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Flashcards in Wounds Deck (21)
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1

6 steps of wound healing

Coagulation
Inflammation
Collagen synthesis
Angiogenesis
Epithelialization
Contraction

4 "phases" = hemostasis/inflammation, proliferation, maturation, remodeling

2

Coagulation

Coagulation and complement cascades activated and platelets form a plug. Release of inflammatory mediators from activated platelets set everything off.

Impaired by:
Anticoagulants
Antiplatelets
Coag factor deficiency
Chronic liver disease
Uremia

3

Inflammation

Signs = pain, swelling, heat, erythema, loss of function

Happens bc wound is invaded by PMNs (through first 48h) and macrophages (peak at 24h)

Macrophages are ESSENTIAL for healing

Bacteria, cell debris, dirt, other foreign material also cleared from wound site by macrophages and PMNs

Impaired by:
Steroids
Immunosuppressants
Congenital/acquired immune deficiency

4

Collagen synthesis

Occurs by fibroblasts in vicinity of wound in response to growth factor peptides

Amino acids hydroxyproline and hydroxylysine are parts of collagen. Their synthesis and hydroxylation is dependent on Fe, alphaKG, and ascorbate (C)

5

Angiogenesis

"Granulation"

Occurs in response to peptide growth factors such as vascular endothelial growth factor (VEGF)

Presence of these new vascular networks is what gives granulation tissue its characteristic beefy-red appearance.

Presence of granulation tissue is reassuring that healing is under way. At one month postinjury the wound is at 85% ultimate cohesive strength.

6

Epithelialization

Happens with migration of epithelial cells over the wound defect.

Integrity of basement membrane restored (type 4 collagen and other matrix components deposited)

Foreign bodies like suture material and necrotic tissue remain separated from wound by migrating epithelial cells

Once this happens, the wound is waterproof

This step is done usually 24-48h after surgical wounds that were closed primarily.

7

Contraction and remodeling

Surrounding uninjured skin is pulled over the wound defect and the size of the scar is reduced

Made possible by myofibroblasts which have a contraction mechanism similar to muscle cells

Takes many months to complete

Wound contraction is NOT scar contracture. SC happens after wound repair is stopped and can lead to undesirable effects since architecture of surrounding tissue may become distorted.

Maturation of scar occurs over next 9m to 2y. Cross linking of collagen and clinical flattening of scar.

8

What is a clean wound?

Wound created in sterile, nontraumatic way in area free of preexisting inflammation

Resp, alimentary, genital, urinary tract non entered

All people involved in case maintained aseptic technique

Risk of infx = 2%

9

What is a clean-contaminated wound?

Resp, alimentary, genital or urinary tract entered BUT no significant spillage of its contents and there was no established local infection

Only minor break in aseptic technique

Risk of infx = 5%

10

What is a contaminated wound?

Gross spillage from GI tract

GU and biliary tracts entered in presence of local infection (cholangitis)

Wound was result of recent trauma

Major break in aseptic technique

Risk of infx = 15%

11

What is a dirty/infected wound?

Wound result of remote trauma and contains devitalized tissue and/or purulent material

Established infection or perforated viscera prior to procedure

Risk of infx = 35%

12

What types of healing involve sutures?

primary and delayed primary intention

13

Primary intention

Seen following closure of clean surgical wounds or traumatic lacs in where there is minimal devitalized tissue

Edges of wound are approximated with sutures or staples

Very small defect so re-epithelialization is fast and healing time is short overall

Dressings changed after 24-48h to less bulky one

Wound strength max at 3m and is 70-80% of normal skin

14

Secondary intention

Healing following closure of wounds not approximated with sutures

Reason for no sutures is:
Wound edges cannot be apposed bc defect is large (donor site skin graft) OR surgeon chooses to not close bc of high infection risk

Pack these wounds loosely with moist gauze and cover with sterile dressing. Assess daily for development of granulation tissue and presence of infx

Wound closes by contraction and then epithelialization. Contraction is from edges inward. Then epithelialization at 1mm per day also edges inward. Granulation tissue generated at center of closing wound.

15

Third (delayed primary intention)

Following closure of wounds in which there is obvious gross contamination at incision site

Following removal of rupture appendix in which there was leakage of pus into peritoneal cavity. Parietal peritoneum and fascial layers closed. ABx given. Skin and subq not sutured until 3-5d later after bacterial contamination is less.

16

Increased risk of wound infection

Similar to reduced healing

Infection remote to site
Diabetes
Smokers
Immunosuppressed (steroids)
Severe protein-calorie malnutrition
AIDS, malignancy

17

Common surg pathogens

Staph aureus and coagulase negative staph = thoracic, neuro, breast, ophtho, vascular, ortho

Gram neg bacili and anaerobes = appi, colorectal, biliary, OB/GYN, urology

Strep and oropharyngeal anaerobes = ENT

Animal bites = pasteurella multocida, strep, staph

18

hematoma

Collection of blood that may form in vicinity of surgical wound

Small ones can be left alone and allowed to reabsorb on their own. Larger ones may need drainage

19

Seroma

Collection of fluid in vicinity of wound that is not blood or pus

Due to creation of a potential space combined with disruption of local lymph channels (mastectomy)

Small ones can be left alone to reabsorb. Large ones need aspiration

20

Dehiscence vs incisional hernia

Dehiscence if early in postop course before all stages of healing have happened (complete disruption).

Incisional hernia if months or years later - at least the skin is intact - partial disruption

21

Hypertrophic scars vs keloids

Keloid = spread beyond margin of original wound. Painful. More in black people. Seen a lot in earlobes, deltoid, presternal, upper back. Need tx with steroid injection or topicals or radiation or pressure.

Hyper = usually go away on own.