Wound dressings - Adhe-Els
Wound dressings - Adhe-Els
Wound dressings - Adhe-Els
You also want an ePaper? Increase the reach of your titles
YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.
<strong>Wound</strong> <strong>dressings</strong><br />
Nicholas F S Watson<br />
Wendy Hodgkin<br />
The rational use of <strong>dressings</strong> for wound healing by secondary intention<br />
is the focus of this contribution, which should be read with<br />
‘Classification and management of acute wounds’, page 47.<br />
Practical selection of dressing<br />
There is a lack of high-quality research data regarding the relative<br />
efficacy of the various <strong>dressings</strong>, so the choice of <strong>dressings</strong> used in<br />
everyday practice in the UK is often based on familiarity, personal<br />
preference and cost.<br />
<strong>Wound</strong> care and dressing selection should be a holistic, structured<br />
process involving close cooperation between medical and<br />
nursing staff. Three factors must be considered when assessing<br />
the requirement for a wound dressing:<br />
general health of the patient<br />
local environment of the wound<br />
specific properties of the dressing.<br />
Patient factors<br />
Patients should undergo systematic assessment to address the<br />
underlying cause of their wound. Factors that may delay the healing<br />
process must be addressed, and may include ensuring that:<br />
nutritional intake is sufficient<br />
anaemia and electrolyte imbalances are corrected<br />
diabetic control is optimized<br />
appropriate pressure-relieving equipment is provided<br />
systemic infection is treated<br />
foreign bodies are removed<br />
peripheral oedema is reduced<br />
smoking is stopped.<br />
Some factors may not be easily resolved (e.g. advanced malignancy,<br />
previous radiotherapy), and this should be considered when monitoring<br />
progress of the wound.<br />
If the patient has to manage the wound himself, assessment<br />
should also include factors such as co-ordination, continence and<br />
general cognitive function, any of which may alter the final selection<br />
of the dressing.<br />
Nicholas F S Watson is a Research Fellow in Colorectal Surgery in the<br />
Department of Surgery, Queen’s Medical Centre, Nottingham, UK.<br />
Wendy Hodgkin is a Clinical Nurse Specialist in tissue viability<br />
for Nottingham Primary Care Trusts and Queen’s Medical Centre,<br />
Nottingham, UK.<br />
SURGERY 23:2<br />
BASIC SKILLS<br />
52<br />
The local environment of the wound<br />
<strong>Wound</strong>s can be divided into four categories (Figure 1) based on<br />
their appearance and stage of healing. Each wound type has slightly<br />
different characteristics and a wound healing by secondary intention<br />
will progress through these different stages over time. There is<br />
no ‘one size fits all’ dressing, hence wounds must be re-evaluated<br />
regularly in order to identify and respond to any changes.<br />
Necrotic wounds (Figure 1a) are usually black or dark green and<br />
contain devitalized tissue. Infected necrotic wounds require sharp<br />
surgical debridement back to viable tissue in order to prevent<br />
systemic sepsis. In the absence of infection, necrotic tissue will<br />
eventually separate from the wound bed by autolysis. Necrotic<br />
wounds are particularly susceptible to dehydration, and autolysis<br />
is inhibited if the wound is allowed to dry out; the main priority<br />
of a dressing is to maintain sufficient moisture in the local environment<br />
of the wound.<br />
Sloughing wounds (Figure 1b) contain a mixture of leukocytes,<br />
wound exudate, dead bacteria and fibrin, typically forming a glutinous<br />
yellow layer of tissue over the wound. The presence of slough<br />
predisposes to wound infection because it provides a nutrient-rich<br />
environment for bacterial proliferation. The formation of granulation<br />
tissue is delayed in a sloughing wound compared with a clean<br />
wound, and hence the optimal dressing will contribute towards<br />
wound debridement and maintenance of a clean wound bed.<br />
Granulating wounds (Figure 1c) are highly vascularized and<br />
are a rich pink or red colour. The amount of exudate produced<br />
is often substantial, and a dressing with the capacity to absorb<br />
