VETN 227B: Wound Management

What is the first thing to do when it comes to wound management?

Proper assessment of animal via :

• History + signalment

• PE - if it’s an emergency, you must stabilize them + basic bandaging

What are the different etiologic classification of wounds?

1. Abrasion

2. Avulsion

3. Incision

4. Laceration

5. Puncture

6. Contusion

What is an abrasion?

When the skin is rubbed/scraped → Reaches up to epidermis or some dermis

Ex: Dog dragged by a car

What is an avulsion?

Tearing from attachments AKA devolving

• Trauma is severe bc it crushes blood vessels

What is an incision?

Sharp cut in tissue

• Trauma is minimal

What is a laceration?

Tearing of the skin

• Trauma is variable

What is a puncture?

Sharp penetration to the skin

Trauma can be variable

• Surface - looks minimal (we can only see surface only)

• Deep - can be variable because we can’t really see deep

What is contusion?

Skin is intact but the blood vessels below are torn AKA bruise

What are the different contamination classifications?

1. Clean

2. Clean-contaminated

3. Contaminated

4. Dirty/infected

What are the two types of clean contaminations?

1. Surgically created

2. Aseptic

What does it mean when it’s a surgically created clean contamination?

It was created in a surgery suite and no trauma was induced

What does it mean when it’s an aseptic clean contamination?

There was a luminal entry - slightly contaminated

Ex: Spay, Gastrotomy (NOT the colon)

What does it mean when a surgery is clean-contamination?

During surgery, you enter the lumen (any hole)

• Minor break in asepsis

• Trauma = minor contamination

What is contaminated in terms of contamination classification?

Major asepsis break where you enter the colon and there’s a lot of bacteria in it

• Most traumatic

What is dirty/infected when it comes to contamination classification?

It can be a visceral perforation - where there is fluid leaking into the peritoneum

It can be old trauma wounds - pus/purulent

What affects primary healing potential?

• “Golden period” - time is primary factor (1 hr vs. 5 mins)

• Bacterial contamination - the # of organisms (10^5 / gram)

• Other factors - wound type, degree of trauma, foreign material, patient (healthy vs. disease)

What does it take to turn contamination into infection?

When bacteria start to proliferate

When it comes to infection, the higher the amount of bacteria…

The higher chances/potential into turning into an infection (>10^5 /gram)

When it comes to infection, the higher the virulence of the bacteria…

The lower/less amount (numbers) of bacteria is needed

When it comes to infection, the lower the resistance of the host…

The lower/less amount (numbers) of bacteria is needed to infect

What is the relationship/equation between bacteria, virulence, infection?

Inverse relationship

Number of organisms x virulence/immunity of host = infection

What are ways to determine bacterial infection?

1. Quantitative cultures - swab → culture

2. Rapid slide technique

3. Clinical estimation

What are the cons of quantitative cultures?

It takes 24-48 hrs which is too long → Defeats purpose bc you have to wait to find out

How do you do a rapid slide technique?

Basically get a tissue biopsy → weight it → homogenize it (crush until its a thin layer of liquid) → Dry it → Stain

What are the pros/cons of clinical estimation of bacterial infection?

You could be right and you could be wrong → Not really effective and no one does it

What are some clinical guidelines?

• Aseptic techniques*

• Prevent further contamination of wound

• Remove foreign debris

• Sufficient debridement

• Eliminate dead/potential space via draining

• Promote vascular bed/granulation tissue

• Appropriate closure

Basically wound healing

What are some things to keep in mind for aseptic techniques?

1. Wear your cap, mask, sterile gloves

2. Have sterile equipment

3. Have a clean environment → don’t use dental table

4. Surgically prep your patient

5. Change out your instruments often bc the more you use it, the more they get contaminated

What are the methods to prevent further contamination?

1. Use a temporary bandage (sterile, moistened with LRS, have antimicrobial)

2. Clean the wound (remove the hair, clip wide, protect the wound)

What are the two ways to remove foreign debris?

1. Intrinsic

2. Extrinsic

What is intrinsic removal of foreign debris?

It means it’s debris that is normally on the wound area

Ex: Hair, normal bacterial flora (unless in an abnormal location)

What is extrinsic removal of foreign of debris?

It means that its debris that is variable or based on where the wound occurred

Ex: Asphalt (if animal was HBC), manure

What is IPF? (Has to do with removal of foreign debris)

Infection potentiating factors

Ex: Organic/soil, highly charged particles, can be hard to remove

When removing foreign debris manually, what are some things you should do?

