what are the properties of normal skin

8/10/2019 WHAT ARE THE PROPERTIES OF NORMAL SKIN

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SECTION I: SKIN (BIOLOGIC PROPERTIES)

WHAT ARE THE PROPERTIES OF NORMAL SKIN

Skin is a bilayer organ whose functions are essential for survival. Although the bilayers worksas a unit, each component has specific properties which need to be recognized if one is toduplicate these properties with a skin substitute.

SKIN FUNCTIONS

Epidermis

• protection from desiccation

• protection from bacterial entry

• protection from toxins

• fluid balance: avoiding excess evaporative loss

• neurosensory

• social-interactive

Dermis

• protection from trauma due to elasticity, durability, properties

• fluid balance thru regulation of skin blood flow

• thermoregulation thru control of skin blood flow

• growth factors and contact direction for epidermal replication and dermal repair

FUNCTIONAL COMPONENTS OF SKIN:

EPIDERMIS: The outer thinner layer known as the epidermis is composed mainly of epithelialcells. The outermost cells contain the protein keratin and are known as keratinocytes. Thebasal or deepest epidermal cells are anchored to the basement membrane by adhesionmolecules (or glue, namely fibronectin. These immature cells are continually dividing andmigrating toward the surface to replace lost surface cells e.g. after an in!ury. The same type of regenerating epidermal cells are found in hair follicles and other skin appendages which areanchored in the dermis. As the cells mature and migrate to the surface they form keratinwhich becomes an effective barrier to environmental hazards such as infection and to e"cess

water evaporation.

#eplacement of the epidermal layer by this regenerative process takes $%& weeks. 'ues andbiologic stimuli at the wound surface are necessary to direct proper orientation and mitoticresponse of the epidermal cells. any of the cues come from dermal elements, especially thematri" proteins and matri" glycosaminoglycan.

COMPONENTS OF EPIDERMIS

• outer cells: keratinocytes



• keratin, a tough protein on surface, preventing bacteria or to"in entry

• inner layer: epidermal cells which are proliferating and migratory to surface and will

become keratinocytes

• innermost layer: basal epidermal cells anchored to basement membrane by adhesion

molecules

• skin appendages anchored in dermis also lined by epidermal cells

• )angerhan*s cells, contain granules, fi" antigens (felt to be responsible for antigen%

antibody and allergy functions

CHARACTERISTICS OF EPIDERMIS

• protection from environmental insults

• ability to regenerate every $%& weeks resulting from biologic cues and contact direction

provided by dermis, basement membrane

DERMIS:

The dermis is a very dynamic layer of thick connective tissue, also in constant turnover. Thedermis is divided into a thin superficial layer known as the papillary dermis containing theanchoring epidermal rete pegs and the thicker deeper portion known as the reticular dermis.The papillary dermis is the ma!or factory for the proteins providing direction for epidermalreplication. The upper dermis also contains the highest blood flow. The primary cell type is thefibroblast which produces the key structural e"tra cellular matri" proteins collagen and elastinas well as matri" or ground substance.

+n addition these cells produce the key adhesion proteins used to attach epidermal cells to thebasement membrane and for used epidermal cell migration and replication. ibronectin is akey fibroblast derived signal protein for orchestration of healing. The ground substance ormatri" is made up of comple" polysaccharide % protein comple" known as glycosaminoglycan

or the -A- component as well as hyaluronic acid. The matri" provides a semi fluid whichallows for cell and connective tissue orientation as well as nutrient diffusion to the cells and ascaffolding for cell migration.

COMPONENTS OF DERMIS

• papillary dermis: upper dermis containing anchoring rete pegs and also is the most

biologically active part of the dermis

• reticular dermis: the thicker deeper portion responsible for durability and anchoring of

skin appendages

• matri" proteins

% collagen is the predominant protein, mainly collagen Type . (besides structure/collagen type provides a contract orientation for dividing and migrating epithelial

cells% fibronectin is the primary adhesive protein playing a ma!or role in healing% other adhesive proteins

• ground substance (glycosaminoglycan

% carbohydrates protein comple"es% hyaluronic acid

• cells

% fibroblasts



% macrophages% platelets% endothelial cells

• blood vessels (auto regulated flow

CHARACTERISTICS OF DERMIS

• provides durability, fle"ibility of skin

• factory for all the components re0uired for replication and repair of epidermis and

dermis

• scaffolding for cell migration and the conduit for nutrient delivery

INTERFACE: The interface between the layers or the dermo%epidermal !unction is thebasement membrane rich in the adhesive protein fibronectin which anchors the epidermal cellsfrom above and dermis from below.

THICKNESS: Average thickness of the bilayer is %$ mm being considerably thinner in infantsand the elderly especially the dermis which is underdeveloped in infants and atrophic in theelderly.

CELL TPES

Epidermis% 1eratinocytes% 2pithelial cells% )angerhan*s cells

Dermis% ibroblasts% acrophages% 2ndothelial cells% 3latelets

EPITHELIAL CELLS: These cells make up the ma!ority of the epidermis. +mmature cells areprogrammed to divide, migrate and mature to keratin producing cells called keratinocytes. Thesignals to activate this process come from messenger proteins called growth factors as well asthrough contact direction from key dermal adhesive proteins, especially collagen.

FIBROBLASTS: The cells of mesenchymal original are normal present in the dermis and

produce normal dermal replacement components. After in!ury these cells migrate into thewound and proliferate/ in order to produce increased 0uantities of these dermal proteins andmatri".

ENDOTHELIAL CELLS: These cells make up the lining of micro and macro vessels and alsomake up the lining of new capillaries produced after in!ury. These cells like fibroblasts dodifferentiate from local mesenchymal cells and are also attracted into the wound by localsignals.



MACROPHAGES: These cells of mesenchymal origin are normally present in tissue butincrease in number after in!ury, attracted by chemical messages released by the activation ofinflammation. The long lived cells release the protein chemical messages, growth factors andgrowth stimulants which orchestrate healing in an organized fashion.

PLATELETS: The factor%rich particles release a host of growth factors and adherence proteinsduring the initial post burn period.

FIBROBLAST PRODUCTS

• collagen (type one in skin

• matri" proteins (fibronectin, tenascin, others

• proteoglycans, glycosaminoglycan, hyaluronic acid, other matri"

components

• cytokines and other growth stimulants

MACROPHAGE PRODUCTS

• growth factors

• growth stimulants

• opsonins

CHARACTERISTICS OF SKIN COLLAGEN TPE !

F"#$%i&#

• creates adherence to wound surface via fibrin and fibronectin

• provides surface orientation for epithelial cell migration

• stimulates dermal cell migration

S%r"$%"re

• provides dermal scaffolding and durability

• comple" surface morphology

CHARACTERISTICS OF MATRI' (GAG)

F"#$%i&#s

• glue or adherence properties in tissue via cell%matri" interaction

• substrate for migration of nutrients, cells and growth factors

• deactivator of to"ic protease released by neutrophils

• conduit for living fibrin, fibronectin and growth factors in contact with the

wound surface



• scaffold for surface deposition of fibrin and fibronectin i.e., cell guidance

proteins

S%r"$%"re

• the foundation for deposition of dermal cells, collagen, other proteins

• these compounds also provide the scaffold for the epidermal basement

membrane

• brings critical matri" proteins and growth factors into contact with each

other

DERMAL MOLECULES INFLUENCING BURN WOUND CLOSURE

M&e$"e S&"r$e L&$%i&#

'ollagen type + ibroblast 4ermis

% Supports epidermal cell attachmentand migration

'ollagen type +5 2pidermal cell, fibroblast )amina densa% Supports epidermal cell attachment

ibronectin ibroblasts, macrophage, serum 6asement membrane% 4ermis

)aminin 2pidermal cell 2pidermal cell adherence

-lycosaminoglycans ibroblast 3romotes cell adherence, migration,nutrient delivery

Fi*r&#e$%i#: This adhesion protein, produced mainly by fibroblasts and macrophages, is alarge glycoprotein found in all tissues and plasma. 7ne of its key functions is as an attachmentprotein for skin cells via collagen type +. 3roduction is induced with a burn. ibronectin plays ama!or role in wound healing.

FIBRONECTIN

Ad+ere#$e F"#$%i&#

• cross linking to fibrin (and collagen causing adherence of tissues to

each

• key adherence molecule attaching epithelial and endothelial cells at cell

!unctions

• contact orientation for all cells in the healing process

Epi%+eii,%i&#

• cell migration, spreading, and orientation

• cell division

• cell re%adherence to form a layer



C+em& A%%r$%#% (Fi*r&#e$%i# Fr-me#%s)

• for fibroblasts

•

for macrophages

A large variety of 8polypeptide growth factors8 have been identified and named. Although eachhas a predominant function on a specific cell, all growth factors have a multitude of actions.2pidermal growth factor (2- is a key component for re%epithelialization of a partial%thicknessburn, and addition of 2- to the wound surface increases re%epithelialization. 1eratinocytegrowth factor (1- is an important fibroblast derived stimulant for epithelialization.acrophages are thought to be the main producers of growth factors/ however, all skin cells,includ9ing fibroblasts and keratinocytes, play an important role in secreting growth factors.The initial stimulus re0uires the onset of wound inflammation, and once activated, furtherproduction continues until the wound is healed.

7nce formed the growth factors can be rapidly deactivated by wound proteases, e.g.

collagenases, proteases, probably in an attempt to break down surface dead tissue. Surface&e"udate is a rich source of such proteases, especially the class of metalloproteases.

GROWTH FACTORS IN.OL.ED IN WOUND HEALING

MOLECULE SOURCE

ACTION

ibroblast -rowth actor 1eratinocytes, macrophages Stimulates angiogenesis

2pidermal -rowth actor 3latelets Stimulates epidermal cell proliferation

1eratinocyte -rowth actor ibroblasts Stimulates epidermal cell growth

+nterleukin % acrophages, epidermalStimulates epidermal growth andmotility

3latelet%4erived -rowth actor3latelets, macrophagesStimulates epidermal growth,

fibroblast proliferation

Transforming -rowth actor%6 ibroblasts, platelets ibrosis and increased tensile strength

FUNCTIONS OF SKIN GROWTH FACTORS

• cell proliferation: epidermis, fibroblasts, endothelial

cells

• cell migration: white cells, epithelial, endothelial,fibroblast

• structure formation: capillaries, epidermis

• cell production of tissue proteins:

collagen, matri" proteins, keratin



As can be seen, skin is a very biologically active organ. 4uplication of skin properties typicallyre0uires a 6ilayer structure, the outer layer having protection properties and the inner layerproperties stimulating tissue growth.

Temporary skin substitutes are not concerned with dermal replacement as would be the casewith a permanent skin substitute.

PROPERTIES OF SKIN SUBSTITUTE

• 6ilayer structure having properties of both an

epidermis and a dermis

• Temporary skin substitute

% 6ilayer with purpose being to protect wound andoptimize healing

• 3ermanent skin substitute

%replacement for one or both layers

SECTION II: PATHOGENESIS OF BURN IN/UR (INITIAL AND DELAED)

The damage to epidermis and dermal elements from a burn is the result of several key insultswhich can be divided also into initial and delayed insults.

KE INSULTS

• eat +nduced +n!ury

• +nflammatory ediator +n!ury

• +schemia +nduced +n!ury

A0 INITIAL IN/UR

HEAT IN/UR

The most immediate and obvious in!ury is that due to heat. 2"cess heat causes rapid proteindenaturation and cell damage. The depth of heat in!ury is dependent on the depth of heatpenetration. ;et heat (scald travels more rapidly into tissue than dry heat (flame. A surface'l% temperature of over <=* ' produces immediate cell death as well as vessel thrombosis. Thedead skin tissue on the surface is known as eschar. The depth of burn is dependent on thetemperature of the heat insult, the contact time and the medium (air%water. +n addition, thedepth of the skin layer is critical as the thinner the skin, the deeper the burn.

INFLAMMATOR MEDIATOR IN/UR (Firs% %& T+ird D1)

+t is now clear that much of the tissue damage, especially in the perfused subsurface burn, iscaused by to"ic mediators of inflammation which are activated with the burn. Although onsetof inflammation is re0uired for healing, e"cess production of mediators especially o"idants andproteases will cause more capillary endothelial and skin cell damage. 2arly release of o"idantsand increased proteolytic activity in the burn is now well recognized. ' rent " ur evidenceindicates that the inflammatory response initiated by the heat in!ury is responsible for furtherearly tissue damage, increased capillary permeability and in large part responsible for the later



wound conversion if inflammation becomes e"cessive. This now well established conceptallows the care providers to intervene early and control the further mediator in!ury therebylimiting the final in!ury. The early use of both mediator inhibitors and skin substitutes is basedon this concept. The clinician therefore has the potential of significantly modifying the degreeof in!ury.

Derm M&e$"es I#2"e#$i#- B"r# W&"#d C&s"re

M&e$"e S&"r$e L&$%i&#

'ollagen type + ibroblast 4ermis

Supports epidermal cellattachment andmigration

'ollagen type +5 2pidermal cell,fibroblasts

)amina densa

Supports epidermal cell

attachment andspreading

'ollagen type 5ibronectin

2pidermal cellsibroblasts

6asement membranezone6asement membranezone and wound surfacewith adhesion properties

)aminin 2pidermal cell 2pidermal celladherence

5itronectin Serum 3romotes cell adhesionand spreading

'lick to 2nlarge the +mage

Mid Derm B"r# I#3"r1Tre%ed 4i%+ T&pi$ A#%i*i&%i$s

INFLAMMATION INDUCED WOUND IN/UR

• 3rotease #elease +n!uring ealing Tissue and 4eactivating -rowth actors

• 7"idants #elease +n!uring 'ells, 4enaturing 3roteins, and Activating

+nflammation

• 'onsumption of ;ound 7"ygen by >eutrophils )eading to Tissue ypo"ia

http://www.burnsurgery.org/Modules/BurnWound/images/Mid_derm_topical.jpg





• +ncreasing Stimulus to ibrosis

ISCHEMIA INDUCED IN/UR

+nstant surface vascular thrombosis occurs along with cell death from the heat insult. +schemia

does not play a role in the initial surface necrosis. owever, the in!ured capillaries below thesurface, where tissue is still viable, can continue to thrombose due to initial heat andsubse0uent mediator in!ury, to endothelial cells, causing further ischemia and further tissuenecrosis. Systemic hypovolemia or local impairment in perfusion due to constricting eschar oredema will produce the same effect.

