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Tobias ECVS > Ch 76 - Open Wounds > Flashcards

Ch 76 - Open Wounds Flashcards

1
Q

What are the 4 phases of wound healing?

A
  • Inflammation
  • Debridement
  • Repair
  • Maturation
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2
Q

What are the four ‘steps’ of wound healing

A
  • Formation of fibrin-platelet plug
  • Recruitment of WBCs to protect from infection
  • Neovascularisation and cellular proliferation
  • Tissue remodeling
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3
Q

What are the most common locations of a decubital ulcer?

A
  • Greater trochanter
  • Lateral elbow
  • Lateral hock
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4
Q

Define contamination, colonisation and infection

A
  • Contamination - The presence of microbes on a surface
  • Colonisation - Surface microorganisms are replicating
  • Infection - Invasion and replication of microorganisms within the tissue
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5
Q

What microbial burden has been associated with a higher rate of infection? What time does it typically take to reach this level?

A

10^5 CFU/g
Within 6 hours

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6
Q

What is a more relevant calculation of microbial burden?

A

Microbial burden = (Number of microorganisms x Virulence) / Host Resistance

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7
Q

How does the production of granulation tissue of cats differ to that of dogs?

A
  • Open wounds in cats produce significantly less granulation tissue and is more likely to have a peripheral, rather than central, distribution
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8
Q

At 21 days after wounding, how does epithelialisation and total healing differ in dogs anc cats?

A

Dogs: epithelialisation 89%, total healing 98%
Cats: epithelialisation 34%, total healing 84%

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9
Q

What are some potential causes of open wounds which fail to progress towards healing?

A
  • Systemic disease (uraemia, herpatic dz, DM, cushings, FIV)
  • Malnutrition
  • Local tissue hypoxia and ischaemia (Normovolaemia must be maintained, blood transfusin if anaemic)
  • Bacterial colonisation
  • Altered cellular and stress response
  • Repetitive trauma
  • Presence of necrotic tissue
  • Tension
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10
Q

What are some options to improve wounds which are incapable of forming granulation tissue?

A
  • Omental flaps
  • Muscular flaps
  • Vascular skin flap for closure
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11
Q

Is tap water hyper-, iso-, or hypotonic?

A

Hypotonic

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12
Q

What pressure is generally recommended for high pressure irrigation?
How is this best achieved?

A

5-8 psi

16-22g needle onto a fluid administration set of a 1L bag of fluids under pressure of 300mmHg

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13
Q

List hyperosmotic wound dressings

A
  • Hypertonic saline (20%)
  • Honey
  • Sugar
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14
Q

List some hydrophilic dressings

A
  • Hydrogel
  • Hydrocolloid
  • Alginate
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15
Q

Is saline or a balance electrolyte preparation recommended for initial wound preparation? Why?

A

Balanced electrolyte prep
- Saline is slightly hypoosmolar and is cytotoxic to fibroblasts

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16
Q

What antiseptics can be used in the wound?

A
  • 0.05-0.1% chlorhexidine
  • 0.1 - 0.01% povidone-iodine

No detergents! (Cytotoxic)

17
Q

Why is debridement important?

A

Presence of contaminants causes inflammation and devitalised tissue acts as a medium for microbial growth

18
Q

What are the 2 braod categories of wound debridement?

A
  • En Bloc Debridement (and then primary closure)
  • Layered debridement
19
Q

What tissues are not well vascularised? How is this overcome?

A
  • Cortical bone - forage
  • Excess fat - removed
  • Intact fascia - debrided to expose underlying muscle and improve vascularization (fasciotomy or fasciectomy)
20
Q

What substances do most enzymatic debridement agents contain?

A
  • Trypsin
  • Collagenase
  • Papain
  • Urea
21
Q

How do nonenzymatic debridement dressings work?
What are some examples?

A
  • Draw exudate and accompanying debris out of the wound
  • Dehydrate microorganisms and have a cidal and inhibitory effect

Hypertonic saline dressings. Sugar-, Honey- and Dextran-soaked dressings

22
Q

How is hydrogen peroxide produced by honey? At what concentration?

A
  • Hydrogen peroxide is produced by the action of glucose peroxidase (within the honey) on glucose.
  • Forms at a very low concentration of 0.003%
23
Q

What antimicrobial effects are provided by Honey?
What is the inhibin number of medical grade Honey?

A
  • Hydrogen peroxide production
  • Oxygen-derived free radicals
  • Phytochemicals (phenols and organic acids)
  • Acidic pH (3.2 - 4.5)

The inhibin number is the amount of dilution to which the honey will retain its antibacterial activity

24
Q

Other than is antimicrobia properties, what other effects of Honey may enhance wound healing?

A
  • Reduction of inflammation due to anti-oxidant content
  • Stimulation of B- and T-lymphocyte proliferation
  • Stimulation of phagocytic activity
  • Stimulation of cytokine release from monocytes
25
Q

What type of maggots are used for wound debridement?

A

Maggots of the green blow fly Lucilia Sericata

Can destroy healthy epithelium - MUST be protected

26
Q

What is the underlying principle of moist wound healing?

A

Application of a hydrophilic (moisture retentive) dressing to maintain the cellular and cytokine-rich exudate at the wound surface

27
Q

What is typically included in a triple antibiotic ointment?

A
  • Bacitracin zinc
  • Neomycin sulphate
  • Polymixin B sulphate
28
Q

How does incorporation of silver into alginate dressing effect its function?

A
  • Increased antimicrobial activity
  • Improved binding affinity for elastase, MMP-2, TNF-a, and IL-8
  • Further inhibited production of free radicals
29
Q

How do bioscaffolds work?
What wounds are they recommended for?

A
  • Provides a substrate for extracellular matrix formation
  • Stimulates matrix deposition, angiogenesis and epithelialisation due to collagenous and growth factor content

Recommended for use with chronic, indolent ulcers/wounds

30
Q

What is chitosan?
What are its reported functions?

A

Chitosan is a lineal copolymer of linked Beta glucosamine and N-acetly-D-glucosamine

Reported functions:
- ENhance the action of inflammatory cells
- Increase production of granulation tissue through upregulation of TGF-B, PDGF, fibroblast production and IL-8 production

31
Q

List 2 growth factor-containing agents which coulf be used in wound management?

A
  • rhPDGD-BB
  • Autologous PRP
32
Q

What is the recommended porosity of the foam and recommended pressures for negative pressure wound management in small animals?

A
  • 400 - 600 mcm pore foam
  • Recommended -125mmHg for foam-based or -80mmHg for gauze based systems
33
Q

What are the purported benefits of negative pressure wound therapy?

A
  • Improve wound perfusion
  • Reduce oedema
  • Stimulate granulation tissue formation
  • Decrease bacterial colonisation
  • Remove exudate
34
Q

Expression of which growth factors/cytokines may be increases in negative pressure wound therapy?

A
  • VEGF and FGF-2 (experiment on rats)
  • IL-8 and VEGF (humans)
35
Q

How may NPWT be beneficial for skin grafting? Used at what pressure?

A

Benefits:
- Stibilisation of the graft
- Reduce fluid accumulation under the graft
- Prevent dessication
- Possibly prevent bacterial contaminations

Pressure -65 to -75mmHg

36
Q

What are the effects of NPWT on bacterial burden?

A

Unclear….
- Upregulation of IL-8 and IL-1B may trigger accumulation of neutrophils and thus accelerate bacterial clearance

Tobias ECVS (110 decks)

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