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