excess exudate is desirable. Significant heat loss may occur with<br />
wounds covering large areas, requiring a dressing with insulating<br />
properties.<br />
Overgranulating wounds have the following properties, they:<br />
contain excessive friable granulation tissue<br />
are prone to recurrent episodes of bleeding<br />
suffer from delayed epithelialization.<br />
In this situation, caustic pencils containing silver nitrate or topical<br />
corticosteroid can be applied directly to the affected areas in order<br />
to control the excess tissue.<br />
Epithelializing wounds (Figure 1d) contain new epithelial tissue<br />
(formed by migration of keratinocytes from the wound margins)<br />
or contain islands of tissue (formed from skin appendages in the<br />
wound bed). The main priorities for dressing are the maintenance<br />
of a warm, moist environment around the wound, and the use<br />
of low-adherence <strong>dressings</strong> (see below) to minimize the trauma<br />
of dressing changes. In addition to the type of wound, the location,<br />
size and depth of the wound may vary considerably. Along<br />
with the condition of the surrounding skin, these should also be<br />
considered when deciding the most suitable dressing.<br />
Dressing factors<br />
The ‘ideal’ properties of a dressing for optimal wound healing are<br />
listed in Figure 2. No product fits this profile exactly, so dressing<br />
selection should address the most important factors identified in<br />
a particular clinical scenario.<br />
Dressings can be grouped into broad categories because many<br />
have similar actions and characteristics (Figure 3).<br />
© 2005 The Medicine Publishing Company Ltd
1<br />
2<br />
SURGERY 23:2<br />
BASIC SKILLS<br />
<strong>Wound</strong> appearances in different stages of healing by secondary intention<br />
a Necrotic wound. b Sloughy wound.<br />
c Granulating wound.<br />
Properties of the ‘ideal’ wound dressing<br />
Maintains a moist environment around the wound<br />
Removes excess exudate, but prevents saturation of the dressing<br />
to its outer surface (‘strike through’)<br />
Permits diffusion of gases<br />
Protects wound from micro-organisms<br />
Provides mechanical protection<br />
Controls local temperature and pH<br />
Is easy and comfortable to remove/change<br />
Minimizes pain from the wound<br />
Controls wound odour<br />
Is cosmetically acceptable<br />
Is non-allergenic<br />
Does not contaminate the wound with foreign particles<br />
Is cost effective<br />
53<br />
d Epithelializing wound.<br />
Tulle <strong>dressings</strong> (e.g. Paratulle, Bactigras, Jelonet) are cotton<br />
or viscose gauze <strong>dressings</strong> impregnated with paraffin (antiseptic<br />
or antibiotic may also be incorporated). Paraffin lowers the dressing<br />
adherence, but this property is lost if the dressing dries out.<br />
The hydrophobic nature of paraffin prevents absorption of moisture<br />
from the wound, and frequent dressing changes are usually<br />
needed. Skin sensitization is also common in medicated types.<br />
Tulle <strong>dressings</strong> are mainly indicated for superficial clean wounds,<br />
and a secondary dressing is usually needed.<br />
Low-adherence <strong>dressings</strong> (e.g. Melolin, Mepore, Mepitel)<br />
are manufactured from materials ranging from knitted viscose to<br />
polyester fabric. Built-in perforations reduce adherence between<br />
the dressing and the wound surface. Removal is easy with little<br />
or no trauma, but they have minimal absorptive capacity and are<br />
unsuited for all but lightly exudating and superficial wounds.<br />
Hydrocolloids (e.g. Granuflex, Comfeel, Tegasorb) contain a<br />
hydrocolloid matrix of gelatin, pectin and cellulose mixed together<br />
to form a waterproof adhesive dressing that interacts with the<br />
© 2005 The Medicine Publishing Company Ltd
3<br />
Main types of wound <strong>dressings</strong><br />
SURGERY 23:2<br />
Tulle <strong>dressings</strong><br />
Low-adherence <strong>dressings</strong><br />
Hydrocolloids<br />
Hydrofibres<br />
Hydrogels<br />
Films<br />
Foams<br />
Alginates<br />
Mechanical devices<br />
Bioactive/biological <strong>dressings</strong><br />
wound bed. Exudates produced by the wound absorb into the<br />
