6: wound healing Flashcards
3 layers of the skin
Epidermis
hypodermis
dermis
Series of thin muscles under the skin in dogs and cats
panniculus
Why is the panniculus so important during surgery
failure to preserve will cause loss of blood supply and wound dehiscence
provide blood supply to skin
run parallel to skin
Cutaneous arteries
Major blood supply to the skin
subdermal plexus
Why is the subdermal plexus important
must be preserved to maintain blood supply
Coagulation times
<5 min
Inflammatory stage time
0-24 hours
debridement stage time
2-5 days
Repair stage
4-21 days
Maturation stage times
21 days - 2 years
3 stages of primary coagulation
- damaged endothelium exposes collagen fibers to blood elements
- Biding of subendothelial collagen with von Willebrand factor
- Platelets form platelet plug
Secondary coagulation
series of factors react resulting in formation of fibrin meshwork around wound
Intrinsic path numbers
12, 11, 9, 8
Extrinsic pathway numbers
3, 7
Common path numbers
10, 5, 2, 1
Which is necessary for wound healing, macrophages or neutrophils
macrophages
First leukocyte to enter wound
numbers increase from 24-48 hours
degrade and clear bacteria
Neutrophils
Required for healing of wounds
predominate 2-5 days after injury
phagocytize necrotic tissue
Macrophages
Removal of necrotic tissue and debris by macrophages
Most important thing we can do to help heal a wound
debridement
End of debridement stages is characterized by influx of
fibroblasts into the wound
what marks the proliferative stage
influx of fibroblasts
rapid accumulation of collagen
when epithelial cells proliferate and move across a wound until they contact each other
contact inhibition
Cells that contain actin and myosin fibers that exert tensile forces on the ECM resulting in closure of the defect
Myofibroblasts
How does collagen remodel
according to tensile forces
How is tensile strength changed during maturation phase
minimally
How does the source of wound strength change over time
as the suture starts to absorb, the tissue strength should increase
Intrinsic wound factors (7)
hypoproteninemia anemia malnutrition uremia diabetes mellitus hyperadrenocroticisim infection
Extrinsic wound factors (4)
mechanism (shear, crush)
foreign material
irradiation
antiseptics
How are wounds classified
based on time and contamination
Class 1 wound
0-6 hours
minimal contamination
Class 2 wound
6-12 hours
moderate contamination
Class 3 wound
> 12 hours
gross contamination
never close
Clean wound
surgical procedure
not entering GI or respiratory tract
Clean-contaminated surgery
GI or respiratory tract entered
minor break in asepesis
Contaminated surgery
Gi with gross contamination,
inflammation
major break in sepsis
Dirty surgery
devitalized or necrotic tissue
gross debris
Pus
When should you use antimicrobials
class 2-3 wound Clean-contaminated to dirty surgeries
What should you always do with bite wounds
open them
First step in addressing an open wound
clip the fur and put sterile lube on it
First and most important aspect of contaminated wound treatment
removal of trash via mechanical lavage using saline
after removal of trash you should
debride the wound
Wet bandages
- layer of saline soaked gauze
- dry laparotomy sponges on top
- vet wrap over all of it
active drain
preferred
just for support
make vacuum in wound to remove fluid
Passive drain
gravity
2-5 days at most
Wound closure stages
Primary
Delayed primary
late secondary
second intention
Primary would closure
immediate closure of wound
<6 hours
Delayed primary wound closure
after 6 hours
before granulation >2 days
Late secondary wound closure
after appearance of granulation tissue >2 days
Second intention wound closure
no surgical closure
dependent on wound healing
