Week 8 Skin Wounds Flashcards
The largest organ of the body:
The skin
Skin
Provides a protective barrier, regulates temperature, gives the dog it’s sense of touch.
Three major layers of the skin:
The epidermis/outer most layer
The dermis/middle layer
Subcutis/innermost layer
The epidermis
Composed of multiple types of cells including keratinocytes, melanocytes, Langerhans cells and Merkel cells
It provides protection from foreign substances –
The epidermis
Keratinocytes
Provide a protective layer, constantly renewed in a process called keratinization.
Keratinization
New skin cells are created near the base of the epidermis and my grade up words. This produces a compact layer of dead cells on the skin surface.
This layer keeps in fluids, salt and nutrients, well keeping out infectious or noxious agents.
Top layer of dead cells are continuously shed and replaced. The rate is affected by nutrition, hormones, tissue factors, immune cells in the skin and genetics. Disease and information also alter normal cell growth and Keratinization
Melanocytes
Located at the base of the epidermis, outer root sheath of hairs and the duct of sebaceous and sweat glands.
Melanocytes produce:
This skin and hair coloring/pigment called melanin.
Melanin production is controlled by:
Or moans and the jeans received from parents.
Melanin helps protect:
The cells from the damaging rays of the sun.
Langerhans cells
Part of the immune system. Damaged when exposed to excessive uv light and glucocorticoids (anti-inflammatory drugs).
Langerhans cells play an important role in:
The skins response to foreign substances and contribute to such things as the development of rashes.
Merkel cells
Specialized cells associated with the sensory organs in the skin.
Help provide sensory information from whiskers and the deep skin areas called tylotrich pads.
Skin Appendages
Hair follicles, oil and sweat glands and claws.
Hair follicles in dogs
Compound, a central hair surrounded by 3 to 15 smaller secondary hairs all exiting from one pore.
The function of the hair coat:
Protect the skin from physical and ultraviolet light damage and helps regulate body temperature.
Oil glands (sebaceous glands)
Secrete an oily substance called sebum into the hair follicles and onto the skin. Present in large numbers near the paws, back of the neck, rum, chin and tail area.
Sebum
A mixture of fatty acids. Important for keeping the skin soft, moist and pliable. Gives the hair coat sheen and has anabiotic properties.
Abrasion
An area of skin that has been a super Fishel he scraped, creating a word.
The phases of wound healing;
Inflammatory, Proliferative, Maturation/Remodeling
Best observed in a wound left to heal by second intention healing.
Inflammatory phase
Begins immediately and lasts 3 to 5 days.
Characterized by formation of a blood clot within the wound; release of growth factors; recruitment of macrophages and neutrophils; serves to clean up the wound and modulate healing.
The wound is at its week is during this phase.
External coaptation
Use of a rigid external device such as a bandage, splint or cast to align fractures.
Second intention healing
Hearing of a wounded by granulation tissue formation, epithelialization and contraction.
Proliferative phase
Begins after 2 to 3 days.
Characterized by invasion of fibroblasts, formation of granulation tissue, deposition of collagen epithelialization across healthy granulation tissue, and wound contraction by myofibroblasts.
Wound strength increases considerably during this phase.
Matureration/remodeling phase
Begins after about three weeks and last weeks to months.
Collagen fibers remodel and align.
Final gain in one strength occurs. But the wound will never be as strong as normal tissue.
Neutrophil
A granulocyte that is the chief phagocytic white blood cell of the blood.
Macrophage
A phagocytic tissue cells of the immune system that may be fixed or freely motile, is derived from Monocytes, functions in the distraction of foreign antigens and serves as an antigen-presenting cells.
The functions of neutrophils and macrophages
Modulate wound healing by releasing more growth factors. Also help to remove bacteria and cellular debris from the wound.
Wound strength is at its lowest during –
The inflammatory phase.
Granulation tissue
Vascularized fibrous tissue that covers a full thickness skin wound if the wound is left to heal by second intention.
Why is granulation tissue important?
