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Wound Healing Junior Basic Science 1/25/2011. 3 Phases of Wound Healing 1. Inflammation- day 1-10 1. Inflammation- day 1-10 2. Proliferation-5 days-3.

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Presentation on theme: "Wound Healing Junior Basic Science 1/25/2011. 3 Phases of Wound Healing 1. Inflammation- day 1-10 1. Inflammation- day 1-10 2. Proliferation-5 days-3."— Presentation transcript:

1 Wound Healing Junior Basic Science 1/25/2011

2 3 Phases of Wound Healing 1. Inflammation- day Inflammation- day Proliferation-5 days-3 weeks 2. Proliferation-5 days-3 weeks 3. Remodeling-3 weeks-1 year 3. Remodeling-3 weeks-1 year

3 Inflammation Phase: Injury Bleeding and vasoconstriction(5-10min), followed by vasodilation Bleeding and vasoconstriction(5-10min), followed by vasodilation Plt plug formation and clotting Plt plug formation and clotting Fibrin binds the plt plug and forms the provisional matrix (platelets+fibrin+fibronectin) Fibrin binds the plt plug and forms the provisional matrix (platelets+fibrin+fibronectin) Platelet degranulation (alpha and dense granules) Platelet degranulation (alpha and dense granules) -> PDGF and TGF-B -> PDGF and TGF-B Chemotaxis for inflammation Chemotaxis for inflammation

4 Inflammation PMNs-almost immediately, clear debris PMNs-almost immediately, clear debris Macrophages-Day 2-3 (essential) Macrophages-Day 2-3 (essential) –Fibroblast proliferation, endothelial cell proliferation (angiogenesis), and extracellular matrix production, and they recruit and activate additional macrophages. Lymphocytes Lymphocytes

5 Proliferation Phase (5-21 days) Fibroblasts-enter provisional matrix and initiate collagen synthesis Fibroblasts-enter provisional matrix and initiate collagen synthesis –Prominent cell type during this phase Macrophages->angiogenesis and neovascularization Macrophages->angiogenesis and neovascularization Collagen and proteoglycans or ground substance replaces the provisional fibronectin–fibrin matrix Collagen and proteoglycans or ground substance replaces the provisional fibronectin–fibrin matrix

6 Remodeling Phase (3wks-1 year) Max collagen accumulation at 2-3 weeks. Only remodeling/crosslinking after 3 weeks. Max collagen accumulation at 2-3 weeks. Only remodeling/crosslinking after 3 weeks. Type III collagen predominates early (days 1-3), but is replaced by type I Type III collagen predominates early (days 1-3), but is replaced by type I 6 weeks-80% of final strength and 60% of original strength 6 weeks-80% of final strength and 60% of original strength 8 weeks-max tensile strength (70-80%) 8 weeks-max tensile strength (70-80%)

7 Collagen Need alpha-ketoglutarate, vit C, O2, and iron for hydroxylation of proline, and crosslinking of proline residues Need alpha-ketoglutarate, vit C, O2, and iron for hydroxylation of proline, and crosslinking of proline residues Proline is every 3 rd amino acid. Lysine is abundant from hydroxylysine crosslinking Proline is every 3 rd amino acid. Lysine is abundant from hydroxylysine crosslinking Type I, most common and most abundant in healed wound Type I, most common and most abundant in healed wound D-penicillamine inhibits collagen crosslinking D-penicillamine inhibits collagen crosslinking

8 Surgical Wound Healing Primary Intention-Tensile strength is important in healing closed incisions Primary Intention-Tensile strength is important in healing closed incisions –Depends on collagen deposition and cross-linking Secondary Intention-Epithelial integrity is important in healing open wounds Secondary Intention-Epithelial integrity is important in healing open wounds –Dependent on granulation tissue (capillaries, fibroblasts and collagen) –Migration from wound edges, sweat glands and hair follicles

9 Essential for wound healing Moist environment- optimizes epithelial migration Moist environment- optimizes epithelial migration Oxygen delivery- Essential Oxygen delivery- Essential Avoid edema- edema causes decreased O2 in wounds Avoid edema- edema causes decreased O2 in wounds Remove necrotic tissue- leads to infection Remove necrotic tissue- leads to infection

10 Factors affecting wound healing Nutrition-Albumin <3 Nutrition-Albumin <3 Infection Infection Foreign body Foreign body Drugs Drugs Diabetes Diabetes Ischemia Ischemia Aging Aging Radiation Radiation Neuropathy Neuropathy

11

12 Scars Contain proteoglycans, hyaluronic acid, and water. Contain proteoglycans, hyaluronic acid, and water. Keloids- AD, dark skinned. Collagen goes beyond original scar Keloids- AD, dark skinned. Collagen goes beyond original scar Hypertrophic scar- Collagen stays within scar Hypertrophic scar- Collagen stays within scar Treatment: Steroids, silicone, pressure garments, XRT. Treatment: Steroids, silicone, pressure garments, XRT. Infants heal with little/no scarring-multifactorial, decreased inflammatory response, increase hyaluronic acid? Infants heal with little/no scarring-multifactorial, decreased inflammatory response, increase hyaluronic acid?

