Lecture 11 9/9/24

Question 1

What are the stages of healing?

Answer 1

-inflammation
-proliferation
-maturation/remodeling

Question 2

What are the processes involved in inflammatory phase hemostasis?

Answer 2

-vessel damage leads to endothelin release and vasoconstriction
-platelets adhere to damaged endothelial collagen and activate, resulting in aggregation
-endothelial damage triggers coagulation cascade to produce thrombin and fibrin

Question 3

Why do greyhounds experience bleeding 36 to 72 hours after surgery?

Answer 3

they have a genetic condition resulting in excessive fibrinolysis/premature clot breakdown

Question 4

What are the characteristics of leukocyte recruitment during the inflammatory phase?

Answer 4

-platelets release chemotactic factors that recruit leukocytes
-blood flow and fluid extravasation increase
-neutrophils flow into the wound to ingest/kill bacteria
-monocytes migrate into the wound and mature into macrophages
-inflammation lasts for 3-5 days

Question 5

What are the characteristics of granulation tissue formation during the proliferative phase?

Answer 5

-most notable during post-op days 4-12 for incisions
-angiogenesis occurs from existing vessels
-fibroblasts differentiate, migrate into wound, and synthesize matrix and collagen

Question 6

What is granulation tissue?

Answer 6

mixture of blood vessels, extracellular matrix, and fibroblasts

Question 7

What are the characteristics of proliferative phase wound contraction?

Answer 7

-begins around day 6 of healing
-myofibroblasts pull wound edges inward
-wound contraction continues until excessive tension stops/prevents contraction
-myofibroblasts gone within 4-5 weeks

Question 8

What are the steps of epithelialization during the proliferative phase?

Answer 8

-keratinocytes migrate from wound edges within hours of wound occurring and become visible within days
-migration continues until they contact other epithelial cells
-basal lamina is re-established once migration stops

Question 9

What are the steps that occur during the maturation phase?

Answer 9

-cross-linking and reorientation of collagen bundles
-changes in collagen content
-development of epidermal layers
-increase in strength; greatest during first 2-6 weeks

Question 10

How does skin tightness impact wound healing?

Answer 10

-tight skin heals through epithelialization
-loose skin heals through contraction

Question 11

What are local factors that impair wound healing?

Answer 11

-poor wound perfusion
-poor tissue viability
-wound fluid accumulation
-mechanical factors
-local infections and toxins

Question 12

What are systemic factors that impair wound healing?

Answer 12

-poor immune function
-uremia
-diabetes mellitus
-high dose glucocorticoids
-chemotherapeutics
-blood transfusions
-malnutrition
-old age
-breed/species specific issues

Question 13

What is primary wound closure?

Answer 13

-freshly traumatized edges
-immediately apposed
-no gap

Question 14

What is delayed primary wound closure?

Answer 14

-appositional closure before granulation tissue is evident
-used for wounds with mild trauma, contamination, or tension

Question 15

What is secondary wound closure?

Answer 15

-delay of wound closure until wound is filled with healthy bed of granulation tissue
-foreign debris and necrotic tissue is removed

Question 16

What is second intension healing?

Answer 16

-healing by contraction and epithelialization, not closure
-usually requires topical dressing +/- bandages
-rapid results in areas with good blood supply and loose skin
-must remove foreign material, necrotic tissue, infection, tension, and pressure