our skin is a major organ of the body that acts as a barrier to pathogens and trauma. skin defects...
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Our skin is a major organ of the body that acts as a barrier to pathogens and trauma.
Skin defects caused by burns, venous and diabetic ulcers, or acute injury occasionally induce life-threatening situations.
Many burned people die, their body couldn’t produce new skin
Skin is largest organs in the body Skin is important to protect body
from infection and harmful bacteria Skin keep vital fluid in
Functions of Skin?Functions of Skin? Skin is the largest organ in the
human body Helps preserve fluid balance Controls body temperature Helps prevent and fight diseases
What are wounds ? Break in skin or mucous membranes
Any breach in the surface of the body or any tissue disruption produced by the application of energy
Usually physical injury Abrasion injury Contusion, crush injury Incision, laceration
Epidermis (5 layers)Keratinocytes provide protective
properties.Melanocytes provide pigmentation.Langerhans’ cells help immune system.Merkel cells provide sensory receptors.
Dermis (2 layers)Collagen, glycoaminoglycans, elastine, ect.Fibroblasts are principal cellular
constituent.Vascular structures, nerves, skin
appendages.
Hypodermis (fatty layer)Adipose tissue plus connective tissue.Anchors skin to underlying tissues.Shook absorber and insulator.
Superficial
Deep (blood vessels, nerves, muscle, tendons, ligaments, bones)
Open Wound Superficial or deep break in skin
(abrasion, puncture, laceration)
Closed: blunt force; twisting, turning, straining, bone fracture, visceral organ tear
Acute: trauma sharp object or blow Surgical incision, gun shot, venipuncture
Chronic: pressure ulcers Causality
Intentional: surgical incision Unintentional: traumatic
Knife Burn
Primary Intention skin edges are approximated (closed) as in a surgical
wound Inflammation subsides within 24 hours (redness,
warmth, edema) Resurfaces within 4 to 7 days
Secondary Intention: tissue loss Burn, pressure ulcer, severe laceration Wound left open Scar tissue forms
Inflammatory Response Serum and RBC’s form fibrin network Increases blood flow with scab forming in 3 to 5
days
Proliferative Phase: 3-24 days Granulation tissue fills wound Resurfacing by epithelialization
Remodeling: more than 1 year collagen scar reorganizes and increases in strength Fewer melanocytes (pigment), lighter color
Age Nutrition: protein and Vitamin C intake Obesity decreased blood flow and increased risk
for infection Tissue contamination: pathogens compete with
cells for oxygen and nutrition Hemorrhage Infection: purulent discharge Dehiscence: skin and tissue separate Evisceration: protrusion of visceral organs Fistula: abnormal passage through two organs
or to outside of body
As wound heals: Fluid and cells drain from damaged tissue Exudate may be:
Clear Bloody Pus-containing
Proper wound healing: Cleanliness and care of lesion Proper circulation Good general health and nutrition
1. Vascular Response
2. Blood coagulation
3. Inflammation4. Formation of new
tissue5. Epithelialisation6. Contraction &
Remodeling
Inflammatory Bleeding/clotting Migration of WBCs Cell swelling
Reparative Laying down of collagen + migration of epith. cells New capillary loops Proliferation of fibroblastsstrands of collagen
Consolodative reorientation +contraction of collagen collagen synthesisdegradation vascularity
Statistics Annually, there are approximately 1.25 million
people in the US who sustain burn injuries
Of these, 5,500 do not survive and 51,000 require hospitalization
Persons whose burn injuries require hospitalization have about a 50% chance of sustaining temporary or permanent disability
The most common part of the body involved in burn injury is an upper extremity, followed by the head and neck
The primary cause of burn injury is exposure to temperature extremes
Heat injuries are more frequent than cold injuries
Cold injuries almost exclusively result from frostbite
Electrical and chemical injuries constitute 5-10% of burn injuries and are largely the result of occupational accidents
Burn injury causes destruction of tissue, usually the skin, from exposure to thermal extremes (either hot or cold), electricity, chemicals, and/or radiation
The mucosa of the upper GI system (mouth, esophagus, stomach) can be burned with ingestion of chemicals
The respiratory system can be damaged if hot gases, smoke, or toxic chemical fumes are inhaled
Fat, muscle, bone, and peripheral nerves can be affected in electrical injuries or prolonged thermal or chemical exposure
Skin damage can result in altered ability to sense pain, touch, and temperature
Old terminology 1st degree: only the
epidermis 2nd degree: epidermis
and dermis, excluding all the dermal appendages
3rd degree: epidermis and all of the dermis
4th degree: epidermis, dermis, and subcutaneous tissues (fat, muscle, bone, and peripheral nerves)
New terminology Superficial: only the
epidermis Superficial partial
thickness: epidermis and dermis, excluding all the dermal appendages
Deep partial thickness: epidermis and most of the dermis
Full thickness: epidermis and all of the dermis
Maintain humidity Remove excess exudates Allow gaseous exchange Provide thermal insulation Impermeable to bacteria Allow removal without causing trauma Non toxic and non allergenic Cost effective Availability
Gauze Dressings Transparent Films Foams Hydrocolloids Alginates Composites
Woven or non-woven materials Wide variety of shapes and sizes. Use on: infected wounds, wounds which require
packing, wounds that are draining, wounds requiring very frequent dressing changes.
