Wound Healing

Question 1

** What are the phases of wound healing?

Answer 1

• TISSUE INJURY and COAGULATION= vasoconstriction and platelet aggreagation, followed by histamine mediated vasodilationg and permeability changes to heal the injured area.
  1. INFLAMMATION
  2. FIBROPROLIFERATIVE= balance between scar formation and tissue regneration.
  3. MATURATION/REMODELING

Question 2

What is the most important cell during the EARLY first stage of wound healing (inflammation)?

Answer 2

• PMNs (granulocytes)

Question 3

** What is the most important cell during the LATE first stage of wound healing (inflammation)?

Answer 3

MACROPHAGE (48-72 hours)= primary producer of growth factors (PDGF, TGF-b):

• recruitment of fibroblasts (proliferative phase).
• proliferation of ECM by fibroblasts.
• proliferation of endothelial cells (angiogenesis).
• proliferation of smooth muscle cells.
• this leads to the fibroproliferative phase.

Question 4

** What is the most important cell during the fibroproliferative phase?

Answer 4

• FIBROBLASTS, which migrate into the wound (predominant cell type by day 7) laying down TYPE 3 COLLAGEN.

Question 5

What makes up 90% of total body collagen?

Answer 5

• TYPE 1 (bones, skin and tendons).

Question 6

When does reepithelialization begin?

Answer 6

within hours of injury (stimulated by loss of contact inhibition and growth factors).

Question 7

How long does the maturation/remodeling phase last?

Answer 7

• 3 weeks to 1 year= wound contraction and collagen remodeling.

Question 8

When are the strength peaks of tensile strength in wound healing?

Answer 8

• at 60 days

* never reaches pre-injury levels (best will be 80%).

Question 9

What are some special characteristics of FETAL wound healing?

Answer 9

• lack of inflammation
• regenerative process with minimal or no scar formation.
• collagen deposition is more organized and rapid (type 3; no type 1).

Question 10

*** What factors influence wound healing?

Answer 10

• oxygen (improves healing)
• hematocrit (improves healing).
• smoking (CO decreases the O2 carrying capacity of Hgb).
• mechanical stress (abnormal tension decreases healing).
• hydration (well hydrated wounds epithelialize faster).
• environmental temperature (healing is accelerated at temperatures of 30 C).
• denervation
• foreign bodies (including necrotic tissue).
• nutrition
• edema (compromises tissue perfusion).
• age
• infection
• chemotherapy
• radiation
• systemic diseases
• STEROIDS (inhibit wound macrophages, but vitamin A can reverse these effects).
• vitamin C (deficiency associated with scurvy, but high concentrations do not accelerate healing).

Question 11

What are some adjuncts to wound healing?

Answer 11

• VACs

- HBO

Question 12

*** What are wound care general principles?

Answer 12

• CLEANING and IRRIGATION

- DEBRIDEMENT (selective, enzymatic using collagenase, autolytic, or biologic using maggots).

Question 13

*** What is a keloid?

Answer 13

• abnormal scar tumor that grows beyond the boundary of the initial injury.

Question 14

*** What is a hypertrophic “widened” scar?

Answer 14

• scar within the original parameters of the initial injury but is just ugly.

Question 15

** What are the surgical wound classifications?

Answer 15

I. CLEARN= uninfected with no inflammation.
II. CLEAN-CONTAMINATED= no unusual contamination.
III. CONTAMINATED= open, fresh, accidental wounds.
IV DIRTY= old traumatic wounds, devitalized tissue.

Question 16

** What is important to remember when suturing a wound?

Answer 16

• everting edges (pucker the edges upward) in taking tensions off of wounds, which ultimately leads to better looking scars.

Question 17

What is the reconstructive ladder?

Answer 17

1. secondary intention (let the wound heal on its own).
2. primary intention (suture)
3. delayed primary closure (wait and then suture).
4. skin grafts
5. tissue expansion
6. local tissue transfer
7. free tissue transfer