PHARMACOLOGY:WOUND DRESSINGS

September 11, 2012

Renan B. Navarro, MD

DIFFERENT CLASSIFICATIONS

Primary / Secondary dressingsPassive / Active / Interactive dressingsMoisture-retentive (occlusive / semi-occlusive)

Semirigid

DIFFERENT CLASSIFICATIONS(Primary / Secondary)

Primary dressing-also called contact layer-comes into direct contact with the wound- Ex. Band aid

Secondary Dressing-is placed over a primary dressing to provide

increased protection- Ex. Self-adhesive elastic Bandage

Primary & Secondary Dressings

(Passive / Active / Interactive Dressings)

Passive dressing- for protection, as protective dressing

Active dressing- promotes healing through the creation of a moist wound environment

Interactive dressing - not only creates a moist wound environment but interacts with the wound bed components to further enhance wound healing

Interactive Dressing

Enhanced wound healing due to:• reduce colonization count• reduce the level of exudates• improves wound bed moisture retention• improves wound collagen matrix• removes cellular products• provides protection for the epithelial bed

Interactive anti-microbial dressings - contain broad spectrum antimicrobials

• silver dressings – silver is an antimicrobial

• dressings with Polyhexamethylene Biguanide (PHMB) - antimicrobial that destroys pathogens (non-irritating to skin) • dressings with Cademoxer iodine - destroy pathogens while absorbing excess exudates preventing wound

infection

• bacteriostatic foam dressings – inhibit bacteria

• honey-based dressing

WHY MOIST WOUND HEALING?•

• moist wounds heal faster than dry wounds• prevent scab or crust formation over the wound

bed, it eliminates the energy and time for the body to break this down;

• reduce travel time for keratinocytes as they easily migrate across the moist wound bed

• traps enzymes at the wound bed facilitating autolytic debridement

• preserves growth factors and promotes collagen synthesis

MOISTURE-RETENTIVE DRESSINGS(OCCLUSIVE / SEMI-OCCLUSIVE)

1. Hydrogel (occlusive / semi- occlusive) - Amorphous gel. - 80-90% water or glycerin based - non-adhesive - permeable to gas and water

1. Hydrogel (occlusive / semi- occlusive)

Common Uses• Min-mod. exudating wounds

• Use to soften eschar and provide moist environment to dry wounds

• Wounds with 50% granulation

• Padding for splints and total casts

Advantages• Moisture retentive• Encourage autolytic debridement• Reduce pressure• Non- or minimally adherent

Disadvantages• May dehydrate• Require secondary dressing• Not used on infected wounds

1. Hydrogel (occlusive / semi- occlusive)

2. Transparent films (occlusive or semi-occlusive)• Hydrates dry wounds as well but is nonselective.• Allows air but not fluids.• waterproof sheet made of clear polyurethane, adhesive

coating on one side, highly elastic and conformable to body contours

• transparency allows visualization of wound bed, • semi-permeable films - permeable to water vapor gases

like oxygen and carbon dioxide, impermeable to bacteria and water

• for minor burns and scalds, simple wounds, partial thickness wounds, donor sites,

• <50% granulation

2. Transparent films (occlusive or semi-occlusive)Common Uses• Superficial wounds• Donor graft sites• Over intravenous catheters to allow bathing/whirlpool• Over wounds for ultrasound treatment

2. Transparent films (occlusive or semi-occlusive)Advantages• Moisture retentive• Encourage autolytic debridement• Reduce friction• Allow visualization of wound bed• Waterproof• Cheaper

Disadvantages• May traumatize periwound upon removal• Difficult to apply especially on larger areas• Not used on infected wounds

Hydrocolloid wafer dressing (occlusive or semi-occlusive)

• consisting of a combination of gel forming polymers that absorb exudates slowly

• provide thermal insulation and are impermeable to water and bacteria

• conforms to body shape

• available in paste, granules, and powder for cavities

• used for partial and full thickness wounds

• for pressure ulcers, burns donor sites and venous insufficiency ulcers, and small cavity wounds (paste, powder or granules are used)