Pros: readily available; cheaper than other dressing types; can be used on virtually any type of wound.
Cons: must be changed frequently, which may add to overall cost; may adhere to the wound bed; must often be combined with another dressing type; often not effective for moist wound healing.
Allow oxygen to penetrate through the dressing to the wound, while simultaneously allowing moisture vapor to be released.
Composed of a polyurethane material. Use on: partial-thickness wounds, donor sites, minor
burns, stage I and II pressure ulcers.
Pros: conforms to the wound well, can stay in place for up to one week; aids in autolytic debridement; prevents friction against the wound bed; does not need to be removed to visualize the wound; keeps the wound bed dry and prevents bacterial contamination of the wound.
Cons: may stick to some wounds, not suitable for heavily draining wounds, may promote periwound maceration due to its occlusive nature.
Less apt to stick to delicate wound beds, are non-occlusive and are composed of a film coated gel or a polyurethane material which is hydrophilic in nature.
Use on: pressure ulcers, minor burns, skin grafts, diabetic ulcers, donor sites, venous ulcers.
Pros: comfortable, won’t adhere to the wound bed, and highly absorbent; allow for less frequent dressing changes, depending on the amount of wound exudate; come in many shapes and sizes.
Cons: may require a secondary dressing to hold the foam in place; if not changed often enough may promote periwound maceration; cannot be used on wounds with eschar or wounds that are not draining.
Varying types and with different performance features and indications.
Available in both non adhesive and adhesive. Allows absorption of exudates. Uses: Traumatic wounds, Leg ulcers, Minor
Burns, Donor sites. Examples: •Lyofoam – allows passage of fluid •Allevyn – has low-adhering wound contact
with moderate exudates •Tielle – allows vapour escape with low
exudates.
Very absorbent and contain colloidal particles such as methylcellulose, gelatin or pectin that swell into a gel-like mass when they come in contact with exudate.
Strong adhesive backing. Use on: burns, pressure ulcers, venous ulcers.
Pros: encourage autolytic debridement; provide insulation to the wound bed; waterproof and impermeable to bacteria, urine or stool; provide moderate absorption of exudate.
Cons: leave a residue present in the wound bed which may be mistaken for infection; may roll over certain body areas that are prone to friction; cannot be used in the presence of infection.
Consist of insoluble polymers with hydrophilic sites, which interact with aqueous solutions, absorb and retain water.
Key Features: Removes slough and necrotic tissue by rehydrating
dead tissue and enabling autolytic debridement. Carries metronidazol to treat fungal and other
malodorous wounds. Uses: Sinuses, Infected wounds, Sloughs and necrotic
wounds.
Examples: Intrasite gel, Neugel, Granugel.
Contain salts derived from certain species of brown seaweed.
Woven or nonwoven Form a hydrophilic gel when they come in
contact with exudate from the wound. Use on: venous ulcers, wounds with tunneling,
wounds with heavy exudate.
Pros: highly absorbent; may be used on wounds that have infection present; are non-adherent; encourage autolytic debridement.
Cons: always require a secondary dressing, may cause desiccation of the wound bed, as well as drying exposed tendon, capsule or bone (should not be used in these cases).
Consist, principally of calcium salts of alginic acid, a polysaccharide derived from seaweed.
