L7: Wounds Flashcards
Epidermis composition & function
Avascular keratinized stratified squamous epithelium & it has protective function
What kind of tissue dermis is? Function?
Thicker and vascular, tough fibroelastic tissue. It has a supportive and nourishing function.
What is subcutis composed of?
Adipose tissue, cutaneous trunci muscle, and direct cutaneous arteries & veins
Wound (term)
Injury to the body that results in disruption of the continuity of the body structure. Can be classified in several ways (clean, contaminated etc.)
Open wounds (8 types)
1.Surgical incision
2.Laceration
3.Abrasion
4.Avulsion
* Degloving
* Shearing
5.Puncture
* Bite/sting: cat/dog; snake; insect; tick
* Firearm
6.Burn: thermal; chemical; electrical; radiation
7.Pressure sores
8.Cast- and bandage-related
Closed wounds (4 types)
1.Contusion
2.Hematoma
3.Crush injury
4.Hygroma
Incisional injuries & lacerations
Are usually surgical or traumatic. Edges generally clean and free from tissue damage, tend not to get infected. Surgical management.
Abrasions
Superficial damage not extending beyond dermis. Frictional forces when moving parallel to a rough surface. Generally heavily contaminated. In severe cases with ongoing necrosis => avulsions. Surgical or open wound management.
Avulsions (degloving)
-Avulsion is the separation of tissue from the deeper attachments.
-In degloving skin and deeper tissues torn from an extremity just as a glove is removed from a hand.
-Initially may be free from bacterial contamination but without proper management rapid colonization and infection of nectoric tissue will occure
-Surgical & open wound management together
Avulsions (shearing)
-Usually involve loss of deeper tissues (tendons, muscle, even bone)
-Joints of distal limb
-Heavily contaminated, extremely prone to infection
-Open wound management
Puncture wounds
-Caused by any sharp object that pierces the skin to create a relatively small deficit or a hole
-Bite wounds (also insects or snake)
-Impalement (full penetration)
-Oropharyngeal or firearm wounds
-Contamination and infection variable
-Damage assessment
- Risk of abscessation
Burns
-Caused by extreme temperature or by contact with a chemical substance, electricity or radiation
-May require prolonged treatment
-Treatment depends on the case
Pressure sores
-Caused by pressure typically on the elbows and hocks of larger dogs
-Can be open or closed
-Open sores prone to infections (bone & joint)
-Medical/surgical treatment
-Hygromas best treated medically, can’t really treat surgically
Cast- and bandage-related wounds
-Iatrogenic wounds are common
(Overtight application, inadequate padding, excessive exercise => bandage slipping, wet or dirty bandages)
-Serious wounds may lead to loss of digits or limbs
Wound healing 4 distinctive phases
1.Acute inflammatory
2.Debridement (breakdown)
3.Proliferation (reparation)
4.Maturation (remodelling)
Inflammatory phase
-Characterized by: redness, pain, heat, swelling, loss of function
-Approximately 5 days
1.Filling with blood & lymph
2.Immediate vasoconstriction of damaged vessels (5-10min)
3.Vasodilation (dilutes toxins, provides nutrients, results blood clot)
4.Epithelial cells migrating from wound periphery to exposed tissue
5.Blood clot dries to form a scab
6.WBC leaking into wounds initiate debridement phase
Debridement phase
-Starts usually 6-12h after injury
-Inflammatory exudate provides all the necessary phagocytic cells and proteolytic enzymes to deal with the demarcation
-An exudate (WBC, dead tissue, wound fluids) forms on the wound
-Necrotic tissue impedes wound healing
-Phase ends with rejection of nonvital tissue
-Sometimes combined with inflammatory phase
Proliferation phase
-Repair phase
-3-5days after injury
-Signs of inflammation subside
-Neovascularization
1.Granulation
2.Wound contraction
3.Epithelialization
Proliferative granulation
-Red irregular surface
-Fragile tissue
-Barrier to infection
-Granulation tissue forming at each wound edge at a rate of 0.4 to 1 mm/24H
Proliferative wound contraction
-Surface and cavity of wound become smaller
-Adjacent skin pulled closer
-5-9days after wounding
-Stops when edges connected or tension is too high
-Risk of contracture
(temporarily thinner skin surrounding)
Proliferative epithelialization
-Proliferation of basal epithelial cells from the adjacent skin edges and their moving over and adhesion to the surface of the wound
-Prevent excessive formation of granulation tissue
-Duration can range from days to weeks
-Surface of the wound that has become epithelialized is known as the epithelial scar = thin and fragile
Maturation phase
-Increasing strength of the scar as a result of remodelling of tissue
-Newly formed collaged is arranged parallel to the tension lines of the skin
-Duration from weeks to over a year
-Healed wound will never regain original strength
Chronic wounds
-Lack of orderly progression of wound healing through four phases
-Infection that causes sustained inflammatory phase
-Factors influencing: Malnutrition, radiation, use of corticosteroids, underlying metabolic disease
Differences between cats and dogs
-Research more in dogs
-Formation of granulation tissue takes longer and first appear only at the edges
-Pseudohealing more common in cats
