Lecture 8, wounds and wound management

Question 1

Wound etiology

Answer 1

• Identification of the causative agent necessary before initiating treatment
• Trauma vs. dermatologic disease (including parasitosis) vs. neoplasia vs. ?
• Important to treat the underlying cause in case of non-traumatic wounds
• Some wounds are impossible to treat successfully

Question 2

Wound irrigation (lavage)

Answer 2

• Dirty or contaminated wounds can be cleaned by irrigation
• Obvious debris, necrotic tissue, dirt and bacteria will be washed away by fluid under pressure
• Irrigation pressure should not be too high because it may damage
  tissue and push contamination further into the wound
• Minimal to moderately contaminated wounds – cleaning performed using isotonic saline or Ri-Lac
• In selected patients, dilute antiseptic solutions such as 0.05%
  chlorhexidine or 1% povidone–iodine solution can be used

Question 3

Debridement

Answer 3

• In case of debris or necrotic tissue
• Anaesthesia often required
• Objective to convert the open contaminated wound into a surgically clean wound
• Different methods (choice depends on the patient): surgical,
  mechanical, autolytic, enzymatic, chemical, biosurgical
• More than one procedure may be necessary

Question 4

Surgical debridement

Answer 4

• Used most commonly
• Goal is to remove all obvious necrotic tissue and debris
• Difficult to distinguish necrotic nonviable tissue from healthy viable
  tissue during the inflammatory phase
• Layered approach often used (superficial tissues removed first)
• Removal to the level where active bleeding is present
• Questionably viable tissue should be left in place and re-evaluated
• En-bloc debridement sometimes used (complete excision of the
  wound and all affected tissue)

Question 5

Mechanical debridement

Answer 5

• Performed using wet-to-dry or dry-to-dry dressings after layered surgical debridement or as the sole means of debridement
• Wet-to-dry dressing (typically changed daily until granulation)
• Primary dressing of gauzes wetted with isotonic saline
• Several layers of wet gauze followed by several layers of dry gauze added
• As the bandage dries, it adheres to the wound surface
• Adhering tissue is removed as the dressing is changed
• Dry-to-dry – same procedure without wetting
• Several disadvantages
• Some authors believe that these dressings no longer meet the expected standard of care in veterinary medicine

Question 6

Autolytic debridement

Answer 6

• Creation of a moist wound environment to allow endogenous
  enzymes to dissolve nonviable tissue
• Often preferred in wounds with questionable tissue viability
• Highly selective for devitalized tissue
• Can be performed with interactive dressings such as hydrogels,
  hydrocolloids, hydrofibres and foam dressings
• Use of honey or sugar topically (attraction of fluid)
• Painless
• Slow process

Question 7

Enzymatic debridement

Answer 7

• Proteolytic enzymes are applied to the wound to break down the
  necrotic tissue
• Wounds with small amounts of necrotic tissue or debris
• (Trypsin, fibrinolysin, chymotrypsin, desoxyribonuclease, papain-urea and collagenase)
• Sometimes used as an adjunct to mechanical and chemical wound
  debridement
• Effectiveness questionable
• Slow process

Question 8

Chemical debridement

Answer 8

• Nonselective method (cells important for healing are also damaged)
• Can be performed with antiseptics
• (Dakin’s solution, chlorhexidine, povidone-iodine, hydrogen peroxide)
• Not generally recommended

Question 9

Biosurgical debridement

Answer 9

• Placement of medical maggots (Lucilia sericata) into the wound
• The maggots produce enzymes that dissolve the necrotic tissue, but
  spare healthy tissue
• Maggots specially bred, expensive
• May be indicated for management of deep wounds

Question 10

Topical antibiotics and antiseptics

Answer 10

• Systemic AB preferred (only for infected wounds)
• The use of topical antibiotics and antiseptics is controversial – no
  beneficial effect once infection is established
• Do not replace proper debridement

Question 11

Topical wound medications

Answer 11

Antimicrobials and antibiotics:
* Triple antibiotic ointment
* Silver sulfadiazine
* Nitrofurazone
* Gentamicin sulfate
* Cefazolin
* Mafenide

Wound-healing enhancers:
* Aloe vera
* Tripeptide-copper complex
* D-glucose polysaccharide
* Honey
* Sugar
* Growth factors
* Hydrolyzed bovine collagen
* Chitosan

