Phases of wound healing

Remodeling/maturation phase

-dermal regeneration -wound contraction -balance between collagen synthesis and lysis with formation of scar tissue -scar tissue becomes more flexible with time -vascularity diminishes -tensile strength increases as cross-linking occurs

Macrophages

-enhance debridement through phagocytosis of matrix and cellular debris left in the wake of neutrophils -serve as transitional marker between the inflammatory and reparative phases of healing -can promote or inhibit angiogenesis

Neutrophils

-first to arrive -kill microbes through phagocytosis and lysosomal degradation -producing free radicals which affect all tissues -predominant infiltrating cell for first 3 days

Physical energy treatments causing trauma

-high pressure irrigation -trauma to granulation tissue

Factors impeding healing process leading to chronic wounds (3)

-local factors -systemic factors -clinician induced factors/ iatrogenic

Clinical induced/ iatrogenic factors leading to chronic wound healing

-meds -topical agents -dressing -physical energy treatments -radiation/chemo

Inappropriate wound care

-misuse of topical agents, wound desiccation, poor technique -applying pressure over bony prominence (friction/shear) -applying compression to mixed arterial wound

Signs of acute inflammation

-pain -erythema -edema -warmth -loss of function

Systemic factors

-stress (psychological, noise, pain, depression, anxiety) -chronic disease (DM, PAD, CVI) -nutritional status -temperature -obesity -advanced aging

Systemic factors -- age

-thinning of epidermis (basement membrane) -decreased inflammation, cell migration, and proliferation -slowed maturation -decreased epidermal and fibroblast activity -decreased epithelialization/contraction -decreased capillary growth -delayed collagen remodeling -decreased elastin fibers -dermis atrophied -increased wound dehiscence

5 phases of wound healing

1. Hemostasis 2. Inflammation 3. Proliferation 4. Maturation 5. Remodeling

Infection > ___ organisms per gram tissue

10 ^5 -invasion of replicating bacteria into host tissue -inflammation, erythema, pain, swelling, increased temp

1 week post wound closure, scar is ___% of ultimate strength

3%

Inflammatory phase typically lasts?

3-7 days

3 weeks post wound closure scar is ___% ultimate strength

30%

When do neutrophils peak

48 hours after injury

Macrophages peak when?

72-84 hours

3 months to 2 years the scar becomes ___% of original strength of skin

80%

Hemostasis

ASAP; Platelet aggregation reduces bleeding and forms fibrin clot -growth factor secretion

Overlap theory

Affected at systemic and iatrogenic levels Ex: trauma, age, COPD, steroids

Chemotherapy damages...

Cell DNA or prevents DNA repair

Irradiation disrupts...

Cell mitosis

How do full thickness wounds close in the proliferative stage of wound healing

Close from wound edges ONLY

How do partial thickness wounds close in the proliferative stage of wound healing

Close from wound edges and adnexal structures *islands of epithelial tissues

What is the predominant cell in the proliferation stage?

Fibroblasts -- predominant cellular mediator assisting in endothelial angiogenesis

In the proliferation stage the 2 types of cells that peak are

Fibroblasts and lymphocytes

Goal of proliferative phase

Fill defect with new tissue and restore integrity of the skin

What is the hallmark sign of the proliferative phase

Granulation tissue consisting of macrophages, fibroblasts, developing blood vessels, immature collagen and newly formed ECM

T lymphocytes arrive when

LAST; around day 5

Vitamin D

Maintenance of calcium homeostasis affecting action of tissue collagenase

Critical colonization

Multiplication of organisms with an absence of local invasion consequently impaired healing

Predominant cell in the inflammatory phase

Neutrophil -1st to arrive on scene

In the inflammation stage the 2 types of cells that peak are

Neutrophils and macrophages

Bio-films

Organisms form bio-films that become highly resistant to antimicrobials and treatment

T lymphocytes

Participate both in down regulation of excessive inflammation and control of proliferation -monitor for infection and control inflammation and proliferation

Vitamin B

Required for cross linking of collagen fibers to rebuild tissue

Vitamin A

Required for inflammatory response

T/F: Phases of wound healing overlap

True

Macrophages, NK, platelets, RBCs, and PMNs are all (upregulated/downregulated)

Up

3 types of leukocytes present in the inflammatory phase

*Neutrophils Macrophages T lymphocytes

What does the remodeling/maturation phase consist of

Collagen maturation and reorganization orchestrated by fibroblasts and growth factors

Vitamin C

Collagen synthesis and increase activation of leukocytes and macrophages to wound site

Local factors that impede wound healing

Conditions that impede healing at the wound bed -presence of bacteria and bio burden (critical colonization and infection) -perfusion deficits (macros and micro circulatory deficits) -foreign bodies -non viable tissue (desiccation and eschar) -moisture -nutrients -oxygen levels

When does the proliferative phase usually begin

Day 4-14

When does the remodeling/maturation phase take place

Day 8 to 2 years after wound closure

Meds - steroids

Delay inflammatory phase of healing and all other phases -topical and oral vitamin A may reverse effects in some cases

T Lymphocytes peak when

During proliferative phase DAY 7

Meds - NSAIDS

Inhibit angiogenesis

Inflammatory phase

Hemostasis considered a part of this phase -infiltration of leukocytes -KILLING PHASE

Meds - anticoagulation

Interfere with platelet aggregation

When you see necrosis (eschar/slough) it is likely indicative of what phase of wound healing?

Inflammation