Wound Care

Gale Encyclopedia of Surgery, (2004) by René A. Jackson, Crystal H. Kaczkowski

Wound care

Definition

A wound is a disruption in the continuity of cells—anything that causes cells that would normally be connected to become separated. Wound healing is the restoration of that continuity. Several effects may result with the occurrence of a wound: immediate loss of all or part of organ functioning, sympathetic stress response, hemorrhage and blood clotting, bacterial contamination, and death of cells. The most important factor in minimizing these effects and promoting successful care is careful asepsis, which can be accomplished using aseptic techniques when treating a wound.

Description

Wound healing is a biological process that begins with trauma and ends with scar formation. There are two types of tissue injury: full and partial thickness. Partial thickness injury is limited to the epidermis and superficial dermis, with no damage to the dermal blood vessels. Healing occurs by regeneration of other tissues. Full thickness injury involves loss of the dermis extends to deeper tissue layers, and disrupts dermal blood vessels. Wound healing involves the synthesis of several types of tissue and scar formation.

The three phases of repair are lag, proliferative, and remodeling. Directly after injury, hemostasis is achieved with clot formation. The fibrin clot acts like a highway for the migration of cells into the wound site. Within the first four hours of injury, neutrophils begin to appear. These inflammatory cells kill microbes, and prevent the colonization of the wound. Next the monocyte, or macrophage, appears. Functions of these cells include the killing of microbes, the breakdown of wound debris, and the secretion of cytokines that initiate the proliferative phase of repair. Synthetic cells, or fibroblasts, proliferate and synthesize new connective tissue, replacing the transitional fibrin matrix. At this time, an efficient nutrient supply develops through the arborization (terminal branching) of adjacent blood vessels. This ingrowth of new blood vessels is called angiogenesis. This new and very vascular connective tissue is referred to as granulation tissue.

The first phase of repair is called the lag or inflammatory phase. The inflammatory response is dependent on the depth and volume of tissue loss from the injury. Characteristics of the lag phase include acute inflammation and the initial appearance and infiltration of neutrophils. Neutrophils protect the host from microorganisms and infection. If inflammation is delayed or stopped, the wound becomes susceptible to infection and closure is delayed.

The first principle of wound care is the removal of nonviable tissue, including necrotic (dead) tissue, slough, foreign debris, and residual material from dressings. Removal of nonviable tissue is referred to as debridement ; removal of foreign matter is referred to as cleansing. Chronic wounds are colonized with bacteria, but not necessarily infected. A wound is colonized when a limited number of bacteria are present in the wound and are of no consequence in the healing process. A wound is infected when the bacterial burden overwhelms the immune response of the host and bacteria grow unchecked. Clinical signs of infection are redness of the skin around the wound, purulent (pus-containing) drainage, foul odor, and edema.

The second principle of wound care is to provide a moist environment. This has been shown to promote reepithelialization and healing. Exposing wounds to air dries the surface and may impede the healing process. Gauze dressings provide a moist environment provided they are kept moist in the wound. These are referred to as wet-to-dry dressings. Generally, a saline-soaked gauze dressing is loosely placed into the wound and covered with a dry gauze dressing to prevent drying and contamination. It also supports autolytic debridement (the body's own capacity to lyse and dissolve necrotic tissue), absorbs exudate, and traps bacteria in the gauze, which are removed when the dressing is changed.

Preventing further injury is the third principle of wound care. This involves elimination or reduction of the condition that allowed the wound to develop. Factors that contribute to the development of chronic wounds include losses in mobility, mental status changes, deficits of sensation, and circulatory deficits. Patients must be properly positioned to eliminate continued pressure to the chronic wound. Pressure reducing devices, such as mattresses, cushions, supportive boots, foam wedges, and fitted shoes can be used to keep pressure off wounds.

Providing nutrition, specifically protein for healing, is the fourth principle of healing. Protein is essential for wound repair and regeneration. Without essential amino acids, angiogenesis, fibroblast proliferation, collagen synthesis, and scar remodeling will not occur. Amino acids also support the immune response. Adequate amounts of carbohydrates and fats are needed to prevent the amino acids from being oxidized for caloric needs. Glucose is also needed to meet the energy requirements of the cells involved in wound repair. Albumin is the most important indicator of malnutrition because it is sacrificed to provide essential amino acids if there is inadequate protein intake.