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Wound dressings
Vanessa Jones, Joseph E Grey and Keith G Harding Updated information and services can be found at: References
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Wound dressings
Vanessa Jones, Joseph E Grey, Keith G Harding
Traditionally wet-to-dry gauze has been used to dress wounds.
Modern dressing technology is based on the principle of
Dressings that create and maintain a moist environment, creating and maintaining a moist wound environment
however, are now considered to provide the optimal conditionsfor wound healing. Moisture under occlusive dressings not onlyincreases the rate of epithelialisation but also promotes healing Characteristics of the ideal dressing
through moisture itself and the presence initially of a lowoxygen tension (promoting the inflammatory phase). Gauze x Capable of maintaining a high humidity at the wound site while does not exhibit these properties; it may be disruptive to the x Free of particles and toxic wound contaminants healing wound as it dries and cause tissue damage when it is removed. It is not now widely used in the United Kingdom.
x Capable of protecting the wound from further trauma Occlusive dressings are thought to increase cell proliferation x Can be removed without causing trauma to the wound and activity by retaining an optimum level of wound exudate, which contains vital proteins and cytokines produced in response to injury. These facilitate autolytic debridement of the wound and promote healing. Concerns of increased risk of infection under occlusive dressings have not been substantiated in clinical trials. This article describes wound dressings currently Low adherent dressings—suitable for use on flat, shallow
Low adherent dressings
wounds with low exudates
Low adherent dressings are cheap and widely available. Their Tulles—Bactigras, Jelonet, Paranet, Paratulle, Tullegras, Unitulle, major function is to allow exudate to pass through into a Textiles—Atrauman, Mepilex, Mepitel, NA Dressing, NA Ultra, secondary dressing while maintaining a moist wound bed.
Most are manufactured in the form of tulles, which are open weave cloth soaked in soft paraffin or chlorhexidine; textiles; ormultilayered or perforated plastic films.
They are designed to reduce adherence at the wound bed and are particularly useful for patients with sensitive or fragileskin.
Semipermeable films
Semipermeable films were one of the first major advances in Left: Healthy venous leg ulcer suitable for dressing with low adherent
wound management and heralded a major change in the way dressing. Right: Wound suitable for dressing with semipermeable film
wounds were managed. They consist of sterile plastic sheets ofpolyurethane coated with hypoallergenic acrylic adhesive and Semipermeable films
are used mainly as a transparent primary wound cover.
Examples include Bioclusive, Mefilm, OpSite Flexigrid,* OpSite Plus, Although they are impermeable to fluids and bacteria, they are permeable to air and water vapour, the control of which is x Suitable for flat, shallow wounds with low to medium exudates dependent on the moisture and vapour transmission rate, which varies depending on the brand. It is through this mechanism x Adhere to healthy skin but not to wound that this dressing creates a moist wound environment.
Films are very flexible and are good for wounds on “difficult” anatomical sites—for example, over joints. They are unable to cope with large amounts of exudate, however, and x Not for infected or heavily exuding wounds may cause maceration of the skin surrounding the wound bed if *Not available on prescription in UK primary care.
Hydrocolloids
Sodium carboxymethylcellulose, gelatin, pectin, elastomers, andadhesives are bonded to a carrier of semipermeable film or afoam sheet to produce a flat, occlusive, adhesive dressing thatforms a gel on the wound surface, promoting moist woundhealing. Cross linkage of the materials used influences the Venous leg ulcer suitable
viscosity of the gel under the dressing. This gel, which may be for dressing with
yellow and malodorous, may be mistaken for infection by the hydrocolloid
BMJ VOLUME 332 1 APRIL 2006
unwary. Hydrocolloids are virtually impermeable to water Hydrocolloid dressings (including hydrofibres)
vapour and air and can be used to rehydrate dry necrotic escharand promote autolytic debridement. They are reported to Type of dressing
reduce wound pain, and their barrier properties allow the patient to bathe or shower and continue with normal daily activities without disturbing or risking contamination of the wound. Caution should be exercised when using hydrocolloids for wounds that require frequent inspection—for example, for Hydrocolloid fibres are now available in the form of a hydrophilic, non-woven flat sheet, referred to as hydrofibre dressings. On contact with exudate, fibres are converted from a Useful in flat wounds, cavities, sinuses, dry dressing to a soft coherent gel sheet, making them suitable for wounds with a large amount of exudate.
high exudate wounds; highlyabsorbent; non-adherent; may be leftin place for several days; needssecondary dressing *Not available on prescription in UK primary care.
Foot wound complicated by
Hydrocolloid fibres (hydrofibres) are often used on
heterotopic calcification
wounds where, traditionally, alginates have been used
suitable for dressing with
hydrofibres
Hydrogels
Hydrogels
Hydrogels consist of a matrix of insoluble polymers with up to Examples include Aquaform, Intrasite, GranuGel, Nu-Gel, Purilon, 96% water content enabling them to donate water molecules to the wound surface and to maintain a moist environment at the x Supply moisture to wounds with low to medium exudate x Suitable for sloughy or necrotic wounds wound bed. As the polymers are only partially hydrated, x Useful in flat wounds, cavities, and sinuses hydrogels have the ability to absorb a degree of wound exudate, the amount varying between different brands. They transmit moisture vapour and oxygen, but their bacterial and fluid permeability is dependent on the type of secondary dressingused.
