wounds, particularly extremity wounds. If utilized in a wound with depth, contact layers are appropriate for clean wounds (that is, wounds free of necrotic tissue). Contact layers are inappropriate for wounds with viscous exudate, wounds with undermining or tunneling, or third-degree burns. These dressings can remain in the wound for as long as one week, depending on the wound and manufacturer guidelines.

Transparent Film

Transparent film dressings are thin sheets of plastic or acrylic with a layer of adhesive on one side. Transparent films are widely used as primary and secondary dressings and most commonly to protect IV sites. A common brand name of transparent film is Tegaderm by 3M. The technology involved with transparent film allows for water vapor to transpire and evaporate out of the dressing, which in terms of wound care promotes autolytic debridement—a process known as moisture vapor transmission. Despite moisture vapor transmission, transparent films have no absorptive capacity. They are used for shallow, dry, or minimal exudate wounds or as cover dressings. Wear time varies and is dependent on wound depth, exudate level, location, and indication. When used as a primary dressing, the typical wear time is three to seven days.

Gauze

Gauze is a commonly used dressing that can be used for wound cleansing and as a wick, wound filler, or cover dressing. Gauze is available in a variety of forms, including rolls, sheets, or strips; it is also available in antimicrobial forms. Nonwoven gauze is usually preferred as a dressing, as woven gauze contains loose strands. All gauze can be cut to fit the wound bed and “fluffed” to help fill the wound depth. Overpacking a wound with gauze may interfere with perfusion and compromise granulation tissue development, so it is important to abide by the adage “fluff not stuff” when using gauze to pack a wound. Gauze is more appropriate as a secondary dressing; as it dries fairly quickly, it should be moistened prior to placement in contact with the wound bed.

Antimicrobial Wound Dressings

Management and treatment of infected and critically colonized wounds is a common issue facing clinicians. Ideal antimicrobial dressings provide sustained antimicrobial activity and a moist healing environment; they absorb and retain bacteria and are comfortable, conformable, and atraumatic upon removal. We will discuss some of the more commonly seen antimicrobial dressings. Each provides a unique but familiar mechanism of action to address wound care needs.