Chapter 5 - Wound healing Flashcards
What is the primary goal of wound healing in all species?
To repair the body after injury
How are wounds traditionally classified?
A) By size and depth
B) By cause and location
C) As open or closed, and further as clean or contaminated
D) By duration and severity
C) As open or closed, and further as clean or contaminated
What characterizes closed wounds?
crushing or contusion injuries without skin loss
What type of wounds are considered clean?
Surgical wounds under aseptic conditions - electives
What bacterial count differentiates contaminated from infected wounds?
A) Less than 1 × 10^5 bacteria/g of tissue for contaminated
B) More than 1 × 10^5 bacteria/g of tissue for infected
C) Less than 1 × 10^4 bacteria/g of tissue for contaminated
D) More than 1 × 10^6 bacteria/g of tissue for infected
B) More than 1 × 10^5 bacteria/g of tissue for infected
What are the three phases of wound healing?
A) Inflammatory, proliferative, and remodeling
B) Hemostasis, infection control, and tissue regeneration
C) Infection, granulation, and epithelialization
D) Blood clotting, cell migration, and scar formation
A) Inflammatory, proliferative, and remodeling
What initiates the inflammatory phase of wound healing?
Hemostasis and acute inflammation
How long does the inflammatory phase last in wound healing?
Several days
what is a clean contaminated wound?
Clean-contaminated wounds are surgical wounds in which
the respiratory, alimentary, or urogenital tract is entered under
controlled conditions without unusual contamination
what is a contaminated wound?
contaminated wounds are open, acute, accidental, or surgical wounds in which there has been a major break in aseptic
technique.
what is a dirt or infected wound?
Dirty or infected wounds are those that are old, have
devitalized tissue, or have gross contamination with foreign
debris
choice of wound closure primarily depends on 2 things which are
the type of wound (puncture vs laceration)
degree of contamination
What is the role of platelets in the early wound healing process?
Stopping blood loss and releasing wound-repair mediators
Which cells are the first to enter the wound during the inflammatory phase?
Polymorphonuclear cells (PMNs)
What characterizes the tissue formation phase?
Angiogenesis, fibrous and granulation tissue formation
What marks the start of the proliferative phase of wound healing?
Tissue formation
What triggers angiogenesis during wound healing?
Decreased oxygen tension and high lactate levels
What defines clean surgical wounds?
Wounds created under aseptic conditions
Which phase of wound healing involves hemostasis and acute inflammation?
Inflammatory or lag phase
What triggers the start of the inflammatory phase of wound healing?
Hemostasis
During wound healing, when do neutrophils peak in number? Day 1, day 2, day 3
Around day 2
What is the role of platelets in the early inflammatory phase?
To release growth factors
What is the primary function of macrophages in wound healing?
To remove necrotic tissue and bacteria
What characterizes the proliferative phase of wound healing?
Angiogenesis and tissue formation
What initiates angiogenesis in wound healing?
Decreased oxygen tension
When do fibroblasts predominantly appear in the wound?
During the proliferative phase
What phase follows the proliferative phase in wound heal
Remodeling phase
When do fibroblasts start to appear in the wound?
Fibroblasts start to appear in the wound during the proliferative phase of wound healing. This phase typically begins about 3 days after the injury.
What unique characteristic distinguishes wound healing in horses compared to other animals?
Greater propensity for developing exuberant granulation tissue
How does the healing rate of ponies compare to that of horses?
Faster than horses
What has been reported about primary- and second-intention wound healing in ponies?
Proceeds more rapidly than in horses
What type of response is quicker and more intense in ponies compared to horses?
Inflammatory response
Which cells are more active in ponies’ wounds, contributing to faster healing and better resistance to infection?
Leukocytes
Why do metatarsal bone wounds in horses often result in prolonged limb enlargement?
Greater periosteal reaction and new bone formation
What factor likely contributes to the less intense but more chronic inflammatory response in horses?
Lack of natural selection for efficient healing
In horses, what type of wounds typically heal slower than those on the upper body?
Limb wounds
What factors adversely affect the rate of epithelialization and contraction in limb wounds?
Excessive motion,
infection,
development of exuberant granulation tissue
What process is delayed in horses’ wounds if bone is exposed?
Granulation tissue development
What type of wounds in horses are more at risk of infection?
Limb wounds
What common development occurs in wounds involving the limbs of horses managed by second-intention healing?
Development of exuberant granulation tissue
name the 3 phases of wound healing
three phases: (1) the inflammatory or lag phase, which involves hemostasis and acute inflammation;
(2) the proliferative phase, during which tissue formation occurs; and
(3) the remodeling phase, during which the healing tissue regains strength.
Acute wounds do expand in the _______ weeks
A
cute wounds in horses, regardless of their location, typically expand in size in the first 1 to 2 weeks because of the tensional forces of the adjacent tissues
what exuberant tissue granulation in distal limbs?
The inefficient inflammatory response (in horses), an imbalance in collagen homeostasis, a shift toward a profibrotic environment, tissue hypoxia, and inappropriate cell apoptosis have all been reported to influence its development
2.5-cm × 2.5-cm full-thickness limb wounds, wound areas expanded___ to ____times the original size during the first 2 weeks.
2.5-cm × 2.5-cm full-thickness limb wounds, wound areas expanded 1.4 to 1.8 times the original size during the first 2 weeks.
what is the reepithelialization in mm/day in experimental distal leg wounds?