1. Can be painful → use analgesics

2. Make sure to use sterile instruments, be careful of hitting vital structures

3. Do this before lavaging/washing out the wound

When lavaging out a wound, how much volume of liquid should you use?

More volume (the more volume, the higher chances of getting rid of any other foreign debris)

How much pressure should you lavage a wound?

7-8 psi (pounds per sq. In) with a 35cc and 18-19g

If you lavage using 15+ psi on a wound, how much percentage of IPF do you remove?

85%

What should you be careful when lavaging a wound?

Creating a tissue edema - can decrease local defenses which can slow down healing

What are some types of fluid that you can use for lavaging wounds?

1. Tap water

2. 0.9% saline

3. LRS - best solution

What are some antiseptics you can use to remove foreign debris?

1. Chlorohexidine

2. Povidone-iodine (betadine)

3. Tris-EDTA

What should you keep in mind when using antiseptics for removing foreign debris? (Has to do with concentration)

The higher the concentration of the antiseptic, the more toxic it is → Dilute it*

What is the percentage/ratio for chlorohexidine?

0.05%

1:40 stock (of chlorohexidine) in sterile H2O* (not tap water)

Ex: 1000mL solution - 50 mL of chlorohexidine and 950 mL of sterile H2O

What is the percentage/ratio for povidone-iodine (betadine)?

0.1%

1:9 stock (of betadine) in saline

Ex: 1000mLs of solution - 100 mL of betadine and 900 mL of saline

What is tris-EDTA used for?

For synergistic - resistant bacteria

What should you NOT use for antiseptics?

H2O2 - will burn/bubbles on surface

What is the goal of debridement?

Get rid of necrotic, foreign, purulent (pus) tissues and be able to reach healthy tissues

What are the two methods to debridement?

1. Selective

2. Non-selective

What is selective debridement and what are some examples of it?

Selective debridement is where the body figures out how to get rid of necrotic tissue (Does it itself) and specifically targets dead tissue

Ex: Autolytic, enzymatic, biological (maggots)

What is non-selective debridement and what are some examples of it?

Non-selective debridement is where they don’t specifically target necrotic tissues, sometimes it can affect living tissues too

Ex: Surgical

Mechanical - bandages

What is autolytic debridement?

Where we put occlusive dressing (like a bandage) in order to keep wound fluids in the wound → wound fluid contains proteolytic enzymes which get rid of dead stuff

How often should you change the dressing when it comes to autolytic debridement?

Change q48-72hrs b/c it needs to stay wet → Make sure to lavage or wash surface of the wound

What are advantages to autolytic debridement?

• Selective* → will only target necrotic tissues

• Painless

What are some disadvantages of autolytic debridement?

• Slowest*

• Can cause infection

• Cost - expensive

What is enzymatic debridement and what are some examples?

Where the body uses specific enzymes to get rid of dead stuff

Ex: Papain-urea (from papaya), collagenase (gets rid of collagen)

What are some limitations/disadvantages of enzymatic debridement?

• Slow

• Cost - expensive

• May damage normal tissues

What is biotherapeutic/biologic debridement?

Where living things (like maggots) selectively target dead tissue

Ex: Fly larva (maggots) - eat ONLY necrotic debris

What are some advantages to biotherapeutic/biological debridement?

• Painless*

• Precise - very

What are some disadvantages to biotherapeutic/biological debridement?

• Slow

• Needs constant bandage changes

• Cost - expensive

What is surgical non-selective debridement?

Where doctors will surgically get rid of necrotic tissues → know your anatomy and be able to recognize it!

What are indications of surgical non-selective debridement?

• If the wound is a large area

• If the patient has good pain tolerance → they are able to tolerate it b/c it will be painful

What are contraindications to surgical non-selective debridement?

• Coagulation problems - blood clotting problems

• If they don’t know their anatomy

• If they don’t know how to do it

What are the two methods of surgical debridement?

1. Enbloc*

2. Layered

What is enbloc debridement?

Where they remove the whole wound → Use a lot of surrounding tissue to immediately close it

• Needs to have ample tissue (a lot of tissue)

What is layered surgical debridement?

Where they take out the wound progressively in layers (from superficial to deep)

• Can be anywhere but must be in stages - remove a few at a time every few days

What is the best instrument for surgical debridement?

Scalpel* - does the least amount of damage

What are some mechanical debridement methods?

