Principles of Wound Healing Flashcards
What are the phases of wound healing?
Haemostasis and inflammation
Proliferation
Maturation
Describe the haemostasis phase
Describe the inflammatory phase
Occurs in first 72 hrs
Vasodilation (following vasoconstriction during haemostasis)
Cytokines in fibrin clot attract WBCs (neutrophils, then macrophages)
Cells destroyed by phagocytosis to ‘clean up’ bacteria and necrotic tissue
Describe the proliferation phase
granulation tissue formed of macrophages, fibroblasts and new blood vessels (makes it red)
Fibroblasts proliferate and produce new extracellular matrix, elastin and collagen (starts to give wound strength)
Formation of new epithelial tissue (pale pink colour around edge)
Myofibroblasts cause wound contraction
Contact Inhibition (when epithelial cells come into contact with each other, it stops them from proliferation further)
Describe the maturation phase
Remodelling
Type III (immature) collagen replaced by Type I (mature) collagen
Cross linking of collagen
Changes in components of extracellular matrix
Increase in tensile strength
What patient factors can affect wound healing
age
co-morbidities (e.g., HAC, diabetes)
nutrition status
What wound factors can affect wound healing
Infection
location (tension, movement, local blood supply)
What concurrent treatments can affect wound healing
Corticosteroids - delays wound healing at all stages
Radiation - tissue fibrosis and vascular scarring
When would you use primary wound closure?
Wound is clean, fresh (<6–8 hrs), and not contaminated.
There’s minimal tissue loss and good vascular supply.
Often used after surgical incisions or clean traumatic wounds (e.g., laceration in a dog that just happened on a walk).
When would you use delayed primary wound closure?
Wound is mildly contaminated or crushed, or you’re unsure of tissue viability.
You need time for debridement or for infection control.
Closure is done before granulation starts.
When would you use secondary intention healing?
Wound is very contaminated, infected, or has large tissue loss.
Closure isn’t possible or would trap infection.
Often used in chronic wounds or after failure of primary closure.
When would you use tertiary wound closure?
Wound was heavily infected or contaminated, but has now formed healthy granulation tissue and is under control.
You want to improve healing time and function by surgically closing over the granulation bed.
