PART 6.docx

PART 6 DISCUSSION TISSUE REPAIR - Replacement of injured tissue by fibrous tissue (composed of fibrin) - Restore the integrity of the tissue to function again properly - Before tissue repair the inflammation should stop first PROCESSES: 1. **Granulation tissue formation** - new sma...

PART 6 DISCUSSION TISSUE REPAIR - Replacement of injured tissue by fibrous tissue (composed of fibrin) - Restore the integrity of the tissue to function again properly - Before tissue repair the inflammation should stop first PROCESSES: 1. **Granulation tissue formation** - new small blood vessels (angiogenesis) - Fibrogenesis (myofibroblasts) - Proliferation of fibroblast and cell differentiation from myofibroblast - Myofibroblast -- special cells that the key role wound to contract - To help synthesis and lay down the extracellular matrix which will provide structural support in the wound - Collagen fibrils (6th day) - Protein that provides strength and support to the new tissue - Early process of tissue repair - New blood vessels will form after injury and are visible within few weeks 2. **Contraction of wounds** - 2-3 days (complete 14th day) - **Dehydration** - As the wound contracts there is also reduction in the wound area - **Collagen contraction** - Promote closure of wound - Process that will help reduce the size of wound and accelerate the wound healing HEALING HEALING BY FIRST INTENTION PRIMARY UNION - Occur at the optimal conditions - Characterized by minimal tissue damage 1. **Clean & uninfected** - Lower risk of infection 2. **Surgically incised** - Made in sterile incision - The wound edges are smooth and aligned 3. **Without much loss of cells & tissue** - Minimal loss - Reduce the need for significant formation of new tissue or formation of scar 4. **Wound edges by surgical sutures** - Via stiches or staple - To keep the wound edges, align and close contact - Prevent the wound from opening PRIMARY UNION: SEQUENCE OF EVENTS 1. **Initial hemorrhage** (after injury) - Blood vessels will constrict to reduce the bleeding - Primary cell involved are the platelets 2. **Acute inflammatory response** - Characterized by filtration of neutrophil - Help to clear any potential contaminants 3. **Epithelial changes** (till 5th day) - Formation of new tissues and blood vessels - Re-epithelialization where the epithelial cells present in the wound edges will begin to proliferate 4. **Organization**: - (3rd day) fibroblast in wound area - (5th day) Collagen fibrils - (4 weeks) Scar tissue - Also termed as Remodeling - Final phase where there's maturation of new tissue 5. **Suture tracks** (close margins of wound) HEALING BY SECOND INTENTION SECONDARY UNION 1. Open with a large tissue defect (at times infected) 2. With extensive loss of cells & tissues 3. Wound not approximated by surgical sutures but is left open. - ***Slow, \"ugly scars\"*** SECONDARY UNION: SEQUENCE OF EVENTS 1. **Initial hemorrhage** (after injury) - Active vascular system 2. **Acute inflammatory response** - Presence of neutrophil, macrophage and lymphocytes 3. **Epithelial changes** 4. **Granulation tissue** -- **main stage** of tissue healing - fibroblasts & Collagen 5. **Wound contraction** -- **Important feature** - during active granulation 6. **Presence of infection** - prevented by debridement & surgical removal of dead (necrotic) tissue. FACTORS THAT IMPAIR WOUND HEALING Influencing Healing 1. Local factors 2. Systemic factors Local factors 1. **Infection** - Proper wound healing, use of antibiotic - Maintaining sterile environment 2. **Poor blood supply** - Decrease in delivery of oxygen, nutrients and immune cell 3. **Foreign bodies (including sutures)** - Sutures that can cause irritation, inflammation and infection - Delay healing 4. **Movement** - Excessive movement or mechanical stress can disrupt the wound healing process, can cause impairment 5. **Type, size & location** - Surgical wounds heal faster - Larger wounds generate longer - Wound in areas with high mechanical stress heal more slowly 6. **UV exposure (facilitates healing)** - Can be beneficial to moderate the synthesis of Vitamin B - Excessive UV exposure can damage skin cells and impair healing and can lead to cancer Systemic factors 1. **Age** -- rapid in young - Young have active cells 2. **Nutrition** -- Scurvy, zinc def. - Vitamin C is important to collagen synthesis - Zinc for cell proliferation 3. **Systemic infection** 4. **Glucocorticoids** (anti-inflammatory) - Inhibit wound healing by suppressing the inflammatory response 5. **Uncontrolled diabetes** - Impaired healing due to high blood sugar level - Delay collagen production 6. **Hematologic abnormalities** COMPLICATIONS OF WOUND HEALING 1. **Infection** 2. **Implantation (**epidermal**) cyst formation** - Epidermal cells are trapped in dermis 3. **Pigmentation (**rust-like**) -- hemosiderin** - Occur due to bleeding 4. **Deficient scar formation** 5. **Inadequate tissue granulation** 6. **Incisional hernia (**weak scar - bursting open**)** - Common in abdomen 7. **Keloid formation** 8. **Excessive contraction \"cicatrisation\"** (Dupuytren\'s palmar contracture) - Manage by physical therapy or surgery 9. **Neoplasia** \"rare\" -- site for carcinoma development. CARDINAL SIGNS OF INFLAMMATION 1. **RUBOR** -- Redness - increase rate of blood flow (site of injury) - Blood vessels dilate 2. **TUMOR** -- Swelling - increased capillary permeability - increased plasma proteins - Occurs due to accumulation of fluids 3. **CALOR** -- Heat - Increased body temperature 4. **DOLOR** - Pain - pressure to the sensory nerve by the exudate or tumor - Increased cell mediators, prostaglandins and bradykinin 5. **FUNCTIO LAESA** -- Loss of function - pain interfering the nerve supply - destruction of tissue functional unit - Combined effects of swelling and pain