SURGICAL DRESSING

Treatment of wounds originally consisted of homemade remedies and evolved very little for many years.

In 1867, Lister introduced antiseptic dressings by soaking lint and gauze in carbolic acid.

The main purpose of wound dressings is to provide the ideal environment for wound healing.

The dressing should facilitate the major changes taking place during healing to produce an optimally healed wound.

Table 9-8 Desired Characteristics of Wound Dressings

Promote wound healing (maintain moist environment)ComfortabilityPain controlOdour controlNon-allergenic and non-irritatingPermeability to gasSafetyNon-traumatic removalCost-effectivenessConvenience

PRINCIPLES Covering a wound with a dressing mimics the barrier

role of epithelium and prevents further damage. In addition, application of compression provides

hemostasis and limits edema. Occlusion of a wound with dressing material helps

healing by controlling the level of hydration and oxygen tension within the wound.

It also allows transfer of gases and water vapour from the wound surface to the atmosphere.

Occlusion affects both the dermis and epidermis, and it has been shown that exposed wounds are more inflamed and develop more necrosis than covered wounds.

Occlusion also helps in dermal collagen synthesis and epithelial cell migration and limits tissue desiccation.

As it may enhance bacterial growth, occlusion is contraindicated in infected and highly exudative wounds.

Dressings can be classified as primary or secondary. A primary dressing is placed directly on the wound

and may provide absorption of fluids and prevent desiccation, infection, and adhesion of a secondary dressing.

A secondary dressing is one that is placed on the primary dressing for further protection, absorption, compression, and occlusion.

Two concepts that are critical in selecting appropriate dressings for wounds are occlusion and absorption.

Winter and colleagues published a study demonstrating that the rate of epithelialization under an occlusive dressing was twice that of a wound that was left uncovered and allowed to dry.

Placement of an occlusive dressing over the wound provides a mildly acidic pH and low oxygen tension on the wound surface.

The steep oxygen gradient is a good environment for proliferation of fibroblasts and formation of granulation tissue.

absorption would be beneficial in wounds that have a significant amount of exudate or wounds with high bacterial counts.

The skin surrounding the wound can become macerated with large amounts of uncontrolled exudate.

These wounds require a dressing that reduces the bacterial load within the wound while removing the exudate produced.

Placement of a pure occlusive dressing without bactericidal properties will allow bacterial overgrowth and worsen the infection.

Wound dressings can be categorized into four classes: nonadherent fabrics absorptive dressingsocclusive dressings creams, ointments, and solutions

1 Non adherent fabricare generally fine-mesh gauze supplemented

with a substance to augment its occlusive properties or antibacterial abilities.

2 Absorptive dressingsused mainly for wounds that produce a

significant amount of exudateWide-mesh gauze is the oldest of this type of

dressing and is very absorbent, but it loses its effectiveness when saturated.

NON ADHERENT DRESSING

ABSORPTIVE DRESSING

Newer materials such as foam dressings provide the absorbent qualities to remove large quantities of exudate and have a nonadherant quality to prevent disruption of newly formed granulation tissue on removal.

Examples are :Lyofoam , Curafoam, Flexzan, and VigiFOAM

Wound healing beneath absorptive dressings appears to be slower than under occlusive dressings, possibly because of wicking of cytokines from the wound bed or decreased keratinocyte migration.

3 Occlusive dressingprovides moisture retention, mechanical

protection, and a barrier to bacteria. The occlusive class can be divided into

biologic and nonbiologic dressings. Examples of biologic dressings are allograft,

xenograft, amnion, and skin substitutes. Pigskin is the most commonly used xenograft.

OCCLUSIVE AND SEMI OCCLUSIVE DRESSING

Homografts and xenografts are temporary dressings in that both are rejected if left on a wound for an extended period.

Amnion is derived from human placentas. These dressings are often used in the treatment of burn wounds.

newest type of wound dressings are skin substitutes that can be used for structural support and scaffolding for regeneration. Examples include :

Integra - Integra is a bilayer membrane system for skin

replacement. The first layer is made of a porous matrix of cross-

linked bovine tendon collagen and a GAG (chondroitin 6-sulfate).

The second layer is made of synthetic polysiloxane polymer (silicone) and functions to control moisture loss from the wound.

The first layer serves as a template for the infiltration of fibroblasts, macrophages, lymphocytes, and capillaries from the wound bed.

During the healing process, a new collagen matrix is deposited by fibroblasts and the dermal layer of the template is degraded.

Once vascularization of the dermal layer is complete, a thin autograft can be applied after removal of the silicone layer.

