Wound Healing

Question 1

four stages of wound healing

Answer 1

1. hemostasis
2. inflammation
3. proliferation
4. remodeling

Question 1

hemostasis

Answer 1

formation of a blood clot to plug bleeding, provide a barrier to infection and fluid loss, and provide an initial substrate for wound healing

• immediate
• involves vasoactive substances, platelets, clotting factors, clotting proteins

Question 2

steps of hemostasis

Answer 2

1. bleeding
2. release of vasoactive substances
3. vasoconstriction
4. vasodilation
5. blood cells move into wound
6. clotting cascade
7. blood clot stabilizes wound

Question 3

inflammation

Answer 3

bacteria and extracellular debris are removed from the wound by WBCs; blood clot stabilizes

• 1-7 days after injury
• involves neutrophils, macrophages
• minimal hemorrhage, less sharp wound edges, scab formation

Question 4

steps of inflammation

Answer 4

1. WBCs migrate to wound
2. neutrophils kill bacteria, degrade debris, release cytokines
3. monocytes proliferate and differentiate
4. macrophages debride, kill, and strengthen clot

Question 5

proliferation

Answer 5

granulation tissue (collagen and blood vessels) fill the defect to provide a barrier to infection

facilitates wound closure via contraction and epithelialization

• 3-35 days after injury
• involves macrophages, fibroblasts, ECM proteins, capillary endothelial cells, new epithelial cells
• rounded wound edges, granulation tissue forms, resistant to infection

Question 6

steps of proliferation

Answer 6

1. fibroblasts and endothelial cells migrate to wound
2. new capillaries form and collagen accumulates
3. ECM is replaced by red granulation tissue
4. myofibroblasts contact wound edges
5. epithelial cells grow inward from edges of wound

Question 7

remodeling

Answer 7

collagen reorganizes to strengthen the closed wound; unneeded cells undergo apoptosis

• weeks to years
• involves macrophages, fibroblasts, matrix metalloproteinases, collagen

Question 8

steps of remodeling

Answer 8

1. wound loses vascularity
2. type III collagen is replaced with type I collagen
3. collagen reorganizes along tension lines
4. wound gains tensile strength
5. unnecessary cells undergo apoptosis

Question 9

wound strength during inflammation

Answer 9

minimal strength

Question 10

wound strength during proliferation

Answer 10

rapid strength gain

Question 11

wound strength during remodeling

Answer 11

slow strength gain

Question 12

how strong is the final scar

Answer 12

70-80% as strong as original tissue

Question 13

ways of classifying wounds

Answer 13

1. inciting injury
2. degree of bacterial contamination
3. type of closure

Question 14

contusion

Answer 14

bruise

blunt trauma causes an accumulation of blood secondary to ruptured vessels

Question 15

abrasion

Answer 15

partial thickness epithelial injury caused by blunt or shearing forces

minimal hemorrhage
rapidly healed by re-epithelialization

Question 16

puncture wound

Answer 16

penetration of an object into the tissue

small opening with deep tissue contamination and damage

Question 17

laceration

Answer 17

sharply incised skin edges that may extend into deep tissues

minimal peripheral trauma to wound edges

Question 18

degloving injury

Answer 18

extensive loss of skin and underlying tissue

caused by scraping across a hard surface or excessive traction on extremity

Question 19

thermal burn

Answer 19

close proximity of direct application of heat to skin

described by depth (superficial partial, deep partial, full thickness)

high risk of infection

Question 20

radiation burn

Answer 20

secondary to external beam radiation therapy

takes weeks to present

Question 21

decubital ulcer

Answer 21

compression of skin and soft tissue between a bony prominence and a hard surface leading to skin loss over bony protuberance

Question 22

classifications by degree of contamination

Answer 22

• clean
• clean contaminated
• contaminated
• dirty

Question 23

clean

Answer 23

controlled surgical wound into STERILE tissue compartments

Question 24

clean contaminated

Answer 24

controlled surgical wound into GI, UG, or respiratory tracts

Question 25

contaminated

Answer 25

- open, fresh, accidental wounds - gross spillage from GI, UG, or respiratory tracts - acutely inflamed tissues

