Chapter 76 Open Wounds

Question 1

What are the four steps of wound healing?

And what are the four phases of wound healing?

Answer 1

Steps of wound healing

1. Fibrin-platelet clot
2. WBC recuitment
3. Neovascularization + cell proliferation
4. Tissue remodelling

Phases of wound healing

1. 1. Inflammation
2. 2. Debridement
3. 3. Repair
4. 4. Maturation

Question 2

How long do neutrophils predomnate in the wound?

Answer 2

5 days after injury, then mononuclear cells predominate

Question 3

How long does it take for some of the fibroblasts to transform into myofibroblasts (–> wound contraction)

Answer 3

Approx 7d

Question 4

List 6 ‘types’ of wound

Answer 4

1. Abrasion
2. Puncture
3. Laceration
4. Degloving (anatomic = skin gone, physiologic = skin lifted off base)
5. Thermal burn
6. Decubital ulcer

Question 5

Define:

Contamination

Colonization

Infection

Answer 5

Contamination: Presence of microbes on surface

Colonization: Surface microorganisms replicating

Infection: Invasion and replication of microbes in tissue

Question 6

What bacterial burden is considered the threshold for development of infection?

In what time frame does this occur?

Answer 6

10⁵ cfu/g

6 hours

Question 7

How is the ‘conceptual effect’ of microbial burden ‘calculated

Answer 7

(No of microorganisms x virulence)

_____________________________

Host resistance

Question 8

List + describe the 4 types of wound closure

Answer 8

1. Primary closure
2. Delayed primary closure: Closure before granulation tissue (3-5d after wounding)
3. Secondary closure: Closure over granulation tissue.
4. Second intention healing (i.e. by contraction and epithelialisation)

Question 9

List 8 factors to consider when deciding re wound management

Answer 9

1. Time since injury
2. Degree of contamination
3. Extent of ST damage
4. Ability to debride/excise
5. Blood supply
6. Systemic wellness
7. Ability to close
8. Consequences of open wound management

Question 10

Name two tests that should be performed in a chronic wound

Answer 10

Histo (e.g. neoplasia, sterile panniculitis) and culture (Mycobacterium)

Question 11

What are the thresholds for low, high and jet pressure irrigation?

Answer 11

<5psi low

>5-8psi high

70 psi jet

Question 12

What is the characteristic of microbial infection in acute vs chronic wound

Answer 12

Acute more likely to be due to one dominating microorganism, chronic more liekly to be polymicrobial

Question 13

Broadly outline how tobias would recommend ‘managing’ an acute wound

Answer 13

1. Large vol lavage (balanced electrolyte not cytotoxic)
2. Protect wound until sx and during clipping
3. Debridement (usually by surgery)
4. Once granulation bed, ensure moist wound healing environment e.g. hydrogel if minimally exudative vs hydrocolloid or alginate if exudative
5. +- consider addition of antimicrobial strategy - topical ointment (recommended in acute phase), silver impregnated,

Question 14

List 4 antimicrobial properties of honey:

Answer 14

1. Hyperosmolar
2. Produces hydrogen peroxide
3. Phytochemicals
4. Low pH (3.2 - 4.5)

Medical grade honey rated according to inhibin number = amount of dilution to which honey will retain antibacterial activity.

Question 15

What species of maggot is used in wound debridement and why?

Answer 15

Lucilia sericata

Don’t damage healthy dermis and sc tissues (but can destroy healthy epithelium so need to protect epithelium)

Question 16

List 2 examples of bioscaffolds?

When would a bioscaffold typically be used?

Answer 16

Porcine submucosa, hydrolized bovine collagen, chitosan

Indicated for chronic indolent wounds

Question 17

What is the pore sixe of NPWT gauze/foam?

Answer 17

400-600 um pore

Question 18

What pressure is recommended in NPWT

Answer 18

• 125 mmHg with foam (and generally)
• 80 mmHg with gauze
• 65-75 mmHg over grafts

Question 19

Aside from surgically, list 4 methods of wound debridement:

Answer 19

1. Hyperosmotic = hypertonic dressing, honey, sugar
2. Maggots (Lucilia sericata)
3. Enzymatic (usually for chronic wounds only - expensive and non-selective)
4. Mechanical wet to dry dressings - non-selective debridement (use discouraged)