Wound healing (Case)

Question 1

Skin functions

Answer 1

• maintain hydration & thermoregulation
• defense against pathogens & chemicals
• Vitamin D synthesis
• Sensory (mechanoreceptors)
• Storage (H2O, electrolytes, fat, proteins)
• Insulation

Question 2

Epidermis

Answer 2

• superficial
• cuboidal / stratified epithelium
• avascular
• variable thickness

Question 3

Dermis

Answer 3

• below the epidermis
• collagen / elasticity
• vascular plexus, lymphatics, nerves
• hair follicles, glands

Question 4

hypodermis

Answer 4

• associated w/ dermis
• mostly fat / connective tissue
• contains panniculus
• subdermal plexus and direct cutaneous artery and vein

Question 5

Wound Healing

(test question)

Answer 5

• Coagulation: < 5 minutes
• Inflammation: 0-24 hours
• Debridement: 2-5 days
• Proliferation (repair): 4-21 days
• Maturation: 21 days - 2 years

Question 6

Coagulation

Primary

Clotting factors

Answer 6

• Primary
  
  • platelets
  • vWF
  • subendothelial collagen
• Clotting factors
  
  • intrinsic (12, 11, 9, 8)
  • extrinsic (7, 3)
  • common (10, 5, 2, 1)

Question 7

Vessels spasming down is a …..

Answer 7

sympathetic response

Question 8

Inflammation

Answer 8

• Vasodilation (redness, heat)
• Egress of leukocytes & serum (swelling)
  
  • fibrin plug >> protects wound bed
• Plateslets >> cytokines (TNF, PDGF, TGF)
  
  • neutrophils 24-48 hours
  • Macrophages 2-5 days

Question 9

Macrophages

Answer 9

• necessary for wound healing
• clean up neutrophil debris
• mark debridement

Question 10

Debridement

Answer 10

• Removal of necrotic tissue & debris by macrophages (lag phase)
• Duration
  
  • depends on amount of necrotic tissue
  • tissue type: collagenase, metalloproteinase, pH

Question 11

Proliferation

Answer 11

• Fibroblast influx
• Epithelialization
• Contraction

Question 12

Fibroblast influx

Answer 12

• max at 7-10 days
• signaled by macs >> FGF, PDGF, TGF
• only after adequate debridement
• random, rapid deposition of type-1 collagen
  
  • rapid gain in tensile strength (log phase)
• angiogenesis >> VEGF
  
  • granulation tissue formation (glistening, pink tissue)

Question 13

Epithelialization

Answer 13

• Begins 1-2 days, peaks at 5-7 days
• slide and divide
• contact inhibition

Question 14

Contraction

Answer 14

• 5-7 days
• myofibroblasts >> actin & myosin
• 1mm/day

Question 15

Maturation

Answer 15

• Collagen remodeling according to tensile forces
• second lag phase

Question 16

Wound factors

Intrinsic

Answer 16

• hypoproteinemia
• anemia
• malnutrition
• uremia
• diabetes mellitus
• hyperadrenocorticism
• infection

Question 17

Wound factors

Extrinsic

Answer 17

• Mechanism
  
  • shear
  • crush
  • laceration
• foreign material
• irradiation
• antiseptics

Question 18

Wound classification

Answer 18

Based on time and contamination

• Class 1: 0-6 hours; minimal contamination
  
  • primary closure = common
• Class 2: 6-12 hours; moderate contamination
  
  • primary closure = reality
• Class 3: > 12 hours; gross contamination
  
  • primary closure = don’t do it

Question 19

Wound classification

Answer 19

Based on surgical factors

• Clean
  
  • surgical procedure not entering GI or respiratory tract
  • no contamination/ break in asepsis
• Clean-contaminated
  
  • GI or respiratory tract entered or minor break in asepsis
  • enterotomy or lung lobectomy SSI = 10%
• Contaminated
  
  • GI with gross contamination, inflammation, major break in asepsis
  • enterotomy with spillage SSI = 30%
• Dirty
  
  • devitalized or necrotic tissue, gross debrus, pus
  • aged dog bite wound infected = infected

Question 20

Antimicrobials

Answer 20

• Class 1 clean: don’t need
  
  • unless systemically unhealthy or foreign material
• Class 2-3 Clean-contaminated, dirty: yes
  
  • broad spectrum penicillin or cephalosporin

Question 21

For lavage

Answer 21

• we want 7-8 PSI
• don’t use something that will kill fibroblasts
• saline may be best

Question 22

Dry to dry bandages

Answer 22

• Non-adherent
• protects wound, allows moist healing
• doesn’t harm wound bed

Question 23

Wound closures

Answer 23

• Primary
  
  • immediate (< 6 hours)
• Delayed primary
  
  • after 6 hours before granulation (< 2 days)
• Late Secondary
  
  • after granulation tissue (>2 days)
• Second intention
  
  • no surgical closure