Key Features: The calcium alginate in contact
with the wound exudates forms a gel on the wound surface that is believed to facilitate healing.
The chemical and physical properties differ in the varieties of alginate on available.
Plain or impregnated with silver.
Examples: Saesorb, Kaltogel, Kaltostat,
Sorbsan, Tegagen, Acquacel.
May be used as the primary dressing or as a secondary dressing.
Made from any combination of dressing types, but are merely a combination of a moisture retentive dressing and a gauze dressing.
Use on: a wide variety of wounds, depending on the dressing.
Pros: widely available; simple for clinicians to use.
Cons: may be more expensive and difficult to store; less choice/flexibility in indications for use.
1. The donor site is a new wound.2. Scarring and pigmentation changes
occur.3. Dermis is not replaced.4. Donor site is a potential site for
infection.5. Donor site is not unlimited.6. Extensive burns makes it impossible.
• Xenografts, particularly porcine skin grafts, are
commercially available and are an effective means of short-term wound closure .
• A Xenograft is normally removed on the third or
fourth day of use before extensive adhesion onto the wound bed sets in, thereby necessitating its traumatic excision prior to drying and sloughing off.
The annual national requirement for cadaver skin is estimated to be only 3000 m2.
Yet only 14% to 19% of human skin needed is being recovered.
Traditional solution replacing the skin with another human or animal skin
Some of the body rejects others skin So, alternative solution needed Synthetic Skin is invented by Burke and
Yannas
Is laboratory production for substitution of human skin (tissue Engineering)
Tissue Engineering is Knowledge of building or repairing human organ
Cells brought from lab or patients blood used to initiate the process
Graft should be flexible enough to conform to wound bed and move with body
Should not be so fluid-permeable as to allow the underlying tissue to become dehydrated but should not retain so much moisture that edema (fluid accumulation) develops under the graft
1. Protect underlying tissues from injury: mechanical, heat, cold, biological.
2. Prevent excess water loss.
3. Act as a temperature regulator.
4. Serve as a reservoir for food and water: adipose tissue
5. Assist in the process of excretion: H20, Salt, Urea, Lactic Acid.
6. Serve as a sense organ for cutaneous senses: pain, heat, cold, pressure, touch.
7. Prevent entrance of foreign bodies: microorganisms.
8. Serve as a seat of origin for Vitamin D.
Polymeric or collagen-based membrane Some are too brittle and toxic for use in burn victims Flexibility, moisture flux rate, and porosity can be
controlled
Fabrics and sponges designed to promote tissue ingrowth
Have not been successful Immersion of patients in fluid bath or silicone
fluid to prevent early fluid loss, minimize breakdown of remaining skin, and reduce pain
Culturing cells in vitro and using these to create a living skin graft
Does not require removal of significant portions of skin
Skin is usually donated by
other donors. Fibroblasts are removed from
the donated skin and are frozen until they are needed.
The fibroblasts are placed on a polymeric mesh scaffolding, gather oxygen, and grow new cells.
The cells are then transferred to a culture system.
After 4 weeks the polymer mesh dissolves and leaves behind a new layer of dermal skin.
When the growth cycle is completed, they add more nutrients.
Keratinocytes are added to the collagen and are exposed to air to form epidermal layers.
The skin is now completed and is stored in sterile contains until ready to use.
A high incidence of infection Low capacity for inducing vascularisation
and epithelialisation
However, useful insights into the requirements for a satisfactory skin replacement have been discovered through the use of synthetic polymers.
"The dermal replacement should provide both the information necessary to control the inflammatory and contractile processes and also the information necessary to evoke ordered recreation of autologous tissue in the form of a neodermis" (Schulz, 2000).
"The initial replacement material should provide immediate physiologic wound closure and be eliminated once it has provided sufficient information for reconstitution of neodermis" (Schulz).
It should protect the wound by providing a barrier to the outside (Beele, 2002)
It should control water evaporation and protein and electrolyte loss (Beele)
It should limit excessive heat loss (Beele) It should decrease pain and allow early mobilization (Beele) It should provide an environment for accelerated wound
healing (Beele) The risk of infection must be taken into account (Beele)
b) Flexural rigidity of graft is excessive; graft does not deform sufficiently under its own weight to make contact with depressions in woundbed surface, thus air pockets form.
d) Peeling force lifts graft away from woundbed.
f) Very low moisture flux causes fluid accumulation at graft-woundbed interface and peeling.