13 Chronic Wounds Pressure Sores- pressure over bony area, occurs when tissue pressure exceeds the capillary filling pressure of 25 mm Hg Pressure Sores- pressure over bony area, occurs when tissue pressure exceeds the capillary filling pressure of 25 mm Hg –Tx: Pressure off loading, debridement, myocutaneous flap Leg ulcers- 90% due to venous insuff. Leg ulcers- 90% due to venous insuff. –Tx: Unna boot, elastic wrap Diabetic foot ulcers- 2 nd MTP joint (Charcot’s joint). Neuropathy leads to increased pressure-> Ischemia Diabetic foot ulcers- 2 nd MTP joint (Charcot’s joint). Neuropathy leads to increased pressure-> Ischemia –Tx: Depends on extent of ulcer

14 Question The most prominent cell type in the 1 st 24 hours of a wound is : The most prominent cell type in the 1 st 24 hours of a wound is : –PMN’s –Macrophages –Lymphocytes –Fibroblasts

15 Answer PMN’s PMN’s –Most abundant in 1 st 24 hrs, help clear debri

16 Question The most prominent cell type day 2-4? The most prominent cell type day 2-4? –PMN’s –Macrophages –Lymphocytes –Platelets

17 Answer Macrophages Macrophages –Fibroblast proliferation, endothelial cell proliferation (angiogenesis), and extracellular matrix production, and they recruit and activate additional macrophages.

18 Question What is the most prominent cell type at 1 week? What is the most prominent cell type at 1 week? –PMN’s –Macrophages –Lymphocytes –Fibroblasts

19 Answer Fibroblasts Fibroblasts -Enter provisional matrix and initiate collagen synthesis. Days 5-21.

20 Question The most predominant type of collagen in the body? The most predominant type of collagen in the body? –I –II –III –IV

21 Answer Type I most common, seen in skin, bone, tendons, and healed wounds –I –II Cartilage –III –IV Basement membrane

22 Question Most abundant collagen in healing wound during 1 st 24hrs? Most abundant collagen in healing wound during 1 st 24hrs? –I –II –III –IV

23 Answer Type III- Most abundant the first 48hrs, and is then replaced by type I. Type III- Most abundant the first 48hrs, and is then replaced by type I.

24 Question What is the most important cell involved in wound healing? What is the most important cell involved in wound healing? –PMN’s –Macrophages –Lymphocytes –Fibroblasts

25 Answer Macrophages Macrophages –Essential, synthesizes cytokines and growth factors necessary for wound healing.

26 Question Maximal tensile strength of a wound occurs at: Maximal tensile strength of a wound occurs at: –3 weeks –6 weeks –8 weeks –3 months

27 Answer 8 weeks- Has 80-90% of original strength 8 weeks- Has 80-90% of original strength

28 Question What vitamin can you give to prevent the negative affects on wound healing? What vitamin can you give to prevent the negative affects on wound healing? –A –D –O –K

29 Answer Vitamin A Vitamin A –25,000 UI daily

30 Question Peripheral nerves regenerate at: Peripheral nerves regenerate at: –0.01mm/year –0.1mm/day –1mm/day –5mm/day

31 Answer 1mm per day 1mm per day

32 Question The most important factor in the healing wounds by secondary intention is: The most important factor in the healing wounds by secondary intention is: –Tensile strength –Epithelial integrity –Platelet activating factor –cocaine

33 Answer Epithelial integrity- epithelial cells migrate from hair follicles, wound edges and sweat glands. Epithelial integrity- epithelial cells migrate from hair follicles, wound edges and sweat glands.

34 Question The most important factor in the healing wound by primary intention is: The most important factor in the healing wound by primary intention is: –Double cheeseburger from McDonalds –Tensile strength –Epithelial integrity –Platelet activating factor

35 Answer Tensile strength, not double cheeseburger Tensile strength, not double cheeseburger –This is created by collagen cross linking

36 Question The dressing change regimen that will produce maximal debridement is: The dressing change regimen that will produce maximal debridement is: –Wet-to-dry dressing changes with saline. – Dressing changes with Xeroflo. –Dressing changes with silver sulfadiazine. –Dressing changes with an occlusive dressing.

37 Answer Maximal debridement is accomplished when the dressing is changed utilizing wet-to-dry dressings. Enzymatic agents, such as collagenase, may augment the debriding effect of wet to dry dressing changes. Maximal debridement is accomplished when the dressing is changed utilizing wet-to-dry dressings. Enzymatic agents, such as collagenase, may augment the debriding effect of wet to dry dressing changes.

38 Question Hypoxia in a wound stimulates: Hypoxia in a wound stimulates: –collagen synthesis –contraction –ovulation –angiogenesis –epithelialization

39 Answer Angiogenesis Angiogenesis

40 Question Cofactors necessary for successful hydroxylation of proline include all the following except: Cofactors necessary for successful hydroxylation of proline include all the following except: –Vitamin C. –Magnesium. –Ferrous ion. –α-Ketoglutarate. –Oxygen.

41 Answer Magnesium Magnesium

42 Question Local factors which invite wound infection include all of the following except: Local factors which invite wound infection include all of the following except: –Foreign material. –Radiation injury. –Poor circulation. –Disruption of fascia. –Hematoma.

43 Answer Disruption of fascia Disruption of fascia –Depth of injury into the fascia has not been identified as a wound characteristic that predisposes to infection

44 Question Significant collagen synthesis first begins in a wound at: Significant collagen synthesis first begins in a wound at: –2 to 4 weeks. –7 to 10 days. –0 to 12 hours. –12 to 24 hours. –3 to 5 days.

45 Answer Significant collagen synthesis begins in a wound at 3 to 5 days. Significant collagen synthesis begins in a wound at 3 to 5 days.


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