B0 DELAED IN/UR'ontinued tissue damage can occur in the burn wound after the initial heat and mediatordamage. The common element is ongoing inflammation perpetuated by surface eschar,bacterial colonization, mechanical trauma or that caused by topically applied antibacterialagents. +ncreased neutrophils, especially in e"udate on the surface, results in increaseddamage to viable tissue by both neutrophil proteases and o"idants and neutrophil

consumption of o"ygen. ;ound surface protease activity, particularly metalloprotease, hasbeen noted to be markedly increased on open burn wounds. 7f great importance is the factthat there is recent evidence that the proteolytic activity, on the normal partial thicknesshuman burn, is markedly increased. This results in a net ongoing proteolysis in the burn both

on the surface and in the matri". 6esides in!ury to new tissue formation, these proteasesdeactivate locally released growth factors, further impairing healing. This constant impedimentto wound healing will stimulate further collagen synthesis, with subse0uent increased scar,even in a mid%dermal burn. 2liminating surface e"udate is a ma!or goal of the use of occlusiondressing but active surface inflammation will persist.

owever, only a wound closure using an adherent membrane or skin substitute will decreasethe degree of surface inflammation as well as prevent surface e"udate. 4ead tissue or anyresidual e"udate needs to be removed prior to an attempt at wound closure since thisapproach will not work unless the wound has a viable tissue wound surface to allow

adherence.

CONTINUING BURN WOUND IN/UR

• ongoing inflammation caused by

% neurotic tissue% bacteria on surface% caustic topical agents% surface e"udate

• e"cess wound proteolytic activity

% activated by surface insults% continued damage to viable cells and new tissue growth% damage to wound surface and matri" denaturation of growth

factors

• e"cess o"idant release

% in!uring viable cells

MID5DERMAL BURN (Admissi&#)



'lick the +mage to 2nlarge

N&%e red dermal surface free of e"udate after initial cleaning prior to placement of topicalantibiotic silver sulfadiazine

MID5DERMAL BURN (6 D1s %er)


N&%e presence of eschar or pseudo eschar. Surface e"udate is adherent and composed of denatured protein, inflammatory cells, and rich in surface metalloproteinase activity which can

denature growth factors and increase the degree of in!ury.

SECTION III: BURN WOUND: HISTOLOGICAL ASSESSMENT (7ONES OF

IN/UR)

The burn wound is defined in terms of the evolving in!ury that occurs. Therefore the

histological description is defined in terms of specific areas of pathologic changecalled zones. Three zones have been classically described. The actual

pathophysiology is now recognized to be much more comple" than the terms usedfor defining the zones.

HISTOLOGICAL ASSESSMENT OF THE BURN WOUND

• zone of coagulation (necrosis

• zone of stasis (in!ury

• zone of hyperemia

A0 7ONE OF COAGULATION

This zone is comprised of the surface tissue necrosis of the initial burn eschar. The

surface in!ury is caused mainly by the heat or chemical insult. 7bviously this zonehas an irreversible in!ury.

http://www.burnsurgery.org/Modules/BurnWound/images/burnwound2.jpg

http://www.burnsurgery.org/Modules/BurnWound/images/mid_derm_admis.jpg



'lick to 2nlarge +mage

ull thickness burn (admission?one of coagulation is the depth of tissue necrosis which, in this patient, compress

both s layers of skin

INSERT IMAGE OF MI'ED DEPTH BURN


?one of coagulation varies markedly from center of burn which is full thickness, tothe very periphery where all necrotic tissue has been removed


?one of necrosis has been removed. ;ound bed is viable tissue although in!ured

(zone of in!ury beneath the surface

B0 7ONE OF IN/UR (STASIS)

4eep and peripheral to the zone of coagulation, there is a sizable area of tissuein!ury where cells are viable but can easily be further damaged. The terms 8stasis8 or

8ischemia8 were used because the progressive in!ury in this area was thought to bedue to capillary thrombosis from in!ured endothelium, leading to ischemia%induced

cell death. ibrin deposition, vasoconstriction, and thrombosis indeed do occur, mostlikely as a result of continued release of mediators. owever, early epithelial cell

death in this area, unrelated to blood flow, is reported to be 0uite high, leading to

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http://www.burnsurgery.org/Modules/BurnWound/images/zone_necrosis.jpg









slowing of healing. 2pithelial cells are particularly prone to environmental insultssuch as desiccation% and inflammation%induced in!ury. This zone is most prominent in

mid%to%deep%dermal burns where there is less reserve in the remaining viable cellsand less blood flow.

C0 7ONE OF HPEREMIA

3eripheral to and below the zone of stasis is the zone of hyperemia. The area is

characterized by minimal cell in!ury but with vasodilatation due to neighboringinflammation%induced mediators. 'ompleted recovery of this tissue is e"pected

unless there is an additional severe insult such as an invasive infection or profoundtissue inflammation.

7ONES OF IN/UR .ARIES WITH BURN DEPTH


INSERT IMAGE OF MID DERMAL BURN FROM PARTIAL BURN SITE


MID DERMAL BURN IMAGE OF HAND


This mid%dermal burn has larger zone of in!ury than a more superficial burn

http://www.imefinc.org/betaweb/Modules/BurnWound/images/Page23btm.jpg

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Ci$8 %+e Im-e %& E#r-e

DEEP DERMAL BACK BURN


4eep dermal back burn (with full thickness on flank 4ry white to dry red appearance

reflective of lack of surface blood flow. The zone of in!ury below the surface is at highrisk for conversion to a full thickness wound.

'lick the image to 2nlarge

IMAGE OF FULL THICKNESS BURN TO BACK


+n a full thickness burn, the zone of in!ury can readily e"tend below the skin into

subcutaneous tissues. The zone of hyperemia develops in the subeschar area beingmost evident beginning about @ days post burn.

IMAGE OF 7ONE OF HPEREMIA


http://www.burnsurgery.org/Modules/BurnWound/images/1_small1.jpg

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http://www.burnsurgery.org/Modules/BurnWound/images/1.jpg


http://www.burnsurgery.org/Modules/BurnWound/images/1_small1.jpg






?one of hyperemia is very evident in this wound e"cised at day =. The blood flow to

this fatty tissue is markedly increased over normal sub%dermis vascularity.

D0 WOUND CON.ERSION

This term refers to the dynamic process whereby the ?one of +n!ury progresses to

the ?one of Tissue >ecrosis thereby deepening the wound. 'onversion is more likelywith a mid to deep dermal in!ury because of less blood flow, longer time to healing

and increased risk of e"cess inflammation and infection. Also environmental hazardscan readily lead to conversion of an open wound.

RISK FACTORS FOR WOUND CON.ERSION

LOCAL SSTEMATIC

+mpaired 6lood low Septicemia

increased inflammation

(infection, open wound, irritantshypovolemia

surface desiccation e"cess catabolism

surface e"udate buildup chronic illness

mechanical trauma

(dressing changes, shearing%%

chemical trauma % topical agents %%

PARTIAL THICKNESS BURN

http://www.burnsurgery.org/Modules/BurnWound/images/hypermia_zone.jpg






C&#9ersi&# $# *e #&%ed &# p&s%5*"r# 5 D1


>ote: +ncreased thickness of eschar with e"udate build%up

F0 BURN EDEMA

A layer of protein%rich edema fluid develops between the eschar (zone of

coagulation and the per fused, heat%in!ured micro vessels as a result of increased(heat and mediator%induced micro vascular permeability. The leak is most prominent

in the first D%$ hours but can persist for days. +n superficial burns, the edemaactually physically separates viable and non%viable tissue, producing blisters, so that

mechanical cleaning can remove the dead tissues. +n deep second%degree and third%degree burns, the edema occurs throughout the in!ured tissue. owever, the necrotic

dermis remains physically adherent to the sub dermal space and re0uires sharpdissection (debridement to remove the dead tissue or the process of necrolysis must

occur. This process is deleterious due to the risk of infection and degree of tissueinflammation, as well as absorption of dead tissue. The degree of tissue edema is

dependent on the amount of resuscitation fluid given and the vascular pressuresperfusing the area.


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>ote: 2dema developing below the zone of coagulation is very prominent in facialburns

SECTION I.: INITIAL WOUND MANAGEMENT

;ound assessment as to size, depth and location is necessary before the correct

treatment can be initiated. Treatment is in large part based on depth.

owever, it is important to recognize which burns should be immediately referred toa burn center as only minimal initial care is needed for those patients who are to be

transferred.

The American 6urn Association (A6A has identified those in!uries that should betreated in a specialized burn center. 3atients with these burns should be treated in a

specialized burn facility after initial assessment and treatment at an appropriatehospital emergency department. Sometimes ma!or burns are directly to a burn

center from scene if the center is within a safe transport time.

Tr#s2er Cri%eri %& B"r# Ce#%er

6urn +n!uries that should be referred to a burn unit include the following:

. 3artial thickness burns greater than =E total body surface area (T6SA

$. 6urns that involve the face, hands, feet, genitalia, perineum or ma!or

!oints (see igh #isk section&. Third degree burns in any age group

F. 2lectrical burns, including lightening in!ury (see 2lectrical 6urn sectionG. 'hemical burns (see 'hemical 6urn Section

<. +nhalation in!ury

@. 'hildren with any of the above burn in!uriesD. 6urn in!ury in patients with pree"isting medical disorders that couldcomplicate management

9. Any patients with traumatic in!ury (such as fractures in which the burnin!ury poses the greatest risk of morbidity or mortality. +f the trauma

poses the greater immediate risk, the patient must be initially stabilized inthe nearest appropriate facility before being transferred to a burn unit

=.Any burned children if the hospital initially receiving the patient does nothave 0ualified personnel or e0uipment for children.

A0 SUPERFICIAL SECOND DEGREE (PARTIAL THICKNESS BURN)

This depth of burn is at low risk for infection unless grossly contaminated. +nitialcleansing should include removal of dirt, broken blisters and dead epidermis. )arge

blisters can be debrided off if using a temporary skin substitute or left intact for a

few days. 7ften blisters get larger with time and impede movement at which timethey should be removed. Topical antibiotics are not needed, especially cream based

agents such as silver sulfadiazine as these agents impede healing and are only usedif infection risk is high.



De2i#i%i&#: Second%degree burns are defined as those burns in which the entireepidermis and variable portions of the dermis layer are heat destroyed. A superficial

second%degree (partial thickness burn is characterized by heat in!ury to the upperthird of the dermis leaving a good blood supply.

C"se: Bsually hot water.

Apper#$e: The micro vessels perfusing this area are in!ured resulting in theleakage 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, wetappearing very painful wound is seen as blisters are disrupted. re0uently, the

epidermis does not lift off the dermis for $ to $F hours and what appears initially tobe a first degree is actually a second degree burn.

O"%$&me:

Hei#- R%e: 4espite loss of the entire basal layer of the epidermis, a burn of thisdepth 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. inimal to no scarring is e"pected to occur. There is a relatively small zoneof in!ury and conversion is uncommon e"cept at e"treme of age or chronically ill.ost antibiotic creams will slow the healing rate.

Tre%me#%:. 'lean, remove small blisters/ apply grease gauze and soft gauze dressing

(occlusion, absorbent dressing, changed daily.$. 7n face, perineum, apply bacitracin or neomycin ointment, applying several times

a day.&. 2"cellent alternative is the use of a synthetic adhesive dressing which seals the

wound and decreases pain.F. Bse a water%soluble topical antibiotic if the wound is grossly contaminated or if

one is unsure if the wound is superficial or deep.

G. 3rophylactic systemic antibiotics are not needed.

HOT WATER (SUPERFICIAL DERMAL BURN)

'lick to 2nlarge

TREATMENT

Transfer to 6urn center due to size, i.e., H GE T6S$ Too big to use cold dressings e"cept for a very brief

initial period& Bse topical antibodies in view of age, high risk of

conversion, infection

F Alternative: temporary skin substitute to generatewound closure

TREATMENT

'old water to control pain

$ -ently cleanse& -rease gauze, plus gauze dressing (closed techni0ue

F Antibiotic ointment is optional but a silver cream notneeded

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'lick to 2nlargeG Apply dressing to allow for mobility of hand

'lick to 2nlarge

TREATMENT

'losed dressing to hand allowing for mobility of fingers

B0 MID5PARTIAL THICKNESS BURN

+t is not necessary to distinguish a superficial from a mid%dermal burn on initialassessment as initial management is basically the same.

De2i#i%i&#: A mid second degree e"tends to the mid portion of the dermis. )ongere"posure to hot li0uids (G%= seconds or flash flames (not direct contact of flames

with skin are the most common causes.

C"se: 6rief e"posure to flames or flash e"plosion: hot water in infant or elderly.

Apper#$e: The burn surface may have blisters but is more red, less wet and onlymoderately painful.

7utcome: These burns usually heal in about two to four weeks. The e"ception is thevery young and elderly where the dermis is thin and dept of burn is invariable

deeper. owever, there is a large zone of in!ury and risk of conversion. +f a burn

heals in two weeks, then minimal to no scarring is e"pected. ;ith healing timebeyond three weeks scarring will occur, the degree being greater in dark skinnedindividuals.

Tre%me#%:

. +n patients si" years to <= years, without diabetes, chronic illness, etc.,

treatment is grease gauze and occlusive dressing. A topical antibioticointment such as bacitracin can also be used daily. The depth can be

underestimated and a switch to an antibiotic cream may be needed if thewound appears deeper on the first dressing change because of risks of

infection.

$. +n very young, and very old patients, or those with chronic illness,

contaminated wounds or perineal wounds, the traditional choice is a topicalantibiotic. irst choice is silver sulfadiazine or a silver dressing with closed

dressing techni0ue.

&. >ew Approach: (a temporary skin substitute which could increase healing and

decrease conversion.

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MID5DERMAL BURN (HOT GREASE)

TREATMENT

Transfer to 6urn 'enter due to size i.e., HGE T6S

$ Too big to use cold dressings e"cept for a very briefinitial period

& Bse topical antibiotic in view of age, high risk ofconversion, infection

F Alternative: temporary skin substitute to generatewound closure

TREATMENT

'old water to control pain$ -ently cleanse

& -rease gauze, plus gauze dressing (closed techni0ueF Antibiotic ointment is optional but a silver cream not

neededG Apply dressing to allow for mobility of hand

TREATMENT

'losed dressing to hand allowing for mobility of fingers

MID5DERMAL BURN (HOT GREASE)

'lick to 2nlarge

TREATMENT

Transfer to burn center due to location (bilateral feet

$ Temporary use of cold to control pain& 4ebride loose tissue

F -rease gauze, topical antibiotics on it, ointment orsilver dressing with closed dressing

G 'onsider temporary skin substitute

'lick to 2nlarge

Skin Substitute at day and day G

C) DEEP PARTIAL THICKNESS (DEEP SECOND DEGREE) BURN

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A deep dermal burn has not only compromised blood flow but also a layer of adhereddead dermis. The combination increases the risk for infection. A topical antibiotic is

re0uired to prevent infection until the area is e"cised and grafted. Spontaneoushealing typically leads to significant scarring. 7ften, there are patches of deep and

less deep burn together. Bnless the more superficial burn is covered with a skinsubstitute, the whole area is often treated with a topical agent. 7intments such as

6acitracin do not ade0uately penetrate the eschar of a deep burn so a silver releasedressing or cream is re0uired.

3rophylactic systemic antibiotics are not needed. 4o not apply a cream on to thewound if the patient is to be transferred immediately to a burn center as it interferes

with a wound assessment.