Question 26

dirty

Answer 26

- established infection - old, traumatic wound - devitalized tissues - GI, UG, or respiratory perforations

Question 27

when do surgical wound infections occur

Answer 27

when bacterial numbers and virulence exceed the host's immune response >10^5 CFUs per gram of tissue

Question 28

what are local or surgical factors that lead to infection

Answer 28

- amount of bacteria - necrotic/devitalized tissues - ischemia - foreign material - excessive hematoma or dead space

Question 29

what are local or surgical factors that lead to impaired healing

Answer 29

- excess tension - excess motion - prior radiation at wound site

Question 30

what are systemic factors that lead to infection or impaired healing

Answer 30

- long surgery/anesthesia - hypotension - hypothermia - concurrent diseases - immunosuppressive medications

Question 31

what are steps of basic wound care

Answer 31

1. clip and clean 2. clean surrounding skin 3. remove foreign material 4. debride infected/necrotic tissue 5. lavage with sterile saline 6. repair

Question 32

wound repair types

Answer 32

1. open: cover with banadge 2. closed: suture edges closed +/- drain

Question 33

what are the types of closure

Answer 33

1. first intention - primary vs delayed primary 2. second intention 3. third intension (secondary closure)

Question 34

first intention healing

Answer 34

wound is closed SURGICALLY and BEFORE granulation tissue forms IDEAL - fast, less new tissue formation

Question 35

first intention - primary closure

Answer 35

immediate debridement, lavage, and closure used on FRESH (<12 hours) and CLEAN wounds (ideally golden period)

Question 36

golden period

Answer 36

the first 6 hours after the injury occurs too soon to allow sufficient replication of microorganisms to cause wound infection

Question 37

first intention - delayed primary closure

Answer 37

1-5 days of open wound management with bandaging followed by surgical closure (still before granulation tissue forms) used on OLDER (>12 hour) and CONTAMINATED wounds with devitalized tissue

Question 38

second intention healing

Answer 38

wound is closed NATURALLY via 4 stages of healing (contraction + re-epithelialization) can used debridement and bandaging to support natural processes SLOW with lots of new tissue formation

Question 39

when to use second intention healing

Answer 39

large areas of tissue loss dirty/contaminated infected surgical wounds financial limitations

Question 40

third intention healing

Answer 40

wound is closed SURGICALLY and AFTER granulation tissue forms open wound management followed by skin flaps/grafts/appositional closure faster than second intention

Question 41

when to use third intention healing

Answer 41

- severely contaminated, infected, or traumatized wounds - large wounds in high motion areas

Question 42

bandaging primary contact layer

Answer 42

sterile material applied directly to the wound surface adherent or non-adherent

Question 43

adherent

Answer 43

used for DIRTY/CONTAMINATED effusive wounds during inflammatory phase provides mechanical debridement when removed ex. gauze 4x4 sponges

Question 44

non-adherent

Answer 44

used on HEALTHY GRANULATION TISSUE or minimally contaminated wounds ex. Telfa pads or Adaptic gauze

Question 45

bandaging secondary layer

Answer 45

holds the primary layer in place over the wound ex. cotton wrap, cast padding

Question 46

bandaging tertiary layer

Answer 46

provides support and protection ex. vet wrap, elastikon

Question 47

tie over bandages

Answer 47

bandage material applied and secured by umbilical tape tied through skin sutures used when concentric bandages would be difficult to apply or maintain ex. face, axilla, inguinal area, abdomen, proximal limbs, perineum

Question 48

what are the two greatest indicators that primary closure is appropriate

Answer 48

1. viability of tissues 2. low contamination

Question 49

what is the number one indicator that a wound will heal well

Answer 49

vascularization of the tissues higher vascularization = greater ability to heal