Wound healing Flashcards
What are the features of first intention healing?
- primary wound healing with primary closure
- sutured incision
- tissue apposition
what are the features of second intention healing?
- open wound healing
2. granulation, contraction, epithelialization
What are the 5 sequence of wound healing
- wounding
- acute vascular phase (bleed)
- inflammatory phase
- cellular phase
- maturation phase
What are the 5 sequence of wound healing
- wounding
- acute vascular phase (bleed)
- inflammatory phase
- cellular phase (fibroplasia?)
- maturation phase (remodelling and maturation)
What changes occur with remodelling and maturation?
- collagen content goes down
- quality of collagen increases
- cross linking between collagen occurs
How long does it take to return to the original tissue strength
it depends on the tissue/original tissue strength
What are the features of the acute vascular phase?
- hemorrhage
2. vasoconstriction (
When a vessel stops bleeding during surgery, what is the cause?
vasoconstriction–the smooth muscle is traumatized and so it contracts (vasospasm) Can be assisted by pressure which helps until clot can form
What are the features of the inflammatory reaction of the inflammatory phase
- localized protective response
- elicited by injury or destruction of tissues
- destroys, dilutes or walls of injurious agent and tissue
- prepares wound for repair process
What are the vascular events of the inflammatory phase
- cellular adhesion
- vasodilation
- increased vascular permeability–inflammatory exudate
What are the vascular events of the inflammatory phase
- cellular adhesion
- vasodilation
- increased vascular permeability–inflammatory exudate
What are the cellular players in the inflammatory phase?
- mast cells
- granulocytes
- platelets
What are the vasoactive substances involved in the inflammatory phase
- histamine
- serotonin
- kinins
- prostaglandins
- chemotactic agents (cytokines?)
What is the role of histamine in the inflammatory phase? How long is it present?
- causes early permeability increase
2.
What is the role of seratonin in the inflammatory phase? When does it have its effect?
- endothelial cell swelling
- induces lysyl oxidase that is responsible for collagen crosslinking during wound healing in the maturation/remodelling phase
- is present later than histamine
What do kinins do in the inflammatory phase
increase capillary permeability
What do prostaglandins do in the inflammatory phase?
- permeability changes
- vasoactive
- chemotaxis
- stimulate mitosis
How do NSAIDs impair healing?
They prevent the production of prostaglandins, which have a role during the inflammatory phase
What are chemotactic agents involved in the inflammatory phase?
- prostaglandins
- lymph node permeability factor
- cytokines
How are granulocytes pH sensitive?
when the pH drops (acidic) they dump their contents, which results in destruction of bacteria, but also destruction of tissue (collagenase, proteolytic enzyme release)
In models with knock out granulocytes, are there changes to wound healing? (if bacterial number is limited)
no
What is the role of granulocytes in a wound?
kill bacteria
Are macrophages necessary for wound healing?
yes
HOw is wound healing (inflammatory phase) localized?
- vasodilation
- leakage
- lymphatics blocked (due to swelling)
HOw is wound healing (inflammatory phase) localized?
- vasodilation
- leakage
- lymphatics blocked (due to swelling)
What are the 4 classic signs of inflammation?
- redness
- heat
- swelling
- pain
Why is pain enhanced with inflammation? Why can it have negative effects?
- fibers upregulated with inflammation
2. can have serious negative catabolic effects
What is the best kind of pain control?
preemptive pain control
What are the 3 main roles of macrophages in the inflammatory phase of wound healing?
- janitors–cleann
- release mitogenic factors
- elaborate cytokines
What are the steps of epithelialization in wound healing?
- fibrin-fibronectin seal
- epithelial migration
- epithelial proliferation
What stimulates epithelial proliferation in the epithelialization stage of wound healing?
EGF from macrophages and platelets
What occurs during the cellular phase of wound healing?
- fibroblasts infiltrated by coming along the fibrin-fibronectin scaffold
- fibrinolysis
- ground substance secretion
- capillary ingrowth!
- granulation tissue
- proliferation
- collagen increases, gains strength
How does granulation tissue form?
- capillaries bud into the fibronectin network
- capillaries bring fibroblasts and macrophages
- fibroblast is the laborer and the macrophage tells it to proliferate and lay down ground substance sand collagen
- collagen type III made first, then type I
The wound is as cellular as it is ever going to be at what point?
in the cellular phase during proliferation (2-4 weeks)
What is involved in the maturation phase of wound healing?
- crosslinking (aldehyde bonds)
- collagen remodeling (type III is removed by collagenases for type I)
- cellularity decreases
- gains strength
- time taken depends on tissue
What two “local” factors affect wound healing?
- surgeon
2. wound environment
What 1 systemic factor affects wound healing?
- patient
What 1 systemic factor affects wound healing?
- patient
What are 6 surgeon factors that affect wound healing (local factors)
- tissue handling
- procedure duration
- suture material
- suture tension
- hematoma
- seroma
What are wound environment/micrenvironment factors that affect wound healing? (6)
- infection
- foreign body
- oxygen tension (low, granulation)
- temperature–warm=good
- pH (acidic–granulation, fibroplasia)
- topical medications
What are 6 systemic (patient) factors in wound healing?
- age–pre-exist dz
- nutrition
- deficiencies
- corticosteroids
- NSAIDs
- immunosuppresion
what do corticosteroids affect?
fibroplasia and tissue healing
Why are NSAIDs used even though they slow wound healing?
it is not to a level that is clinically significant and their benefits outweight their negative effects
