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ABSITE > Fiser Chapter 14. WOUND HEALING > Flashcards

Fiser Chapter 14. WOUND HEALING Flashcards

1
Q

Order of wound healing

A
  1. Inflammation
  2. Proliferation
  3. Remodeling
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2
Q

Inflammation phase (days 1-10)

A

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

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3
Q

Proliferation phase (5 days to 3 weeks)

A

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

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4
Q

Remodeling phase (3 weeks to 1 year)

A

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

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5
Q

How fast do peripheral nerves regenerate?

A

1mm/day

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6
Q

Order of cell arrival to wound?

A
  1. Platelets
  2. Neutrophils
  3. Macrophages
  4. Lymphocytes
  5. Fibroblasts (proliferation and remodeling)
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7
Q

Predominant cell type in days 0-2?

A

PMNs

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8
Q

Predominant cell type in days 3-4?

A

Macrophages

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9
Q

Predominant cell type in days 5 onward?

A

Fibroblasts

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10
Q

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

A

True, as cells are already present there

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11
Q

Most important factor in healing open wounds (secondary intention)

A

Epithelial integrity

-unepithelialized wounds leak serum and protein, and promote bacteria

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12
Q

Most important factor in healing close wounds (primary intention)

A

Tensile strength

-Depends on collagen deposition and cross-linking of collagen

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13
Q

Strength layer of bowel

A

Submucosa

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14
Q

Weakest time point for small bowel anastomosis

A

3-5 days

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15
Q

How do myofibroblasts communicate?

A

Gap junctions

-Involved in wound contraction and healing by secondary intention

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16
Q

Does the perineum or leg has better wound contraction?

A

Perineum

17
Q

Collagen types

A

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
Q

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

A
  • Alpha-ketoglutarate
  • Vitamin C
  • Oxygen
  • Iron

-d-Penicillamine inhibits collagen cross-linking

19
Q

Collagen has a lot of what amino acid?

A

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

20
Q

Tensile strength of a wound gets how good?

A

80% pre-wound max

21
Q

Predominant collagen type in healing wound

A

1-2 days: type 3

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

22
Q

When does a wound reach maximum tensile strength?

A

8 weeks (80%)

23
Q

When is maximum collagen accumulation in a healing wound reached?

A

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

24
Q

What is essential for wound healing?

A
  • 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
Q

Impediments to wound healing

A
  • 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
Q

How does DM impede wound healing?

A

Hyperglycemia causes poor leukocyte chemotaxis

27
Q

How do steroids prevent wound healing?

A

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

28
Q

How can you counteract effect of steroids on wound healing?

A

Vitamin A 25,000 IU per day

29
Q

Diseases associated with abnormal wound healing

A

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
Q

Leg ulcers usually due to what?

A

90% due to venous insufficiency

Tx: unna boot (elastic wrap)

31
Q

Scar revisions

A

Scars have a lot of proteoglycans, hyaluronic acid, and water

Wait for 1 year to allow maturation; may improve with age

Infants heal with little or no scarring

32
Q

How does cartilage get nutrients without blood vessels?

A

Diffusion of oxygen and nutrients

33
Q

What effect does denervation have on wound healing?

A

None

34
Q

What effect does chemo have on wound healing?

A

None after 14 days

35
Q

Keloid versus hypertrophic scars

A

Keloids: dark skinned, autosomal dominant; collagen goes beyond original scar; tx intra-lesional steroid injection, silicone, pressure garments, XRT

Hypertrophic scar tissue: dark skinned; flexor surfaces of upper torso; collagen stays within confines of original scar; often occurs in burns or wounds that take a long time to heal; tx steroid injection, silicone, pressure garments

36
Q

Plateletgranules: alpha and dense

A

Alpha granules: PF4 (aggregation), beta-thrombomodulin (binds thrombin), PDGF (chemoattractant); transforming growth factor beta TGF-beta (modulates above responses)

Dense: contain adenosine, serotonin, calcium

37
Q

What are the platelet aggregation factors?

A

PF4, TXA2, thrombin

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