Types of Skin ReplacementsTypes of Skin Replacements
Epicel skin replacement technology ◦ Introduced by Genzyme Biosurgery in 1987.◦ Isolation of individual cells from a postage-
stamp-sized biopsy of skin. ◦ Grow the cells for about 2 to 3 weeks and
allow them to form individual sheets of tissue.
◦ Surgeons transplant these sheets of tissue to the burnt area where these sheets fuse over time with the burnt area.
Artificial skin is already being used for burn victims and soon will be available for other skin disorders.
The skin is not used for a permanent replacement, but to temporary cover the skin until your skin can grow back naturally.
BenefitsBenefits
Protect skin from infection Keep in moisture to
prevent dehydration Encourage healing through
construction of new tissue by infiltration of epidermal cells and fibroblasts
Allow for less severe scarring
More readily available
Biodegradable skin Doesn’t need to be removed
Slowly releasing antibiotic Prevents infection
Re freeze dried artificial skin Easier storage and reconstitution
Addition of epithelial growth factor and basic fibroblast growth factor
Increased regeneration of tissue
BiobraneCan be easily peeled off; good for donor sites and superficial partial-thickness burns within 6 hrs; shortens time in hospital; low cost
Temporary coverage
TranscyteReadily available; easier to remove than allograft; good for partial-thickness burns; stimulates epithelialisation; less scarring; improves healing rate.
Temporary coverage; cost 16 times more than Biobrane
ApligrafImmediate availability; 1 step procedure; easy to handle; primary role is treatment of chronic ulcers; hastens healing in deep and chronic wounds; improves cosmetic and functional outcomes
Temporary coverage; limited viability; most expensive
DermagraftReadily available; living dermal structure; used for chronic lesions, foot ulcers.
Temporary coverage; only 1 main application
ProductAdvantagesDisadvantages
Advantages and Disadvantages of Temporary Skin Substitutes
IntegraImmediate permanent wound coverage; allows ultra-thin split-thickness skin autografts; most widely accepted for burn patients; allows migration of patient’s own endothelial cells and fibroblasts; studies over 10 years now; cosmetically better than using just autograft; greater elasticity; avoids risk of infection
Complete wound excision; 2 step procedure; susceptible to infection; relatively expensive compared to cadaveric allografts; learning curve is steep.
AllodermImmediate permanent wound coverage; good for being a template for dermal regeneration; good take rates; reduces scarring; allows 1 step grafting of an ultra thin split skin graft
Allograft supply; little barrier function; no virus screening; 2 step procedure; most expensive
EpicelCovers large areas; permanent; immediate permanent wound coverage; minimal risk of disease transmission
3 – 5 wks to produce 1.8 m2 from 2 cm2; fragile; expensive because of quality control; spontaneous blistering; susceptible to infection and contractures;
LaserskinDelivers keratinocytes to the wound in an upside-down manner
Expensive
ProductAdvantagesDisadvantages
Advantages and Disadvantages of Permanent Skin Substitutes
Types of Skin Types of Skin Replacements Replacements Integra Dermal Regeneration Template®
Semi -synthetic approach to skin regeneration
Researchers develop a bi-layer membrane system called the Dermal Regeneration Template
The first and only FDA approved tissue engineered product for burn and reconstructive surgery
Dermal replacement layer is constructed of a porous, biodegradable matrix of cross-linked bovine tendon collagen and the glycos-aminoglycan chondroitin 6-sulfate.
Allows a the wound to establish a new tissue base
How does it work?How does it work?
Skin replacement. Using a bilayer membrane system, scientists at Integra LifeSciences help repair skin lesions and burns.
Drape a sheet of Integra ® over the wounded area for 2 to 4 weeks.
Allows the victim’s cells to grow a new dermis on top of matrix of the Integra ®.
Remove the top layer of the Integra® and applies a very thin sheet of the victim’s own epithelial cells.
Over time, a normal epidermis (except for the absence of hair follicles) is reconstructed from these cells.
Using only labor manual process only 50,000 skins produces in a year
So Automated processes needed Machine that refresh nutrient liquid
every day (increase the time of growth)
Temperature monitor, steady environment increase the growth
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