ENI - Wound Healing Flashcards
Describe an abrasion and give common causes
- Loss of epidermis and some dermis
- Blunt trauma/shearing
- Skin rubbed along surface most common e.g. RTA case
Describe an avulsion and give common causes
- Tearing of tissues from attachments
- On limbs
- e.g degloving injury, stake injury
- Torn skin and underlying tissues
- Can also be bite injuries
Describe an incision wound and give common causes
- Created by sharp object
- Minimal trauma
- Usually associated with surgery
Describe a laceration wound
Tearing wound creating irregular defect
Describe a puncture wound and give common causes
- Penetrating wound
- Often do not show full extent of damage i.e. superficial damage often minimal, deep substantial
- Projectile injury, shot, stab, bite
What are the stages of wound healing?
- Haematosis and inflammation
- Proliferation (fibroplasia)
- Maturation
Describe the inflammatory phase of wound healing
- Transient vasoconstriction prevent bleeding
- Followed by vasodilation to increase capillary permeability
- Activation of intrinsic and extrinsic clotting cascade
- Removal of clot to allow influx of inflam. ells
- Chemotaxis of inflam cells
- Neutrophils to macrophages
Describe the fibroplasia phase of wound healing
- Cessation of inflammatory phase
- Fibroblast migration - contact inhibition removed, produce and secrete proteoglycans, collagen and elastin
- Wound contraction
- Epithelialisation (contact inhibition removed)
Describe the mauration/remodelling phase in wound healing
- Matrix synthesis and matrix degradation
- Cross linking of colalgen
- Increase in tensile strength
- Weeks to months
What is the function of collagen in wound healing?
Improve tensile strength of wound
List factors that affect wound healing
- Age
- Nutrition
- Co-morbidities
- Medication
- Radiation
- Vascular supply
Describe the basic vascular supply of the skin
- 3 layers
- Deep (subdermal)
- Middle and superficial in dermis
Describe the vascular supply to the skin in cats and dogs
- Subdermal plexus
- Major network
- Supplied directly by cutaneous artery
Explain how the subdermal plexus in dogs and cats is useful in wound healing
- Can move an area of skin around and know that it will have blood supply
- As long as arterial supply to that plexus is kept in tact
What is the effect of steroids on wound healing?
Delay healing
Give the important features of a wound assessment in order to decide on management of acute wounds
- Type of wound
- Wound age
- Level of contamination
- Lavage +/- debridement
- Then management
- Also asses other injuries and stabilise
Outline the importance of assessing type of wound in terms of its management
- Type of wound relates to level of contamination
- Degree of tissue damage
- Depth of wound
- Vital structures that may have been damaged e.g. bones, joints, nerves, tendons
Outline the importance of wound age in terms of management
- Golden period 6-8 hours
- Time take from wound occuring to when it will be contaminated/colonised
- Earlier dealt with reduces bacterial contamination and can prevent becoming a colony and causing infection
Outline the assessment and importance of the level of contamination in terms of wound management
- Linked to type/cause of wound
- Whether or not will have large bacterial inoculum
- Presence of foreign material, devitalised tissue
- Golden period as guideline
- Affected by vascular supply
- Swabbing and send off for culture
Outline lavage and/or debridement in management of acute wounds
- Gross contamination removed with tap water
- Sterile solution followign water (lactated Ringer’s)
- Avoid pushing bacteria deeper into wound (20-50ml synringe and 18G needle ideal)
- No added antiseptics
- Debridement using dressings or surgical
What are the 3 types of management for acute wounds?
- Primary intention
- Secondary intention healing (takes time)
- Tertiary intention (delayed primary closure)
Outline primary closure
- Immediate suture
- Used for clean or clean-contaminated
- Most likely with surgery, elective surgical procedure
- Make wound and then close it again
Outline delayed primary closure
- Used for clean-contaminated to contaminated wounds
- Reduces incidence of infection
- Closure after 3-5 days
- Leave wound open for period of time, systemic and local treatment until fit state for closure
- Usually requires debridement, lavage, culture and wet-to-dry dressings
- Gradual
Outline secondary intention healing
- Allowing wound to close itself
- Granulation tissue, wound contraction and epithelialisation
- Suitable dressings required at each stage
- Time consuming
- Careful management
What are the disadvantages of secondary intention healing?
- Careful management to ensure healing does not stop
- Often get granulation response, won’t move on from there
- Often hospitalised to ensure correct care
- Need to reduce movement
- Regular changing of dressings to support stage of healing
- Risk of “proud flesh”
Why might granulation stop in healing?
- Co-morbidities
- Movement
What factors affect prognosis of wound healing?
- Level and type of contamination
- Vascular compromise
- Viability of tissues
- Types of tissues
- Foreign material
- Patient status
What are the basic aims of wound management?
- Promote healing
- Convert contaminated into clean
- Control infection
What are the advantages of secondary intention healing?