De2i#i%i&#: A deep partial thickness or deep second%degree burn e"tends well into

the dermal layer and fewer viable epidermal cells remain. Therefore, re%epithelialization is e"tremely slow, sometimes re0uiring months. -rafting is often

the preferred treatment for long%term function.

Apper#$e: +n these patients, blister formation does not characteristically occurbecause the dead tissue layer is sufficiently thick and adherent to underlying viabledermis 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 woundvery prone to conversion to a deeper in!ury and to infection. +t is often not possible

to distinguish a deep partial from a full thickness burn by initial appearance.re0uently the wound is a mi"ed second and third degree. 4irect contact with

flames is a common cause. ost chemical burns are also deep. The appearance of

the deep dermal burn changes dramatically over the ne"t 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 atopical 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 becausepain is usually absent in a full thickness in!ury. luid losses and the metabolic effects

of deep dermal burns are basically the same as that seen with the third degreeburn.

O"%$&me: A deep dermal burn will re0uire F%= weeks or longer to heal. Since thenew epidermis is very thin and not adhered well to dermis (no rete pegs, wound

breakdown is common. 2"cision and grafting is the preferred treatment. 4ensescarring is usually seen if the wound is allowed to heal primarily.

Tre%me#%: After initial cleaning and removal of dirt and loose dead tissue, a

topical antibiotic is re0uired. A silver based dressing or cream is the first choice.

TREATMENT

Admit to 6urn 'enter due to size, i.e. H GE T6S

$ Too big for cold dressings (avoid hypothermia& -ently clean, 4ebride loose tisue

F id dermal areas, use grease gauze, antibiotic ointment.4eeper areas, especially arm, use Silver sulfadiazine

F 4ry gauze dressing changed at least daily

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'lick to 2nlarge

'lick to 2nlarge

TREATMENT

-ently clean with mild soap$ Apply topical antibiotic ointment or cream followed by

"eroform and soft gauze dressing& 3erineum treat open

F eets criteria for 6urn 'enter due to high risk location

MID %& DEEP DERMAL BURN

'lick to 2nlarge

TREATMENT

'onsider admission because of area involved (hand$ Bse topical antibiotics& 'losed dressing which allows function

F ay re0uire grafting

D) THIRD DEGREE (FULL THICKNESS BURN)

A third degree or full thickness burn is at high risk for infection due to the presence

of dead tissues and lack of blood flow. Surgical e"cision and grafting will be needed.+nitial use of a silver dressing or cream is re0uired. 4o not apply any agent if patient

is to be immediately transferred to a burn center.

De2i#i%i&#: A full thickness or third degree burn occurs with destruction of the entireepidermis and dermis, leaving no residual epidermal cells to repopulate. This wound

will therefore not re%epithelialize and whatever area of the wound is not closed by

wound contraction will re0uire skin grafting.

Apper#$e: A characteristic initial appearance of the avascular burn tissue is a

wa"y white color. +f the burn produces char or e"tends into the fat as with prolongedcontact with a flame source, a leathery brown or black appearance can be seen along

with surface coagulation veins. 4irect e"posure with a flame is the usual cause of athird degree burn. owever, contact with hot li0uids such as hot grease, tar or

caustic chemicals will also produce a full thickness burn. The burn wound is alsopainless and has a coarse non%pliable te"ture to touch. A ma!or difficulty is

distinguishing a deep dermal from a full thickness (third degree burn that e"tends !ust through the dermis. This burn is termed an indeterminate burn.

O"%$&me: 2"cept for a very small wound, e.g. $"$ inches, the burn wound willre0uire e"cision and a skin graft.

Tre%me#%:

. -entle wash, removing loose tissue, char.








$. 2schar penetrating antibodies, silver cream or dressing first choice, usingclosed dressing.

&. 2arly surgical e"cision and grafting.

F. 3rophylactic parenteral antibiotics are not indicated.

DEEP BURN TO KNEE

'lick to 2nlarge

TREATMENT

'lean. Apply topical antibiotic$ 'lean dry dressing applied

& 3lan early e"cision and grafting

DEEP BURN TO LEGS

'lick to 2nlarge

TREATMENT

Admit to burn center due to size and depth$ +f circumferential, consider escharotomy prior to transfer

& -ently cleanse and debrideF Apply SS4 (in view of depth plus gauze dressing (closed

G 2arly e"cision and grafting

>ote the white patches are the deep burn surrounded by a id%dermal in!ury

SUPERFICIAL DERMAL BURN (STEAM)

'lick to 2nlarge

'onsider transfer to burn center because of hand

wound$ Assess distal perfusion if circumferential

& -entle cleansing

F Apply silver cream or dressing

E) CHEMICAL BURNS









'ommon strong acids and alkali used in industry cause the ma!ority of in!uries.7ther less common agents are described in the table. The burn in!ury is typically

caused by coagulation necrosis of tissue rather than by direct heat production. Thedegree of tissue in!ury is dependent on the to"icity of the chemical and the e"posure

time. The burn wound is characteristically gray to brown in color due to thechemically denatured protein. 3ersistent burning pain is commonly described as the

burning in process continuous as long as the chemical is in contact with the skin.6urns are invariably deeper than first appearance indicating ongoing in!ury. Also thedegree of tissue damage takes longer to declare itself such that after & to $F hours

the wound is invariably deeper. The specific nature of the chemical in!ury, itIs

characteristics, diagnosis and treatment are described.

'lick to 2nlarge

>ote the brownish%gray appearance characteristic

of coagulation necrosis. ;ounds usually deeper in

first $F hours.

W&"#d M#-eme#%

+nitial management of the chemical burn has a ma!or impact on outcome$ 'ontinuous water irrigation of the area should be initiatedJ

% use of showers in the workplace is optimum% use tepid water if possible, to avoid long e"posure to cold or hot water

% irrigation for strong acid or alkali e"posure is &=%<= minutes

% continuous irrigation if eye is e"posed to chemicals

% do not attempt to neutralize acids with alkali or vice versa, !ust use copiouswater

& Solid chemicals should be brushed off first prior to irrigation using safetygloves

F 'onsider transferG ;ill need topical antibiotic as burn is invariably deep

SECTION .: DAIL CARE OF THE BURN WOUND

The topics in this chapter include:A0 Ge#er pri#$ipes &2 W&"#d Cre

B0 S"per2i$i %& mid5derm *"r#s

C0 Deep *"r#sD0 W&"#d $&#9ersi&#

A0 GENERAL PRINCIPLES OF WOUND CARE

There are a number of general rules regarding burn care that must be followed:

First , cardiopulmonary monitoring should continue during burn care. The addition ofmedications for wound care itself can only lead to a potential for further instability.



Second , invasive catheters, such as vascular and urethral, must not become wet atthe skin site or be submerged in water. These catheters are at high risk for being a

source of systemic infection.

Third , the patient must not be allowed to have a significant heat loss. 7verheadheaters, warm water, and the se0uential management of the wounds, rather than

total patient e"posure, are methods to avoid heat loss.

Fourth, the risks of bacterial cross%contamination must be controlled. #isks relatedto transmission from personnel are minimized by the wearing of caps, mask, gloves,

and a gown. Transmission from a dirty wound to a clean wound can be minimized bye"posing and cleaning these areas separately. 3referably, the less infected areas

should be done first and closed before approaching dirtier areas.

The fifth principle is that ade0uate stress management, analgesia and sedation,

should be initiated before initiation of burn care. +t is much easier to control painand an"iety by pretreatment than it is to treat once it develops. Antipyretics given

before burn care attenuate the fever seen after wound manipulation. 3retreatment

of the dressing change with an antipyretic such as +buprofen, is indicated in patientswho demonstrate a marked temperature spike, i.e., H=&K after wound care.

The sixth principle is that motion should not be impaired (e"ception: a new graft.

The patient needs to maintain !oint motion and muscle activity to avoid stiffness andatrophy.

GENERAL PRINCIPLES OF DAIL CARE

+f conversion is going to occur, it is typically several days

(sometimes weeks post%burn

• 'ontinue monitoring if indicated

• Avoid hypothermia

% warm room

% warm water

% do not e"pose entire body at once

• Avoid 'ross%'ontamination

% ;ear caps, masks, gown, gloves wash hands before

and after

% 2"pose, clean, and rewrap less infected areas first

% )ook for sources of bacteria in e0uipment used

• Assure Ade0uate 'ontrol of 3ain, An"iety, ever

% 3re%indication with narcotics and short%acting sedative



% Bse intravenous route

% 'onsider antipyretic pre%treatment pre%burn care

• ;ound 4ressing

% Bse comfortable but no immobilizing dressing, as muscle

activity is importantL (e"ception: new grafts

B0 SUPERFICIAL TO MID5DERMAL BURNS

)oose epidermis and remaining blisters are debrided from the wound surface. Areas

such as the face and ears are then treated open, usually with an ointment such as



bacitracin to maintain wound moisture as well as control the predominantly gram%positive bacteria. The open areas are usually gently washed daily with a dilute

chlorhe"idine solution to remove crust and surface e"udates. Areas such as thehands, upper and lower e"tremities, and trunk can be treated with a grease gauze

impregnated with antibiotic ointment, usually 6acitracin. The grease gauze iscovered with several layers of dry absorbant gauze. +f the grease gauze appears well

adhered to the superficial wound with no underlying e"udates, the gauze does notneed to be changed, as is the case with a donor site dressing. +f some e"udates ispresent, the dressing should be removed, the wound gently washed with dilute soap

and the dressing reapplied. 2"ceptions would be the dirty wound that has not been

totally cleaned of initial dirt and debris or the perineal or buttock wound where asilver based topical antibiotic is usually re0uired.

The wound can also be managed with a temporary skin substitute, such as biobrane,once wound adherence has occurred. 7nly the outer layer of gauze needs to be

changed once wound adherence has occurred, usually once a day when it becomessaturated with plasma from the wound surface.

!0 MANAGING THE DRESSING

• +nspect daily

• +f gauze adherent and no e"udates, simply change outer dry gauze

• 'hange dressing, wash surface and reapply if e"udates present

• Bse topical antibiotic if infection considered

60 AREAS TREATED OPEN WITH BACITRACIN

• #eapply ointment two to three times daily

• -ently wash off crusts, e"udates, especially on face and neck



;0 AREAS CO.ERED WITH TEMPORAR SKIN SUBSTITUTES

• 'hange outer dry gauze daily to remove collected e"udates

•

#oll out small pockets of e"udates from beneath substitute• 'an leave open without dressing once drainage has ceased if substitute well

adhered

• #emove skin substitute if e"udate e"tensive or if nonadherent with topical

agent and change to grease gauze method

• #emove once wound reepithelialized

The mid%dermal burn is at higher risk of infection or conversion compared to the moresuperficial burn. Skin substitutes appear to provide better wound protection then

grease gauze but they are also more e"pensive.



C0 DEEP BURNS

+nitial non%surgical management is debridement of loose dead tissue and application

of a silver based cream or dressing. +f using the cream silver sulfadiazine thewounds need to be gentle washed daily with removal of old cream and reapplication

of new cream followed by a secondary dressing.

+f using a typical silver dressing, with a constant silver release for &%@ days, an outer

secondary dressing change is all that is re0uired. Some silver dressings re0uireapplication of water to release more silver but the actual silver dressing can remain

in place for &%@ days.

2arly surgical e"cision and skin closure is recommended.



4eep burn cleaned4ressed with topical antibiotic followed by gauzeto close The wound and maintain warmth

5iable tissue should not be left e"posed unless it is to be occluded by a graft or a

skin substitute because desiccation of the tissue with reformation of eschar is likelyto occur. This daily care procedure can be performed with home care (if minor at

the bedside or on a slant board in a hydrotherapy tank, avoiding total bodyimmersion. The bedside approach is particularly useful for the critically ill patient.

Silver is released from a silver sulfadiazine cream only for a matter of hours.

Therefore, the cream needs to be reapplied at least once a day.



Silver is released from a silver sulfadiazine cream only for a matter of hours.Therefore, the cream needs to be reapplied at least once a day

le"net is helpful to hold dressings on,thereby avoiding circumferential

wrapping

Silver sulfadiazine is removed and replaced

twice a day

Pse"d& es$+r is # d+ere#% s"r2$e 1er &2 e<"d%es which adheres to thewound typically in deeper burns with the use of topical antibiotic creams. This film is

hard to get off and also hard to distinguish from the process of woundconversion.3seudo eschar present on wound surface



Silver release dressings have the advantage of a steady silver release for days sothere are fewer dressing changes needed and a pseudoeschar typically doesnIt

develop.



Although infection is not particularly common in the first several days post burn(unless the burn was heavily contaminated or inade0uately cleaned, the wound

bacterial flora should be monitored with surface cultures. 3ositive cultures do notmean infection. +nfection is usually diagnosed by changes in the wound, systemicsigns and biopsy. The information on the organisms however will assist in the

assessment of the ade0uacy of the topical agent being used as well as provideepidemiologic information, especially important in controlling resistant hospital%based

organisms.

W+1 is S"r-er1 Pre2erred 2&r Deep Derm B"r#s=



3rimary healing of a deep dermal burn often leads to hypertrophic scar or skin

breakdown, especially if the burn takes over < weeks to heal.

D0 WOUND CON.ERSION

This term refers to the dynamic process whereby the ?one of +n!ury progresses tothe ?one of Tissue >ecrosis thereby deepening the wound. 'onversion is more likely

with a mid to deep dermal in!ury because of less blood flow, longer time to healingand increased risk of e"cess inflammation and infection. Also environmental hazards

can readily lead to conversion of an open wound. This process is in large partpreventable with newer methods of early wound closure and better control of wound

inflammation using slow release silver dressings or skin substitutes.

#ISK FACTORS FOR WOUND CON.ERSION

LOCAL SSTEMIC


+ncreased inflammation (+nfection, openwound, irritants

ypovolemia

Surface desiccation 2"cess catabolism



Surface e"udates buildup 'hronic illness

echanical trauma (dressing changes,shearing

4iabetes

'hemical trauma Mtopical agents Steroid Bse

+f conversion is going to occur, it is typically several days (sometimes weeks post%

burn



SECTION .I: CARE OF BURNS DUE TO HIGH RISK AREAS

Some 6urns are considered ma!or burns because of location, and the risk ofsignificant morbidity. These areas which include face, hands, feet and perineumre0uire special care preferably in a burn center. unction is so important in hands

and feet that optimum care is re0uired. acial burns are at high risk for ma!orcosmetic deformity if not managed correctly. 3erineal burns are difficult to manage

and at high risk for infection.

6urn depth is defined based on the depth of coagulation necrosis into epidermis and

dermis (recognizing that the anatomical depth may change with wound conversion.

