Skin Barrier Function

 

Skin Barrier Functions: Epidermis (outer layer) Protection from drying Protection from bacterial entry (infection) Protection from toxin absorption , like chemicals on the skin Fluid balance: avoiding excess evaporative water loss that would cause dehydration Neurosensory (touch, pain, pressure, sensation) Social-interactive (visible portion of the body covering)

Skin Barrier Functions: Epidermis (inner layer) Protection from injury because of the properties of elasticity and durability     Regulation of body temperature to avoid hypothermia with cold air exposure or high body T° with exercise and a hot environment Prevention of excess loss of body heat Protection from injury because of the properties of elasticity and durability

Skin Structure: Epidermis: The outer thinner layer known as the epidermis is composed mainly of epithelial cells. The deepest epidermal cells are immature cells which are continually dividing and migrating toward the surface, to replace lost surface cells; e.g. after an injury. The same types of regenerating epidermal cells are found in hair follicles and other skin appendages, which are anchored in the dermis. As the cells mature and migrate to the surface, they form keratin, which becomes an effective barrier to environmental hazards such as infection and excess water evaporation. Stratum Corneum: The “outer most” layer of the epidermis consisting of several flattened layers of dead keratinocytes as well as keratin. This layer protects against entry of bacteria and toxins. The epidermal layer regenerates every 2-3 weeks but regeneration requires the presence of the dermis. Dermis: The deeper layer responsible for skin durability and flexibility. The nerves for touch and pain, blood vessels and hair follicles are present in the dermis. The dermis is responsible for reforming the outer epidermis. So, if the outer layer is burned, the wound can heal as long as there is dermis. If the dermis is totally destroyed, the burn cannot heal.

2. Burn Injury

A skin burn is the damage to the skin caused by heat or other caustic materials like chemicals. The most immediate and obvious injury is one due to heat. Excess heat causes rapid protein denaturation and cell damage. The depth of heat injury is dependent on the depth of heat penetration. Wet heat (scald) travels much more rapidly into tissue than dry heat (flame). A surface temperature of over 156°F (68°C) by wet heat produces immediate tissue death as well as vessel clotting. A higher temperature would be required with dry heat (flames). The dead tissue on the surface is known as eschar. The depth of the burn is dependent on the temperature of the heat insult, the contact time, and the medium
(air-water). In addition, the thickness of the skin layer is critical as the thinner the skin, the deeper the burn. Children and the elderly have very thin skin. Chemicals destroy skin by chemically killing the tissue. It is now clear that toxic agents released by inflammation, which are activated with the burn, cause much of the tissue damage after he burn, especially in the deeper burns.

It is important for to know that a burn can become deeper than that present initially, due to any continued exposure to the heat source, any degree of shock or later infection.

Reason for Burn Worsening:

continued contact with the heat or chemical source decrease in burn blood flow: shock or constriction infection

Burn Severity is determined by: Burn depth. Burn size. Burn location.

Burn with Loss of Barrier Protection

Deep Hand Burn: Increased risk of infection Increased pain and risk of scar formation Increased risk of loss of skin elasticity leading to disability Increased surface fluid and heat loss

3. Burn assessment

Burn Depth: How deep is the burn? Burn depth is defined by how much of the two skin layers is destroyed by the heat source. Burns can be categorized by degree:

1st degree: confined to the outer layer only

2nd degree: also involves part of the dermis

3rd degree: destruction of both layers

or

Partial thickness: is a second degree burn consisting of injury to part if the dermis

Full thickness: is a third degree burn consisting of injury to both layers

Only burns extending into the second layer (the dermis) are considered significant.

 

First-degree burn: A first-degree burn is confined exclusively to the outer surface and is not considered a significant burn. No barrier functions are altered. The most common form is a Sunburn which heals by itself in less than a week without scar.