0.09 mm/day
How many mm/day do wound in the body contract versus in legs?
body 0.8 to 1 mm/day
leg 0.2mm/day (high motion, high tension, low vascularization)
soil components in contaminated traumatic wounds reduce a number of important cells which one?
white blood cells effectiveness, decrease humoral defenses and neutralize antibodies
what are the 2 most common organisms in polymicrobial wounds?
Pseudomonas aeruginosa and Staphylococcus spp. being the most common isolates.
What is a characteristic feature of exuberant granulation tissue or “proud flesh”?
Abundance of capillaries surrounded by collagen
What is hypothesized to contribute to a profibrotic state leading to the formation of exuberant granulation tissue in horses?
The imbalance of mediators released by PMNs
Which factor is NOT associated with the development of exuberant granulation tissue?
A) Chronic inflammation
B) High levels of TGF-β1
C) Efficient inflammatory response
D) Downregulation of MMPs
C) Efficient inflammatory response
What effect does microvascular occlusion in granulation tissue have on wound healing?
A) Accelerates healing
B) Has no effect
C) Delays healing due to local hypoxia
D) Increases infection risk
C) Delays healing due to local hypoxia
What is the recommended management for controlling exuberant granulation tissue?
Excision of protruding tissue and minimizing inflammation
What is the effect of equine amnion as a wound dressing?
Decreases development of granulation tissue and accelerates epithelialization
What is a potential benefit of using extracorporeal shock wave therapy on limb wounds?
Reducing TGF-β1 and preventing exuberant granulation tissue
How does advancing age affect wound healing in horses?
Slows it down
What condition in older horses may delay wound healing due to high cortisol levels?
Cushing disease
How does malnutrition at the time of injury affect wound healing?
Delays healing
What type of injury is most prone to infection and slow healing in horses?
Contusion and crush injuries
What role do vitamins and micronutrients play in wound healing?
Significant in the healing process
What is essential for wound healing in terms of tissue perfusion?
Adequate arterial circulation
How can anemia impact wound healing?
No impact if blood flow is maintained
What is the effect of hyperbaric oxygen therapy (HBOT) on local wound oxygen?
Increases it
How do seromas and hematomas affect wound healing?
Impede healing
What impact do chemotherapeutic drugs have on wound healing
Impair healing
What is the benefit of early wound débridement?
How does gabapentin, a common analgesic, affect wound healing?
Delays it
What is the effect of local anesthetics on wound healing?
Can detrimentally affect healing
What is the primary function of PMNs?
Phagocytosis of microbes
Which of the following is a function of PMNs in the immune response?
Macrophage activation
How do PMNs contribute to the body’s defense mechanisms?
Through amplifying the inflammatory response
What role do PMNs play in tissue healing?
Stimulation of the repair process
Which of these is a mediator released by PMNs?
A) Insulin
B) Reactive oxygen species
C) Glucose
D) Hemoglobin
Reactive oxygen species
Eicosanoids, produced by PMNs, play a role in which process?
Activate macrophages
Proteases released by PMNs are involved in:
Breaking down proteins
VEGF, as a mediator from PMNs, is primarily involved in:
Angiogenesis
which type of lesion is prone to infection? cutting or crush injury?
Of the seven types, those with the least risk of developing infection are caused by sharp objects (e.g., an incision, a laceration caused by a nail). Contusion and crush injuries, which often include vessel thrombosis, are most prone to infection.
what is the intestitial pressure within the center of the incision aboce capillary pressures that can lead to tissue necrosis?
above 30 to 40 mmHg
what is the ideal fluid for wound cleaning?
fresh wound can be safely cleaned with tap water, but isotonic fluids should be used once a granulation tissue bed has developed to avoid cellular swelling and destruction
what are chlorhexidine dilution values for cleaning of wound?
Dilute chlorhexidine solution (0.05%) can be made by adding 25 mL of a 2% chlorhexidine stock solution to 975 mL of sterile saline. Higher concentrations are cytotoxic to both tissue and bacteria
what are povidone-iodine dilution values for cleaning of wound?
If povidone-iodine is used, it should be diluted to a concentration of 0.1% to 0.2% (10 to 20 mL of a 10% stock solution added to sterile saline to a total volume of 1 L l).
Concentrations greater than this have been shown to be toxic to canine fibroblasts, lymphocytes, and monocytes and to inhibit neutrophil migration
Lastly, hydrogen peroxide is cytotoxic to
fibroblasts in aqueous 3% solution
what are the spectrums of acitivity for triple antibiotic ointment and silver sulfadizine?
Triple-antibiotic ointment (bacitracin, polymyxin B, and neomycin) and silver sulfadiazine (SSD) have broad spectrums of activity,
Silver sulfadiazine is good for a type of bacteria, which one?
but SSD, unlike triple antibiotic, is effective against Pseudomonas spp. and fungi.
what are the disadvantages of nitrofurazone?
decrease epithelialization and to delay wound contraction. It also possesses carcinogenic properties.
Platelets are rich in (name the factors)
TGF-β, PDGF,
epidermal growth factor (EGF),
transforming growth factor-α (TGF-α),
VEGF,
serotonin,
and histamine
what is the dosage for tx with cisplatin?
1 mg/cm3 during the perioperative period did not reveal any adverse effect on wound healing
which 2 type of neoplasia can be similar to granulation tissue?
SCC and sarcoids
