Wound healing: It is a complex and dynamic process of replacing devitalized and missing cellular structures and tissue layers.https://www.google.com/url?sa=t&source=web&rct=j&opi=89978449&url=https://en.m.wikipedia.org/wiki/Wound_healing&ved=2ahUKEwi288iqgcSAAxWGwTgGHfiFD80QFnoECCwQAQ&usg=AOvVaw1CcNtCRHT6fPcA6IChlDC_y
Types of wounds:
Acute wound: Heals without many complications within expected time frame, e.g. surgical wound and trauma wounds.
Types of wound
Chronic wound: Underlying pathology or infection causes the wound or interferes with the healing process. For example, diabetic ulcer and pressure ulcer.
Wound healing process:
Healing by primary intention: No or little scar tissue. For example, surgical wounds.
Healing by secondary intention: Marked loss of tissue. Edges of the wound are too far, and the wound gets closed naturally through granulation and epithelialization. For example, lacerated wounds, pressure ulcers, and traumatic injuries.
Healing by tertiary intention: Characterized by delayed wound closure. This results in granulation of wound edges. Characterized by edema, infection, exudates from wound and excessive scar formation.
Four stages of Wound healing: Hemostasis: Causes coagulation, Inflammation: Destroys bacteria and removes debris, Proliferation: Fills and covers the wound, Maturation: Tissue gain strength and flexibility. Wound healing can progress backward or forward, depending on internal and external patient conditions.
Hemostasis: (A brief period of vasoconstriction in an attempt to stop the bleeding). Begins at the onset of injury, and its objective is to stop bleeding. Blood vessels constrict to restrict the blood flow. Platelets stick together and adhere to the sub- endothelium surface of the epithelial wall of the blood vessel in order to seal the break. After this, the first fibrin strand begins to adhere in about 60 seconds. As the fibrin mesh begins, blood is transferred from liquid to gel through coagulation.
Inflammatory Phase: (Starts immediately after injury and lasts for 2-6hrs). Injured blood vessels leak transudate (neutrophils, water, salt and proteins) and cause localized swelling. Increased capillary permeability and blood flow to the site of injury assists phagocytosis. During this phase, damaged cells, pathogens and bacteria are removed from the wound area. Swelling, redness and pain in the injured / affected area are common in this phase.
Proliferation:
This stage has three distinct phases: Filling the wound, Contraction of wound margins, covering the wound (Epithelialization): It is a phase of rebuilding of new tissue made up of collagen and extracellular matrix. Formation of granulation tissue (pink to red moist tissue) followed by epithelialization (migration of epithelial cells across wound surface). A new network of blood vessels is constructed for sufficient supply of oxygen and nutrients to granulation tissue.
Maturation phase: (Remodeling Stage)
Strengthening and reorganization of collagen occurs (remodeling of collagen). Cells that had been used to repair the wound but no longer needed are removed by apoptosis. Scar thick down reduces and make the area stronger. The process takes months to a year. It takes 2_3 weeks to regain 50% of strength. Only 70%-75%of its original strength will be regained at the end of the wound healing process.
Key points:
- Healthy granulation tissue is pink or red and uneven in texture. Dark granulation tissue can be a sign of poor perfusion or infection. Stages of wound care can be speeded up by keeping wound a clean and moist. Factors that lead to chronic wounds are: Venous disease, infection, diabetes, metabolic deficiencies.
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