CAUSE

DEPTH

DEGREE APPEARANCE PAIN

ot )i0uids

% Shorte"posure

% )ong e"posure

Superficialdermal

4eep dermal

web, pink, blisterswet, dark red

severeminimal

lames

% lash e"posure% 4irect contact

partial thickness

full thickness

severe

minimal

wet, pink blisters

dry, white, wa"yor



brown, black

leathery

'hemicalsusually full

thicknesssevere

light brown to light

gray

A0 FACE

Superficial burns of the face are best managed with a gentle wash or soak with mild

soap two to three times daily. ;ash is followed by application of a thin layer ofbacitracin to keep the wound from drying as well as to maintain control of the

predominantly gram%positive organisms on the face. Skin substitutes can also beused. 4eeper burns will re0uire a topical antibiotic cream with better eschar

penetration. Silver sulfadiazine or silver dressing is the first choice, to be reappliedafter a gentle wash two to three times daily. This agent can be applied without

dressings or on a layer of fine mesh gauze which prevents the cream from running

into the eyes, nares, and mouth.

B0 EES

6urns to the eyes must always be considered with a facial burn. Superficial

corneal burns should be managed like any corneal abrasion. 7phthalmicantibiotic ointment applied three to four times daily is indicated. An eye patch



is then applied. Artificial tears every several hours will be re0uired if the tearducts are involved. 6urns to the eyelids are managed in a similar fashion. As

the lids retract with healing, a patch is often re0uired at night along with thelubricant to avoid corneal drying. Tarsorrhaphy may be re0uired with deep

burns.

C0 EARS

Superficial burns to the ears can be managed like those to the face. owever,

e"ternal pressure should not be applied to the in!ured heli". The cartilage isalready poorly vascularized and any compression will potentate further in!ury.

>o pillows or any e"ternal pressure are allowed. +n addition, the topical

agent, silver sulfadiazine or mafenide, must be applied multiple times a day,especially if any cartilage is e"posed. afenide is the agent of choice for deep

burns with a thick eschar. 'hondritis is a ma!or complication that re0uires an

e"tensive (several weeks course of systemic antibodies. 'hondritisinvariably leads to loss of cartilage and permanent deformity. 3seudomonas

is the most common pathogen.

D0 HANDS



2scharotomies on the hand and fingers must be considered with deepcircumferential burn. Superficial burns of the hands can be effectively

managed using Neroform gauze with a thin layer of bacitracin followed by asoft gauze dressing. Temporary skin substitutes are also ideal and markedly

decrease pain and improve motion. Topical antibiotics are necessary fordeeper burns. ingers should be wrapped separately to avoid any

impairment. ands must be elevated for the first $F to FD hours to minimizeedema. and splints to maintain position of function are advantageous for allburns, especially if pain is limiting motion. otion, however, must be strongly

encouraged. or deeper second and third degree burns, hand splints are

absolutely necessary to avoid permanent loss of tendon function anddevelopment of fle"ion contractures. owever, active and passive range of

motion e"ercises should begin as soon as possible after in!ury, during whichtime splints are removed.

itted hand splint2arly scar in web of thumb: needscontinued hand therapy

E0 FEET

6urned feet must also be elevated initially. A compression wrap over a bulkydressing can be used when walking. 6lood supply to the feet is not as good



as that to face and hands, and therefore, better topical antibiotic coverage,e.g. silver antibiotic, is usually needed e"cept in the superficial burn. At least

once a day cleaning and reapplication of the topical agent is needed with adeep burn. 6ecause of the difficulty of function and of self%cleaning, foot

burns of any significance should be admitted at least for the initial $F to FDhours until home care can be arranged.

F0 PERINEUM

Superficial burns can be managed open with an antibiotic grease%based

ointment that has a broad%spectrum coverage, such as >eosporin.ospitalization is usually necessary, at least initially, for observation of urinary

obstruction secondary to edema. 4eeper burns by definition re0uireadmission with two to three times daily application of topical antibiotic cream,

usually silver sulfadiazine. 7pen techni0ue or closed dressing, with a loosediaper dressing, can be used.



SECTION .II: SURGICAL E'CISION > GRAFTING MANAGEMENT

4eep partial thickness burns fit into this category as healing takes longer than &

weeks and hypertrophic scars or scar breakdown often is the result of primaryhealing. 2arly e"cision and grafting should be considered as a treatment option for

all burns that will not heal by primary intention within & weeks. ull%thickness burnswill by definition re0uire grafting unless smaller than & to F cm in diameter. The

more rapidly the wound is closed with skin grafts, the better. 6urns, less than &=Eof total body surface can be, at least theoretically, rapidly closed because ade0uate

donor sites are available. )arger burns will be more difficult, if not impossible, tocompletely graft early. +nitial coverage is often accomplished using available skin

along with temporary skin substitute to cover ungrafted areas until skin is available.The other option is the use of a permanent skin substitute. 4eep partial thickness

burns are also difficult to assess clearly as to time of healing. 'onsiderable !udgment and assessment skills are therefore essential for this approach to yield

optimal results.

The topics to be discussed in this chapter include both the indications and the

general and specific techni0ues used:

A. -eneral 3rinciples of 2arly 2"cision

6. Types of Surgical 2"cision

Tangential (Se0uential 2"cision

2"cision to ascia

'. 7btaining Skin -rafts (4onor Sites

4. -rafting and 4ressing the ;ound

2. ;ound 'onversion

A0 GENERAL PRINCIPLES OF EARL E'CISION



There are two key !udgments that are re0uired:

The first judgment is determination of cardiopulmonary stability and operativerisk. The patient should be reasonably stable.

The second judgment is a determination as to potential morbidity of the wound

itself if not rapidly removed. This !udgment takes into consideration wound depth,functional loss, and the risk of the inflammatory wound on the host. A key

component of this assessment is defining wound depth, i.e., what will heal and whatwill not heal.

The following facts which can aid in decision making:

• +nfants and the elderly tolerate burn inflammation and infection

poorly so early burn removal is preferred.

• 6urns in infants and the elderly are usually deeper than initially

perceived.

• 6urns can get deeper over the first several days as a result of

necrosis of ischemic areas. (conversion

• 6urns caused by direct contact with flames, hot grease, chemicals,

or electricity are invariably deeper than first appearances would

suggest.

• 6urns on the low back, scalp, palms, and soles usually have

sufficient remaining dermis to allow primary healing in & to G weeks.

• )arge full%thickness burns are life%threatening until closed.

GENERAL PRINCIPLES

There are a number of general principles that apply to all methods of e"cision and

grafting:

The first principle is that the patient must be thermodynamically stable before

considering e"cision. 3ulmonary function can be impaired, but the patient must

be able to be safely moved to the operating room and back.

The second principle is the potential for significant blood loss must berecognized and ade0uate amounts of red cells, plasma, and platelets, if indicated,

are available before starting an e"cision procedure.

The third principle is that ma!or pulmonary abnormalities in the burn patient

can become very problematic with general anesthesia if preplanned safeguardsare not initiated. Stiff lungs and increased dead space often re0uire special

mechanical ventilatory needs, which must be prepared for and met in theoperating room.



The fourth principle is that hypothermia must be avoided during surgery. Theoperating room and fluids used must be warmed to avoid severe hypothermia, a

ma!or hazard. The operating room temperature should be maintained betweenD=O and DGO to minimize hypothermia and postoperative problems.

The fifth principle is that the stress induced by anesthesia and surgery must be

limited to that which the patient can safely tolerate. The time in the operatingroom should be carefully controlled, again to avoid postoperative complications.A $%& hr operative period is best for a large burn. +t is better to do several

moderate operative procedures or $ days apart than one massive procedure.The e"ception is children, i.e., older than G years old, who tolerate large e"cision

procedures much better than adults. A reasonable operating time limit, includinganesthesia, is $%& hours. A shorter period is indicated for elderly or compromised

patients. Total blood loss per procedure should be restricted to avoiddevelopment of a coagulopathy.

The sixth principle is that blood loss should be replaced with blood productsrather than crystalloid in the ma!or burn patient. Typically the patient already

has massive edema in the first week and red cell production will be markedlydepressed until the wound is healed, especially in a massive burn. +t is therefore

unrealistic to assume that red blood cell mass will 0uickly return to baseline byincreased production.

TIMING OF E'CISION

Timing of e"cision relative to changes in the wound itself is crucial to minimize

risks. 6lood flow to the burn wound is markedly increased beginning about Fdays after in!ury and peaking between G and F days. The increasing blood flow,

which parallels the development of wound inflammation, is present in the viabletissue beneath the eschar. A significant increase in blood loss should be e"pected

with wound e"cisions after G to < days. 'lotting abnormalities at this stage canalso be a ma!or problem.

+n addition, colonization of the wound develops during the first week andmanipulation of the colonized or infected wound runs an increasing risk of

bacteremia. 6ecause of these facts, the size of the planned e"cision must bedetermined based on a clear understanding of increasing risks of blood loss and

bacteremias.

GENERAL PRINCIPLES FOR BURN E'CISION AND GRAFTING

The patient must be thermodynamically stable before considering e"cision

The potential for significant blood loss must be recognized

3ulmonary problems clearly present P re0uire a plan of management in the 7#

ypothermia must be avoided during surgery

The stress induced by anesthesia and surgery must be limited to that which the

patient can safely tolerate



Significant blood loss in a ma!or burn should be replaced with blood products

B0 TPES OF SURGICAL E'CISION

There are two types of surgical procedures to remove the eschar: tangential e"cisionand e"cision to fascia. There are also several types of grafts and dressing

techni0ues, which will be described.

!0 T#-e#%i (Se?"e#%i) E<$isi&#

The principle is to e"cise the wound in thin layers using a blade held at a very

acute angle with the skin surface. The ob!ective is to remove only the

nonviable tissue, sparing, in particular, as much viable dermis as possible inthe case of the deep dermal burn. The dermis contains the elasticity in skin.

+n addition, the viable dermal surface is an e"cellent base for grafting. at isa less attractive bed for skin grafting because of decreased vascularity as well

as the difficulty of determining viable fat on inspection.

The e"cision is performed with a hand%held dermatone using guards ofvariable thickness (=.==D to =.=$= inch to help control depth of e"cision. Aback and forth motion is utilized for cutting with very little forward force.

'ontrol of depth is based not only on the gauge of the guard, but also on theangle of the blade in relation to the surface. A sharp blade is needed for this

approach, and fre0uent blade changes are re0uired. A -oulian or a ;atsonknife is used, depending on the area being e"cised. The ;atson, being larger,

is used for larger flatter surfaces, whereas the -oulian is used over curvilinearareas, e.g., over bony prominences or on fingers, toes, neck, and

occasionally, face. 2"cision over bony surfaces can be aided by in!ecting salebeneath the eschar to flatten and push the wound surface away from the

bone. The endpoint of e"cision is brisk punctuate bleeding and a completely

viable wound base. 5iable dermis is white and shiny in color. 7ne or twolarge bleeders can make the wound look red, so careful inspection and

considerable e"perience is needed to assess the ade0uacy of the wound bed.+n!ured fat is particularly difficult to diagnose. Any fat that is dark yellowish%

brown in color should be removed.



ealthy fat is light yellowish in color and shiny. +t is easy to under%e"cise,leaving a poor bed for graft take. +n addition, it is easy to e"cise too much

tissue, thereby removing potentially viable dermis.

7ver%e"cision would be particularly detrimental if done on hands, neck orface, or over !oint surfaces. +t is very difficult to detect accurately the proper

endpoint of this techni0ue using tourni0uets to control bleeding and thereforetourni0uets are usually not used.

The procedure itself should be performed by e"cising small burn areas at a

time controlling hemostasis in each e"cised area before continuing on to otherareas. Bsually, a ma"imum of D to $GE of total body surface can be

e"cised at one time. >ormally, this much is only feasibly e"cised on the firstoperation if done to & days postburn. )ater e"cisions are usually limited to

9E total body surface or less because of blood loss. 'autery is typically thefirst approach to bleeding. The smaller punctuate bleeding from dermal

vessels can often be stopped by application of the skin graft. The e"posedcollagen on the dermal surface of the graft stimulates hemostasis.

7ther approaches to hemostasis include application of topical thrombin or asolution of Q=,=== epinephrine. +f epinephrine or thrombin is used, one

must be assured of the ade0uacy of the wound bed before their application,since bleeding ceases, making a subse0uent assessment very difficult.

icrocrystalline collagen can also be applied, but a coagulum is left on the

wound surface, which should be removed before graft placement.

7nce the wound is e"cised, the wound bed must be closed. Bsually,immediate application of skin grafts is performed. Sheet or mesh grafts can

be used. Sheet grafts result in a better cosmetic effect but there is anincreased risk of bleeding beneath the graft, impeding take while meshing

with minimal opening of the mesh allows for drainage of blood or plasma.;ider meshing is used to cover larger surface areas when there is a shortage

of donor skin. A functional skin will result with a wider mesh but a cosmeticproblem is inevitable. The mesh, used with tangential e"cision, is usually no

greater than .G to to avoid any e"cessive e"posure of viable tissue,especially fat, which can then desiccate and form new eschar. A temporary

skin (allograft or synthetic substitute can be applied over the graft if a wider



mesh, e.g. &: is used to protect the interstices. A skin substitute can also beused on an area e"cised and not grafted. Any neighboring burn must

continue to be treated with an antibacterial agent.



esh graft appearance will diminish withtime but will not disappear

The advantages and disadvantages of tangential approach are listed:

TANGENTIAL E'CISIONAd9#%-es:

7ptimal functional and cosmetic result

'an be performed rapidly

Disd9#%-es:

)arge blood loss

4ifficult endpoint to define

2"cise to e"cise too much or too little

60 E'CISION TO FASCIA

2"cision of the burn wound to fascia is used in cases of very large full%thickness burns or with very deep burns that e"tend well into the fat or

underlying tissues. This approach is used in the large burn with limited donorsfor the following reasons.

First , this endpoint of e"cision is well defined and graft take is always

e"cellent. Therefore less e"perience is re0uired to define an ade0uatelye"cised wound surface.

Second, wider meshed skin grafts can be used as the fascia appears to beless vulnerable to desiccation than fat or dermis especially when covered with

a skin substitute.

Third, a large e"cision, when performed early, can be done in most body

areas (e"ception being the face and perineum with only modest blood loss.



+n the case of the very deep small wound, e"cision to this depth or deeper isre0uired because of the e"tent of the in!ury itself.

2"cision is performed using a combination of sharp dissection, constant

tension, and electric cautery. The vessels encountered at the fascial plane arefewer in number and larger in size than encountered in a tangential e"cision

and easier to control with cautery and ligatures. +f performed in the firstseveral days, the edema fluid separates fascia from overlying subcutaneoustissue, making e"cision very easy. The ma!or bleeding occurs from the wound

edge.