• absorb fluid slowly so they are not suitable for bleeding wounds or heavily draining wounds

• should not be used in dry wounds, wounds with minimal drainage, or on wounds with exposed tendons and fascia

Hydrocolloid wafer dressing (occlusive or semi-occlusive)

• because of the occlusive nature, hydrocolloids are used only on patients with good skin integrity

• contain hydrophilic colloidal particles

• Absorb exudate slowly by swelling into a gel like mass

Hydrocolloid wafer dressing (occlusive or semi-occlusive)

Common Uses• Min-moderate exudates• Granular and necrotic wounds• Minor burns• Pressure ulcers• Venous insufficiency• Periwound to attach adhesive tape in the case of large wounds

Hydrocolloid wafer dressing (occlusive or semi-occlusive)

Advantages• Moisture retentive• Encourage autolytic debridement• Impermeable to urine, stool and bacteria• Provide thermal insulation• Waterproof

Hydrocolloid wafer dressing (occlusive or semi-occlusive)

Disadvantages• May traumatize fragile periwound upon

removal• Leave residue within wound bed• May cause hypergranulation• May roll in areas of friction• Not uses on infected wounds

Hydrocolloid wafer dressing (occlusive or semi-occlusive)

-made of polyurethane foam*Hydrophilic inside & Hydrophobic outside

Semipermeable foams (semi-occlusive)

Common Uses• Moderate-maximum exudates• Burns• Skin Grafts• Donor Sites• Ostomy sites• Pressure ulcers• Venous insufficiency• Neuropathic ulcers

Semipermeable foams (semi-occlusive)

Advantages• Moisture retentive• Encourage autolytic debridement• Thermal insulation• Provide cushioning

Disadvantages• May traumatize periwound upon removal• May roll in areas of friction• Not used on infected wounds unless changed

daily

Semipermeable foams (semi-occlusive)

Calcium alginate (occlusive)• From brown sea weeds converted into

calcium/sodium salts• are made from natural polysaccharide fibers

derived from processed seaweed • highly absorbent and conforms to any shape• because they have no adhesive properties,

secondary dressings must be used• available in many forms and shapes and capable of

absorbing a large amount of exudate• when the dressing comes into contact with the

wound exudate, alginate forms a gel-like substance

Calcium alginate (occlusive)

• since it does not adhere to the wound site, pain and trauma in changing dressings are much less

• the gel is easily removed from the wound site by irrigation

• ideal for moderate to heavy draining wounds, for venous insufficiency ulcers, pressure ulcers, diabetic ulcers, surgical wounds, donor sites, and first and second degree burns

Calcium alginate (occlusive)

• ideal primary dressings for infected wounds

• can be used for granular and slough covered wounds

• unsuitable for dry and minimally draining wounds.

• unsuitable for full thickness third degree burns

• should not be used for wounds with exposed tendons or bones

Common Uses• Absorbs mod. - highly exudating wounds• Venous insufficiency ulcers• Tunneling wounds• Swabs used to probe, fill and measure wound depth

Calcium alginate (occlusive)

Advantages• Encourage autolytic debridement• Highly absorbent• Used on infected and uninfected wounds• Biocompatible

Disadvantages• Require secondary dressing• Used with extreme caution with exposed

tendon, capsule, bone to prevent desiccation

Calcium alginate (occlusive)

Foam dressings (semi-occlusive)

• absorbent dressings that may be adhesive or non-adhesive, and may be used as primary or secondary dressing

• formed from polymers such as polyurethane

• are able to trap moisture and permeable to gas

• absorb exudate and promote gaseous exchange and thermal insulation

Foam dressings (semi-occlusive)

• maybe removed without adding trauma to frail skin

• conforms to the shape • for granulating or sloughed-covered partial and

full-thickness with minimal to heavy exudates, minor burns, post-op sites, diabetic ulcers, and venous insufficiency ulcers, used under compression bandaging for amorphous hydrogels and alginates

• for infected wounds, foams should be changed daily

Foam dressings (semi-occlusive)

GAUZE DRESSINGS

(non-occlusive dressings allow all the moisture to escape from the surface of the wound leading to drying of the wound.)

