Wound healing and reconstruction Flashcards
What is an abrasion?
loss of epidermis and some dermis
What is an avulsion?
tearing of tissues from attachments
What is a laceration?
Tearing of wound creating irregular defect
Describe the initial/inflammatory phase of wound healing
Transient vasoconstriction initially to control blood loss
Vasodilation follows:
- increases capillary permeability
- intrinsic and extrinsic clotting cascade
- chemotaxis of inflammatory cells
- neurtophils -> macrophages
Describe the repair phase of wound healing
Fibroplasia
Cessation of inflammatory phase
Fibroblast migration:
- contact inhibition
- produce and secrete proteoglycans, collagen and elastin
Granulation tissue forms
Wound contraction
Epithelialisation
Describe the remodelling/maturation phase of wound healing
Matrix synthesis and degradation
Cross linking collagen
Increase in tensile strength
Takes weeks-months
How is cat wound healing different to dogs?
Granulation tissue forms slower
What systemic/general factors negatively affect wound healing?
Old age
Meds (Steroids)
Radiation
Co-morbidities (e.g., Cushing’s)
Nutrition (e.g., hypoproteinaemia)
What local factors negatively affect wound healing?
Contamination/infection
Seroma
Neoplasia
Foreign material
Self trauma
Necrotic tissue
Describe the factors contributing to bacterial contamination of a wound
Golden period (6-12 hrs = infection)
Factors that influence:
- vascular supply (reduced ability to fight infection)
- devitalised tissue
- Type of contamination
- Cause of wound e.g., glass vs bite
- type of bacteria
- foreign bodies
What are the principles of wound management?
Clip hair to protect wound
Debride wound
Antimicrobial therapy
Open vs closed healing
What is the function of a wound lavage
Dilute bacteria
Mechanically remove foreign bodies
Encourage healing
Isotonic is best (Hartmann’s)
Describe debridement of a wound
Removal of foreign material
Surgical vs non-surgical
Describe surgical debridement of a wound
aseptic
sharp incision
remove necrotic material
repeat as often as necessary
Describe the process and function of non-surgical debridement
Acts to draw away purulent and necrotic material
Wet-to-dry dressing:
Sterile swabs are moistened with sterile isotonic and excess fluid squeezed out/removed
Placed directly onto wound and layered with dry sterile swabs
Debridement occurs by osmosis
Swabs changed daily until repair phase
What wound closure techniques are there?
Primary closure
Delayed primary closure
Secondary intention healing
Walking sutures
Local flaps
Skin grafts
Axial pattern flaps
Describe primary closure of a wound
Immediate suture
For clean or clean-contaminated
Describe delayed primary closure of a wound
For clean-contaminated or contaminated wounds
Reduces incidence of infection
Closure after 3-5 days of wound management (debridement, lavage, wet-to-dry dressings)
What is secondary intention healing?
Allowing the wound to heal on its own by formation of granulation tissue, wound contraction and epithelialisation
What are the advantages and disadvantages of secondary intention healing?
What is the function of surgical drains?
Remove fluid accumulation
Eliminate dead space
What are the advantages and disadvantages of surgical drains
What is a seroma?
build up of fluid in an area where tissue has been removed
What types of drains are there?
Active and passive
Describe how passive drains/penrose drains work?
Latex rubber tube
Gravity and capillary action
Needs large SA
Always cover (risk of ascending infection)
Do not cut (reduces surface area)
Describe how active suction drains work
Closed system
Needs reactivating when -ve pressure reduced
-ve pressure applied to allow wound to remain dry and reduce infection rate
Can easily monitor production
More expensive
Describe removal of surgical drains
ASAP
all drains cause FB reaction so fluid is produced
Daily assessment for fluid reduction
Removed in 1-5 days
Describe the potential benefits of vacuum assisted closure
increased wound perfusion
Increased granulation tissue
decreased bacterial count
Decreased oedema
Describe the ideal wound healing environment
Moist
Free of infection and excessive debris
Free of toxic chemicals
Warm
New tissue undisturbed (minimise dressing changes)
Allow for adequate gas exchange/oxygenation
Dressing painless to apply and remove
Dressing minimises contamination
What moisture absorbing wound dressings are there?