This bleeding can often be better controlled and the e"posure of fat on the

wound edge minimized if the skin edge is sutured to the fascia. This form ofmarsupialization can also decrease the total size of the wound as the edges

are pulled toward the middle. Total e"cision per operation should be limitedto D to $=E of total body surface. Tourni0uets are also applicable in cases

of e"tremity e"cision, especially if delayed for several days, because theendpoint is an anatomic one rather than punctuate bleeding.

ascial e"cision becomes less feasible with time after burn in!ury. +nitially the burnedema layer helps separate the fascial plane from the fat. The reabsorption of edema

over G to @ days and the increase in wound blood flow increases the difficulty andrisks. The separation of the fascial plane becomes more difficult. 6eyond @ days

when the eschar is heavily colonized and the subeschar space is infected, fasciale"cision can be very dangerous. 'omplications of bleeding and septicemia will be

much higher with time postburn. +t is important to remember that this procedure is



usually performed on large burns, and therefore patients tend to be at greater risk

for perioperative problems.

Timing of fascial incision is very important: the earlier the

better.

There are a number of disadvantages to this approach that must be

outweighed by the advantages. The ma!or disadvantage is a potentialimpairment in long%term function to the e"cised and grafted areas, especially

e"tremities. 4istal edema becomes a problem because of removal ofsuperficial veins and lymphatics. owever, in many cases they have already

been heat destroyed. +n addition, removal of cutaneous nerves will lead toimpaired sensation. Sensation on any skin graft is decreased compared with

normal skin. There is, also, a significant risk of in!ury to other superficialnerves that have motor function. +n addition, e"posure of the relatively

avascular fascia near !oints along with potential e"posure of tendons will

result in a non%graftable surface that is now prone to desiccation. 'overageof this area becomes a ma!or problem. The second problem of fasciale"cision is cosmetic, since a rim of tissue remains at the edge of the e"cised

and non%e"cised tissue producing a step up defect, especially on thee"tremities. Tapering of the e"cision at its endpoints can help decrease this

problem. The cosmetic defect is persistent, particularly in the obese patient.re0uently, a combination of fascial and tangential e"cision is used in the

patient to ma"imize benefits of early wound closure and minimize

complications.

7nce e"cised, the fascial surface must be covered. Since donor sites are

usually limited, a wider meshed graft is often used. Skin substitutes are veryeffective in occluding the fascial wound until the mesh fills in (= to F days

or until new donor sites become available with re%healing (= to F days.

Ad9#%-es

'an be done rapidly with much less blood loss

;ell%defined endpoint of e"cision

'an be done using tourni0uets

'an use wide mesh grafts

Disd9#%-es

#isk of in!ury to nerves

#isk of increasing distal edema

#isk of e"posing !oints, tendons



'osmetic defect



C0 OBTAINING SKIN GRAFTS (DONOR SITES)

4onor sites are obtained wherever unburned skin is available (e"ception: face,

hands. 3referred areas are thighs, buttocks, and abdomen. owever, large burnshave limited donors and other areas need to be used, e.g. arms, lower legs, back

and soles of feet. The scalp is an e"cellent donor site when needed. As opposed tomost other areas that re0uire F days or more to heal sufficiently before reuse, scalp

heals in @ days and can be re%harvested & to F times. The only area in which colormatch between donor and recipient site is of significant concern is the face and

neck. Bpper chest and upper back are a good color match for face and neck. Split%thickness skin can be removed using a variety of dermatomes. Air pressure driven

or electric powered dermatomes are the most common. Small free hand skin graftscan also be obtained using the -oulian knife used for tangential e"cision. +n!ection

of saline beneath the dermis will greatly assist the removal of split%thickness skin

from areas around changes in contour or from the scalp.

-raft thickness is dependent on the size of the burn and the potential need for re%harvesting the same donor site, the area to be grafted, and the donor site to be

used. The ideal thickness for most areas to be grafted is =.=$ inch for the adult.Slightly thicker grafts (=.=$ to =.=F inch would be ideal for face, neck, hands and

over !oints because less scarring and more pliability would be anticipated for athicker graft that contains more dermis. A donor site =.=$ inch will re0uire

appro"imately = to F days to re%epithelialize and about $ days or longer before itcan be used again. A second use of this area will be limited because of concern over

producing a full%thickness in!ury. A donor site where a thick graft is obtained usuallycannot be used again. A thinner donor site, =.== inch, will often be ready for re%

use in F days where another graft of =.=%inch thickness can be obtained. Sincefewer epidermal cells are present with a reuse donor, a less wide mesh is usually

used. Skin graft thickness is also dependent on the thickness of the donor skin.'hildren and elderly patients have a thinner dermis and therefore a thinner graft,

i.e., =.==D to =.== inch, is usually obtained to avoid ma!or morbidity at the donorsite. +n addition, areas such as inner arms and legs have thinner skin, and

ad!ustments need to be made in the dermatome when obtaining skin grafts fromthese areas.

OBTAINING DONOR SITESL&$%i&#

6est: thigh, buttocks

>e"t: upper arms, scalp, back, abdomen

>e"t: lower legs, arms, chest

T+i$8#ess: (%+&"s#ds &2 i#$+)

. oderate burn, most areas (=.= to =.=$

$. ands, neck, !oint areas (=.=$ to =.=F

&. assive burn (=.==D%=.==



F. 2lderly, child (=.==D to =.==

G. A reuse site use (=.==D to =.==Hem&s%sis

. 3ressure

$. 2arly application of dressing

&. 'an use topical thrombin or epinephrine

to =,=== dilution

4epth is usually the upper third of the dermis which includes mainly papillary

dermis, leaving sufficient number of epidermal cells, in skin appendages, toheal.

6leeding from a donor site is similar in amount to that of tangential e"cision

of a fresh, deep dermal burn, i.e., diffuse, punctuate, and profuse. 6leedingfrom a re%use donor is even more profuse and again an analogy can be made

with tangential e"cision of a hyperemic wound. 6ecause blood loss will be

substantial, hemostasis at the donor site should be controlled before pursuing

wound e"cision. The ideal situation is the use of two teams, one whose role isto obtain skin grafts and maintain hemostasis. 3ressure followed byapplication of fine mesh gauze or Neroform gauze, again followed by pressure

( to $ minutes, is usually ade0uate to control bleeding. As with the e"cised

wound, topical thrombin or dilute epinephrine solution can also be used.

A number of dressings can be used on donor sites. ine mesh or grease

gauze is porous and allows the initial bleeding to e"it from the wound surface



as well as the e"it of blood and plasma that leak during the postoperativeperiod. -auze, however, is not fle"ible and is not sufficiently occlusive to

control pain. +n fact, ambulation or motion is very difficult with donor sitescovered with these dressings. +n addition, there are minimal to no

antibacterial properties, increasing the potential for infection if nearly openburn wounds are present. Application of moist antibiotic%moistened gauze

over the "eroform for $F to FD hours assists in removal of blood beneath thedressing as well as provides antibacterial protection. 4ilute bacitracin,neomycin, or mafenide solutions have been used with success. After $ to &

days, the donor site should be left e"posed and the dressing allowed to dry.

The e"ception would be if an open wound is ad!acent, in which case theantibacterial solution should continue or the wound should be occluded from

nearby burn. -auze dressings are applied over the donor site covered by anouter moderate compression dressing to maintain hemostasis. The outer

dressings are changed until the wound can be e"posed to air. -rease gauzeimpregnated with antibacterial ointment, e.g., scarlet red, provides some

protection against infection, but it also impairs removal of clot or e"udatesbecause of the multiple layers of gauze used. An effective alternative

dressing is a skin substitute, such as biobrane or polyurethane dressing such

as 7psito. The skin substitute will provide a seal, thereby eliminating the riskof e"ternal infection as well as diminishing pain. 4isadvantages, however, arethat e"cellent hemostasis must be obtained before application. +n addition,

these dressings have no antibacterial properties. This is less of a problemwith biobrane if adherence to the wound is good. 4ry dressings and

moderate compression maintain hemostasis while allowing optimum woundadherence over the first $F to FD hours. The inner donor site dressing is

gradually removed at = to F days with re%epithelialization.

DONOR SITE DRESSING

Grese G",e Dressi#-

• #easonable hemostasis needed

• Apply grease gauze

• Apply dry gauze followed by compression

• 'hange outer dressing using same techni0ue for $F to FD hours

• )eave e"posed after $F to FD hrs (e"ception: if open wound is

ad!acentS8i# S"*s%i%"%e Dressi#-

• 'omplete hemostasis needed

• Apply dressing under some tension

• Apply dry gauze followed by compression for $F to FD hours

• )eave in place until wound heals

• #emove if purulent e"udates develops beneath dressing



Fres+ D&#&r Si%e

-rease gauze allowed to dry

D&#&r Si%e C&9ered 4i%+ Bi&&-i$

The dermal matri" 7AS+SR is covering this donor site which

stimulates healing

A number of complications can occur in the donor site. +nfection can occur,which can result in deepening and possibly conversion of the wound to full

thickness. +nfection is usually evident from surrounding cellulites. Systemicantibiotics as well as topical antibiotics are re0uired for treatment. 6listering

and continued breakdown are also seen, especially with deep donors ordonors in small children or the elderly. ealing usually occurs in time. yper%

or hypo%pigmentation may persist for long periods of time and may bepermanent. ypertrophic scarring is seen, especially in dark%skinned persons

and with deep donor sites.



COMPLICATIONS

. +nfection

$. 4elayed healing, blistering

&. Abnormal pigment deposition

F. ypertrophic scarring

De1ed D&#&r Si%e Hei#-

Superficial infection resulted in breakdown and delayedhealing

D0 GRAFTING AND DRESSING THE WOUND

. S8i# Gr2% P$eme#%

+t is best to place grafts on the wound at the time of e"cision. Since the graft itself

controls hemostasis and protects the wound, it makes little sense to wait $F to FDhours until bleeding has stopped. This approach re0uires an additional procedure and

there is a significant risk of the wound bed becoming desiccated or reinfected.

2ven if skin meshing is not going to be performed, a number of small slits can be

placed along the skin lines to allow efflu" of any blood or plasma that collects. -rafts

are best placed longitudinally in most areas and transversely across the !oints tomatch the normal skin lines and forces during movement. +t is better to have aslight overlap of skin on the wound rather than to leave e"cised wound uncovered.

ypertrophic scarring will result and most evident at the edges of the graft,especially if a ridge of open wound is left to heal primarily. +t is important to avoid

the edges of the graft from rolling up, thereby preventing skin adherence in thisarea. Ad!acent grafts should be carefully appro"imated. Sutures can be used but

are very time consuming. Staples or Steri%strips usually work very well to secure thegraft in place.



60 Dressi#- %+e E<$ised W&"#d

The dressing applied over the grafted area must accomplish two goals. irst, it mustprotect the graft from environmental insults, in particular desiccation and avulsion as

well as infection. +nfection is most likely to develop from nearby areas of openwound. Secondly, the dressing must immobilize the area and allow graft

vascularization to occur, i.e., graft take. To summarize, the role of dressing is asfollows:

a. ust control environmental hazards especially desiccation and avulsion, and

b. ust immobilize the grafted area.

Sheet grafts can be managed in two ways. The most common is the application of

grease gauze (Neroform or fine meshed gauze followed by dry gauze and moderatecompression. -rafts can also be left open if there is no e"posed wound not grafted.

This approach is best used on face and neck. The e"posure method has limited usein other areas, since the grafted area needs to be immobilized in some fashion. The

usual method of immobilization is the use of a firmly placed gauze dressing followedby a compression dressing and splint. Skeletal traction can also be used, althoughthis method is usually not necessary and further hampers patient mobility, which

should be initiated in & to F days.

There are a number of techni0ues used for dressing mesh grafts, depending on thesize of the mesh and the area grafted. A .G to mesh is best managed by

application of a single layer of grease gauze or fine mesh gauze followed by gauzemoistened in an antibiotic solution. The most common solutions used are bacitracin,

$G,=== B, or neomycin (=. to gQ) of saline. The advantages of the antibioticsolution are to: help remove blood and wound e"udates from beneath the graft by

acting as a wick: $ protect the area between the mesh from desiccation/ and &protect the skin graft from bacteria in any ad!acent ungrafted wound. An outer dry

gauze dressing is then applied, followed by a compression dressing. The graftedarea needs to be immobilized. A nearly !oint can be immobilized using a fabricated

splint or a soft splint, such as a pillow wrapped around the e"tremity with an elasticbandage. The outer gauze dressings should be changed daily to remove blood and

e"udates. The burn wound is contaminated and should be managed like acontaminated wound rather than completely occluded for any prolonged period. The

innermost grease gauze dressing is usually left in place for & to G days beforechanging.

;ide meshed grafts, i.e., & to , can be managed in a similar fashion. owever,

there is an increased risk of desiccation of tissue between the mesh, especially if the

wound surface has any e"posed fat. 3lacement of a skin substitute, i.e. biobrane,

pigskin, or cadaver skin, over the wide mesh protects the intertices.

2"cised but not grafted wounds need to be covered with a skin substitute becausethe surface will invariably desiccate with an attempt at wet dressings alone. +n

addition, the skin substitute restores the barrier to heat and evaporative loss as wellas invasive infection.



Mes+ Gr2% Dressi#-

A :G to mesh graft is covered and immobilizedwith "eroform gauze over which is placed a moist dressing

followed by compression

Mes+ Gr2% C&9ered *1 Temp&rr1 S8i# S"*s%i%"%e

The temporary skin substitute protects the graft and

interstices maintaining moist wound healing.

Second 4egree #isk

Superficial low risk

id%4ermal moderate, higher in children, elderly

4eep%4ermal high risk

+ndeterminate ($nd or &rd

Third 4egree (fullthickness



TREATMENT

Admission is preferred but can be treated briefly ($F hrs as

an outpatient prior to surgery$ SS4 used after initial washing& 2arly surgery for best cosmetic and functional result and

also to minimize disability time

TREATMENT

Same as for deep burn

$ aintaining body T= more critical in view of size& 2arly e"cision and grafting

F 'onsider use of permanent skin substitutes in view of burnsize (@=E T6S

TREATMENT

Same as for deep burn$ aintaining body T= more critical in view of size& 2arly e"cision and grafting

F 'onsider use of permanent skin substitutes in view of burnsize (@=E T6S

N&%e: Skin substitute (6iobrane in place at $F hrs

.ISUALL DECEI.ING BURN

Some burns usually caused by contact with flames or e"tremely hot temperature,

like e"plosion, have the destroyed epidermis still present on the wound. The depth



can be underestimated unless the wound is gently washed and debrided after whichthe size and depth is more clearly defined.

FLAME BURN (DIRECT CONTACT))ooks superficial with blisters but mechanism suggests deep

burn

;hen gently cleaned, wound is noted to be a combination of

deep second and third degree burn

TREATMENT @

-entle wash, removing loose epidermis

$ SS4, preferably twice daily, under closed dressing& 2"cision and grafting will be needed for deep burn

E0 WOUND CON.ERSION

This term refers to the dynamic process whereby the ?one of +n!ury progresses to

the ?one of Tissue >ecrosis thereby deepening the wound. 'onversion is more likely

with a mid to deep dermal in!ury because of less blood flow, longer time to healingand increased risk of e"cess inflammation and infection. Also environmental hazards

can readily lead to conversion of an open wound.