Hydrogels promote wound debridement by rehydration of non-viable tissue, thus facilitating the process of naturalautolysis. Amorphous hydrogels are the most commonly usedand are thick, viscous gels.
Hydrogels are considered to be a standard form of management for sloughy or necrotic wounds. They are notindicated for wounds producing high levels of exudate or wherethere is evidence of gangrenous tissue, which should be kept Dry, sloughy leg wound
dry to reduce the risk of infection.
suitable for dressing with
hydrogel
Alginates
Alginates
Alginates are produced from the naturally occurring calcium Examples include Algisite, Algosteril, Kaltostat,* Melgisorb, SeaSorb, and sodium salts of alginic acid found in a family of brown seaweed (Phaeophyceae). They generally fall into one of two x Useful in cavities and sinuses, and for undermining wounds kinds: those containing 100% calcium alginate or those that contain a combination of calcium with sodium alginate, usually Alginates are rich in either mannuronic acid or guluronic *Not available on prescription in UK primary care acid, the relative amount of each influencing the amount ofexudate absorbed and the shape the dressing will retain.
Alginates partly dissolve on contact with wound fluid to form ahydrophilic gel as a result of the exchange of sodium ions inwound fluid for calcium ions in the dressing. Those high inmannuronic acid (such as Kaltostat) can be washed off thewound easily with saline, but those high in guluronic acid (suchas Sorbsan) tend to retain their basic structure and should beremoved from the wound bed in one piece.
Diabetic foot ulcer with
maceration to
Alginates can absorb 15 to 20 times their weight of fluid, surrounding skin suitable
making them suitable for highly exuding wounds. They should for dressing with alginate
BMJ VOLUME 332 1 APRIL 2006
not be used, however, on wounds with little or no exudate as The ion exchange properties of some alginates make
they will adhere to the healing wound surface, causing pain and them useful haemostatic agents, and as such they are
particularly useful for postoperative wound packing
Foam dressings
Foam dressings
Foam dressings are manufactured as either a polyurethane or Type of dressing
silicone foam. They transmit moisture vapour and oxygen and Adhesive sheets: Allevyn Adhesive, provide thermal insulation to the wound bed. Polyurethane foams consist of two or three layers, including a hydrophilic wound contact surface and a hydrophobic backing, making them highly absorbent. They facilitate uniform dispersion of exudate throughout the absorbent layer and prevent exterior leakage (strike-through) due to the presence of a Non-adherent sheets: Allevyn,* Allevyn Polyurethane foam dressings are also available as a cavity dressing—small chips of hydrophilic polyurethane foamenclosed in a membrane of perforated polymeric film, giving a *Not available on prescription in UK primary care.
Silicone foams consist of a polymer of silicone elastomer derived from two liquids, which, when mixed together, form afoam while expanding to fit the wound shape forming a softopen-cell foam dressing. The major advantage of foam is theability to contain exudate. In addition, silicone foam dressingsprotect the area around the wound from further damage.
Venous leg ulceration
in background of
chronic oedema
Antimicrobial dressings
suitable for dressing
with foam
Silver, in ionic or nanocrystalline form, has for many years beenused as an antimicrobial agent particularly in the treatment ofburns (in the form of silver sulfadiazine cream). The recentdevelopment of dressings impregnated with silver has widenedits use for many other wound types that are either colonised orinfected.
Iodine also has the ability to lower the microbiological load in chronic wounds. Clinically it is mainly used in one of twoformats: (a) as povidone-iodine (polyvinylpyrrolidone-iodinecomplex), an iodophor (a compound of iodine linked to anon-ionic surfactant), which is produced as an impregnated Top left: Sloughy, infected
tulle; and (b) as cadexomer iodine (a three dimensional starch arterial ulcer suitable for
lattice containing 0.9% iodine). Cadexomer iodine has good dressing with compound
absorptive properties: 1 g of cadexomer iodine can absorb up antimicrobial dressing (silver
to 7 ml of fluid. As fluid is absorbed, iodine is slowly released, or iodine based). Top right:
Gangrenous foot suitable for
reducing the bacterial load and also debriding the wound of dressing with antimicrobial
debris. This mode of action facilitates the delivery of iodine over iodine impregnated dressing.
a prolonged period of time—thus, in theory, maintaining a Left: Malodorous malignant
melanoma ulcer suitable for
constant level of iodine in the wound bed.
treatment with topical
Caution is required in patients with a thyroid disease owing metronidazole
to possible systemic uptake of iodine. For this reason, thyroidfunction should be monitored in patients who are treated withiodine dressings.
Antimicrobial dressings
Metronidazole gel is often used for the control of odour caused by anaerobic bacteria. This is particularly useful in the management of fungating malignant wounds. It may be used alone or as an adjunct to other dressings.