 

Second-degree burn: This degree burn destroys the epidermal layer and portions of the dermis. Since it does not extend through both layers, it is termed a partial thickness burn. There are a number of depths of a second-degree or partial thickness burn typically used to characterize the burn. Each corresponds with a predictable healing time, treatment modalities and outcomes. However, it is not necessary to make these distinctions with initial assessment but more knowledge is always better.
Superficial Second-Degree Burn: Involves the entire epidermis and no more than the upper third of the dermis is heat destroyed. Rapid healing occurs in 1-2 weeks, because of the large amount of remaining skin and good blood supply. Scar is uncommon. Initial pain is the most severe of any burn, as the nerve endings of the skin are now exposed to the air.
This depth of burn is at low risk for infection unless grossly contaminated.  Initial cleansing should include removal of dirt, broken blisters and dead epidermis.  Large blisters can be debrided off if using a temporary skin substitute or left intact for a few days.  Often blisters get larger with time and impede movement at which time they should be removed.  Topical antibiotics are not needed, especially cream based agents such as silver sulfadiazine as these agents impede healing and are only used if infection risk is high.
Definition: Second-degree burns are defined as those burns in which the entire epidermis and variable portions of the dermis layer are heat destroyed.  A superficial second-degree (partial thickness) burn is characterized by heat injury to the upper third of the dermis leaving a good blood supply
Cause: Usually hot water.
Appearance: The micro vessels perfusing this area are injured resulting in the leakage of large amounts of plasma, which in turn lifts off the heat-destroyed epidermis, causing blister formation.  The blisters will continue to increase in size in the post-burn period as well and protein breakdown occurs.  A light pink, wet appearing very painful wound is seen as blisters are disrupted.  Frequently, the epidermis does not lift off the dermis for 12 to 24 hours and what appears initially to be a first degree is actually a second-degree burn.
Outcomes:
Healing rate: Despite loss of the entire basal layer of the epidermis, a burn of this depth will heal in seven to fourteen days if non-infected due to repopulation of the epithelial cells that are also present in skin appendages, anchored deep in the dermis.  Minimal to no scarring is expected to occur.  There is a relatively small zone of injury and conversion is uncommon except at extreme of age or chronically ill.  Most antibiotic creams will slow the healing rate.
Characteristics: Confined to upper third of dermis usually caused by hot liquids Blisters, wet pink, painful low risk of infection Heals in 10-12 days without scarring
Superficial 2° burn caused by hot water: a scald burn	Superficial burn with plasma leaking into wound (note blisters)
Treatment: Clean, remove small blisters; apply grease gauze and soft gauze dressing (occlusion, absorbent dressing, changed daily) On face, perineum, apply bacitracin or neomycin ointment, applying several times a day. Excellent alternative is the use of a synthetic skin substitute which seals the wound and decreases pain. Use a water-soluble topical antibiotic if the wound is grossly contaminated or if one is unsure if the wound is superficial or deep. Prophylactic systemic antibiotics are not needed.
Superficial Partial Thickness Burns Covered with Synthetic Skin Substitute
Proper use requires initial debridement of blisters to allow firm adhesive Closed Dressing Approach
The soft gauze over the primary dressing will protect the wound and help soak up fluid leaking from the surface

 

