Wound Healing Flashcards
Key events in healing
Specifics in each?
Haemostasis–>inflammation–>proliferation–>remodeling
Haemostasis- platelets, fibrin, proteogylcans
Inflammation- neutrophils, macrophages, lymphocytes
Proliferation- fibroblasts, collagen, epithelial cells, endothelial cells
Remodeling- scar maturation, collagen fibril cross linking
Difference between repair and regeneration
Regeneration- proliferation of cells and tissue with replacement of lost tissue (regeneration of liver/superifical abrasions of skin)
Repair- combination of scar formation and regeneration by the deposition of collagen (healing by second intention)
Problems with wound healing and repair- def and impairments
What stages are affected?
Deficiency- inadequate blood supply, poor nutrition, clotting deficiency
Impairment- infection, foreign body, movement, mediation (corticosteroids), radiation, defective collagen synthesis
Poor perfusion affects ability to get to inflammatory stage
Infection affects inflammatory stage and ability to transition to proliferative stage
Hypertrophic scars, keloids, contractures affect remodeling stage
Impair collagen synthesis with corticosteroids or congenital diseases in proliferation phase
Healing impairments in different phases of time/wound healing
0-3 hours phase- impaired clotting, poor nutrition, infection
24-48 hours- poor perfusion, reduced influx of inflammatory cells needed to remove foreign material and secrete signal for repair, movement
Day 5-21- if early phase was poor formation of collagen by fibroblasts will be decreased, abnormal collagen synthesis
Common bacteria that infect wounds
S. Aureus P. Aeruginosa E. Coli Kiebsiella spp Often polymicrobial
Pilonidal sinus
Hair as foreign body- sinus tract from skin to deep subcutaneous tissue–>abscess formation
Hair breaks off and bacteria can penetrate the skin
Dehiscence
Wound splitting open- most frequent after abdominal surgery
Increased mechanical stresses
How wounds become chronic risk factors
Usually halted in inflammatory phase*
Poor nutritional status- chronic disease states like diabetes: hyperglycemia inhibits fibroblasts
Poor oxygenation- smoker/PAD
Chronic edema- congestive heart failure from CAD
Cellular events at the chronic wound
Increased chances of infection Poor granulation tissue formation Degradation of needed components Increased inflammatory cytokine present Stalled in inflammatory phase Elevated tissue matrix metalloproteinases Prolonged inflammatory phase
Chronic leg ulcers are defined as
In the skin below the level of knee persisting for more than 6 weeks and shows no tendency to heal after 3+ months
Many causes*
Most common type of chronic wound in adults
Venous ulcers- venous insufficiency incompetence leads to leg discomfort, edema, elevated venous pressure resulting in decreased skin perfusion.
Usually ulcer is anteriolateral leg- hyperpigmentation is common due to RBC deposition and breakdown in interstitium. Brown colors because low pressure ulcer and hemosiderin
Arterial insufficiency ulcers
Combination of mural thickening or accretion and intramural restriction
Most acute forms of vasculitis and some sub-acute and chronic forms are likely to cause leg ulceration due to tissue hypoxia and exudation of fibrin-like substances
Toes, heels, bony prominences of foot
Punched out appearance with well demarcated edges and a pale, non-granulating and necrotic base. Has gangrene (neutrophils)
Associated with atherosclerotic obstruction of large arteries supplying lower limbs- can extend into deeper structures to expose tendon or bone
Vasculitic leg ulcers
Infectious, immunologically mediated- immune complex formation (leg prone due to increased hydrostatic pressure because of gravity) with vascular wall damage leading to activation of complement system
Necrobiosis Lipoidica
More common in diabetics
Rare granulomatous skin disorder of unknown cause that can affect the shin of insulin dependent diabetics and others
Tender, yellowish brown patches on shin over several months persisting for years
Center of the patch becomes shiny, pale, thinned, with prominent blood vessels
Minor injury can cause it to ulcerate
Septal panniculitis with chronic inflammation, macrophages with destruction of collagen and fat*
Marjolin’s ulcer
Exuberant vegetations on sacral region that appear warty- lesion has infiltration patterns areas with presence of ‘keratin pearls’
Squamous cell carcinoma complication