Unwanted effects of dressings
Maceration of the skin surrounding a wound may occur if a dressing with a low absorptive capacity is used on a heavilyexuding wound. If the dressing is highly absorptive then morefrequent dressing changes may be needed, in addition to Inappropriate use of dressings may lead to
investigation and management of the cause of the exudate unwanted effects
BMJ VOLUME 332 1 APRIL 2006
The skin surrounding a highly exuding wound may be further protected through the use of emollients (such as 50:50mix of white soft paraffin and liquid paraffin) or the applicationof barrier films (such as Cavilon). Conversely, use of a highlyabsorptive dressing on a dry wound may lead to disruption ofhealthy tissue on the wound surface and cause pain whenremoved.
Allergic reactions are not uncommon: the dressing should be avoided, and the allergy may need to be treated with potenttopical steroids. Tapes used to keep dressings in place arecommon causes of allergy. Many dressings require secondarydressings—for example, padding on highly exuding Abdominoperineal resection wound treated with vacuum
wounds—which may make them bulky. Secondary dressings assisted closure. The skin edges are protected with a barrier
should not be too tight, especially on patients with peripheral cream to prevent maceration
Further reading
x Choucair M, Phillips T. A review of wound healing and dressings material. Skin and Aging 1998;6:(suppl):37-43.
x Hermans MH, Bolton LL. Air exposure versus occlusion: merits and disadvantages of different dressings. J Wound Care1993;2:362-5.
x Morgan DA. Wound management products in the drug tariff.
Pharmaceutical Journal 1999;263:820-5.
Left: Allergy to dressing used to treat arterial leg ulceration. Note
x Thomas S, Leigh IM. Wound dressings. In: Leaper DJ, Harding KG, erythematous skin with sharply demarcated edges corresponding to the
eds. Wounds: biology and management. Oxford: Oxford University shape of the offending dressing. Right: Ulceration over the anterior aspect
of the ankle caused by inappropriately tight bandage
x Turner TD. Development of wound management products in chronic wound care. In: Krasner D, Rodeheaver G, Sibbald RG, eds.
Chronic wound care: a clinical source book for healthcare professionals.
3rd ed. Wayne, PA: HMP Communications, 2001.
x Winter G. Formation of scab and the rate of epithelialisation of Vanessa Jones is senior lecturer at the Wound Healing Research Unit, superficial wounds in the skin of the young domestic pig. Nature The ABC of wound healing is edited by Joseph E Grey x Vermeulen H, Ubbink D, Goossens A, de Vos R, Legemate D.
(joseph.grey@cardiffandvale.wales.nhs.uk), consultant physician, Dressings and topical agents for surgical wounds healing by University Hospital of Wales, Cardiff and Vale NHS Trust, Cardiff, and secondary intention. Cochrane Database Syst Rev honorary consultant in wound healing at the Wound Healing Research Unit, Cardiff University, and by Keith G Harding, director ofthe Wound Healing Research Unit, Cardiff University, and professorof rehabilitation medicine (wound healing) at Cardiff and Vale NHSTrust. The series will be published as a book in summer 2006.
Competing interests: For series editors’ competing interests, see the firstarticle in this series.
“Seeing” is believing
“Your next batch of students arrive tomorrow,” the administrator positive and inspirational impact on the team, and “the trio” told me, “and one of them has a visual impairment.” became instantly recognisable in the hospital.
It turned out that 20 years previously he had had retinitis He relied on innovative ways to overcome his disability. For his pigmentosa diagnosed, and by the time he joined medical school medical boards (equivalent to MRCP), he used a reader and he was registered blind. My colleagues were sceptical about his scribe. During the anatomy exam, his palpation skills helped him choice of profession, and we pondered how best to deal with this to identify various parts on the cadaver. Since he had become situation and what impact his presence would have on the rest of blind in adulthood, he did not read Braille and instead consulted audiobooks and e-text. The most amazing development has been I met him the next day. Tall and elegant, he radiated a calm JAWS, a computer program that allows him to “write” case notes, confidence. Accompanying him every step of the way was his search the internet, and respond to emails.
guide dog, and a fellow medical student relayed the case notes to I had great respect and admiration for this remarkable medical him (forming “the trio,” as I soon called them). His history taking student and indicated that to him at our last meeting. To skills turned out to be excellent, and he was able to extract overcome such personal hardship and, against all odds, choose to important information that had been missed by earlier students.
study medicine required strength of character and conviction that He picked up all the findings on palpation and auscultation. The many of us lack. He graduated recently and is now training to be hepatic bruit is a specific sign of alcoholic hepatitis but can be a psychiatrist. Before I met him, if someone had asked my difficult to hear even for experienced hepatologists—but he never opinion about a blind student training to be a doctor, I would nothave been optimistic. I guess “seeing” is believing.
missed one. During ward rounds, I was impressed by how well heconnected with his patients and how comfortable they seemed Sumita Verma locum consultant, liver and antiviral unit, St Mary’s with him. It was soon apparent that his presence was having a Hospital NHS Trust, London (sumitaverma6@hotmail.com) BMJ VOLUME 332 1 APRIL 2006

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