Alloderm is an acellular dermal matrix derived from donated

human skin tissue. It provides the matrix for revascularization and incorporation into host tissue.

Apligraf is a living, bilayered biologic dressing that has been

designed to simulate normal skin. Initially, neonatal-derived dermal fibroblasts are

cultured in a collagen matrix for 6 days. Human keratinocytes are then cultured on top of this neodermis.

The dressing contains matrix proteins and expresses cytokines.It does not contain melanocytes, Langerhans cells, macrophages, lymphocytes, or the adnexal structures normally present in human skin.

4. Creams, ointments, and solutions. This is a broad category that extends from

traditional materials, such as zinc oxide paste, to cutting-edge preparations containing growth factors.

The various categories include those with antibacterial properties such as acetic acid, Dakin's solution, silver nitrate, mafenide (Sulfamylon), silver sulfadiazine (Silvadene), iodine-containing ointments (Iodosorb), and bacitracin.

They are indicated when clinical signs of infection, such as an increase in exudate or cellulitis, are present or if quantitative culture demonstrates greater than 105 organisms per gram of tissue.

Types of surgical dressingA. POLYMERIC FILM

Opsite Bioclusive Tegaderm• They are transparent dressing for sutured

wounds or donor sites.• Their advantages are:Barrier to bacteria including MRSAReduce the risk of macerationReduce the risk of blistering

Reduce pain on removalWaterproof  ,conformable and comfortable to

wearManage exudate through a highly absorbent pad

and breathable filmEasy to apply and remove asepticallyAllow constant monitoring on the wound and peri-

wound area are permeable to gases such as water vapour

and oxygen but impermeable to larger molecules including proteins and bacteria.

This property enables insensible water loss to evaporate, traps wound fluid enzymes within the dressing, and prevents bacterial invasion. 

Transparent film dressings were found to provide the fastest healing rateslowest infection ratesmost cost-effective method for dressing split-

thickness skin graft donor sites.

OPSITE

OPSITE TEGADERM

B FOAMS silastic foams can be shaped to fit deep cavities

and granulating wounds.It is absorbent and non adherent. They consist of two layers, a hydrophilic silicone

or polyurethane-based foam that lies against the wound surface, and a hydrophobic, gas permeable backing to prevent leakage and bacterial contamination.

Some foams require a secondary adhesive dressing.

FOAM

Advantages of foams include their high absorptive capacity and the fact that they conform to the shape of the wound and can be used to pack cavities.

Minimize maceration of peri-wound edges (can be used in areas of fragile skin)

Can be used under compression . Disadvantages of foams include the opacity of the

dressings and the fact that they may need to be changed each day.

Foam dressings may not be appropriate on minimally exudative wounds, as they may cause desiccation.

c. ALGINATES Natural complex polysaccharides from various types

of algae form the basis of alginate dressings. Their activity as dressings is unique because they

are insoluble in water, but in the sodium-rich wound fluid environment these complexes exchange calcium ions for sodium ions and form an amorphous gel that packs and covers the wound.

Alginates come in various forms including ribbons, beads, and pads.

 these dressings are more appropriate for moderately to heavily exudative wounds.

ALGINATES

Advantages augmentation of hemostasis they can be used for wound packingmost can be washed away with normal saline in order to

minimize pain during dressing changesthey can stay in place for several days.

Disadvantagesthey require a secondary dressing that must be

removed in order to monitor the wound they can be too drying on a minimally exudative woundthey have an unpleasant odor

D. HYDROCOLLOIDS consist of a gel or foam on a carrier of self-

adhesive polyurethane film. The colloid composition of this dressing traps

exudate and creates a moist environment. Bacteria and debris are also trapped, and

washed away with dressing changes in a gentle, painless form of mechanical debridement.

Another advantage of hydrocolloids is the ability to use them for packing wounds

DisadvantagesMal-odourDaily dressing change Allergic dermatitis.

Cadexomer iodine is a type of hydrocolloid in which iodine is dispersed and slowly released after it comes in contact with wound fluid.

The concentration of iodine released is low and does not cause tissue damage

Hydrocolloid products include DuoDERM, Tegasorb, J and J Ulcer Dressing, and Comfeel.

E. HYDROGELS Hydrogels are a matrix of various types of

synthetic polymers with >95 percent water formed into sheets, gels, or foams that are usually sandwiched between two sheets of removable film.

The inner layer is placed against the wound, and the outer layer can be removed to make the dressing permeable to fluid.

 These unique matrices can absorb or donate water depending upon the hydration state of the tissue that surrounds them.

Hydrogel products include Intrasite Gel, Vigilon, Carrington Gel, and Elastogel.