RISK FACTORS FOR WOUND CON.ERSION

)7'A) SCST2AT+'


+ncreased inflammation (infection, open wound, irritantsypovolemia

Surface desiccation 2"cess catabolism

Surface e"udate buildup 'hronic illness

echanical trauma (dressing changes, shearing %%



'hemical trauma % topical agents

SECTION .III: USE OF SKIN SUBSTITUTES

a!or advances in care have resulted in a marked decrease in mortality and alsomorbidity, especially with massive burns. +n addition to survival the current focus in

burn care is on improving the long term function and appearance of the healed orreplaced skin cover as well as 0uality of life.

This focus on 0uality has generated a significant interest in the use of skinsubstitutes to be used to improve wound healing, to control pain, to more rapidly

close a burn wound, to improve functional and cosmetic outcome, and, in the case of massive burns, to increase survival.

To more effectively address these new roles, the new generation of skin substitutes is

biologically active. The bioactivity can modulate the burn wound instead of !ustcovering the wound. The new products to be discussed have not displaced the moreinert standard burn wound dressings but rather are used in con!unction and for 0uite

specific indications.

The skin substitutes are initially classified according to whether they are to be used

as a %emp&rr1 4&"#d $&9eri#- to decrease pain and augment healing or aperm#e#% s8i# s"*s%i%"%e to add to or replace the remaining skin components.

The ideal properties and indications for these products will be better clarified after adiscussion of the function of normal skin and the effect of a burn on skin integrity.%D

A0 ROLE OF BIOACTI.E SKIN SUBSTITUTES

The ma!or stimulus for advances in skin substitutes is to improve the 0uality

of the closed burn wound, control pain and avoid poor 0uality skin.D%$=

Temp&rr1 s8i# s"*s%i%"%es can improve the healing while decreasing pain

in superficial burns once the blisters and non%viable tissue has been removed.

<,@ +n deeper burns the dead tissue will cause an inflammatory response

producing both local and systemic effects. The systemic effects include aprofound increase in metabolic rate with a marked increase in muscle

wasting, and impairment in immune defenses.,$ 'ontrolling this systemicresponse, by earlier removal of the dead burn tissue and closure of the

wound, has markedly decreased overall mortality morbidity.l%&

Perm#e#% s8i# s"*s%i%"%es can then be used to permanently close the

e"cised burn, especially in large burns where there isnIt enough remaining

skin to completely close the wound.D%$

The addition of *i&&-i$ $%i9i%1 to the skin substitute, improves thehealing process with the intention of more rapidly healing a superficial burn

and restoring valuable dermal components in a deeper burn wound bedthereby minimizing scarring and optimizing function.D%$ A list of the non%



cellular components of dermis, used in available skin substitute, is shownbelow.$$%$< uman epidermal and dermal cells are usually also added to

dermal elements in permanent skin substitutes in addition to these dermalcomponents.

DERMAL COMPONENTS STIMULATING HEALING6656

• Structural component or scaffolding

• 6iologically active component stimulating

all phases of healing

• 'ollagen (protein

% Scaffold for cell migration and matri" deposition

% 'ell guidance

• 2lastin (protein

% Tissue elasticity

• ibronectin (protein

% 'ell to cell adherence

% 'ontact orientation for cells

% +ncreases epithelial cell division, migration

% 'hemo attractant for fibroblasts, macrophages

• -rowth actors (proteins

Stimulate all phases of wound healing

• -lycosaminoglycan (glycosylated protein

% 'ell adherence properties

% 'onduit for healing factors

% 4eactivator of proteases

% Scaffold or foundation for dermal elements

• yaluronic Acid (comple" carbohydrate



% aintaining matri" hydrated

% 4ecreases inflammation

% Stimulates healing

% 3roper cell alignment

B0 A.AILABLE BIOACTI.E

SKIN SUBSTITUTE

A list of skin substitutes, categorized by biologic make%up, is presentedbelow. All have some degree of biologic activity for improving the wound%healing environment. A disd9#%-e &2 &2 %+ese s8i# s"*s%i%"%es is

%+e *se#$e &2 $%i9e #%imi$r&*i $%i9i%10 H&4e9er er1 e22e$%i9e

4&"#d $&s"re d&es de$rese %+e ris8 &2 i#2e$%i&#0

A.AILABLE BIOLOGICALL ACTI.E

SKIN SUBSTITUTES

• >aturally occurring tissues

'utaneous allografts

'utaneous "enografts

Amniotic membranes

3orcine small intestinal submucosa

• 'omposite Synthetic%6iological

• 'ollagen based dermal analogs

+ntegra

• 'ulture%derived tissue

6ilayer human tissue

'ultured autologous keratinocytes



ibroblast seeded dermal analogs

2pithelial seeded dermal analog

Skin substitutes can also be categorized as to use and indication into

temporary or permanent.

Temp&rr1 skin substitutes are used to:

% elp heal the partial thickness burn (or donor site

% 'lose the clean e"cised wound until skin is available for grafting

There are typically no living cells present.

Perm#e#% skin substitutes are used:

% To replace lost skin providing either epidermis or dermis, or both

% To provide a higher 0uality of skin than a thin skin graft

ost permanent skin substitutes contain viable skin cells as well as components of

the dermal matri".

C0 TEMPORAR BIOACTI.E SKIN SUBSTITUTES

The purpose of a temporary skin substitute is twofold. Temporary skin substitutesare typically a bilayer structure. There is an outer epidermal analog and a more

biologically active inner dermal analog.D%$ The first ob!ective is to close the wound,

thereby protecting the wound from environmental insults.D,9,$@%$9 The secondob!ective is to provide an optimal wound healing environment by adding dermalfactors which activate and stimulate wound healing.D%$9 6iologically active dermal

components naturally are typically provided to the inner layer, which is then appliedto the remaining dermis in a partial thickness burn or to an e"cised wound. 6elow is

a list of the commonly available dermal matri" elements present in these products,and their actions.

IDEAL PROPERTIES OF A TEMPORAR SKIN

SUBSTITUTE

• #apid and firm adherence properties for

closure of the wound• #elieves pain

• 2asily applied and secured

• 4oes not incite inflammation

• Stimulates wound healing

• 6arrier to micro%organisms

• Avoids wound desiccation



• 7ptimizes healing environment

• 4oes not cause hypertrophic tissue

response

• aemostatic

• 3revents evaporative water loss

• le"ible yet durable

• 2asy to remove when

% ;ound has re%epithelialized

% ;ound ready for grafting

• 'annot transmit disease

• +ne"pensive

• )ong shelf life

• 4oes not re0uire refrigeration

The currently available products are listed below:

A9i*e Bi&$%i9e Temp&rr1 S8i# S"*s%i%"%es

Pr&d"$% C&mp#1Tiss"e &2Ori-i#

L1ers C%e-&r1 UsesH&4s"ppied

H"m#&-r2%

Skin bankumancadaver

2pidermisand dermis

Splitthicknessskin

Temporarycoverage of largee"cised burns

rozen inrolls ofvarying size

Pi- s8i#'e#&-r2%

6rennan edical

St. )ouis, o

3ig dermis

4ermis

4ermis

Temporary

coverage ofpartial thicknessand e"cisedburns

rozen orrefrigeratedin rolls

H"m#m#i&#

7n siteprocurement

3lacentaAmnioticmembrane

2pidermis4ermis

Same as above #efrigerator

Osis

ealthpoint )T4San Antonio, T"

Nenograft

2"tracellularwoundmatri" fromsmallintestinesubmucosa

6ioactive4ermal likeatri"

Superficial burnsSkin graft donorsites 'hronicwounds

#oom TOstorageultiple sizes&"&.Gcm@"$=cm

Bi&*r#e

4owickamQ6ertek3harmaceuticals

Synthetic withaddeddenaturedbovine collagen

6ilayerproductoutersilicone+nner nylonmesh withadded

collagen

Syntheticepidermisand dermis

Superficial partialthicknessburns,Temporarycover of e"cisedburns

#oom TOstorageG"$=inch="Gcm

G"Ginch G"Ginch



Tr#s$1%e

Smith P >ephew;oundanagement

)argo, )

Allogenic4ermis

6ilayerproduct7utersilicone+nner nylon

seeded withneonatalfibroblasts

6ioactive4ermalatri"'omponentson Syntheticdermis andepidermis

Superficial tomid%3artialthickness burnsTemporary

coverage ofe"cised burns

rozen in

G"@.G inchsheets

!0 H"m# A&-r2% (Cd9er s8i#)

uman allograft is generally used as a split%thickness graft after being procured

from organ donors.&=%&$ ;hen used in a viable fresh or cryopreserved state, itvascularizes and remains the gold standardU of temporary wound closures. +t

can be refrigerated for up to @ days, but must be stored frozen for e"tendedperiods. +t is also used in a non%viable state after preservation in glycerol or

after lyophilization: however, most e"isting data describe best results when it isused in a viable state. The epidermal component provides a barrier until re!ected

by the host in &%F weeks. The dermis revascularizes and incorporates.

omograft, another term for human allograft, can only be obtained from a tissue

bank as strict protocols are re0uired for harvesting and storage. 4onors must berigidly screened for potential viral and bacterial disease to avoid any transmission

of disease. The product is in limited supply and very e"pensive.

The primary indication for use is to cover a large e"cised burn wound until an

autogenous skin or a permanent skin substitute becomes available. Allograft isalso used to cover a wide meshed skin graft, sealing the interstices during the

healing process.



A&-r2% S8i#

Ad9#%-es

• A bilayer skin providing epidermal and

dermal properties

• #e%vascularizes maintaining viability for

weeks

• 4ermis incorporates into the wound

Disd9#%-es

• 2pidermis will re!ect

• 4ifficult to obtain and store• #isk of disease transfer

• 2"pensive

• >eed to cryopreserve

A&-r2% Appi$%i&# %& E<$ised W&"#d

'adaver skin is nicely adherent to the wound

60 'e#&-r2%s

Although various animal skins have been used for many years to providetemporary coverage of wounds, only porcine "enograft is widely used today.&&%&F



The epidermis of the porcine "enograft is removed and the split thickness dermisis provided in rolls. Split%thickness porcine dermis can be used after

cryopreservation, or after glycerol preservation. +t effectively provides temporarycoverage of clean wounds such as superficial second degree burns and donor

sites.&&,&F 3orcine "enograft does not vascularize, but it will adhere to a cleansuperficial wound and can provide e"cellent pain control while the underlying

wound heals.

+n general, "enograft is not as effective as homograft but is more readily

available and less e"pensive.

3rimary indications are for coverage of partial thickness burns during healing and

used burn wounds prior to skin grafting.

'e#&-r2%s

Ad9#%-es

• -ood adherence

• 4ecreases pain

• ore readily available compared to allograft

• 6ioactive (collagen inner surface with fresh

product

• )ess e"pensive than allograft

Disd9#%-es:

• 4oes not revascularize and will slough• Short term use

• >eed to keep the fresh product frozen

C"rre#% Use &2 Pi-s8i#



3igskin consists of a thin dermal layer (epidermis removed

which is stored frozen to maintain adhesive properties. Thedermis is meshed to allow drainage to seep through

The pigskin dermis adheres to a cleaned partial thicknessburn % a dry gauze dressing follows

3.

Human Amnionuman amniotic membrane is used in many parts of the world as a temporarydressing for clean superficial wounds such as partial%thickness burns, donor sites,

and freshly e"cised burns.&G,&< Amniotic membrane is generally procured freshand used after brief refrigerated storage. +t can also be used in a nonviable state

after preservation with glycerol. Amnion does not vascularize but still canprovide effective temporary wound closure. The principal concern with amnion is

the difficulty in screening the material for viral diseases. The risks of diseasetransmission must be balanced against the clinical need and the known

characteristics of the donor. The primary indications are the superficial burn andthe e"cised wound.



H"m# Am#i&# Mem*r#e

Ad9#%-es

• Acts like biologic barrier of skin

• 4ecreases pain

• 2asy to apply, remove

• Transparent

Disd9#%-es

• 4ifficult to obtain, prepare and store

• >eed to change every $ days

• 4isintegrates easily

• #isk of disease transfer

0 Osis W&"#d M%ri<

This product is made of the submucosa of the porcine small intestine found betweenthe mucosa and muscularis, in the wall of the porcine small intestine.&@,&D The freeze

dried cellular natural matri" retains its natural collagen and matri" structure andcontains most of the bioactive matri" proteins found in the human dermis.

The submucosal layer is appro"imately =.$mm in thickness but is 0uite durable. Theproduct is freeze%dried removing the cells. The product is sterile, porous,

biocompatible and non%immunogenic. +t has a long shelf life and can be stored atroom temperature. The 7AS+S is incorporated into the wound bed over

appro"imately @ days and needs to be re%applied if the wound has not yet healed.

The outer barrier function is diminished with incorporation.

The primary indication is for use in difficult to heal non%burn wounds. +ts use inburns is for the partial thickness burn and the skin graft donor site.

OASIS Appi$%i&# %& Pr%i T+i$8#ess B"r#



Bpon application, product is moistened with saline, then

covered by a non%adherent secondary dressing

OASIS W&"#d M%ri< &# D&#&r Si%e

OASIS &# D&#&r Si%e D1

>early totally re%epithelialized: matri" is incorporating withwound surface

Osis W&"#d M%ri<



Ad9#%-es

• 2"cellent adherence

• 4ecreased pain• 3rovides bioactive dermal like properties

• )ong shelf life, store at room TO

• #elatively ine"pensive

Disd9#%-es

• ainly a dermal analog

•

+ncorporates and may need to be reapplied

0 Bi&*r#e

This product is a two%layer membrane.&9,F= The outer epidermal analog is constructed

of a thin silicone film with barrier functions comparable to skin. Small pores presentin silicone allow for e"udates removal and has permeability to topical antibiotics.

The inner dermal analog is composed of a three%dimensional irregular nylon filamentweave upon which is bonded type + collagen peptides. The surface binding of inner

membrane is potentiated by collagen%fibrin bonds as well as fibrin depositionbetween the nylon weave. A thin water layer is maintained at the wound surface for

epidermal cell migration maintaining moist wound healing.

2"cellent adherence to the wound significantly decreases pain in the superficial

partial thickness burns. The silicone and nylon weave provides fle"ibility. The

biobrane is removed once the partial thickness wound has re%epithelialized or thecovered e"cised burn wound is ready for grafting. owever, if left in place for more

than $ weeks the product is difficult to remove as tissue grows into the inner layer.6iobrane ) contains a nylon fabric woven from monofilament threads that provide a

less dense matri" and less adherence, preferred e.g. on a donor site. There is likely

very little direct bioactivity from the collagen peptides.F= The product has a long

shelf life and can be stored at room temperature. +t is also relatively ine"pensive.

The primary indication is for closure of the clean superficial burn or the e"cised burnwound.



