Wound healing and management Flashcards
What are the 4 phases of wound healing?
- Haemostasis
- Inflammatory phase
- Proliferation a.k.a. repair phase
- Maturation phase
Describe the the first phase of wound healing (Haemostasis)
Describe the second phase of wound healing
- Inflammatory phase
- Overlaps with haemostasis
- Occurs in the first 72hrs after injury
- Vasodilation (following transient vasoconstriction in haemostasis)
- Cytokines in the fibrin clot attract white blood cells (initially)
- Destruction of cells by phagocytosis helps clean up bacteria and devitalised tissue
- Normal for 72hrs after injury
T/F: the inflammatory phase of wound healing is normal
True
Inflammation is normal for the first 72hrs after injury
Only worry if it persists for longer than this time frame
Describe the third phase of wound healing
- Proliferation a.k.a. repair phase
- Some overlap with the inflammatory phase
- Formation of granulation tissue
- Fibroblasts proliferation and produce new ECM, elastin and collagen
- Next steps:
- formation of new epithelial tissue → wound shrinks
- myofibroblasts cause wound contraction → wound shrinks
Describe the characteristics of granulation tissue and how it is formed
- Granulation tissue is formed in the proliferation a.k.a. repair phase
- It is formed of macrophages, fibroblasts and new blood vessels
- It has a characteristic red appearance
- Granulation tissue is not as strong as fully healed tissue, but provides some strength and barrier to infection
Contact inhibition
when epithelial cells come into contact with each other, further division is inhibited. This allows a wound to be closed.
When this goes wrong = neoplasia.
Describe the fourth phase of wound healing
- Maturation phase
- Remodelling occurs
- Type III (immature) collagen is replaced by Type I (mature) collagen
- Cross-linking of collagen fibres occurs → increase in tensile strength
- This can takes weeks to months
Give some factors which affect wound healing
- Patient factors: age, co-morbidities, nutrition status especially hypoproteinaemia (hence post-op nutrition v. important!)
- Wound factors: ±infection, location (tension, movement, local blood supply)
- Concurrent treatment
- Corticosteroids delay all stages of wound healing
- Radiation causes tissue fibrosis and vascular scarring
What are the available methods of wound debridement?
- Surgical
- Mechanical
- Autolytic
- Enzymatic
- Biological
Surgical debridement
- Surgical removal of wound biofilm and devitalised tissue
- Good option for wounds stuck at the granulation phase:
- Scrape away the unhealthy granulation bed → lavage → dress
- This will hopefully promote a healthier granulation bed
Mechanical debridement
e.g. via irrigation, wet-to-dry dressing, negative pressure wound therapy (NPWT)
Autolytic debridement
Using the body’s own enzymes beneath a dressing to liquefy tissues
Can use hydrocolloids, hydrogels, honey, foam
Enzymatic debridement
Use of a prescribed topical agent that chemically liquefies necrotic tissues with enzymes
Biological debridement
Use of maggots (typically green bottle fly)
Describe how lavage (mechanical) debridement should be carried out
- Hartmann’s is best - ideal pH and compatible with tissue; 0.9% is often used and is acceptable
- Ideally fluid should be at body temperature
- HIGH volume should be used on newly presented wound (1L is not unusual!)
- 20-35ml syringe, 18G needle to generate 7-8psi
Describe how to undertake wet-to-dry debridement dressing
- Soak sterile swabs in an isotonic crystalloid solution (e.g. Hartmann’s), squeeze out so that they are wet but not dripping
- Dress the granulation bed
- Layer dry and other dressings above
- Change every 24 hrs
- They are very effective at converting chronic granulation beds to healthy ones in small animals
Describe how topical negative pressure wound therapy works
- Provides a partial vacuum at the site of the wound, drawing fluid out
- When turned on, pump gently reduces air pressure under the dressing → draws off exudate, reduces oedema in surrounding tissues
- This process
- reduces bacterial colonisation
- promotes granulation tissue development
- increases the rate of cell mitosis
- spurs migration of epithelial cells in the wound
- stimulates increased blood supply which brings in wound healing factors
- Can be difficult to produce an air tight seal
Describe the beneficial effects of honey on wounds
- Antibacterial effect (reduce or eradicate bacteria)
- Healing stimulating properties: reduction in wound size, healing time etc.
- Debriding effect
- Anti-inflammatory effect
- Odour-reducing capacity
- Reduction in wound pain
Describe the debridement properties of honey
Honey has good debridement properties due to:
- Low pH (~3.7)
- Osmotic effect: draws fluid up from wound in a mild form of debridement
Which method of debridement is quickest? Which is cheapest? What about most expensive? Which method is slowest?
Generally popular is scraping with a scalpel blade and wet-to-dry dressings as they are quick and effective.
Honey may not be a first choice as it is slower.
Which of these wounds is likely to be associated with a poor outcome?
- The L wound could involve the brachial plexus and thoracic cavity; if not, the horse may recover fine.
- The R wound is associated with a synovial structure: the calcaneal bursa at the hock).
- Based on the potential for structures involved in R to become infected/septic, R wound may result in level of lameness not compatible with life.
If this horse cannot move its fetlock back into the normal position, what could you conclude?
The extensor tendon is ruptured
What structures are injured here?
What is the likely prognosis?
What is the cost estimate?
- The horse has injured SDFT and DDFT
- It could recover, but will require huge amounts of money to have a chance of returning to previous workload, if at all
What does this ultrasound image show?
- An object is casting an acoustic shadow
- This is a foreign object in the boundary between the SDFT and DDFT
What is this and what do we call it in equine?
Excessive granulation tissue
“Proud flesh”
Why is excessive granulation tissue a problem? How do we fix this?
- Excessive granulation tissue stops epithelialisation as this can only occur from the border of the wound
- If epithelial cells can’t migrate, the wound won’t close.
- Trim back the excess tissue so that granulation tissue is below the level of the skin surface.
- Then re bandage the wound and immobilise as much as possible.
Abrasion
- Loss of epidermis and some dermis; can expose bone
- Typically caused by blunt trauma/shearing
Avulsion
- Tearing of tissues away from attachments
- No loss of skin, just tearing away from the attachment
- On limbs this is a degloving injury
Incision
- Created by a sharp object
- Causes minimal trauma
Laceration
- Tearing of the wound causing irregular defect
- Generally jagged
Puncture
- Penetrating wound
- Superficial damage may be minimal but deep damage could be substantial
- Images = bite wound through pectorals
Describe the skin’s vascular supply in veterinary species and explain why this is relevant
- Unlike us, veterinary species have a subnormal plexus: terminal branches of the direct and cutaneous arteries within the panniculus muscle and the subcutis
- When doing surgery and mobilising the skin, need to have some idea of where direct cutaneous arteries are and protect them to some degree → don’t want to jeopardise the skin’s blood supply
Describe the skin’s vascular supply in veterinary species and explain why this is relevant
- Unlike us, veterinary species have a subnormal plexus: terminal branches of the direct and cutaneous arteries within the panniculus muscle and the subcutis
- When doing surgery and mobilising the skin, need to have some idea of where direct cutaneous arteries are and protect them to some degree → don’t want to jeopardise the skin’s blood supply