It creates a barrier against infection and surface for re-epithelialization.
Epithelialization
Process of wound coverage by epithelial cells during the final stage of the Proliferative phase of wound healing.
Exudate
Fluid or semi solid that has exuded out of a tissue or it’s capillaries, characteristically high in protein and white blood cells.
Patient factors that affect wound healing
Older animals have problems that my alter their healing capabilities. Endocrinopathies such as Cushing’s and hyperthyroidism. Chronic viral infections. Diabetes alters tissue perfusion and release of oxygen. Hyperglycemia interferes with defense against infection. Orthopedic or neurologic problems. Poor nutritional status especially diseases that cause low protein and albumin levels. Obesity associated with increased risk of infection and dehiscent’s due to decreased vascularization of fatty tissues.
Wound factors that affect wound healing
Origin of the word. Contamination. Presence of suture/drains. Critical number of bacteria. Increased production of wood exudate. Tension on the wound edges or movement of surrounding tissues.
Concurrent factors that affect wound healing
Radiation therapy that leads to tissue fibrosis and vascular scarring. Certain types of chemo can suppress bone marrow and decreased resistance to infection. Long-term corticosteroids decrease the bodies inflammatory response thereby increasing risk of infection.
Six steps in proper wound management;
- Prevent further contamination
- Remove foreign debris and contamination
- Debride nonviable tissue
- Manage wound drainage
- Protect the wind through the inflammatory and proliferative phases
- Select appropriate wound closure
Types of wound debridement
Staged surgical debridement En block excision Enzymatic Mechanical Biological
Staged surgical debridement
Obviously compromised tissue is removed, tissue of questionable health is preserved and removed at a later stage if needed. Used for larger wounds with substantial trauma
En Block Excision debridement
If surrounding skin allows, a small wound can be excised completely an closed primarily.
Enzymatic debridement
Enzymes are used to slowly digest necrotic tissue. Use only in small, contaminated wounds. This technique is not a substitute for surgical debridement.
Mechanical debridement
And adherent primary bandage layer is used to nonselectively debride healthy contaminated wounds. Use only in the inflammatory phase.
Biological debridement
Maggots can be used to ingest necrotic tissue. Used for chronic wounds with poor tissue health.
Classifications of wounds
Clean
Clean-Contaminated
Contaminated
Dirty and infected
Clean wounds
Wound made under aseptic conditions; Nondramatic, uninfected operative word that does not enter a hollow viscous.
Clean-Contaminated wound
SX wound into which a hollow viscus is entered without significant contamination; Natural occurring wound with minor contamination; SX wound with a minor break in sterile technique.
Contaminated wound
Open traumatic wound; SX wound with a minor break in sterile technique; SX wound into contaminated area e.g. colon or inflamed/contaminated skin.
Dirty and infected wound
Old traumatic wound/infected wound/perforated viscera; wound with a high bacterial count >100,000 organisms/gram of tissue
Methods of wound closure;
- Primary closure with primary intention wound healing
- Delayed primary closure
- Secondary closure
- Second intention wound healing
Primary closure with primary intention wound healing
SX opposition of wound edges. Performed in fresh, clean wounds with little loss of soft tissue. Primary intention wound healing occurs. Epithelialization begins within 1-2 days because cells can cross over the incision. Granulation tissue is not needed. En block debridement can convert a small, contaminated wound into a clean wound, which then can be closed primarily.
Delayed primary closure
Appropriate for wounds older than 6-8 hours, with some contamination and questionable ability to heal with primary closure. Treated as an open wound for 2 or 3 days to allow drainage and elimination of infection, then surgically closed primarily .
Secondary closure
Wounds older than 6-8 hours, for infected necrotic wound, and for failed primary wound closure. Wound is allowed to form healthy granulation tissue and then is closed by apposition of granulation surfaces or by excision of granulation tissue and primary closure. Also known as third intention wound healing.
Second intention wound healing
Wounds older than 6 to 8 hours/infected, necrotic. Wound allowed to heal by granulation tissue formation and epithelialization.