Hydrogels are most useful for dry wounds. They initially lower the temperature of the

wound environment they cover, which provides cooling pain relief for some patients.

hydrogels have been found to selectively permit gram-negative bacteria to proliferate .

HYDROCOLLOID AND HYDROGELS

F. HYDROACTIVE Hydroactive, the most recently developed

synthetic dressing, is a polyurethane matrix that combines the properties of a gel and a foam.

Hydroactive selectively absorbs excess water while leaving growth factors and other proteins behind .

G. ENZYMATIC Enzymatic debridement involves applying

exogenous enzymatic agents to the wound. collagenase may promote endothelial cell and

keratinocyte migration, thereby stimulating angiogenesis and epithelialization.

Streptokinase/ streptodornase helps in fibrynolysis and liquefy pus on chronic skin ulcer.

H. BIOLOGIC Maggot therapy can be used as a bridge between

debridement procedures, or for debridement of chronic wounds when surgical debridement is not available or cannot be performed.

Maggot therapy may also reduce the duration of antibiotic therapy in some patients.

Maggot therapy has been used in the treatment of pressure ulcers , chronic venous ulceration ,diabetic ulcers and other acute and chronic wounds .

maggot therapy has additional benefits, including antimicrobial action and stimulation of wound healing.

Dressing changes include the application of a perimeter dressing and a cover dressing of mesh (chiffon) that helps direct the larvae into the wound and limits their migration.

Larvae are generally changed every 48 to 72 hours.

The larvae can also be applied within a prefabricated “biobag”

TOPICAL THERAPY1. GROWTH FACTORSPlatelet derived growth factor

 Becaplermin is a platelet-derived growth factor (PDGF) gel preparation that promotes cellular proliferation and angiogenesis.

 for the treatment of diabetic foot ulcers and chronic wounds, it is the only pharmacological agent approved.

It is delivered in a topical aqueous-based sodium carboxymethylcellulose gel.

It is indicated for noninfected diabetic foot ulcers

Epidermal growth factortopical application of human recombinant

epidermal growth factor was associated with a greater reduction in ulcer size and higher ulcer healing rate.

Granulocyte macrophage colony stimulating factor  Intradermal injections of granulocyte-

macrophage colony stimulating factor (GM-CSF) promote healing of chronic leg ulcers, including venous ulcers.

2. ANTISEPTIC AND ANTIMICROBIALSCadexomer iodine (eg, Iodosorb) is an

antimicrobial that reduces bacterial load within the wound and stimulates healing by providing a moist wound environment.

Cadexomer iodine is bacteriocidal to all gram-positive and gram-negative bacteria.

3. BETA BLOCKERS Keratinocytes have beta-adrenergic receptors,

and beta blockers may influence their activity and increase the rate of maturation and migration.

Timolol is a topically applied beta blocker with some limited evidence

SKIN SUBSTITUTESManufactured by tissue .they promote healing, either by stimulating host

cytokine generation or by providing cells that may also produce growth factors locally.

Their disadvantages include limited survival high cost need for multiple applications .

Desired Features of Tissue-Engineered Skin

Rapid re-establishment of functional skin (epidermis/dermis)

Receptive to body's own cells (e.g., rapid "take" and integration)

Graftable by a single, simple procedure

Graftable on chronic or acute wounds

Engraftment without use of extraordinary clinical intervention (i.e., immunosuppression)

Cultured epithelial autografts (CEAs) represent expanded autologous or homologous keratinocytes.

CEAs are expanded from a biopsy of the patient's own skin, will not be rejected, and can stimulate re-epithelialization as well as the growth of underlying connective tissue.

Keratinocytes harvested from a biopsy roughly the size of a postage stamp are cultured with fibroblasts and growth factors and grown into sheets that can cover large areas and give the appearance of normal skin

CEAs are available from cadavers, unrelated adult donors, or from neonatal foreskins

fibroblasts can be grown on bio-absorbable or non-bioabsorbable meshes to yield living dermal tissue that can act as a scaffold for epidermal growth.

Fibroblasts stimulated by growth factors can produce type I collagen and glycosaminoglycans (e.g., chondroitin sulfates), which adhere to the wound surface to permit epithelial cell migration, as well as adhesive ligands (e.g., the matrix protein fibronectin), which promote cell adhesion.

Indicated for use with standard compression therapy in the treatment of venous insufficiency ulcers and for the treatment of neuropathic diabetic foot ulcers

ReferencesSabiston test book of surgerySchwartz principles of surgery.Basic priniples of wound dressing-UPTODATE.

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