Flashcards in Wound healing and its impact on dressings and postoperative care Deck (61):
Acute wounds have been shown to heal 40% faster in a moist environment than when air exposed.
In moist wound healing of acute wounds, wound resurfacing occurs more rapidly because of a higher rate of mitosis.
F Because keratinocytes begin to migrate sooner.
Moist wound healing promotes a greater rate of vascularisation.
Dressings help establish a steep oxygen gradient, which stimulates capillary growth toward the more hypoxic centre.
The higher bacterial count in occlusive dressings predisposes to infection.
Occ dressings have higher bacteria count but lower rate of infection - 2.6% compared to non occlusive dressings - 7.1%
In contrast to acute wound fluid, chronic wound fluid is inhibitory to epithelialisation.
Chronic wounds have considerably lower protease activity than acute wounds.
Gauze, foams and alginates are types of absorptive dressings.
Hydrophilic types of non-adherent fabrics have greater occlusive capability, but hinder fluid drainage through them.
This is true for hydrophobic dressings, such as Telfa, Xeroform, Vasgauze, Jelonet, Bactigras (same as the others but impregnated with chlorhexidine)
Hydrophobic types of non-adherent dressings are less occlusive, but have the ability to readily facilitate the drainage of fluids and exudates into overlying dressings.
This is true for hydrophilic dressings eg. Mepitel, Adaptic, Xeroflo
Wide mesh gauze is usually not placed in direct contact with wounds because it adheres to the surface of the wound, resulting in pain on removal.
T Only exception is when mechanical debridement is desired
Gauze usually used over non-adherent, non-occlusive fabric dressings such as Xeroform
Foam dressings and alginates are both absorptive and occlusive/moisture-retentive dressings.
The moisture vapour transmission rate of wounded skin is 40 times higher than intact normal skin.
The primary advantage of foam dressings are that they can be used on wounds with unusual configurations and are highly absorptive.
T Eg. Allevyn, Mepilex
Should cover a 2cm margin around the wound edges
Too drying to use as primary dressing on dry wounds
Foam dressings are often used on dry wounds
F Because of their dehydrating capabilities they are not used on dry wounds
Film dressings do not contain acrylic adhesive.
F They are self adhesive.
Film dressings are permeable to oxygen, carbon dioxide and water, and impermeable to fluids and bacteria.
T Eg. Tegaderm
Generally used alone without a secondary dressing
The biggest disadvantage of film dressings is that they are non-absorptive, therefore fluid can collect under them.
Film dressings are recommended for patients with fragile skin, such as the elderly.
Film dressings should be used as the primary dressing of moderately to heavily exuding or infected wounds, sinus tracts, or cavities
Hydrocolloid dressings contain a hydrocolloid matrix consisting of materials such as gelatin, pectin, and carboxymethylcellulose.
T Eg. Duoderm, Comfeel.
Hydrocolloid dressings are permeable to water vapour, oxygen and carbon dioxide.
Hydrocolloids may initially cause the size of the wound to increase.
T Due to their debriding abilities. The skin around them may macerate
Can be reduced by applying zinc oxide to the wound margins
Hydrocolloids are associated with the formation of a yellow gel.
Gel has an unpleasant odour and can be confused with wound infection
Hydrocolloids are the dressing of choice for third degree burns and actively infected ulcers
Hydrogel dressings are available as gels, sheets or impregnated gauze.
T Eg. Solosite wound gel
Alginate dressings consist of the soft non-woven fibres of a cellulose-like polysaccharide derived from the calcium salt of seaweed.
T Eg. Algiste, Kaltostat.
Alginates should not be used for heavily exuding wounds.
Good for these but hydrofibre dressings better as more absorptive
Should not be used on dry or mildly exuding wounds
Alginates have haemostatic properties.
They form a gel after absorbing blood which can be foul smelling and mimic wound infection
Hydrofibre dressings are composed of soft, absorbent carboxymethyl cellulose fibres that interact with wound exudates to form a soft gel.
T Eg. Aquacel.
Alginates are three times more absorbent than hydrofibre dressings.
F Other way around
Hydrofibre best choice for heavily exuding wounds
Hydrofibre ribbons used to pack wound cavities
Alginated dressings are hydrophobic
Silver-impregnated dressings are bactericidal without antibiotics and maintain a moist environment to facilitate wound healing.
T Eg. Aquacel Ag, Acticoat
Maggot therapy is most efficacious in wounds infected with Gram-negative bacteria.
F Gram-positive eg. MRSA
The closed technique of wound dressing after laser surgery is associated with more rapid re-epithelialisation and less pain than the open technique.
After laser resurfacing there is pain, burning and stinging for the first few days, and during the first 1-2 days there is oozing of thermally denatured collagen
Bleeding frequently occurs after laser resurfacing
F Rare due to hemostatic action of the laser
The recommended ankle pressure in patients with venous ulcers of the leg is 50-60mmHg.
Occlusive dressings maintain a basic pH which inhibits bacterial growth
Mildly acidic pH which inhibits growth of some bacteria eg staph and pseudomonas
Acute wound fluid stimulates DNA synthesis in cultured skin cells
Chronic wound fluid does not
Moisture retentive occlusive wounds offer advantages for chronic wounds such as venous ulcers
Painless wound debridement
Containment of wound exudates
Absorptive dressings include;
All are non-adherent fabrics
Skin grafts and skin substitutes can be considered biologic dressings
Occlusive non-biological dressings include traditional types and new types
New types are
Hyaluronic acid dressings
Hydrocolloids are new type non-biological occlusive dressings
Foams and films are traditional type non-biological occlusive dressings
Dressings with a moisture vapour transmission rate of
Wounded skin has a moisture vapour transmission rate of 200g/m2
This is for intact normal skin
Wounded skin MVTR is 40x higher than this
Foams and gauze are both Absorptive and occlusive dressing types
Foams and aliginates are both types
Gauze is absorptive only
Foam dressings may be self adhesive or non-adhesive types
Can be used as primary dressing or secondary dressing to provide additional absorption or protective cushioning
Film dressings may be left in place for several days until a pocket of fluid accumulates under the dressing
They can reduce pain from the wound while in situ
When applying a hydrocolloid dressing the warmth of the hand can be used to help seal the dressing
Hydrogels consist of up to 80% water
Hydrophilic polymer + water
Polymer is usually starch type such as polyethylene oxide
Hydrogels are good for heavily exudative wounds
Good for superficial wounds with mild exudate such as post dermabrasion or peel or for dry or necrotic wounds
Hydrogels should be changed daily
Change every 3 days for necrotic wounds and every 7 days for granulating wounds
Collagen dressings are derived from cow hide
Consist of type 1 bovine collagen
Provide a collagen matrix for cellular migration
Hyaluronic acid dressings are biodegradable absorbent polymers that form a hydrophilic gel with the wound exudate
Accelerate the formation of granulation tissue and re-ethelialization
Honey increases healing in venous ulcers when used with compression
Honey may be better than conventional dressings in partial thickness burns
But delays healing when compared with early excision and grafting of partial and full thickness burns
Aloe Vera delays wound healing by secondary intention
No evidence for use of aloe Vera on skin wounds