Kapitel 76 (Tobias) - Open Wounds

Question 1

How many steps does wound healing consist of? Describe the steps.

Answer 1

4 steps

1) Formation of a fibrin-platelet clot at the site of injury
2) Recruitment of white blood cells to protect the site from infection
3) Neovascularization and cellular proliferation
4) Tissue remodelling

Question 2

Which inflammatory cells predominate initially in a wound and which cells predominate after about 5 days?

Answer 2

Initially: Polymorphnuclear cells

Later: Mononuclear cells

Question 3

After initial injury, how long time does it take for early repair to initiate?

Answer 3

3-5 days

Question 4

Describe what fascilitates contraction of a wound.

Describe what strengthens the wound after full contraction.

Answer 4

Some fibroblasts transform into specialized myofibroblasts approximately 1 week after wounding.
Contraction of myofibroblasts decreases wound size.

Eventually, collagen is deposited by fibroblasts, whereas fibrin strands are removed. Collagen undergoes continuous remodeling to strengthen the wound.

Question 5

1) Define “Abrasion”

2) Describe in one word how an abrasion heals

Answer 5

1) A partial-thickness epithelial injury typically resulting from blunt trauma or a shearing force.
2) Reepitheliazation

Question 6

Define “Puncture wound”

Answer 6

1) Penetration of an object into the tissues and is characterized by a small skin opening with deep tissue contamination and damage

Question 7

Define “Laceration”

Answer 7

Sharply incised skin edges and may extend into deep tissue, such as muscle and tendons.

(Lacerations are typically associated with minimal peripheral trauma to the wound edges; however, if the incised tissue is elevated or avulsed, large areas of tissue may become devitalized from concurrent avulsion of the blood supply.)

Question 8

1) Define “Degloving injury”

2) What is the difference between an anatomic and a physiological degloving injury?

Answer 8

1) Extensive loss of skin and underlying tissue and immediate or delayed exposure of the wound bed.
2) With an anatomic degloving injury, the skin and various levels of underlying tissue are torn off the body.

With a physiologic degloving injury, the skin surface is intact but separated or avulsed from the underlying subcutaneous tissues and blood supply, resulting in delayed necrosis of the skin.

Question 9

What is a “decubital ulcer”?

Answer 9

A decubital ulcer is the result of compression of the skin and soft tissues between the bony prominence and a hard surface, resulting in skin loss over a bony protuberance.

Question 10

What is the difference between contamination, colonization and infection?

Answer 10

By definition, contamination is the presence of microbes on a surface. Contamination can lead to colonization, in which surface microorganisms are replicating. Colonization can lead to infection, in which there is invasion and replication of microbes within the tissue.3

Question 11

1) What amount of CFUs (Colony Forming Units) has long been considered the threshold for development of infection?
2) What is a more relevant conceptualization of the effect of the microbial burden on the wound? (Formula)

Answer 11

1) 10^5 colony-forming units (CFUs) per gram of tissue

2) (Number of microorganisms × Virulence)/Host resistance

Question 12

What is meant by “Primary Wound Closure”?

Answer 12

With primary wound closure, wound edges are apposed and allowed to heal by first intention. First intention healing is appositional healing (minimal gap), which is achieved by fixing the edges in contact (e.g., with suture, tissue glue, staples, and bandages) or by application of a graft soon after injury. Primary closure occurs in most surgical wounds and is indicated in clean, sharply incised wounds that have minimal trauma and contamination and are seen within hours of injury. Any wound that can be completely excised (en bloc debridement) can be converted to a surgical wound and managed by primary closure.

Question 13

1) What is meant by “Delayed Primary Wound Closure”?

2) What are the indications for this type of wound closure?

Answer 13

1) Delayed primary wound closure describes appositional closure within 3 to 5 days after wounding but before granulation tissue is evident in the wound bed.
2) Indicated for mildly contaminated, minimally traumatized wounds that require some cleansing, debridement, and open wound management before closure. This management practice allows manipulation of the wound bed environment over several days to ensure microbial contamination is effectively reduced and tissue health is maximized before closure is performed.

Question 14

1) What is meant by “Secondary Wound Closure”?

2) What are the indications for this type of wound closure?

Answer 14

1) Secondary wound closure describes appositional closure of a wound more than 3 to 5 days after wounding, by which time granulation tissue has formed in the wound bed.
2) Secondary closure is indicated for severely contaminated, traumatized wounds in which ongoing open wound management allows manipulation of the wound environment to ensure reduction of microbial contamination, treatment of infection if present, and improvement in tissue health before closure. Development of granulation tissue in the wound bed provides a microbial-resistant, vascular substrate that facilitates healing. Closure is performed over the granulation tissue, although some debridement may be necessary to allow closure.

Question 15

1) What is meant by “Second Intention Healing”?