7uter surface shown. >ote pores

6iobrane on modest stretch: surface smooth

S$d B"r#



Bi&*r#e &# De*rided S$d

4ay one: nicely adherent to wound

S"per2i$i %+i-+ *"r#

'overed with 6iobrane (4ay =

Bi&*r#e rem&9



7pa0ue appearance indicates burn wound has re%

epithelialized

Temp&rr1 S8i# S"*s%i%"%e C&9eri#- Mes+ Gr2%

The coverage avoids damage to the interstices as re%

epithelialization occurs

0 Tr#sC1%e

This product is also a bilayer skin substitute.F,F$ The outer epidermal analog is a thinnonporous silicone film with barrier functions comparable to skin. The inner dermal



analog is layered with human neonatal foreskin fibroblasts which produce productsmainly collagen type +, fibronectin and glycosaminoglycans.

A subse0uent cryo%preservation destroys the fibroblasts but preserves the activity of

fibroblast%derived products on the inner surface. These products do stimulate thewound healing process. A thin water layer is maintained at the wound surface for

epidermal cell migration.

The nylon mesh provides fle"ibility and e"cellent adherence properties significantlydecrease pain in the partial thickness burn. The product is peeled off after the

wound has re%epithelialized.

Trans'yte must be stored at M@= 'O in order to preserve the bioactivity of the dermal

matri" products.

The primary indication is for closure of the clean superficial to mid%dermal burn,

especially useful in children. Trans'yte is also indicated for the temporary closure ofthe e"cised wound prior to grafting. Tissue growths tends to be less of a problem

even if the product is kept in place for over two weeks.

Tr#sC1%e

Ad9#%-es

• 6ilayer analog

• 2"cellent adherence to a superficial to mid%

dermal burn

•

4ecreases pain• 3rovides bioactive dermal components

• aintains fle"ibility

• -ood outer barrier function

G&&d Disd9#%-es

• >eed to store frozen till use

• #elatively e"pensive

C&mp&#e#%s &2 Tr#sC1%e



Schema demonstrating the two%layer structure, the inner layer being bioactive.



Tr#sC1%e i# Seed Csse%%e

Stored at %@=O'entigrade

Tr#sC1%e 2&r Pr%i T+i$8#ess H#d B"r#



'utting the sheet to fit with a small overlap followed by initial immobilization until

adherent

Tr#sC1%e &# F&&% B"r# (; d1s)

>ote fle"ibility of the dressing

Tr#sC1%e &# Le- B"r# (! d1s)



7pa0ue appearance indicating re%epithelialization beneath dressing for removal

Tr#sC1%e (D1 !6)

Skin substitute being removed

D0 PERMANENT SKIN

SUBSTITUTES

The purpose of these products is to replace full thickness skin loss as well as

to improve the 0uality of the skin, which has been replaced after a severe

burn.$=%$&

As opposed to the bilayer concept of the ideal temporary skin substitute,permanent skin replacement is much more comple".

There are two approaches to developing a permanent skin substitute.$%$& Thefirst approach is the use of a bilayer skin substitute, with the inner layer being



incorporated into the wound as a neodermis, rather than removed like atemporary product. The outer layer is either a synthetic to be replaced by

autograft (epidermis or actual human epithelial cells. The epithelial cells,which will form epidermis barrier function, is not often sufficiently developed

at placement to act immediately as an epidermal barrier.

The second approach is the provision of either !ust an epidermal or a dermalanalog, i.e. a one layer tissue. These products are technically not permanentskin substitutes upon initial placement as there is no bilayer structure.

Perm#e#% S8i#

Rep$eme#%

• 6ilayer structures with biologic dermal analog and

either synthetic or biologic epidermal analog

• Skin components

% 2pidermal cells alone

% 4ermis alone

% 'o%culture of epidermal cells and fibroblasts

The ideal property as shown below would be that of a bilayerstructure.

+deal 3roperties of A 3ermanent Skin Substitute

• #apid and e"cellent adherence properties

• 2asily applied and secured to an e"cised wound

• inimum wait period from time of burn to

availability of skin substitute

• 6ilayer tissue containing both epidermal and

dermal eliminates to best replicate normal skin

• #apid incorporation

• 'annot transmit disease

• -ood functional and cosmetic result

• +ne"pensive

The currently available clinical products are listed below. There are a number ofpermanent skin substitutes in the development stage, which will not be listed.

A.AILABLE PERMANENT SKIN SUBSTITUTES



Pr&d"$% C&mp#1 Tiss"e &2 Ori-i#

L1ers C%e-&r1 UsesH&4

s"ppied

Api-r2

7rganogenesis

+nc and >ovartis3harmaceuticals

'orp

Allogenic'omposite

'ollagenmatri"seeded with

humanneonatalkeratinocytesandfibroblasts

'omposite:2pidermisand 4ermis

'hronicwounds,

often usedwith thinSTS- 2"ciseddeep burn

@.Gcmdiameter

discQpack

OrCe

7rtec+nternational

+nc.

Allogenic'omposite

'ollagenspongeseeded withhumanneonatalkeratinocytesandfibroblasts

'omposite:2pidermisand 4ermis

Skin graftdonor site,chronicwounds

<"<cmsheets

Epi$e-enzyme Tissue

#epair 'orpAutogenouskeratinocytes

'ulturedautologouskeratinocytes

2pidermis7nly

4eep partialand fullthicknessburns H&=ET6SA

G=cm$ sheets inculturemedium

A&derm )ife 'ellAllogenicdermis

A cellular4ermis(processed

allograft

4ermis only

4eep partialand fullthicknessburns, Softtissue

replacement,Tissue

patches

"$cm toF"$cm

I#%e-r +ntegra )ifeScience 'orp

Synthetic

Silicone outerlayer oncollagen -A-dermalmatri"

6iosynthetic4ermis

ull thicknesssoft tissuedefectsdefinitive closureUre0uires skingraft

$"$ inchF"= inchD"= inchGQpack

. Bsed mainly in burns

!0 Epi$e

This product, used mainly for very large burns is composed of the patients skin

epithelial cells and referred to as cultured epithelial autograft ('2A. Therefore, onlythe epithelial layer is provided.F@%F9 The product is made from a small biopsy ofnormal skin ($"$cm from the burn patient. The epithelial cells are e"tracted and

cultured. Bse of a cell culture techni0ue allows the keratinocytes to be grown in athin sheet =,=== times larger than the initial biopsy. This process does re0uire $%&

weeks from the time of biopsy. 7ften the burn wound is e"cised and covered withhomograft (allograft until the cells are ready to be transplanted. The '2A is then

applied to the clean e"cised (or allograft covered wound.



The '2A is supplied in sheets $%< cells thick on small pieces of petroleum gauze(G=cm$ which are bathed in culture medium. +mmediate application is necessary.

The '2A grafts are very fragile and easily rubbed off for at least several weeks. Thebacking is removed in several weeks as the '2A thickens and adheres. -raft%takes

ranges from &=%@GE of total epithelium applied. The epithelium gradually thickensbut has a low resistance to sheer forces for some time. Application of allograft

dermis, prior to '2A grafting appears to improve skin 0uality. +n this case a dermalanalog e"ists resulting in a bilayer skin. The primary indication is for very largeburns.

Epi$e

Ad9#%-es

• 3atients own keratinocytes e"panded

several thousand fold• Small skin biopsy re0uired

• 'an cover very large surfaces with

reasonable graft take

• Bsed in large burns

Disd9#%-es

• $ to & week lag time for production

•

3rovides only the epidermal layer• 2pithelial layer can be 0uite fragile for some

time

• >eeds to be used immediately on delivery

• 5ery e"pensive

Epi$e P$eme#%



The epidermal cells are placed on the wound on pieces of

G=cm$ petroleum gauze. The pieces are then secured to the

wound bed and immobilized for $%& weeks

Epi$e % ; 4ee8s

>ote new epithelium (whitish patches on the upper leg

where the gauze has been removed

60 A&derm

This product is basically treated human allograft with the epidermis removed.G=%G$

The dermis is treated to produce a co preserved lyophilized allodermis, whichincorporates. The product is used as a dermal implant. Therefore application of

a thin epithelial autograft is re0uired. 3rimary indication is for use in the



replacement of soft tissue defects. This product is not commonly used in largeburns. A period of incorporation is re0uired before the epithelial skin graft can be

applied. The product has a long shelf life in its lyophilized form. +t re0uires re%hydration prior to use.

A&derm

Ad9#%-es

• 2asy to store, an off the shelf product

• 4oes not re0uire skin bank

• 'omes in large and small pieces

Disd9#%-es• #e0uires thin skin graft to provide epidermis

• Two procedures re0uired to achieve bilayer

skin

• #elatively e"pensive

;0 I#%e-r

This product is composed of a dermal analog made of a biodegradable bovine

collagen%glycosaminoglycan copolymer matri" The collagen andglycosaminoglycan is cross linked to attempt to ma"imize ingrowths of the

patients own cells.G&%GG

The epidermal analog is a thin silicone elastomer providing temporary barrier

protection. After the dermal analog incorporates and the surface revascularizes,

at about $%& weeks, the silicone layer is removed and replaced with a very thinskin graft from the patient (or '2A cells. The +ntegra needs to be carefully

immobilized for the first $ weeks as movement will cause devascularization and

loss of the product.

The primary indication is the treatment of large deep burns as well as

reconstruction procedures. The incorporated neodermis appears to improve thefunction of the final skin once the epithelial graft is applied. The product is

provided in a number of sizes and sheets stored in @=E isopropyl alcohol. Shelflife is very good.



T+e I#%e-r Pr&d"$%

The two layer dermal analog is shown



I#%e-r

Ad9#%-es

• 3rovides thick dermal analog

• #easonable shelf life

• >o risk of transmitting viruses

• #elatively ine"pensive

• Bsed in large burns

Disd9#%-es

•

>eed to provide epidermis from the patient• 4ermal cells must come from the patient

re0uiring product incorporation

• Two procedures

SUMMAR

The scientific principles and practical approaches, to replacing skin either temporarilyor permanently are advancing at a rapid rate. uch of these advances can be

attributed to both advances in the field of bioengineering as well as increasinginterest in optimizing the outcome of the burned skin.

The ideal properties of a bioactive temporary and a permanent skin substitute havebeen well defined.

As e"pected, the properties of temporary skin substitutes are more concrete, easier

to categorize and determine efficacy. A bilayer structures is the current standard

with the dermal component being bioactive. 3ermanent skin replacement on theother hand is much more comple". A variety of approaches are being used which

can be loosely categorized as either use of bilayer products (usually the outer layerto be replaced by epidermal autograft or replacement of either dermal or epidermal

elements separately. The terminology of the latter approach is difficult becausethese component products are really not permanent skin substitutes on initial

application but become so only when all the elements are in place.

An understanding of the properties of each product is essential for the user to

optimize outcome.

REFERENCES



. ast 6: The Skin. +n: ;ound ealing. 'ohen 1, 4iegelmann +,editors, ;6 Saunders. 3hiladelphia 99$:&FF%&GG.

$. ;right >, Allison . The biology of epithelial cell populations.'larendon press 9DF:$D&%&FG.

&. Stenn S., alhotra #. 2pithelialization. +n ;ound ealing.

6iochemical and 'linical Aspects. ' 'ohen (ed ;6 Saunders,3hiladelphia 3A 99$:G%$@.

F. -rillo . 7rigin of fibroblasts in wound healing. Annals of Surgery9<&:G@:FG&%F<@.

G. 1arasck . echanism of angiogenesis in normal and diseased

skin.<. #aghow #. The role of e"tracellular matri" in post%inflammatory

wound healing and fibrosis. AS26 99F: D:D$&%DG=.

@. 4emling #. 6urn care/ in A'S Surgery. ;ilmore 4, ed >C, >C.

;eb 4 $==$, p.F@9.

D. erndon 4. Total 6urn 'are. Saunders, 3hiladelphia $==$.9. >eely A, 6rown #, 'hendening ', et al. 3roteolytic activity in

human burn wounds. ;ound #ep #egen 99@:G/ &=$%9.=. Coung 3, -rinnel . etalloproteinase Activation 'ascade

after burn in!ury: longitudinal analysis of the human wound

environment. ournal of +nvestigative 4ermatology 99F:=&/<<=%<<F.

. 1omgova #. 6urn wound coverage and burn woundclosure. Acta 'hir 3last $===:F$/ <F%<D.

$. Sheriden #, anagement of burn wounds with prompt

e"cision and immediate closure. +ntensive 'are ed 99F:9/ <%@.

&. 4emling #, 4eSanti ). Scar management strategies inwound care. #ehab anage $==:F/ $<%&$.

SECTION I': BURN SCAR AND ITS COMPLICATIONS

A0 O.ER.IEW

4uring the first < days, wound inflammation has begun and the variouscomponents of healing have been initiated. +n superficial burns, epidermal

regeneration will be relatively rapid, if the wound environment is optimized. Thein!ured dermal elements are usually covered by new epithelium within $ weeks.

The hyperplasia of dermal fibroblasts then begins to resolve, and healing iscomplete with only modest amounts of collagen deposited. The wound usually

becomes relative pliable with time and minimal wound contraction is seen.'osmetically, the superficial second degree burn, which heals in $ weeks, results

in minimal to no long%term scarring.

+f the healing takes & weeks as would be the case with a mid%dermal burn, scar is

likely to be minimal e"cept in higher risk groups, e.g. dark skin.



POST BURN SCAR RELATI.E TO RE5EPITHELIALI7ATION

• Healing in 2 weeks – minimal to no scar

• Healing in 3 weeks – minimal to no scar except in high risk scarformers

• ealing in F weeks or more M hypertrophic in more than G=E of

patients

POST BURN SCAR RELATI.E TO SKIN GRAFT

• Early grafting leads to less scar

• The thicker the skin graft, the less the scar

•

Sheet grafts have less scar then meshed grafts• The wider the mesh, the more the scar

• Scar will develop at the edges of a graft in high risk scar formers

(dark skinned

B0 BIOCHEMISTR OF BURN SCAR

The biochemistry of the wound changes dramatically if it has not closed by & weeks

or longer as would be the case of a healing deeper burn or a deep skin graft donorsite.

2"aggeration of the inflammatory phase, in an open or infected burn, increases theconcentration of growth factors known to produce increased fibroblast numbers and

e"cess amounts of collagen and e"tracellular matri".

+ncreased mast cells leads to increased release of histamine. istamine is known to

stimulate growth of fibrous tissue.

Scar shows an increase in the thickness of the new epithelial layer but without rete

pegs, making the surface vulnerable to in!ury. The keratinocytes becomes a factoryfor fibrotic growth factors. +n addition, an e"cess and prolonged neovascularization

is found in both types of scar compared to normal scar. ibroblasts are also found in

increased numbers, leading to increased collagen deposition as well as more matri".

These fibro%blasts are more sensitive to growth factors than normal skin fibroblasts.The released chondroitin develops sulfated side chains, which lead to a more rigid

scar. +ncreased and persistent levels of chondroitin sulfate are present, located inthe modular areas of e"cess collagen. This is characterized by increased water

content, which increases scar firmness. A decrease in interferons, cytokines thatdownregulate collagen and matri" synthesis is also noted. This abnormality leads to

less collagenolysis and matri" degradation with remodeling.