The most readily available dressing, cost-effective, may be used as primary or secondary dressing.-

1. Standard Gauze (not impregnated)2. Impregnated Gauze

Standard Gauze dressingsStandard Gauze (not impregnated)• sterile / non-sterile• woven (from yarn) / non-woven (synthetic)• maybe used as primary or secondary wound

dressings

Standard Gauze dressings

Common Uses• Wound which requires frequent change = 6 hrs• For wounds with <50% granulation• Infected & non-infected wounds• Highly exudating wounds• Provide cushioning

Standard Gauze dressingsLimitations• Costly• May adhere to wound bed• Highly permeable• Higher infection rate than occlusive dressings • Readily available• Wet to dry – Min. exud. wounds• Continuous dry – Mod.&max. exud.• Continuous moist – Dry wounds

Impregnated Gauze Dressings• woven or non-woven materials • substances such as iodinated agents,

petrolatum, chlorhexadine gluconate (CHG), bismuth tribromophenate (BTP), water, aqueous saline, or other agents have been incorporated into the dressing material by the manufacturer.

• when left at the wound to dry they are called wet to dry dressings - sometimes used for mechanical debridement--not universally done

Impregnated Gauze Dressings• a moist dressing maybe allowed to adhere to

the necrotic tissue as it dries out to allow debridement; drawbacks:

1. non-selective because granulation tissue may also be removed with the necrotic tissue

2. fibers of the gauze may remain on the wound causing infection

3. the gauze dries out on the wound causing a painful change of dressing

Impregnated Gauze Dressings

• Gauze is impregnated with solution that promotes healing such as antiseptic, hydrogel or hypertonic saline solution. This requires a secondary dressing.

• Hypertonic solutions are infused with sodium

chloride that reeks moisture away from wounds- dependent on wound moisture to moisten and thus, not

appropriate for dry to minimally draining wounds or dry wounds covered with eschar

Impregnated Gauze DressingsImpregnated gauze dressings- maybe as a

contact layer for granulating wounds, helps exposed tendons from dehydrating

– ideal for burns, and wounds infected or non-infected of any size and shape

– if used for non- draining or minimally draining wounds, a topical agent should be applied to the wound bed to maintain a moist environment or the gauze may be moistened with normal saline

– for heavily draining wounds would need additional layers should be used to aid in absorption

Impregnated Gauze Dressings

SEMIRIGID DRESSINGS (for wounds in legs of ambulatory people)

1. Unna’s boot- for leg wounds (ulcers, sores, edema) -compression gauze containing zinc oxide paste and

other substances- pliable nonstretchable dressing impregnated with

ointmentsEx. Zinc oxide, calamine and gelatin-inexpensive means of covering the wounds-provides compression and supports the calf pump to

empty venous blood from the lower ext.

Unna’s boot

2. Total contact walking cast• A fiberglass shell with a bar on the bottom• Used to treat ulcers (serious, deep sores) on a

person's foot. • Protects the skin on the person's foot.• has only a small amount of padding around

the rest of the foot• Assist edema control• Allows weight bearing

Total contact walking cast

3. Posterior walking splint• for patients with fragile skin• a total contact cast that is bivalved to allow it to be removed for frequent monitoring of skin and wound

4. Profore

• Four layer compression bandage system used for venous leg ulcers

• consist of a cotton , crepe and 2 compression layers• Can be left in place for up to a week

Summary

• For dry / dessicated wound– Wet to wet – Hydrogel– Continuous moist– Transparent film

• For minimal exudating wound– Wet to dry– Hydrocolloid– Transparent film

• For moderate to maximum exudating– Dry to dry– Calcium alginate, semipermeable foams

• For highly exudating– Calcium alginate– Semipermeable dressing

THE END