Clinical meaning
Wound healing is a complex, dynamic process that proceeds through four overlapping phases: hemostasis, inflammation, proliferation, and remodeling. During hemostasis, platelet aggregation and the coagulation cascade form a fibrin clot that stops bleeding and provides a temporary scaffold. The inflammatory phase begins within hours as neutrophils and macrophages migrate to the wound bed, removing bacteria and devitalized tissue through phagocytosis and releasing cytokines that recruit fibroblasts and endothelial cells. The proliferative phase involves granulation tissue formation, where fibroblasts synthesize collagen and extracellular matrix while new capillaries (angiogenesis) supply oxygen and nutrients. Epithelial cells migrate across the wound surface from the edges (epithelialization). The remodeling phase can last months to years as type III collagen is replaced by stronger type I collagen, though healed tissue only reaches approximately 80% of original tensile strength. Negative pressure wound therapy (NPWT) accelerates wound healing through several mechanisms. The VAC (Vacuum-Assisted Closure) system applies controlled subatmospheric pressure (typically 75 to 125 mmHg) to the wound bed through a sealed dressing connected to a suction device. This negative pressure removes excess exudate and infectious material, reduces edema by drawing interstitial fluid away from the wound, increases local blood flow by up to four times baseline (macrodeformation), and mechanically stimulates cell proliferation through microdeformation of wound bed cells. The foam or gauze filler material is cut to fit the wound dimensions, and an adhesive drape creates an airtight seal. The therapy can be delivered continuously or intermittently. Wound bed preparation is essential before NPWT application, requiring debridement of necrotic tissue and achievement of adequate hemostasis. The practical nurse plays a critical role in monitoring the NPWT system, documenting wound characteristics, and recognizing complications such as bleeding, infection, or loss of seal integrity. Understanding the physiology of wound healing enables the practical nurse to assess healing progress accurately and identify when the wound is not responding to therapy.