Fiser Chapter 14. WOUND HEALING Flashcards Preview

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Flashcards in Fiser Chapter 14. WOUND HEALING Deck (37)
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1

Order of wound healing

1. Inflammation
2. Proliferation
3. Remodeling

2

Inflammation phase (days 1-10)

PMNs, macrophages, EPITHELIALIZATION (1-2 mm/day)

3

Proliferation phase (5 days to 3 weeks)

Fibroblasts, COLLAGEN DEPOSITION, neovascularization, GRANULATION TISSUE, type 3 collagen replaced with type 1

4

Remodeling phase (3 weeks to 1 year)

Decreased vascularity, net amount of collagen does not change, although significant production and degradation occur, collagen CROSS LINKING occurs

5

How fast do peripheral nerves regenerate?

1mm/day

6

Order of cell arrival to wound?

1. Platelets
2. Neutrophils
3. Macrophages
4. Lymphocytes
5. Fibroblasts (proliferation and remodeling)

7

Predominant cell type in days 0-2?

PMNs

8

Predominant cell type in days 3-4?

Macrophages

9

Predominant cell type in days 5 onward?

Fibroblasts

10

True or false, reopening a wound results in quicker healing the 2nd time?

True, as cells are already present there

11

Most important factor in healing open wounds (secondary intention)

Epithelial integrity

-unepithelialized wounds leak serum and protein, and promote bacteria

12

Most important factor in healing close wounds (primary intention)

Tensile strength

-Depends on collagen deposition and cross-linking of collagen

13

Strength layer of bowel

Submucosa

14

Weakest time point for small bowel anastomosis

3-5 days

15

How do myofibroblasts communicate?

Gap junctions

-Involved in wound contraction and healing by secondary intention

16

Does the perineum or leg has better wound contraction?

Perineum

17

Collagen types

I: Most common; skin, bone, tendon; primary collaged in a HEALED WOUND
II: Cartilage
III: Increased in HEALING wound; vessels; skin
IV: BM
V: Cornea, widespread

18

Hydroxylation (prolyl hydroxylase) and cross-linking of proline residues in collagen need what?

-Alpha-ketoglutarate
-Vitamin C
-Oxygen
-Iron


-d-Penicillamine inhibits collagen cross-linking

19

Collagen has a lot of what amino acid?

Proline (every 3rd aa): proline cross-linking improves wound tensile strength

20

Tensile strength of a wound gets how good?

80% pre-wound max

21

Predominant collagen type in healing wound

1-2 days: type 3
3-4 days: type 1, and replaces type 1 by 3 weeks

22

When does a wound reach maximum tensile strength?

8 weeks (80%)

23

When is maximum collagen accumulation in a healing wound reached?

2-3 eweks, after that the amount stays the same, but you have continued cross-liking to improve strength

24

What is essential for wound healing?

-Moist environment
-Oxygen delivery (fluids, no smoking, pain control, revasc, supplemental O2 if needed): want transcutaneous oxygen measurement TCOM > 25 mm Hg
-Avoid edema (leg elevation)
-Remove necrotic tissue

25

Impediments to wound healing

-Bacteria > 10^5/cm^2

-Devitalized tissue and foreign bodies

-Cytotoxic drugs (5FU, methotrexate, cyclosporine, FK-506, etc can impair wound healing in 1st 14 days after injury)

-DM: impedes early-phase inflammation response, hyperglycemia causes poor leukocyte chemotaxis

- Albumin <3.0

-Steroids: inhibit macrophages, PMNs, and collagen synthesis by fibroblast; also decreases wound tensile strength

-Wound ischemia: fibrosis, pressure, atherosclerosis, venous stasis, smoking, radiation, edema, vasculitis

26

How does DM impede wound healing?

Hyperglycemia causes poor leukocyte chemotaxis

27

How do steroids prevent wound healing?

Inhibiting macrophages, PMNs, and collagen synthesis by fibroblasts; decrease wound tensile strength

28

How can you counteract effect of steroids on wound healing?

Vitamin A 25,000 IU per day

29

Diseases associated with abnormal wound healing

Osteogenesis imperfect: type 1 collagen defect

Ehlers-Danlos syndrome

Marfan's syndrome: fibrillin defect

Epidermolysis bullosa: excessive fibroblasts, tx phenytoin

Scurvy (vit D def)

Pyoderma gangrenosum

30

Leg ulcers usually due to what?

90% due to venous insufficiency

Tx: unna boot (elastic wrap)