2) Name some negative aspects of this type of healing

Answer 15

1) When a wound is left to heal by contraction and epithelialization, eventually producing a continuous epithelial surface
2) Although any wound can be left to heal by second intention, the process may be inefficient and fail to produce a functional outcome in some cases. New epithelium is fragile and easily abraded, and wound contraction, sometimes excessive, may impede normal function. Some wounds may fail to completely reepithelialize, leaving exposed, sometimes proliferative, granulation tissue in the center of the wound.

Question 16

What are the indications for second intention healing?

Answer 16

Open wound management that relies on second intention healing is indicated for dirty, contaminated, traumatized wounds in which cleansing and debridement is necessary but primary or delayed closure is prohibited.

Opportunities to close the wound during open wound management (secondary closure) should be considered to expedite the wound closure process, preserve function, and provide a durable epithelial surface. Open wound management can be used for surgical wounds after tumor excision, usually restricted to the lower limbs where primary closure is difficult

Question 17

The opportunity to close a wound during openwound management should always be considered.

Mention factors to take into consideration.

Answer 17

1) The time lapse since injury
2) Degree of contamination and extent of tissue damage, 3) Thoroughness of debridement or ability to excise wound
4) Status of blood supply
5) Animal’s systemic condition
6) Possibility of closure without tension
7) Likelihood of undesirable consequences of open wound management (e.g., contracture).

Question 18

Are there species differences when it comes to wound healing?

Answer 18

Yes, fx. cats are not as effective at healing as dogs.

Compared with dogs, the strength of primarily closed wounds is lower in cats, and healing of open wounds is slower. In one experimental study, open wounds in cats contained significantly less granulation tissue than dogs, and the granulation tissue was more likely to have a peripheral, rather than central, distribution. Total wound healing was significantly lower at 7, 14, and 21 days after wounding in cats, and the percentage of epithelialization was also significantly less at 14 and 21 days. At 21 days after wounding, epithelialization and total healing were 34% and 84%, respectively, for cats and 89% and 98%, respectively, for dogs.12 Causes of these differences are unknown.

Question 19

Mention some factors that could be responsible for an open wound failing to progress into healing.

Answer 19

1) Systemic disease
2) Malnutrition
3) Local tissue hypoxia and ischemia
4) Bacterial colonization
5) Altered cellular and stress response
6) Repetitive trauma
7) Presence of necrotic tissue
8) Tension

Question 20

What are the aims of immediate wound care?

Answer 20

Immediate wound management is aimed at reducing the microbial burden and preventing further contamination.

In unstable animals at initial presentation, this may include copious irrigation with a readily available solution such as tap water, coverage of the wound with an antimicrobial agent, and ongoing protection with a bandage. This bandage can be left in place until the animal is stable and more definitive wound management can take place.

Question 21

What is more important in an irrigation solution for immediate wound management - Sterility of the solution or amount available?

Answer 21

Amount available!

Systematic review of clinical studies evaluating tap water and sterile saline for wound irrigation in people showed no difference in occurrence of wound infection after tap water or sterile saline irrigation.81 This was verified by a later randomized clinical trial in 715 people that showed no difference in risk for infection (relative risk, 1.21; 95% confidence interval, 0.5 to 2.7).56 Some studies suggest that tap water reduces the risk for infection.

No difference in development of wound infection is evident with use of tap water, distilled water, or boiled water.25

Question 22

Describe a consistent technique for producing 7 to 8 psi (for irrigation)

Answer 22

Attach a 16 to 22 gauge needle to a fluid administration set and 1 liter fluid bag and to place the fluid bag under 300 mm Hg pressure using a pressure cuff

Question 23

Describe best practice of antimicrobial agents in early wound care

Answer 23

In general, topical agents are indicated early in wound management to control contamination and reduce microbial burden.

Systemic agents are indicated for treatment of wound infection.

Topical agents are generally broad spectrum, which is a desirable property because a contaminating microbial population is often quite mixed. Systemic antimicrobial treatment should be narrower in spectrum and is best based on results of culture and sensitivity testing of tissue from the wound. An exit tissue culture after wound debridement and lavage is most representative of what remains in the wound. Detection of a positive tissue culture result is consistent with the definition of wound infection. Cultures from swabs of the exudate or surface of a wound are more representative of contaminants.

Question 24

Mention some topical antimicrobial agents suitable for immediate wound management

Answer 24

1) Antimicrobial ointments
2) Silver-based dressings
3) Hyperosmotic dressings (20% hypertonic saline, honey, sugar)

Hypertonic saline dressings are profoundly antimicrobial, naturally debriding, and more cost effective than silver in the immediate wound management period.

Question 25

Describe wounds that are suitable for En Bloc resection

Answer 25

Small wounds or wounds in a suitable location for closure, regardless of the extent of tissue damage or level of contamination (or infection)