2: Principles of Wound Healing - Bennett

Question 1

phases of wound healing

Answer 1

(injury)
inflammatory
proliferative
maturation

Question 2

mechanisms of wound repair

Answer 2

• connective tissue deposition
• epithelization
• contraction

Question 3

types of wound closure

Answer 3

• primary intention
• secondary intention
• delayed primary closure
• partial thickness (scratch or superficial abrasion)

Question 4

characterized by hemostasis and inflammation

Answer 4

inflammatory phase

• collagen exposed, during wound deformation activates the clotting cascade
• damaged cells release thromboxane A2 and prostaglandin 2 alpha (vasoconstrictors)
• initial response limits the hemorrhage
• capillary vasodilation occurs due to histamine release and the inflammatory cells migrate to the wound bed

Question 5

first response cell

Answer 5

platelets

• release epidermal growth factors, platelet derived growth factors, histamine
• stabilie wound through clot formation

Question 6

EGF and PDGF regulate …

Answer 6

EGF - cell growth, proliferation and differentiation

PDGF - cell growth and division of blood vessels

Question 7

vessel adherence
diapedesis
chemotaxis
phagocytosis

Answer 7

• pavementing, margination
• movement through vessel walls
• chemical directive to injury site
• opsinization
• PMN (second response) migrate to wound for complement mediated opsonization of bacteria

Question 8

most essential cell for wound healing

Answer 8

macrophages

• macrophages release TNF which stimualtes fibroblasts and angiogenesis
• TGF stimulates keratinocytes

Question 9

increased blood flow and congestion is evident by increased number of red cells

Answer 9

inflammatory phase

- the increase in PMNs is also evident as well as increased prtn exudates

Question 10

3 parts of proliferative phase

Answer 10

• epithelization
• angiogenesis
• collagen deposition

Question 11

basement membrane damaged v. not damaged

Answer 11

intact = cells migrate in normal pattern, normal layers of epidermis restored in 2-3 d

destroyed = re-epitheliaztion from cells in periphery

Question 12

what stimulates angiogensesis?

Answer 12

TNFalpha

• endothelial cell migrationa nd capillary formation
• maintains granular bed
• mmigration of capillaries delivers nutrients to wound bed

Question 13

cytokines involved in granulation tissue formation during proliferative phase

Answer 13

• fibroblasts differentiate and lay down collagen fibers in varying patterns
• IGF, PDGF

Question 14

histological features of proliferative phase

Answer 14

numerous fibroblasts

new capillary formation

Question 15

describe maturation phase

Answer 15

• increased collagen and vascularity
• wound contraction
• wound reaches max strength at one year
• has tensile strength 30% of normal skin

Question 16

major cells each phase

Answer 16

inflammation- neutrophils
proliferation - macrophages
maturation - fibroblasts and endothelial cells

Question 17

4 wound healing principles

Answer 17

• vascular perfusion
• bacterial balance
• nutritional balance
• control contributing factors

Question 18

parting of layers of surgical wound

Answer 18

wound dehiscence
due to: infection, hematoma, seroma, poor surgical technique, inappropriate closure technique, excessive motion at surgical site, pt non-compliance

Question 19

side to side closure of wound

Answer 19

primary intention

ex: use sutures to reapproximate skin edges

Question 20

wound is left open to granulate to closure

Answer 20

secondary intention

Question 21

wound is left open for a period of time and then primarily closed

Answer 21

delayed primary closure

Question 22

abnormal scar that extends beyond boundary of original skin injury

Answer 22

keloid

• raised, thickened growth associated with pruritus and pain
• scanning electron microsocopy reveals randomly organized collagen fibers in dense connective tissue matrix
• sternum, deltoid, upper back have increased susceptibility (elevated m and skin tension), also earlobes and post portion of neck
• 50% recurrence
• tx with compressive dressings, intralesional corticosteroid injections, cryosurgery, laser ablation

Question 23

widened or unsightly scar that does not extend beyond original boundaries of wound

Answer 23

hypertrophic scars

- usually reach a certain size and then stabilizes or begins to regress