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WVSOM - Wounds
Wound Healing
| Question | Answer |
|---|---|
| Phases of wound healing | Inflammatory phase, migratory phase, proliferative phase, late phase scar remodeling |
| What occurs during hemostasis of the inflammation vascular phase (2-5 days)? | Bleeding, vasoconstriction, platelet aggregation, cytokine release, factor XII release (stimulates intrinsic cascade), tissue factor release from injured tissue (stimulates extrinsic cascade) |
| What occurs during vasodilation of the inflammation phase? | Increased permeability releases plasma proteins, RBCs, WBCs; mediated by histamine, leukotaxine, kinins, prostaglandins |
| Signs of the inflammation phase? | Erythema, edema, heat, pain (5-7 days) |
| What occurs during the inflammation cellular phase? | Phagocytosis (macrophages, neutrophils) |
| PMNs | Phagocytic, die within days, part of inflammation cellular phase of wound healing |
| Monocytes | Phagocytic (transform into macrophages), N.B. to chronic inflammation, engulf damaged tissues & digest them, part of inflammation cellular phase of wound healing |
| Migratory phase | Begins 2-3 days after laceration; lasts 2 days-3 weeks; angiogenesis is initiated (neovascularization); epithelialization begins (granulation if too much angiogenesis and epithelialization) |
| Describe epithelization | Marginal basal cells undergo increased mitosis, daughter cells flatten and spread, wound covered in several days |
| Proliferative phase | Begins ~5 days after wounding |
| What process begins in the proliferative phase of wound healing? | Fibroplasia - undifferentiated, extravascular mesenchymal cells transform to fibroblasts stimulated by injury |
| What hinders fibroplasia? | Necrotic tissue, hematoma, infection |
| When does collagen synthesis begin? | 5-7 days |
| What happens at 5-6 weeks after wounding? | Fibroblasts decrease, well-defined capillary network, rate of collagen synthesis decreases |
| Collagen makes up what percentage of total body protein? | 20-30% |
| Type I collagen makes up what percentage of collagen in the skin? | 80-90% |
| What collagen makes up the remaining 10-20% in the body? | Type III |
| Collagen is made from? What does it require? | Fibroblasts; oxygen, ascorbic acid, ferrous iron |
| How does collagen get its strength? | Cross-linking of strands |
| The role of myofibroblasts | Wound contraction |
| How long does wound contraction take? | 12-15 days (or until the wound edges meet) |
| Does collagen have contractile properties? | NO |
| Late phase scar remodeling (3 weeks) | Continued turnover of collagen, continues for 3 weeks-2 years, rate gain of tensile strength plateaus at 6 weeks after injury, cross-linking provides increasing strength, goal = adequate collagen for strength & integrity w/o excessive scarring |
| What factors affect wound healing? | Nutrition, vitamin deficiencies, trace element deficiencies, anemia and hemorrhage, hypoxia, steroids, anti-inflammatory drugs, radiation, cytotoxic drugs, diabetes |
| What type of wound healing is affected in the severely malnourished? | Visceral and cutaneous wound healing |
| What supplies adequate nutrition? | Protein, carbohydrates, fatty acids, vitamins, etc. |
| When does serum protein become a problem in wound healing? | When albumin < 2 grams |
| Why is ascrobic acid necessary in wound healing? | Co-factor for hyrdoxylation of proline and lysine in collagen synthesis |
| Vitamin deficiencies and fibroblasts | Decreases strong cross-linked collagen production |
| Vitamin deficiencies and vitamin C | Deficiency takes months to develop |
| Overall process of vitamin deficiencies and wound healing | New wounds don't heal and old wounds break down due to collagenolysis without synthesis |
| Zinc deficiency | Necessary co-factor for DNA/RNA synthsis; deficiency inhibits cellular proliferation & granulation tissue formation; toxicity inhibits macrophage migration & phagocytosis |
| Does wound healing occur in the presence of severe anemia? | YES (if hypovolemia is not present) |
| What does hemorrhage do to wound healing? | Shuts down microcirculation, decrease oxygen to tissue |
| Why is oxygen necessary for wound healing? | Hydroxylation of proline and lysine; oxygenation requires circulation |
| What aspects of wound healing do steroids affect? | All aspects |
| What role do steroids normally play? | Moderate inflammatory response by inhibiting fibroplasia and neovascularity; impairs epithelization and contraction |
| What do anti-inflammatory drugs do in wound healing? | Inhibit prostaglandin synthesis (typical daily doses do not inhibit wound healing) |
| Effects of acute phase radiation on wound healing | 80% reduction in fibroblast and endothelial cell proliferation |
| Where are the intermediate effects of radiation on wound healing seen? | Endothelial and connective tissue |
| What do late effects of radiation reflect on wound healing? | Total dosage, especially blood vessels, produce avascular scarring and obliterative vasculitis |
| How do cytotoxic agents affect wound healing? | Impair healing primarily through inhibition of cellular proliferation |
| Key aspect of diabetes and wound healing | Infection is 5X more likely in diabetic |
| How does diabetes affect wound healing? | Impaired circulation due to vascular occlusive disease, hyperglycemia inhibits inflammatory response, neuropathy decreases sensation which exacerbates traumatic injuries |
| Classification of wound closure | Primary intention, secondary intention, tertiary intention |
| Primary intention | Surgically clean wound, SUTURED immediately after wounding, granulation tissue minimal, scarring minimal |
| Examples of primary intention wounds | Simple lacerations, surgical incisions, most dog bites, kitchen knife wounds |
| Secondary intention | Loss of soft tissue, contaminated wound left open, considerable granulation tissue, epithelialization and contraction; NO SUTURES! |
| Examples of secondary intention wounds | Puncture wounds, superficial abrasions, most ulcers, snake bites |
| Tertiary intention | Grossly contaminated wound, left open for 4-5 days, delated primary closure |
| Examples of tertiary intention wounds | Uncontrolled hemorrhage (pack and pressure), acute wounds with questionably viable tissue / foreign bodies (wounds embedded with road tar, severely contused tissue), human bites |
| Steps in wound closure | Lidocaine (with/without epi - no epi for finger / toes)->control bleeding->flush wound with saline (0.9%)->apply betadine around skin surface->use sterile field->examine wound->check vessels, tendons, nerves->use appropriate material for close |
| Materials for wound closure | Sutures (used for full / partial thickness wounds), staples (skin), steri strips (partial thickness), tapes (skin), tissue adhesives (usually skin) |
| Types of sutures | Absorbable (plain/chromic cat gut, polyglactin, polyglycolic acid, polydioxanone) vs. non-absorable (nylon, silk, ethibond, polypropylene, wire) |
| Non-absorable sutures | Removable; remain in skin 7-10 days (4-5 days on face); remain in longer in areas of more stress |
Created by:
JaneO
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