The status of the wound bed will dictate the degree of surface inflammation.+ncreased surface and matri" metalloproteases o"idants and other mediators of

inflammation result in a continued breakdown of new tissue and stimulatefibroplasia.

C"ses &2 E<$ess W&"#d I#2mm%i&#

• hronic open !ound

• Surface necrosis of desiccation

• +nfection, increased bacterial burden

C0 HPERTROPHIC SCAR CHARACTERISTICS

ypertrophic scar is an aberration of the normal healing process.

ypertrophic scar occurs only in humans, making the study of pathogenesis andtreatment more difficult. +t occurs in males and females, being more common in the

teenager or younger adult.

ypertrophic scarring is seen in more than G=E of healed deep burns as !ust

described.

The characteristics of proliferative or hypertrophic scar are shown in the list below.

3roliferative scar is characteristically red, raised, rigid and painful. +tching is alsouniversally present.

C+r$%eris%i$s &2 H1per%r&p+i$ B"r#



• Surface erythema

• "aised from wound surface

• #ack of elasticity

• $ncreased collagen

• %ainful and itchy

The increased scar is particularly prominent around !oints,where tension is more common.

H1per%r&p+i$ B"r# S$r

'ontinued scar deposition in the re%epithelialized wound results in a raised,

hyper%pruritic wound that produces functional impairment due to rigidity and pain

as well as a severe cosmetic abnormality. Severe discomfort results. 3ain with

any scar movement retards activity and continued itching leads to scratching and

skin breakdown. Superficial infection of the skin breakdown can then result. The

scar often splits with e"ercise, especially if it becomes dry. -rafted wounds

develop much less hypertrophic scarring than the deep dermal burn that heals

spontaneously. 6oth the contracture and hypertrophic scarring process peak

between & and < months after in!ury, fre0uently long after the patient has been

discharged.

'ontracture formation and hypertrophic scarring peak & to < months after in!ury

and partially resolve at $ to D months.



+t is crucial that the care providers recognize the delayed onset so that

precautionary measures can be taken. The hypertrophic scar begins to decrease

with time as collagen lysis begins to e"ceed the rate of deposition. The latter

begins to decrease as the inflammatory process diminishes. 6etween $ and D

months, a softening and flattening of the scar can be seen along with a loss of

scar hyperemia. The presence of a hyperemia indicates that active scar turnover

is still present. The lack of hyperemia is a good sign that the scar is now mature

and will remain in its present state, although the scar may rela". The underlying

tissues can be permanently contracted.

C"ses &2 Pr&i2er%i9e B"r# S$r

• Tension on the wound

• Excess inflammation in wound &ed

• $nflammatory stimulus

• +nfection

• !ound open for more than 3 weeks

• #ack of dermal elements

•

-enetic predisposition

D0 SCAR ASSESSMENT

There are a variety of methods to control and decrease scar formation, and in most

patients, more than one approach is used. owever, the assessment of the responseof the scar process to the approach used is problematic as an accurate method for

the ob!ective 0uantitative assessment of scar remains to be developed.

Since scar is the sum of the response to in!ury repair, and intervention, the scar is

not a static process, but rather a dynamic one changing over time, especially duringthe first D months or until healing is complete.

Sub!ective assessment includes various factors that contribute to the patientIs ownevaluation (visual and tactile contributions, which includes both perception and

attitude (body image. 7b!ective assessment includes the physical characteristics ofsize, shape, volume, color, te"ture, and probability. +n addition, structural,

mechanical and physiologic characteristics are included. The 5ancouver Scar Scale isa commonly used method that attempts to 0uantify most of these parameters.

4espite an attempt at ob!ectivity, all ob!ective markers are very much dependent on



the e"aminerIs e"pertise and perceptions, and assessment will vary considerablybetween different e"aminers.

uture approaches currently being tested include two%dimensional and three%

dimensional imaging techni0ues and computer vision algorithms. A range scanner isa device that allows ac0uisition of &%4 data and can accurately estimate scar

volume. This approach can also be used to assess pliability.

V3ain and itching are also assessed and documented usually using the =%= scale

H1per%r&p+i$ S$r &# D&#&r Si%e



4elayed healing of donor site led to scar

#ed and #aised

M%"ri#- S$r (!6 m&#%+s)



>ote scar is less red

Er1 S$r F&rm%i&# (6 m&#%+s)

and burn which healed in !ust over & weeks

>ote beginning of red raised scar

E0 PRE.ENTION OF HPERTROPHIC SCAR

3revention is best achieved by early wound closure. Skin grafting should be theapproach to a burn e"pected to take more than & weeks (high risk scar formers or F

weeks to re%epithelialize. Temporary skin substitutes may be of benefit for decreasingscar in the partial thickness wound by increasing healing rate while protecting the

wound. 3ermanent skin substitutes with a dermal component may be advantageousin the full thickness wound.

• 2arly wound closure

% Temporary skin substitutes

% Skin grafting



% 3ermanent skin substitutes

% ;ound protection

+t has been well established that a dermis containing active dermal elements iscritical for the orchestration of a normal healing process, and the absence of dermal

elements will lead to e"cess scar. The role of the dermis can be divided into itsstructural component and its biological messenger component.

The scaffolding or structure of the matri", mainly collagen type +, is made up of thecollagen fibres. The collagen lattice provides contact orientation for dividing and

migrating cells (&=%&G. This cell%guidance system allows for a more organized, lessabundant scar. 3roviding a collagen lattice onto the wound surface prior to scar

formation allows for the ingrowth of a new matri" over time. The matri"orchestration system is composed of dermal proteins like fibronectin and growth

factors, yaluronic acid, a comple" carbohydrate and the glycosaminoglycan content.

A deep partial%thickness or full%thickness burn no longer has these key dermal

elements. owever, there are a number of collagen%matri" products now availablewhich are designed to restore some of the dermal%like properties when placed on aclean full%thickness wound bed. The addition of these dermal%like properties should

allow for a more normal healing process, thereby potentially decreasing scar.

3roviding a dermal%like layer to a full%thickness wound especially a wound, which isclosing by secondary intent, should help to control scarring in cutaneous wounds,

especially if the components maintain the biological activity of normal dermalelements. Several studies have demonstrated decreased scarring using some of the

more novel matri" dressings

F0 TREATMENT OF HPERTROPHIC SCAR

!0 E<$isi&# Appr&$+es

E<$isi&# is only feasible for a small scar. A simple e"cision of either an established

hypertrophic scar or keloid has a very high recurrence rate (over G=E. Thee"ception for hypertrophic scar appears to be tension%releasing procedures, e.g. z%

plasties to release burn contractures of burn scar removal with tension%free closure

where results are much better. 1eloid recurrence also remains a ma!or problem,although the addition of corticosteroids to the edges of the e"cision decreases

recurrence. Therefore, surgical approaches to late scar need to be combined with

other approaches.

Lser S"r-er10 This promising approach to both hypertrophic scar and keloids uses

a laser beam to cause a thermal tissue reaction, which can heat the in!ury orcoagulate specific tissues. The '7$ and argon lasers are ineffective. owever, the

newer flash lamp%pumped pulse dye laser selectively decreases scar blood flow witha demonstrated improvement of more than G=E in over G=E of cases. A more

pliable, less pruritic, and less erythematous scar results.

Cr1&%+erp10 'omparable to laser therapy, cryotherapy results in microcirculatory

disturbances leading to tissue damage, especially fibroblasts. 3ositive response is



seen in G=E to @=E of patients, which is comparable to laser therapy. Treating earlyhypertrophic scars has the best results.

Typically, these surgical approaches are combined with other modalities, such as

corticosteroids and other pharmacologic approaches and biophysical therapies likepressure, to optimize results.

60 Bi&p+1si$ T+erpe"%i$s

The biophysical basis for therapeutic efficacy in scar management remainscontroversial, especially the relevance of abnormal biochemical pathways, and their

pharmacologic modifications. owever, these approaches have become the standardof care for hypertrophic scar control M both prevention and treatment. 1eloids in

general respond minimally to these approaches.

;0 C&mpressi&#

The use of fitted elastic garments to generate about $F mm g on the hypertrophic

scar was popularized more than $= years ago, especially for burn scar. 3ressure, ifused D%$F hours a day for at least < months, appears to have at least partialsuccess in producing a thinner, more mature, and more pliable scar in over G=E of

patients. The garments should be used as soon as the wound is closed. Thepressure decreases scar blood flow, decreasing protein deposition, increasing lysis,

decreasing edema and chondroitin sulfate. owever, it is clear that the initialmeasured pressure lasts only for a very short time as tissue edema decreases,

lessening the pressure. Cet a positive effect may persist. #ecent theories include anincrease in scar tissue temperature due to the tight garment weave. +ncreased

temperature, even by O', will significantly increase collagenolysis and scarmaturation, thus the use of heating as a treatment modality.

Tre%me#% M&di%ies

• Surgery Therapies

% e"cision

% laser

% cryotherapy

• Biophysical Therapies

% compression

% ultrasonic, microwave heating

% gel sheeting

% scar massage



• Pharmacologic Therapy

% corticosteroids

% interferon

% protein kinase ' inhibitors

Mes"reme#%s 2&r Press"re Grme#%s

'areful fitting is done to obtain correct pressure

Fi%%ed Press"re Grme#%

To be worn $& out of $F hours a day

0 U%rs&#i$ &r mi$r&49e +e%i#-

Bsed to soften scar and loosen still%stiff !oints, ultrasonic or microwave heatingdecreases the tensile strength of a scar, and appears to reduce collagen content

possibly by increasing collagenase activity/ some benefit is seen in at least half thepatients.



. Ge S+ee%i#-

orm%fitted silicone gel sheets held in place by elastics and worn at least $D hours aday for several months also appear to increase scar maturation and decrease

hypertrophy. Although the mechanism was initially thought to be due to pressure orincreased temperature, neither appears to occur. Silicone itself is not playing a role

has the same results occur with the use of a hydrogel. 'urrent evidence suggeststhat maintaining scar hydration is the common element, although the effect ofhydration !on decreasing scar is unclear. owever, the fitted sheet also takes tension

off the wound, a known stimulant of scar. 2arly use has the best results.

0 S$r mss-e

This approach is usually combined with several other modalities. 4eep massagereportedly stretches fresh scar and breaks down the cement or matri" holding the

scar contracted. assage therapy appears most beneficial in preventing

contractures. owever, massage also mechanically stimulates fibroblast synthesis ofcollagen. Therefore, this approach must be combined with an anticollagen synthesisapproach to be of significant benefit.

0 P+rm$&&-i$ T+erp1

>onsteroidal anti%inflammatory agents have been shown to decrease fibrosis throughinhibition of +l% and prostanoids, known to stimulate fibrosis. owever, data

verifying clinical efficacy in controlling e"cess scar are lacking.

A#%i+is%mi#es have been shown to be effective not only in controlling pruritus, butalso suppressing histamine%induced tissue proliferatives. Topical agents such as

do"epin cream would likely be more effective as the concentration in the scar wouldbe greater. +n addition, do"epin (3rudo"in is D== times more potent than

diphenhydramine as an antihistamine.

Some newer antiallergic drugs also inhibit the release of histamine and prostanoids

from wound mast cells. These agents, e"cept for some mild sedation, are very safe.'orticosteroids are, of course, used to control hypertrophic scar and keloids by

in!ection into the scar itself. owever, the corticosteroids, e"cept for stabilizing mastcells, are not acting as an anti%inflammatory agent, but rather by inhibiting protein

synthesis.

C&r%i$&s%er&ids are the main agent in the protein synthesis inhibitors category.These agents, when in!ected into scar, decrease fibroblast proliferation, decrease

angiogenesis, and inhibit collagen synthesis and also e"tracellular matri" protein

synthesis. 'omplications include pain on in!ection, thinning of surrounding skin if thesteroid spreads to normal tissue, systemic absorption, and recurrence of scar at a

later date.



I#%er2er&#s are known to reduce the production of ma!or scar forming growth factorT-%W. 6oth intravenous and intralesion in!ections of interferon have shown

significant clinical benefits on reducing hypertrophic scar and keloid. 3opularity todate is hampered by high cost and unfamiliarity with this approach. Agents that

inhibit collagen cross%linking would decrease scar rigidity and collagen deposition.The most promising agent in this category is topical putrescine, which has been

reported to decrease hypertrophic scars with no side effects.

Stimulation of 3roteolytic enzyme synthesis works by increasing the degradation rate

of collagen and matri" proteins. 'almodulin and protein kinase ' inhibitors havebeen shown to be somewhat effective, but further data are needed. 'alcium channel

blockers inhibit the incorporation of protein into e"tracellular matri" protein. Severalstudies have reported an increased rate of scar degradation.

G0 BURN WOUND CONTRACTURE

ypertrophic scar can lead to wound contracture if the scar crosses a !oint.

'ontracture is the result of shortening of the hypertrophic scar with time.

Ne$8 $&#%r$%"re

;ound contraction develops. This is produced the contractile myofibroblasts and the

deposition of ground substance and collagen%end result is a shortened noncompliantwound that, if it crosses a !oint, will result in contracture. The most common

contractures are essentially identical to the most common position abnormalities

produced with inade0uate motion:

• Fe<i&#: elbows, wrists, neck, interphalangeal !oints

• Add"$%i&#: shoulder

• E<%e#si&#: feet, metacarpophalangeal !oints

TREATMENT

A$%i9e #d Pssi9e E<er$ise



% #esistive

% Stretching

% 2ndurance

% Ambulation

Splinting to maintain position of function

REFERENCES

. Su ', Aladeh 1, )ee #. The problem scar. 'lin 3last Surg 99D:$G/ FG.

$. )adin 4A, -arner ;), Smith 4, !r. 2"cessive scarring as a conse0uence of

healing. ;ound #epair #egener 99F:&/ <%F.

&. 3owers 3 Sarkar S, -oldgaf 4, et al. Scar assessment: current problems and

future solutions.

6urn 'are #ehabil 999:$=/ GF%<=.

F. >essen , Spauven 3, Schalkwyk , 1on . 7n the nature of hypertrophic scarsand keloids: a review. 3last #econstr Surg 999:=F/ FF=%FGF.

G. Scott 3, -hahary A, 'hambers , et al. 6iological basis of hypertrophic scarring.Adv Structural 6iol 99F:&/ G@%<G.

<. 'lark , 'heng , )eung . echanical properties of normal skin and hypertrophicscars. 6urns 99<:$$/ FF&%FF<.

@. 2hrlich 3, 4esmouliese A, 4iegelmann #, et al. orphological andimmunochemical differences between keloid and hypertrophic scar. Am 3athol

99F:FG/ =G%&.

D. >edelce 6, Shankowsky, , Tredget . #ating the resolving hypertrophic scar/

comparison of the 5ancouver Scar Scale and Scar 5olume. 6urn 'are #ehabil$===:$/ $=G%$$.



9. )arabee ;, Sutton 4. A finite element model of skin deformity

what are the properties of normal skin

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