- Optimum wound drainage
- Local infection control
- Initially cheaper (but likely to become expensive as treatment progresses)
Explain what is meant by “proud flesh”
- Exuberant granulation tissue
- Contact inhibtion of cells coming together to produce single layer ineffective
- End up with chronic granulation tissue that epithelium cannot form over
- Will roll under granulation tissue
Outline the control of infection to promote wound healing
- Local agents with antimicrobial effects
- Systemic antibodies with care
- Establish what bacteria are and use specific antibiotics
Outline the role of wound lavage in wound healing
- Dilutes bacteria
- Removes foreign bodies
- Encourages healing
- Isotonic solutions best
- Culture after lavage
- Swab before or after, unlikely to clean to extent where will get no results
Outline the role of surgical debridement in wound management
- Removal of foreign material
- Aspetic technique sharp incision, removal of nectroic material
- Often repeat
- Aim to save as much as possible
Give examples of non-surgical debridement
- Use dressings: wet-to-dry or dry-to-dry
- Both act to draw away purulent and necrotic material
- Both need external protection
Describe wet-to-dry dressings
- Sterile swabs
- Moisten with sterile isotonic solution
- Place on wounds, dry swabs on top
- Fluid drawn from wet to dry, wound fluid drawn into dressing by capillary action
- Dressing will dry out, removal of dressing also has mechanical properties orf removal
Describe tie-over (bolus) dressings
- Useful for hard to dress areas
- Loops of sutures around wound
- Apply dressing
- Hold in place using umbilical tape passing through suture loops (like shoe-laces)
What are the indications for use of surgical drains?
- Removal of fluid accumulation
- To eliminate dead space
Why eliminate dead space?
- Can fill with fluid = seroma (mostly fill with serum, not blood)
- Prime inoculum site for bacteria
- Remove surgically or insert drain to remove fluid
What are the advantages of drains in wound healing?
- Increase healing capacity
- Remove contaminated fluid
- Reduce tension formed by seroma
What are the disadvantages of drains in wound healing?
- Introduction of foreign bodies
- Introduction of infection
What are the different types of drains used in wound healing?
- Active
- Passive
Give an example of a passive drain
Penrose drain
Describe Penrose drains
- Latex rubber tube
- Work using gravity and capillary action
- Place lower down wound for support from gravity
- Do not exit wound directly
- Do not use “ingress/egress” method i.e. drain either side
- Cover to avoid risk of ascending infection
Describe active suction drains
- Closed system
- Negative pressure applied
- More expensive
- 2 readily available: grenade and concertina
- grande: rigid tube into wound site, empty grenade tray, made of elastic material that wants to expand so is applying constant mild negative pressure, sucking out wound
Outline Topical Negative Pressure (TNP) therapy
- Chronic non-healing wounds
- Produces negative suction pressure
- Removes exudate and bacterial colonisation
- Promotes granulation response, better perfusion, better epithelialisation closer to wound more rapidly than otherwise
- Increases rate of cell mitosis
- Increases wound perfusion
Describe the wound healing continuum model
- Different wounds have different colours associated
- Can use to decide what stage and thus what management
- Aim for left to right movement along continuum
Describe the wound healing progression model
- Different wounds have different colours and different moisture levels
- Shown in relation to the optimum moisture and so know whether management should involve addition or removal of moisture
Outline how wound tension affects prognosis in wound management
- Circulatory compromise
- Reduced wound healing
- Dehiscence
- Skin necrosis
How can wound tension be reduced?
- Patient positioning
- Undermining of skin
- Suture patterns
- Relaxing incision
- Advancement flaps
- Understanding of tension lines
Explain how patient positioning affects skin tension
- Skin trapped by animal’s own weight
- Weight of skin dragging it down e.g. lying on back
Outline the use of skin undermining in reduction of wound tension
- Makes use of natrual elasticity
- Increases dead space and seroma
- Takes tension of wound as removing elastic attachment undeneath
- Skin can move more freely where needed
What are important considerations in skin undermining?
- Skin with panniculus, undermine below
- Skin withouth panniculus, undermine in deep fascia
- Aim to preserve direct cutaneous arteries using atraumatic technique
Outline the use of walking sutures
- After skin undermined
- Distribution of skin tension
- Advance skin towards wound site
- Pull skin forward in increments
- Sutures within fascia/muscle layer
- Pull skin forward (max 2-3cm), place suture, repeat
- Cumulative effect of multiple sutures
Outline the use of relaxing incision in wound tension
- Incisions parallel to wound
- Debride edges of primary wound
- Undermine bipedicle flap
- Allows stretch of primary wound, but leaves secondary wound (however this is clean and so will heal)
- Can also use 2 large relaxing incisions, or multiple smaller ones
When might relaxing incisions be used?
- Closing of chronic non-healing wounds
- To close wounds exposing essential tendons, ligaments and nerves
- Protection of surgical implants
- Areas susceptible to external trauma
Outline the use of multiple relaxing incisions as opposed to one
- Describe for lower extremities
- Multiple stab incisions parallel to long axis where there is too much lateral tension
- Staggered
- Not as much advancement possible
- Risk of circulatory compromise and infection
- However easier to heal
What types of skin flaps can be used in advanced wound closure?
