Small animal basic wound management

What are the three phases of normal wound healing?

• Lag or inflammatory phase (~5 days)

• Repair phase (~6-18 days)

  • Connective tissue repair

  • Wound contraction

  • Epithelialisation

• Remodelling phase

(Considerable overlap between phases)

List the local factors that effect wound healing?

• Wound perfusion —> hypovolaemia, hypotension, vessel injury, pain

• Tissue viability —> trauma, dehydration, osmotic injury (if high disinfectant conc.), envenomation, chemical injury

• Wound fluid accumulation —> haematoma or seroma

• Infection

• Mechanical factors —> tension, motion, pressure

List the systemic factors that affect wound healing?

• Immunosuppression

  • Systemic disease (FIV, hyperadrenocorticism)

  • Glucocorticoid administration

• Neoplasia

  • Residual disease

  • Cytotoxic drugs / radiotherapy

  • Cachexia

What is taken into consideration in order to classify wounds?

(evaluate whole patient):

• Degree of contamination

• Aetiology

• Location

Recall the classification of wounds in terms of degree of contamination

Abrasion definition 

A partial thickness wound with loss of epidermis and part of dermis

Avulsion definition

Tearing of tissue from its attachments

De-gloving injury definition

Low-velocity avulsion of skin due to rotational forces (typically in road accidents).

Incision definition 

Sharp trauma resulting in a smooth-edged wound with minimal tissue trauma.

Laceration definition

Sharp trauma resulting in an irregular wound with tearing of tissue and trauma of underlying tissue.

Puncture wound definition

Penetration by a missile or sharp object. Often minimal superficial damage with substantial damage to deeper structures

How to prepare wound for treatment?

• Take swabs for bacteriology before cleaning

• Prevent further contamniation by covering with sterile water soluble gel or sterile saline-soaked swabs

• Begin clipping at wound edges and work away (minimises hair contamination)

• Can prepare skin with but DO NOT allow surgical scrub to enter wound

• Lavage

What are the aims of lavage?

• Decrease the number of bacteria in the wound

• Remove debris

• Prevent further contamination

• Prevent transformation of acute clean-contaminated or contaminated wounds into infected wounds

• Convert contaminated or clean-contaminated wounds into wounds suitable for primary closure

How to carry out pressure irrigation for hydrodynamic debridement (lavage)?

• Using a 20ml syringe with an 18g needle

• Antiseptics can be added to the final lavage —> they must not contain detergent

How does hydromechanical debridement work?

• Amorphouse hydrogel dressing (e.g. Intrasite)

• Promote hydration and autolysis of necrotic tissue, absorb sloughing tissue, allow optimum cell migration and proliferation

• Contain bacteriostatic propylene gel

(when first take dressing off may appear worse because gel has absorbed pus)

How does surgical debridement work?

• Use aseptic technique to avoid further infection

• Evaluate viability of issues based on colour, pulse and bleeding

• Remove all devitalised tissue and foreign material (scalpel not scissors), preserve important structures for function unless very obviously necrotic and non viable

• Lavage again after debridement

What to do if unsure about viability of tissues?

• Manage as open wound for 48-72 hours until obvious demarcation of devitalised tissues occur

• Immediate debridement is only essential in massive, deep or grossly necrotic wounds that may cause sepsis

After debridement how do we decide an appropriate management technique? List these techniques and what they require

Reassess and recategorise

What is open wound management?

Combines continued debridement by lavage, repeated surgical debridement or use of topical preparations and dressings and protection of the wound to provide an optimum environment for healing

How many layers are there in a dressing?

3 layers

• Primary (contact) —> adherent (no longer standard of care) or non adherent

• Secondary

• Tertiary (outermost)

Describe a wet-to-dry bandage

Adherent primary bandage —> pulls debris off surface of wound —> delayed healing because takes surface cells away with it when taken off

What does the choice of primary layer depend on?

• Desired function

• For debridement you would choose nonadherent dressing with hydrogel

• For protection of wound and maintenance of optimum enviroment for healing you would you simple non adherent dressing

What factors do you consider when choosing the type of non adherent primary layer?

• Amount of exudate production —> prevent wound drying out but allow excess moisture to escape (preventing maceration), more exudate requires more absorbable or permeable dressing

• If wound in infected require more frequent dressing changes & lavage (at least daily)

What are the classifications of non adherent dressings and what is the aim

• Semi occlusive (passes moisture through) or occlusive (traps moisture underneath)

• All aim to allow excess exudate to drain but to keep wound moist

List the types of non adherent dressings and their general features

• Calcium alginate (seaweed) —> absorb exudate & water on contact with wound surface

• Fenestrate polyester film dressing (Melolin) —> polyester film stops dressing adhering to tissue

• Hydrocellular dressings (Allevyn) —> extremely absorbent but do not transmit liquids to secondary layer

• Hydrocolloid dressings —> mainly composed of cellulose that absorbs moisture and exudate becomes gel

• Polyethylene/polyurethane film dressings —> non-absorben but some pass water vapour into secondary layer

• Petrolatum-impregnated gauze —> non absorbent and hydrophobic

• Hyperosmolar agents —> honey and home-made sugar dressing which are hyperosmolar and dehydrate bacteria (must be sterile - clostridia is in untreated honey)

• Maggots —> larvae of lucilia sericata —> enzymatic destruction of necrotic healing & secretions stimulate fibroblast activity 

• Silver dressings —> release bactericidal silver ions

When is each non adherent dressing used?

• Calcium alginate —> wounds at any stage of healing with moderate to heavy exudation, removed by lavage

• Fenestrate polyester film dressing (Melolin - shiny side face down) —> protecting wounds with intact epithelial surface

• Hydrocellular dressings (Allevyn) —> surface wounds or cavities e.g. ulcers 

• Hydrocolloid dressings —> can handle wide range of exudate volumes

• Polyethylene/polyurethane film dressings —> indicated for protection of wounds with an intact epithelial surface

• Petrolatum-impregnated gauze —> wounds in later stages of repair because may slow epitheliasation- mainly used for protecting wounds with an intact surface but fragile epidermis

• Maggots —> may be more useful as antibacterial resistance becomes more common

What are the roles of the secondary layer?

• Absorbs excess fluid from wound

• Secures primary layer

• Obliterates dead space

• Protects wound

List some types of secondary layer

Cast padding, disposable nappies, absorbent pads and cotton wool

What are the functions of the tertiary layer?

• Secures rest of dressing

• Keeps dressing clean and dry

• Ensure not too tight

  • Use sufficient secondary layer

  • Distribute tension evenly

  • Estimate pressure manually

  • Monitor the patient after application

What is commonly used for the tertiary layer?

Gauze bandage (elastic or nonelastic) covered by surgical tape or a self-adhesive elastic bandage e.g. Vetrap