Question 12

Open wound management

Answer 12

• Due to wound characteristics/financial reasons/until surgical closure
• Superficial wounds
• Dressing, bandage?
• Wound-healing enchancers used
• Healing process often time-consuming
• Might need some surgical intervention

Question 13

Wound closure

Answer 13

• Decision whether or not to close the wound, when?
• Primary closure
• Delayed primary closure
• Secondary closure
• Drainage
• Tension lines (incisions/closure
  parallel to tension lines if possible)

Question 14

Primary closure

Answer 14

• Preferred for clean wounds, including surgical wounds and
  contaminated wounds that have been debrided and are less than 6
  hours old
• Direct closure of the wound after lavage and debridement
• Leads to a more rapid anatomical and functional recovery than
  delayed and secondary closure
• Sutures can generally be removed in 1-2 weeks
• If the level of contamination, tissue viability, depth of tissue damage
  or vascular supply is questionable, other options should be
  considered

Question 15

Delayed primary closure

Answer 15

• Wound managed as an open wound until it is clean and without
  formation of granulation tissue, then closed
• Closure 3-5 days after the emergence of the wound
• Allows for drainage of the wound, a decrease in contamination and
  the development of a clear demarcation line between viable and necrotic tissue prior to surgery

Question 16

Secondary closure

Answer 16

• Closure of the wound after the formation of granulation tissue
• Contaminated or infected wounds

Two methods:
* Leaving the existing granulation tissue intact, only separating the edge of the skin from the granulation tissue bed and advancing it over the wound
* Excision of the granulation tissue bed followed by primary closure

• Second method usually preferrable
• Wound edges more mobile
• Incidence of infection lower
• Cosmetic reasons

Question 17

Drainage

Answer 17

• Necessary at times (moderate contamination or a large dead space)
• Dead space resulting from suturing of large wounds promotes fluid accumulation, which is a good medium for growth of bacteria

Passive drains (Penrose drain)
- Easier to insert, cost less
- Draining under gravity
- Risk of ascending infection

Active drains
- Creation of a vacuum that removes fluid by suction
- Can be placed anywhere on the body
- Containers need to be emptied regularly

• Removal as soon as possible (usually 2-4 days)

Question 18

Wound dressings and bandages

Answer 18

• Dressing – materials applied directly to the surface of a wound,
• Most important function to allow moist healing
• No single dressing perfect for all wounds in all phases of wound
  healing – initial and follow-up assessments necessary
• Bandage – wraps to hold plain and medicated dressings in place
  (immobilization, pressure to control hemorrhage, obliteration of dead
  space, protection from external trauma and contamination)
• Primary layer (contact dressing)
• Secondary (absorptive) layer
• Tertiary (protective) layer

Question 19

Functions of wound dressings

Answer 19

• Provide a moist environment
• Provide a warm environment
• Protect from trauma
• Protect from external contamination
• Application of topical medication
• Immobilization of the wound
• Support of the wound edges
• Absorb exudate
• Prevent or reduce oedema
• Provide an aesthetic appearance

Question 20

Bandage

Answer 20

• Appropriate materials of adequate width should be used
• As smoothly as possible to prevent irritation and skin necrosis
• Each turn of the bandage should overlap the previous turn by 50%
• Patients should be observed for discomfort, swelling, hypothermia,
  skin discoloration, dryness, or odor
• (absorbent, adherent, non-adherent, stabilizing, pressure bandages, pressure relief bandages etc.)

Question 21

Advanced techniques

Answer 21

• Used for chronic wounds
• Topical negative pressure
• Low-level laser therapy
• Hyperbaric oxygen therapy
• Ultrasound
• Seldom used, research warranted

Question 22

Protocol for wound management

Answer 22

1. Use a clean room and aseptic technique
2. Obtain a complete medical history of the patient
3. Obtain information about the cause and age of the wound
4. Make a complete assessment of the wound
5. Debride necrotic tissue
6. Remove contamination
7. Choose the appropriate method of closure
8. Choose the appropriate dressing
9. Make regular assessments to monitor the progression of wound healing
10. When dealing with chronic wounds not responding to normal wound management, consider using an advanced technique.