Wet to dry
Alginates (made from seaweed)
Foam dressings
Hydrocolloid dressing
What types of dressings retain moisture?
Hydrogels
What types of dressing maintain moisture
Contact layer - woven or perforated material
Requires secondary layer
What is the effect of honey as a wound dressing?
Osmotic action draws fluid out (Debridement)
Antibacterial
How do live maggots function as a wound dressing?
Stage 1 larvae of green fly
Debride necrotic material and absorb bacteria
what the issues associated with wound tension?
Circulatory compromise
Reduced wound healing
Infection
Dehiscence (splitting)
Skin necrosis
What methods can be used to provide minimal to moderate wound tension
Patient positioning
Undermining
Suture patterns
Relaxing incisions
Advancement flaps
How can patient positioning be used to minimise wound tension?
Maximises skin availability:
- skin trapped by animals weight
- elevation of area in front or behind
- release leg ties for inguinal region
- chain mastectomies
How does skin undermining minimise wound tension?
makes use of natural elasticity
Increases dead space and seroma
Undermine below panniculus or in deep fascia
How can walking sutures be used to minimise wound tension?
Used after skin undermining
Distributes skin tension
Advances skin - skin pulled forward in increments - cumulative effect of multiple walking sutures
How can relaxing incisions be used to minimise wound tension?
Single or multiple incisions on either or one side of wound to reduce tension
Allows primary wound to be closed
Relaxing incisions heal by secondary intention
On what kind of wounds would relaxing incisions be used?
closing chronic non healing wounds
wounds exposing essential tendons, ligaments and nerves
protecting surgical implants
areas susceptible to trauma
What is a skin flap?
a section of skin elevated and moved into wound for coverage
Skin flap retains its own blood supply
What are the main types of skin flap?
Subdermal plexus flap (may not include direct cutaneous artery)
Axial pattern flap (will always include a direct cutaneous artery)
What types of subdermal plexus flaps are there?
advancement
rotational
transposition
What complications can arise from subdermal plexus flaps
partial thickness necrosis
full thickness necrosis
desensitisation and self trauma
Why can axial pattern flaps be larger?
Supplied by a names diect cutaneous artery/vein so larger area can be elevated due to more consistent blood supply
How do free skin grafts work?
Elevating and removing a section of skin from one area and placing it on another
Relies on revascularisation of graft
Which in turn relies on immobilisation, bandaging and placement on a well vascularised bed
What is a pocketing wound and how is it managed?
Space between skin and underlying granulation tissue prevents closure
Tissue under skin is debrided and dead space closed
Continue with secondary intention healing until pockets reduce
What are the benefits of a tie-over bolus dressing?
Local
Can change easily by releasing tie over
Avoids bandage trauma over joints
skin stretching achieved
Describe the common anatomy of arachnida (ticks and mites)
1 part/non-segmented body
4 pairs of legs
one pair of chelicera mouth parts
one pair of pedipalps mouth parts
What are the 2 main differences between soft ticks (argasidae) and hard ticks (ixodidae)?
Describe the lifecycle of ixodidae ticks
How many hosts can hard ticks have?
May need 1,2 or 3 hosts to complete its lifecycle
What is questing in hard ticks?
ticks crawl up stems of grass with front legs extended ready to climb onto passing host
Describe the mite lifecycle
Eggs
6-legged larvae
Moults to become 8-legged nymph
3 nymphal stages:
- protonymph
- deutonymph
- tritonymph
Moults to become 8-legged adult
What are the main clinical sympotoms of babesiosis?
fever
pale mucous membranes
coloured urine
enlarged spleen
swollen lymph nodesw
What are the clinical signs of louping ill?
muscular tremors
nervous nibbling
ataxia
weakness
collapse