1. Hydrodynamic therapy

2. Adherent bandages

3. Drain/eliminating space

What are some characteristics of mechanical debridement?

• Non-selective → doesn’t always target necrotic tissues

• Painful → needs analgesics (pain meds)

What are the two types of adherent bandages? (stick to the wound)

1. Dry-to-dry

2. Wet-to-dry*

What is a dry-to-dry bandage?

Initially sticks on wound dry → Absorbs some of the moisure and becomes moist → Then dries which makes it stick better

• Requires more moist but not gooey wounds

What is a wet-to-dry bandage?

When they put the bandage directly on the wound

• Has higher amount of necrotic tissue to be removed and the exudate is a little gooey

• Which is why its wet to dry, it sticks to a moist, gooey wound

What are some guidelines to wet-to-dry bandages?

• Make sure it’s moist with LRS (not dripping)

• Make sure it touches all wound surfaces

• Don’t keep in contact with skin → can cause maceration

• Use sterile gauze

• Switch to non-adherent when appropriate → only a temporary bandage

When draining/eliminating space in a wound, what are the two types of wounds?

1. Open wound

2. Closed wound

When it comes to open wounds, what should you do?

Ultimate drainage - drain everything, make sure to explore all pockets

What does closed wounds create?

Potential/dead space → fills up with fluid and can slow healing

What are the drain types when it comes to closed wounds?

1. Passive - no energy, use gravity flow

2. Active - requires energy, use negative pressure or suction

What are indications to passive drainage?

1. Small to moderate sized wound

2. Minimal drainage is expected - don’t use when there’s a lot of fluids

What are indications for active drainage?

• Large wounds

• Needs to drain excess fluids (a lot)

When using negative pressure for active drainage, what should you do or keep in mind?

• Keep it air tight

• Create a wound bed

• Have a suction device attached to the patient

When promoting a vascular bed, what are some things you can do for wound care?

• Use aseptic techniques

• Make sure to prevent further contamination

• Remove foreign debris

• Sufficient debridement

• Eliminate space by drainage

How do you protect wounds?

With bandages via non-traumatic techniques and proper application of it

When should you close a wound?

When there is less inflammation and when there is a healthy bed of granulation tissue

What are some techniques to close wounds?

Use absorbable sutures and preferably monofilament ones (smaller diameter)

• Eliminate potential space and use minimal suture

What are the types of closure selections?

1. Primary

2. Delayed primary

3. Secondary

4. Open wound

What is primary closure?

Immediate - after wound is made, uses stitches

• 1st intention healing

What is delayed primary closure?

Clean up the wound and create a healthy vascular bed → close wound before granulation tissue forms

• 1st intention healing

What is secondary closure?

Close wound after healthy bed of granulation is formed and on top of the granulation tissue

• 3rd intention healing

What is open wounds closure?

We don’t close it at all → The body closes it by itself and fills in

• 2nd intention healing

What is 1st intention healing?

Surgically close a wound before granulation tissue forms

• Primary and delayed primary closure

• The wound was surgically created and has no infection or any wounds

What is second intention healing?

We don’t do anything to close the wound → The body does it naturally via enzymes, chemotactics, cytokines, etc.

• Open wound closure

What is third intention healing?

Where we close the wound AFTER granulation tissue forms (and on top of it)

• Only secondary closure

What are some new directions for wound management?

1. Vacuum-assisted closure

2. Prevent hypothermia

3. Growth. factor stimulation

When do we use vacuum-assisted closure?

When open wounds are chronic and/or infected

How do we use vacuum-assisted closure?

We use negative pressure in a controlled environment with NO AIR

• 125 mmHg negative pressure

What does negative pressure do in vacuum-assisted closure?

• Lowers edema

• Lowers bacteria

• Increases blood flow - b/c of negative pressure

• Increases proliferation of cells

Why do we prevent hypothermia when managing wounds?

• Lowers vasoconstriction (vessels will be more open) → helps maintain O2 levels

• Lowers surgical infection

Basically helps the wound heal better

What are ways/methods to prevent hypothermia?

• Use sensor controlled heating - like a HotDog

• Forced air warmer - like Bair Hugger (but don’t use during OR, use post-op)

• Water circulation

• Body wraps

What does growth factor stimulation do?

Can enhance healing (idk how but its there)

What are some human products for growth factor stimulation?

• TGF - b

• PDGF

• EGF

What is a disadvantage to using growth factor stimulation?

Expensive