Mid-Second Degree (mid-partial thickness) Burn: Destruction to about half of the dermis occurs. Healing is slower (2-4 weeks) due to the fact that there is less remaining dermis and less blood supply. Pain can be severe but is less intense than superficial 2°. The reason is that part of the nerve is now heat destroyed.  It is not necessary to distinguish a superficial from a mid-dermal burn on initial assessment as initial management is basically the same. Definition: A mid second degree extends to the mid portion of the dermis.  Longer exposure to hot liquids (5-10 seconds) or flash flames (not direct contact of flames with skin) are the most common causes. Cause: Brief exposure to flames or flash explosion: hot water in infant or elderly. Appearance: The burn surface may have blisters but is more red, less wet and only moderately painful. Outcome: These burns usually heal in about two to four weeks.  The exception is the very young and elderly where the dermis is thin and depth of burn is invariably deeper.  However, there is a large zone of injury and risk of conversion.  If a burn heals in two weeks, then minimal to no scarring is expected.  With healing time beyond three weeks scarring will occur, the degree being greater in dark skinned individuals.
Treatment: 1.     In patients six years to 60 years, without diabetes, chronic illness, etc., treatment is with grease gauze, an occlusive dressing and a topical antibiotic ointment.  The depth can be underestimated and a switch to an antibiotic cream or dressing may be needed because of risks of infection. 2.     In very young, and very old patients, or those with chronic illness, contaminated wounds or perineal wounds, the traditional choice is a topical antibiotic.  First choice is silver sulfadiazine or silver dressing with closed dressing technique. 3.     New approach is the use of a temporary skin substitute, which can increase healing, protect the wound and decrease pain.
Mid-Dermal Burn
	Treatment: Transfer to Burn Center due to location (bilateral feet) Too big to use cold to control pain Debride loose tissue Grease gauze, topical antibiotic ointment or silver dressing with closed gauze dressing Consider temporary skin substitute
Treatment: Transfer to Burn Center due to size i.e., >15% TBS Too big to use cold dressings except for a very brief initial period Use topical antibiotic in view of age, high risk of conversion, infection Alternative: temporary skin substitute to generate wound closure
	Treatment: Cold water to control pain Gently cleanse Grease gauze plus dressing (closed technique) Antibiotic ointment is optional but a silver cream is not needed Apply dressing to allow for mobility of hand

 

Deep Second Degree (deep partial thickness) Burn: Most of skin is destroyed except for small amount of remaining dermis.  The wound looks white or charred indicating dead tissue.  Blood flow is compromised and a layer of dead dermis or eschar adheres to the wound surface.  Pain is much less as the nerves are actually destroyed by the heat.  Usually, one cannot distinguish a deep dermal from a full thickness (third degree) by visualization.  The presence of sensation to touch usually indicates the burn is a deep partial injury.
Definition: A deep partial thickness or deep second-degree burn extends well into the dermal layer and fewer viable epidermal cells remain.   Therefore, re-epithelialization is extremely slow, sometimes requiring months.  Grafting is often the preferred treatment for long-term function.
Appearance: In these patients, blister formation does not characteristically occur because the dead tissue layer is sufficiently thick and adherent to underlying viable dermis that it does not readily lift off the surface.  The wound surface may be red and dry in appearance with white areas in deeper parts (dry since fewer blood vessels are patent).  There is a marked decrease in blood flow making the wound very prone to conversion to a deeper injury and to infection.   It is often not possible to distinguish a deep partial from a full thickness burn by initial appearance.  Frequently the wound is a mixed second and third degree.  Direct contact with flames is a common cause.  Most chemical burns are also deep.  The appearance of the deep dermal burn changes dramatically over the next several days as the area of dermal necrosis along with surface coagulated protein turns the wound a white to yellow color.  The amount of surface coagulum is accentuated with the use of a topical antibiotic, making the deep second degree burn difficult to differentiate from a third degree burn.  The presence of some pain can assist in the diagnosis because pain is usually absent in a full thickness injury.  Fluid losses and the metabolic effects of dermal burns are basically the same as that seen with the third degree burn.
Outcome: A deep dermal burn will require 4-10 weeks or longer to heal.  Since the new epidermis is very thin and not adhered well to dermis (no rete pegs), wound breakdown is common.  Excision and grafting is the preferred treatment.  Dense scarring is usually seen if the wound is allowed to heal primarily.
Characteristics: Involves majority of the inner dermal layer Cause is usually flames Dry, white, or charred skin  Pain is minimal High risk for infection May heal in 2-3 months If heals: scar is severe   Readily converts to a full thickness burn
Deep Partial Thickness Burn
Flame Burn: Deep dermal burn to forearm. Note patches of white indicating a deeper burn. Less pain is usually present in the deeper burn.
Deep Partial Thickness Burn
General Treatment Principles:
Deep Partial Thickness Burn Admit if over 2% due to need for early grafting Transfer to Burn Center based on Transfer Criteria ( no need to perform burn care if transfer is immediate) Gentle washing with antibacterial soap Silver sulfadiazine using a closed dressing Or silver impregnated dressing Cold is not beneficial once the burning has stopped as pain is minimal
Deep burn to back treated with silver dressing
Silver is constantly released over a 3-5 day period resulting in excellent infection control but with fewer dressing changes
Mid to Deep Hand Burn treated with silver cream
Note fingers are wrapped separately to maintain motion