- Vascularised
- Non-vascularised
Describe the use of vascularised skin flaps
- Resistance to infection
- Any tissue bed
- May withstand radiation therapy
- Rapid healing (single procedure)
Describe the use of non-vascularised skin flaps
- Technically relatively simple, covers large tissue defects
- Requires vascularised tissue bed
- Poor resistance to infection or radiation
Describe the blood supply in vascularised skin flaps
- May be subdermal plexus
- Terminal branch of direct cutaneous arteries
- Within panniculus and subcutis
- Own inherent blood supply or not i.e. is there a subdermal plexus
- More risky in species other than cat and dog where there is no subdermal plexus, cannot guarantee blood supply
Name the different types of subdermal plexus flaps
- Rotation
- Transpositional
- Single pedicle advancement
- Distant
Describe rotation subdermal plexus flaps
- Undermine panniculus layer below
- Move and rotate skin into wound site
- Allows good cosmetic results
Describe transpositional subdermal plexus flaps
- Brad flap, rotate into wound
- 90degree, 45 degree
- Harvest skin along line of tension, rotate along least line of tension
- Can easily close subsequent defect as the line of tension is running the other way
- Produces Y shape
Describe advancement subdermal plexus flaps
- Move local skin utilising subdermal plexus to maintain blood supply
- e.g. single pedicle advancement flap
- Makes rectangle shape/H shape
Describe axial/inguinal flank fold subdermal plexus flaps
- Can be used as transposition flap
- Skin in fold loose
- Rotate into nearby wound
- However if desensitised due to severed nerve supply then have tendency to self traumatise
Describe distant subdermal plexus flaps
- Pouch
- Site with wound into pouch made at another site e.g. flank
- Will have inherent blood supply
- However takes long time and is uncomdortable
Describe axial pattern flaps
- Supplied by named direct cutaneous artery/vein
- Mobilise large areas of skin if certain of blood supply
- More blood supply than subdermal plexus
- e.g. caudal superficial axial pattern flap
Describe punch/pinch grafts used in wound healing
- Non-vascularised
- names after artery supplying that portion of skin
- Take portion of skin using scalpel or skin punch
- Remove core and defat
- Place in area of lesion
- Narrows the gap that epithelium needs to vocer
Describe non-vascularised skin grafts
- Free skin grafts partial/full thickness, meshed/non-meshed
- LArge areas of skin from one part to another
- Remove fat
- Attach to healthy granulation bed
- rely on skin drawing nutrients and blood suply from underlyiing granulation bed
- No nerve supply so no risk of no danger of self-traumatisation
Outline some complications with using skin flaps to support wound healing
- Partial thickness necrosis
- Full thickness necrosis
- Desensitisation and self trauma
Describe the ideal healing environment
- Optimum moisture (may need to add or remove moisture)
- Free of infection and debris
- Free of toxic chemicals, particles or fibres
- Warm
- New tissue undisturbed
- Adequate gas exchange
- Minimal contamination to and from wound using dressings
Describe alginate dressing
- Seaweed
- Sterile pads, ribbons, rops
- Non-occlusive, non-adherent
- Autolytic debridement to soften and remove necrotic tissue
- Stimulates granulation tissue
- Become jelly like when absorb moisute, can be used to maintain moisture levels
Describe foam dressings
- Absorbent, sponge like polymer dressings
- Provide thermal insulation
- Moist wound environment maintained
Give examples of contact layer dressings
- Knitted viscose
- Silicone mesh
- Paraffin gauze
Describe contact layer dressigns
- Woven or perforated material
- Lie directly on wound’s surface
- Holes to allow drainage to pass through to secondary dressing
- Remains in place during dressing changes to minimise trauma
Describe hydrogel dressings
- Water or glycerin base
- Hydrate wounds, soften necrotic tissue
- Limited absorption
- Sheet or gel
- Good for hydration of wounds
Describe antimicrobial dressings
- Ingredients: silver, iodine, polyhexamethylene
- Protect against bacteria
- Various forms (gauze, foam, absorptive fillers)
- Some provide moist environment
Describe honey for use in in dressings
- Autolytic debridement (pH 3.7)
- Draws fluid from wound area
- Alternative to hydrogels
- Impregnanted gauze, alginate, tube
- Cover with secondary absorbent dressing
- Osmotic action of honey draws fluid out, antibacterial properties
Describe the use of silver sulphadiazine in dressings
- Antibacterial and antifungal
- No known resistance
- Effective against Gram -ve organsism e.g. Pseudomonas
- Effective against MRSA
Outline the use of maggots in wound healing
- Stage 1 larvae only eat liquid protein (so only eat necrotic)
- Accurate and efficient debridement
- Reduce risk of infection
- Difficult to ensure do not escape from wound site
In what wound healing stage does moisture need to be removed?
Sloughy
In what wound healing stage does moisture need to be added?
Granulating
What wound healing stage required debridement?
Necrotic