Disadvantages: length of time required for complete healing, cost, fragility of the newly formed epithelialized would, loss of function as a result of excessive scarring or contraction, poor cosmetic results.
Factors influencing choice of wound closure:
- Time since the injury
- Extent of foreign body contamination
- Degree of bacterial contamination
- Viability of the tissue
- Damage to the neurovascular supply
- Location of the wound
- Availability of skin for closure
- Tension on the wound
2 antiseptic solutions that can safely be used to lavage I want
Chlorhexidine and Povidone-iodine. Should be diluted, can have cytotoxic potential.
Debridement
The removal of obviously contaminated, devitalized, or necrotic tissue and the illumination of foreign debris. It is the fastest, most effective way to clean a heavily contaminated/necrotic wound.
Depending on - - passive or active woman drains may be used in conjunction with wound closure.
The quality of wound exudate and disrupted soft tissues causing dead space.
Passive drains work by
Allowing fluid flow along the drain surface as the result of capillary action.
The most common passive drain used in small animals
The Penrose drain
The appearance of nonviable tissue
Blue-black, leathery, thin or white skin
Sugar dressings
High osmolality, draws out fluid, inhibiting growth of bacteria. Also aids in the debridement of necrotic tissue, while preserving viable tissue.
Honey dressings
Beneficial effects are thought to be a result of hydrogen peroxide production from activity of the glucose oxidase enzyme. The low pH may also accelerate healing. Must be unpasteurized, the source of the honey appears to be a factor in its effectiveness. Manuka honey may be the best option for wound care.
A wound is considered infected when:
The bacterial count is greater than 100,000 organisms/gram of tissue
Signs of infection
Swelling, heat and redness of surrounding tissue.
Sugar and honey can be beneficial in the management of some open wounds because
They create a hypertonic environment, producing an antimicrobial affect and are able to draw fluid and debris away from the world.
Laceration
Sharp cut or tear through the skin and possibly deeper tissues.
Degloving injury
Injury, typically to the distal limb, in which a large section of skin is torn off the underlying tissue in a glove-like fashion.
First Degree burns
Superficial, confined it to the outermost layer/epidermis. Recovers in a few days without treatment.
Second Degree burns
Partial thickness dermal injury, may form fluid filled blisters or show discoloration of part of the dermis. Full extent may not be known until several days later. Often manage to buy second intention healing with re-epithelialization.
Third Degree burns
Full thickness, characterized by a thick, leathery, often black layer of dead dermis (eschar). Treatment: removal of the eschar and wound debridement. Left to heal by second intention, must contract and re-epithelialize. Larger burns may require skin grafts to cover the defect.
Fourth Degree burns
Involve deeper tissues apart from the dermis and require surgical reconstruction if large.
Decubitus ulcers
Pressure sores that develop when an animal lies on a bony prominence for too long.
Clinical signs of infection
- Increased pain around the wound
- Increased redness around the wound
- Discoloration of the wound bed tissue
- Cellulitis and inflammation
- Presence of pus
- Abscess formation
- Non-healing wound
- An increase in exudate/odor
- Fragile granulation tissue that bleeds easily
- Wound deterioration or dehiscence
- Superficial pocketing/bridging at the base of the wound
Three distinct layers of bandages
The primary layer; secondary layer; tertiary layer
Primary layer of bandages
Most important for wound protection and healing, directly influences the wound environment.
Secondary layer of bandage
Absorbs exudate, provides support.
Tertiary layer of a bandage
Outer, protective layer. Keeps the other layers in place, determines the appropriate amount of pressure and support to be applied. Must not be occlusive, or moisture will accumulate within the bandage.
The Robert Jones bandage
Used to temporarily immobilize limbs distal to the elbow or stifle joint. Relies on an extremely thick secondary layer, tightly compressed to cause uniform compression of the limb. Applied properly the finished bandage sounds like a ripe melons when taped.
The modified Robert Jones bandage
Most commonly applied distal limb bandage in SA
