An acute wound can be defined as a traumatic disruption in the integrity of the skin, including the epidermis and dermis. The goals of wound management are to restore tissue continuity and function, minimize chances of infection, repair with minimal cosmetic deformity, and distinguish wounds that require special care. The principles of wound management will be emphasized over specific repair techniques in this chapter. The following chapters will discuss specific details regarding different wounds. Appropriate management of a wound will result in optimal healing while minimizing the risk of complications.1,2 This includes wound cleaning, debridement of the wound edges if needed, and determination of whether a wound requires closure, when wounds are closed, and how wounds will be closed.3
PHYSIOLOGY OF WOUND HEALING
THE THREE PHASES OF WOUND HEALING
There are three phases of wound healing (Figure 114-1). The first phase involves coagulation and inflammation. The second phase is the proliferative phase. The final phase is the re-epithelialization or remodeling phase.
Phase I consists of coagulation and inflammation, also known as the vascular phase. It occurs in the first 5 days. A fibrin clot forms a transitional matrix that allows for the migration of cells into the wound site over a period of 72 hours. Elevated levels of immunoglobulin G and wound C-reactive protein are found in this phase of wound healing. Inflammatory cells (i.e., macrophages, monocytes, and neutrophils) break down soluble wound debris, kill microbes, prevent microbial colonization, and secrete cytokines.4 The cytokines signal fibroblasts to initiate phase II. Most sutured wounds develop an epithelial covering that is impermeable to water within 24 to 48 hours.
Phase II is the proliferative phase and occurs 5 to 14 days after the injury. Fibroblasts proliferate and synthesize a new connective tissue matrix that replaces the transitional fibrin matrix. Granulation tissue consists of abundant capillaries, epidermal cells that have migrated, fibroblasts, and immature connective tissue within the wound. Fibroblasts release collagen, a protein component of connective tissue. The tensile strength of the wound at 5 days is 5% that of normal skin. Collagen formation peaks at day 7.
Phase III is the remodeling, re-epithelialization, or maturation phase. It occurs from day 14 and lasts until there is complete healing of the wound. The new granulation tissue is being converted into a scar. The scar consists of a matrix with lower cell density and lower vascular density compared to unscarred skin, with increased thickness of collagen fiber bundles packed in parallel arrays.5 The wound will have 15% to 20% of its full strength at 3 weeks and 60% of its full strength at 4 months. Tensile strength continues to increase up to ...