 

Third Degree (Full Thickness) Burn: Both layers of skin are completely destroyed leaving no cells to heal. Any significant burn will require skin grafting. Small burns will heal with scar.
Definition: A full thickness or third degree burn occurs with destruction of the entire epidermis and dermis, leaving no residual epidermal cells to repopulate.  This wound will therefore not re-epithelialized and whatever area of the wound is not closed by wound contraction will require skin grafting.
Appearance: A characteristic initial appearance of the avascular burn tissue is a waxy white color.  If the burn produces char or extends into the fat as with prolonged contact with a flame source, a leathery brown or black appearance can be seen along with surface coagulation veins.  Direct exposure with a flame is the usual cause of a third degree burn.  However, contact with hot liquids such as hot grease, tar or caustic chemicals will also produce a full thickness burn.  The burn wound is also painless and has a coarse non-pliable texture to touch.  A major difficulty is distinguishing a deep dermal from a full thickness (third degree) burn that extends just through the dermis.  This burn is termed an indeterminate burn.
Outcome: Except for a very small wound, e.g. 2x2 inches, the burn wound will require excision and a skin graft.
Characteristics: Complete destruction of both layers            Cause is usually flames White, char, dry, painless High risk for infection Needs to be excised and skin grafted
Full thickness (3º degree) burn of the arm and chest. Note presenic char. The area is painless due to loss of nerve endings (meets transfer criteria based on size, depth and patient's age).
General Treatment Principles:   Transfer to Burn Center based on Transfer Criteria (no need to perform burn care if transfer is immediate) Gentle washing with antibacterial soap. Silver sulfadiazine using a closed dressing twice a day. Or use of a silver impregnated dressing Cold is not beneficial once the burning has stopped as pain is minimal.

 

visually deceiving burns: Some burns usually caused by contact with flames or extremely hot temperatures like explosions have destroyed epidermis still present in the wound. The depth can be underestimated unless the wound is gently washed and debrided after which the size and depth is more clearly defined.
	Flame Burn (direct contact) looks superficial with blisters but mechanism suggest a deep burn.
	When gently cleansed, the wound is noted to be a combination of deep second and third degree burn.
Treatment: Gently wash, removing all loose epidermis Application of silver cream or dressing

 

immersion scalds: Scald burns in which a part or all of the body is immersed in hot water. Hot water contact can be prolonged, producing a deep burn. This process is characteristically seen in the elderly or in young children who cannot escape hot water. Forced immersion or abuse must be considered. The water vehicle transmits heat to tissues 20 times greater than air, therefore the tissue is injured deeper than with a flash flame of short exposure. However, the water T° is usually not hot enough to immediately coagulate vessels, so the wound looks red like a superficial burn but soft tissue injury including nerves can be severe and the burn can be very deep.
Appearance: The major characteristic is a dark red color due to myoglobin and hemoglobin pigment released in the tissues, which can be mistaken for viable tissue. The depth of a long term scald exposure is invariably underestimated.
Outcome: Since the burn is usually deeper with this form of scald and the area is often buttocks and/or feet, morbidity both short term and long term is high.
	Typical appearance: looks red, like a Mid Second burn but is not wet and is less painful. The burn is actually a Full Thickness.
	Note the sharp borders of the burn indicating the child was unable to move.
Treatment: Burn size and area are indicators that patient needs care in a Burn Center Notification of Social Service