Chapter 14 - Wound Healing Flashcards
This is the first stage of Wound Healing. Days? Cells?
Inflammation; Days 1-10; PMNs, Macrophages; Epithelialization at 1-2mm/day
This is the second stage of wound healing. Days? cells?
Proliferation; 5 days-3 weeks;
Fibroblasts
-neovascularization,
-production of collagen and granulation tissue
This is the third stage of wound healing. Days? what happens?
Remodeling; 3 weeks to 1 year
- Type III collagen replaced with type I
- Net amount of collagen does not change
- Collagen cross linking occurs
At what pace do peripheral nerves regenerate?
1mm/day
The order of cell arrival in a wound:
- Platelets
- PMNs
- Macrophages
- Fibroblasts
- Lymphocytes
What do macrophages do in wound healing?
essential for wound healing
-release growth factors, cytokines, etc.
What do fibroblasts do in wound healing?
replace fibronectin-fibrin with collagen
What does fibronectin do in wound healing?
Chemotactic for macrophages; anchors fibroblasts.
What does Thrombin and Fibrin do in wound healing?
act as growh factors for endothelial cells and fibroblasts.
These are the primary cells in days 0-2
PMN’s
These are the primary cells in days 3-4
Macrophages
These are the primary cells in days 5 and on
Fibroblasts
What makes up the platelet plug?
Platelets and Fibrin
What makes up the provisional Matrix?
platelets, Fibrin, Fibronectin
What is meant by accelerated wound healing?
Reopening of a wound results in quicker healing the 2nd time, as cells are already present
Platelet Alpha granules contain what?
- Platelet Factor 4- aggregation
- Beta Thrombomodulin- binds thrombin
- PDGF - chemoattractant
Dense Granules of platelets contain what?
- Adenosine
- Serotonin
- Calcium
Platelet Aggregation factors include what?
- TXA2
- Thrombin
- Platelet factor 4
Where is platelet activating factor released from?
Platelets
Where is transforming growth factor-alpha released from?
platelets
Where is fibroblast growth factor released from?
Platelets
Where is Beta Lysin released from and what does it do?
Platelets; antimicrobial
Where is PGE2 and PGI2 released from and what do they do?
Platelets; Vasodilator
Where is PGF2 released from? what does it do?
Platelets; Vasoconstriction
What is the most important fact in healing open wounds (secondary intention)?
Epithelial integrity; migration from wound edges, sweat glands, hair follicles
-dependent on granulation tissue
Unepithelialized wounds leak what and promote what?
Leak serum and protein, promote bacteria
The most importan factor in healing closed incisions (primary intention) is what?
Tensile strength
Tensile strength depends on what?
collagen deposition and cross linking of collagen
What is the strength layer of bowel?
Submucosa
When is the weakest time point for small bowel anastamosis?
Days 3-5
Which has better wound healing, Perineum or leg?
Taint, Nacho, Grundel, Gooch, Banus, et al
Type I collagen?
Most common type
- skin, bone, tendons
- Primary collagen in healed wound
Type II Collagen?
Cartilage
Type III Collagen?
Healing wound, also in blood vessels and skin
Type IV collagen?
Basement Membranes
Type V collagen?
Widespread, particularly in the cornea
These substances are required for the hydroxylation of proline and crosslinking of proline residues:
- Alpha-ketoglutarate
- Vitamin C
- Oxygen
- Iron
Collegen has ________every 3rd amino acid and abundant___________
Proline; Lysine
The tensile strength of a sound is only ever what percentage of the prewound strength?
80%
The predominant Collagen produced for days 1-2 is?
Type III
Predominant Collagen synthesized by days 3-4
Type I
At 6 weeks a wound is ____% of final strength and ____% of original
80; 60
At what point does a wound reach its maximal tensile strength?
8 weeks
When does a wound have maximum collagen accumulation?
2-3 weeks. After than amount stays same but cross linking improves strength
What does d-Penacillamine do to collagen?
Inhibits cross-linking
What do you want transcutaneous oxygen measurement to be in a healing wound?
25 mmhg
What is essential to wound healing?
moist, O2 delivery, no edema, necrotic tissue must be removed
What level of Bacteria inhibits wound healing and why?
> 10^5
- Decreases O2 content
- collagen lysis
- Prolonged inflammation
What is the effect of devitalized tissue and foreign bodies on wound healing?
retards granulation tissue formation
How does diabetes contribute to poor wound healing?
impedes early phase response
What level of albumin can be a factor in poor wound healing?
<3.0
How do steroids inhibit wound healing?
inhibit macrophages, PMNs, Collagen synthesis by fibroblasts, decrease tensile strength
What can be given to counteract steroid effect on wound healing?
Vitamin A
Osteogenesis Imperfecta is a defect in what?
Type I collagen
Ehlers-Danlos syndrome is what?
Collagen disorder; 10 types identified
Marfan’s syndrome is a defect in what?
Fibrillin (Collagen)
What is Epidermolysis Bullosa, and how is it treated?
Excessive fibroblasts; phenytoin
What is Charcot’s joint?
2nd MTP- diabetic foot ulcer 2* to neuropathy
How long do you wait before doing a scar revision?
1 year
Does cartilage contain blood vessels?
No
Does Denervation have an effect on wound healing?
No
Chemo can be given how many days after surgery and have no effect on wound healing?
14
What inheritance is Keloiding?
Autosomal Dominant
In Keloids, How far does collagen extend, and what is Tx?
Beyond the original scar; XRT, steroids, silicone, pressure garments
Where are hypertrophic scars usually found?
flexor surfaces of upper torso
In hypertrophic scars, how far does collagen extend?
Stays within confines of scar, treat with steroids, silicone, pressure garments
