Small Animal Wounds: Initial Approach Flashcards
what are the 3 stages of wound healing
- inflammatory stage
- debridement stage
- maturation stage
what occurs in the repair stage
granulation tissue forms
what occurs in the maturation stage
wound contraction, remodelling
what stages are managed with dressings
inflammatory, debridement, repair
what occurs in the inflammation stage
- hemorrhage + clot formation: scaffold for repair
- increase blood flow: increase oxygenation, source of inflammatory cells
what are the cells in the inflammatory stage
neutrophils which control the bacteria infection by phagocytosis
die and sit in the wound as dead white cells
what occurs in the debridement stage
- the neutrophils phagocytose bacteria and then die
- macrophage stakes over
- exudate
what is the major cell type of the debridement stage
macrophages
what are the functions of macrophages in the debridement stage (3)
- phagocytosis of debris
- proteases digest protein debris
- release cytokines to drive the cellular response
what is the exudate made up of in the debridement stage
sloughing of tissue, cells (dead neutrophils) and bacteria
what occurs in the repair stage (2)
- granulation tissue forms
- epithelialization
how does granulation tissue form (3)
- macrophages promote fibroplasia and angiogenesis
- vessels migrate into fibrin clot
- collagen matrix is laid down
how does epithelialization occur
migration between eschar and granulation tissue
why is granulation tissue important
framework for wound to epithelialize
reorganizes to increase wound strength and contraction
what is healthy granulation tissue
- highly resistant to infection
- lattice for scar formation
- nutrient and oxygen supply –> red, flat, epithelializing
what is unhealthy granulation tissue
- pale
- not progressing
- usually due to necrotic debris or infection
what factors promote epithelialization
- absence of infection
- absence of necrotic debris
- oxygen at wound surface (vessels)
- moist wound environment
- healthy granulation bed
what is the maturation phase (3)
- scar contracts
- collagen remodels increasing strength
- continues for weeks and months
what are local factors that impede wound healing
- foreign material in wound
- infection (including infected biofilm)
- surface trauma (inadequate bandaging)
- desiccation (failure to keep wound covered)
what are host factors that can delay healing (5)
- debility (geriatric patient)
- endocrine disease: cushings, diabetes mellitus
- metabolic disease: uremia
- hypoalbuminemia
- exogenous steroids
what things can be done to promote wound healing (5)
- removal of non-viable tissue (debride)
- control infection
- promote good blood supply
- maintain moist surface (keep covered)
- prevent surface trauma (dress properly)
what is the endpoint of initial wound management
granulation tissue with epithelialization
what is primary wound closure
immediate closure of healthy wounds (free of necrotic debris, free of infection)
ex. surgical wounds, some traumatic wounds (<6 hours)
what is delayed primary closure
ex. dog bite injury
closure after bacteria and debris have been eliminated but before granulation starts
what is secondary closure
closure once granulation tissue has formed
healthy granulation implies no infection or necrotic debris
ex. degloving injuries