dressing, which dissolves and forms a gel. The moisture from<br />
this gel enhances autolytic debridement of necrotic and sloughing<br />
tissues and promotes the formation of granulation tissue. Hydrocolloid<br />
<strong>dressings</strong> absorb light-to-moderate levels of exudate, do not<br />
require a secondary dressing, and are shower-proof.<br />
Hydrofibres (e.g. Aquacel) are produced from similar materials<br />
to hydrocolloids and also form a gel on contact with the wound, but<br />
are softer and more fibrous in appearance, with a greater capacity<br />
to absorb exudate. Moisture from the gel assists in debridement<br />
and facilitates non-traumatic removal.<br />
Hydrogels (e.g. Intrasite, Nu-gel, Aquaform) consist of starch<br />
polymers with a very high intrinsic content of water. They conform<br />
to wounds with unusual shapes due to their gel-like nature. In<br />
contrast to hydrofibres, hydrogels are used primarily to donate<br />
fluid to dry necrotic and sloughing wounds, and their absorbency<br />
is limited. A secondary dressing is usually needed.<br />
Films (e.g. Opsite, Tegaderm, Bioclusive) are made from a<br />
thin polyurethane film coated with adhesive. Film <strong>dressings</strong> are<br />
highly comfortable, shower-proof and their transparency allows for<br />
wound monitoring without dressing removal. Vapour-permeable<br />
films allow diffusion of gases and water vapour, but are minimally<br />
absorbent. Problems can arise if these <strong>dressings</strong> are applied to<br />
heavily exudating wounds because fluid tends to accumulate<br />
underneath the film, leading to maceration of the wound and<br />
the surrounding skin. Films are thus suited to superficial, lightly<br />
exudating or epithelializing wounds.<br />
Foam <strong>dressings</strong> (e.g. Lyofoam, Allevyn, Tielle) are constructed<br />
from polyurethane and absorb exudate without interacting<br />
with the wound bed. They absorb low-to-moderate amounts of fluid<br />
and usually have a semi-permeable backing to allow the escape of<br />
moisture. Foams do not require a secondary dressing and are often<br />
used as an outer dressing with other products (e.g. hydrogels).<br />
Alginates (e.g. Sorbsan, Kaltostat, Algisite) are derived<br />
from a calcium salt of alginic acid, producing highly absorbent<br />
<strong>dressings</strong> suitable for heavily exudating wounds; some alginates<br />
also possess haemostatic properties. As they absorb exudate,<br />
BASIC SKILLS<br />
54<br />
alginates change from a soft fibrous texture into a gel, facilitating<br />
easy removal and preventing dressing fibres from contaminating<br />
the wound. Alginates are manufactured as flat sheets or as rope,<br />
and are suitable for packing cavities.<br />
Odour-reducing <strong>dressings</strong> (e.g. Clinisorb, Actisorb) are used<br />
primarily for fungating, infected and gangrenous wounds where<br />
malodour is a particular problem. They usually contain charcoal<br />
and should not be cut into because the charcoal fibres may shed<br />
into the wound.<br />
Dressings containing iodine(e.g. Inadine, Iodosorb,<br />
Iodoflex) come in two forms, as povodine–iodine impregnated<br />
into a low-adherent dressing or <strong>dressings</strong> containing concentrated<br />
cadexomer iodine paste. They possess broad antibacterial activity<br />
and are indicated for infected or heavily colonized wounds.<br />
Iodinated <strong>dressings</strong> should be removed when they change colour<br />
from brown to white (indicates uptake of available iodine). Systemic<br />
absorption of iodine can be significant with prolonged use,<br />
especially if used in wounds with a large surface area. Hence,<br />
these <strong>dressings</strong> should be avoided in patients with a history of<br />
thyroid disorders.<br />
Dressings containing silver exist in many different formulations, and<br />
exhibit a broad antibacterial spectrum. They are often used in burn<br />
wounds, and are also indicated for infected and heavily colonized<br />
wounds. Their use is occasionally limited by hypersensitivity.<br />
A summary of the most commonly used primary wound <strong>dressings</strong><br />
for different wound types is shown in Figure 4.<br />
Mechanical devices<br />
