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Comprehensive Prep > Chapter 14: Wound Healing > Flashcards

Chapter 14: Wound Healing Flashcards

1
Q

Wound healing: days 1-10

A

Inflammation: PMNs, macrophages

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2
Q

Rate of epithelialization during wound healing

A

1-2 mm/day

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3
Q

Wound healing: 5 days - 3 weeks

A

Proliferation: fibroblasts, collagen deposition, neovascularizaiton, granulation tissue formation; type 3 collagen replaced with type 1

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4
Q

Wound healing: 3 weeks - 1 year

A

Decreased vascularity

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5
Q

What happens during the remodeling phase of wound healing?

A

Net amount of collagen does not change with remodeling, although significant production and degradation occur. Collagen cross-linking occurs.

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6
Q

Rate of regeneration of peripheral nerves

A

1 mm/day

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7
Q

Order of cell arrival in wound

A

Platelets, PMNs, Macrophages, Lymphocytes, (recent research shows arrival before fibroblasts), fibroblasts

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8
Q

Essential for wound healing (release of growth factors, cytokines, etc)

A

Macrophages

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9
Q

Chemotactic for macrophages; anchors fibroblasts

A

Fibronectin

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10
Q

Replace fibronectin-fibrin with collagen

A

Fibroblasts

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11
Q

Predominant cell type by day:

  • Days 0-2
  • Days 3-4
  • Days 5 and on
A
  • Days 0-2: PMNs
  • Days 3-4: Macrophages
  • Days 5 and on: fibroblasts
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12
Q

What comprises platelet plug?

A

Platelets and fibrin

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13
Q

What comprises the provisional matrix?

A

Platelets, fibrin, fibronectin

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14
Q

Definition: accelerated wound healing

A

Reopening a wound results in quicker healing the 2nd time (as healing cells are already present there)

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15
Q

Most important factor in healing open wounds (secondary intention)

A

Epithelial integrity

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16
Q

What does secondary intention wound healing depend on?

A
  • Epithelial integrity.

- Migration from hair follicles (#1 site), wound edges, sweat glands. Dependent on granulation tissue in wound.

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17
Q

Unepithelialized wounds leak…

A

Serum and protein, promote bacteria.

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18
Q

Most important factor in healing closed incisions (primary intention)

A

Tensile strength

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19
Q

What does tensile strength / primary intention depend on?

A

Depends on collagen deposition and cross-linking of collagen

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20
Q

Strength layer of bowel

A

Submucosa

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21
Q

Weakest time point for small bowel anastomosis

A

3 - 5 days

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22
Q
  • Smooth muscle cell-fibroblast; communicate by gap junctions
  • Involved in wound contraction and healing by secondary intention
  • Perineum has better wound contraction than leg
A

Myofibroblasts

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23
Q

Collagen: MC type of collagen; skin, bone, tendons. Primary collagen in a healed wound.

A

Type 1

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24
Q

Collagen: Cartilage

A

Type 2

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25
Q

Collagen: increased in healing wound, also in blood vessels and skin

A

Type 3

26
Q

Collagen: Basement membrane

A

Type 4

27
Q

Collagen: widespread, particularly found in the cornea

A

Type 5

28
Q

Required for hydroxylation (prolyl hydroxylase) and subsequent cross-linking of proline residues in collagen

A

Alpha-ketoglutarate, vitamin C, oxygen, and iron

29
Q

Collagen: every third amino acid

A

Proline

30
Q

What does proline cross-linking do?

A

Improves wound tensile strength

31
Q

Vitamin C deficiency

A

Scurvy

32
Q

% tensile strength to pre-wound strength

A

80%

33
Q

Predominant collagen type synthesized for days 1-2

A

Type 3 collagen

34
Q

Predominant collagen type synthesized by days 3-4

A

Type 1 collagen

35
Q

When is type 3 collagen replaced with type 1 collagen?

A

By 3 weeks

36
Q

When does the wound reach maximum tensile strength?

A

At 8 weeks.

37
Q

When is maximum collagen accumulation?

A

2-3 weeks. After that the amount of collagen stays the same, but continued cross-linking improves strength.

38
Q

Inhibits collagen cross-linking

A

d-Penicillamine

39
Q

Essentials for wound healing

A
  • Moist environment (avoid desiccation)
  • Oxygen delivery
  • Avoid edema
  • Remove necrotic tissue
40
Q

How do you optimize oxygen delivery for wound healing?

A

Optimize fluids, no smoking, pain control, arterial revascularlization, supplemental oxygen.

41
Q

What do you want transcutaneous oxygen to measure for wound healing?

A

Want transcutaneous oxygen measurement (TCOM) > 25 mm Hg

42
Q

Impediments to wound healing

A

Bacteria > 10^5, devitalized tissue and foreign bodies, cytotoxic drugs, diabetes, albumin

43
Q

How does bacteria 10^5 impede wound healing?

A

Decreased oxygen content, collagen lysis, prolonged inflammation

44
Q

How does devitalized tissue and foreign bodies impede wound healing?

A

Retards granulation tissue formation and wound healing.

45
Q

How do cytotoxic drugs impede wound healing?

A

5FU, methotrexate, cyclosporine, FK-506, etc can impair wound healing in first 14 days after injury

46
Q

How can diabetes impede wound healing?

A

Can contribute to poor wound healing by impeding the early-phase inflammation response (hyperglycemia causes poor leukocyte chemotaxis)

47
Q

How do steroids impede wound healing?

A

Inhibit macrophages, PMNs, and collagen synthesis by fibroblasts; decreases wound tensile strength as well

48
Q

Counteracts effects of steroids on wound healing

A

Vitamin A (25,000 IU qd)

49
Q

What can cause wound ischemia (hypoxia)?

A

Fibrosis, pressure (sacral decubitus ulcer, pressure sores), poor arterial inflow (atherosclerosis), poor venous outflow (venous stasis), smoking, radiation, edema, vasculitis

50
Q

Diseases associated with abnormal wound healing

A

Osteogenesis imperfecta, Ehlers-Danlos syndrome, Marfan’s, Epidermyolsis bullosa, Scurvy, Pyoderma Gangrenosum

51
Q

Common location of diabetic foot ulcer

A

Charcot’s joint (2nd MTP joint) secondary to neuropathy

52
Q

90% due to venous insufficiency.

- Tx: Unna boot

A

Leg ulcers

53
Q

What do scars contain?

A

A lot of proteoglycans, hyaluronic acid and water.

54
Q

When can you revise a scar?

A

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

- Infants heal with little to no scarring.

55
Q

Contains no blood vessels (get nutrients and oxygen by diffusion)

A

Cartilage

56
Q

Has no effect on wound healing

A

Denervation

57
Q

Has no effect on wound healing after 14 days

A

Chemotherapy

58
Q

Autosomal dominant, dark skinned

  • Collaged goes beyond original scar
  • Tx: intra-lesion steroid injection; silicone, pressure garments, XRT
A

Keloids

59
Q

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
A

Hypertrophic scar tissue

60
Q

What are contained in alpha granules of platelets?

A
  • Platelet factor 4: aggregation
  • Beta-thrombomodulin: binds thrombin
  • Platelet-derived growth factor (PDGF): chemoattractant
  • Transforming growth factor beta (TGF-beta): modulates above responses
61
Q

What do dense granules of platelets contained?

A

Contain adenosine, serotonin, and calcium

62
Q

Platelet aggregation factors

A

TXA2, thrombin, platelet factor 4

Comprehensive Prep (45 decks)

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