In the UK, the most commonly used mechanical device in wound<br />
care is the vacuum-assisted closure device, which applies topical<br />
negative pressure (50–125 mmHg) spread evenly over the<br />
wound bed. A specialized open-pore foam dressing is cut to fit<br />
the wound dimensions and is then attached to a vacuum pump<br />
unit via tubing placed under an occlusive secondary dressing.<br />
Vacuum-assisted closure is extremely effective in removing<br />
exudate and reducing oedema in the surrounding tissue, while<br />
leaving the surface of the wound moist. Local blood flow to the<br />
wound is improved, with a subsequent increase in vascularity of<br />
the wound bed and formation of granulation tissue. The wound<br />
is completely sealed to the external environment and, because<br />
exudate is removed, bacteria are drawn away, and the risk of<br />
wound sepsis is reduced.<br />
Vacuum-assisted closure is used in the management of large<br />
or deep wounds where very high levels of exudate are produced<br />
which would quickly overwhelm conventional <strong>dressings</strong>. Necrotic<br />
wounds or those with thick, dry slough require adequate debridement<br />
before vacuum-assisted closure can be applied.<br />
Vacuum-assisted closure is contraindicated in:<br />
wounds with exposed blood vessels or organs<br />
unexplored fistulas<br />
untreated osteomyelitis<br />
local malignancy.<br />
Biological <strong>dressings</strong><br />
Larvae (LarvE) of the common greenbottle fly (Lucilia sericata)<br />
are bred in sterile conditions. These larvae are necrophagous<br />
© 2005 The Medicine Publishing Company Ltd
4<br />
Dressings for different wound types<br />
SURGERY 23:2<br />
Dry necrosis<br />
Dry slough<br />
Wet, loose slough<br />
Granulating<br />
Epithelializing<br />
Infected<br />
Malodorous<br />
Fungating<br />
*Requires secondary dressing<br />
(avoiding healthy, viable tissues) and are very effective in treating<br />
sloughing and necrotic wounds. The number of larvae applied is<br />
relative to the size of the wound, and they are usually left in situ<br />
for three days. The larvae feed by a process of extracorporeal digestion,<br />
secreting various enzymes that break down the dead tissue to<br />
an ingestible consistency. Larvae also possess direct antibacterial<br />
activity, although the exact mechanism for this is unknown.<br />
Side-effects (physical discomfort, transient pyrexia, bleeding)<br />
are rare. Larvae therapy is contraindicated in wounds that connect<br />
with body cavities.<br />
‘Skin-substitute’ <strong>dressings</strong> (e.g. Integra, Alloderm) are<br />
increasingly finding clinical application in the UK, but their use<br />
is restricted to the specialist setting.<br />
BASIC SKILLS<br />
Superficial wound<br />
Cavity wound<br />
Sinus cavity<br />
Treat with systemic<br />
antobiotics<br />
Check for signs of infection<br />
and treat if appropriate with<br />
systemic antibiotics<br />
No infection<br />
Bleeding<br />
Not bleeding<br />
55<br />
UK guidelines<br />
Hydrogel*<br />
Hydrocolloid<br />
Saline-soaked hydrofibre*<br />
Dry hydrofibre*<br />
Larvae (seek<br />
specialist advice)<br />
Foam<br />
Hydrocolloid<br />
Hydrofibre<br />
Alginate<br />
Low adherent*<br />
dressing<br />
Hydrocolloid*<br />
Film<br />
Dressing containing<br />
silver or iodine<br />
Deodorizing dressing*<br />
(consider debridement if<br />
appropriate)<br />
Haemostat (i.e. alginate)*<br />
Treat as above, but<br />
consider non-adherent<br />
primary layer to reduce<br />
risk of bleeding<br />
Current guidance from the UK National Institute for Clinical Excellence<br />
on the use of debriding agents and specialist wound care<br />
clinics for difficult-to-heal surgical wounds states that ‘although<br />
there is no randomized controlled trial evidence to support any<br />
particular method, both modern <strong>dressings</strong> which promote autolytic<br />
debridement and larvae therapy may reduce pain and be more<br />
acceptable to patients when compared with traditional <strong>dressings</strong>’.<br />
They also advise that the individual choice of dressing should<br />
consider aspects related to patient acceptability, type and location<br />
of wound, and total costs. u<br />
© 2005 The Medicine Publishing Company Ltd