Wound care: selecting the right dressings

The management of wounds costs the NHS £5.3 billion a year. There is a plethora of dressings to choose from, yet failure to accurately assess a wound and choose the right dressing will delay healing, cause distress to the patient and incur cost

Modern day dressings have evolved dramatically over the last few years, providing the clinician with an immense range of dressings to choose from, all of which support a segment of the wound healing continuum and specific wound care requirements. This plethora of wound care products also has the potential to lead to confusion, resulting in inaccurate dressing selection and potentially inappropriate use.

Wound dressings are chosen for an assortment of reasons, including odour, pain and exudate control, prevention or management of wound infection, as well as rapid and cosmetically acceptable wound healing.¹ Any choice of dressing needs to minimise potential distress to the patient and take cost implications into consideration. Because of the abundance of dressing choices most trusts have wound care formularies. These provide guidance to the clinical dressing user by limiting the range of dressing choice and categorising them into the appropriate section depending on their mode of action. Dressing evaluations usually take place to prove efficacy prior to formulary inclusion and holistic costs will have been considered.

Patients with wounds cost the NHS £5.3 billion a year. However, only a small percentage of this is due to wound dressing costs. The remaining, larger percentage is spent on practice nurse, GP, community nurse and other specialist clinician visits, hospital in- and out- patient charges, prescription and device costs.²

ACUTE AND CHRONIC WOUNDS

There are two main types of wounds: acute and chronic. Generally, for acute wounds, healing will be fast, varying from 5-15 days depending on location and depth of the wound.³

Wounds are deemed to be chronic if the wound has been present for 4-6 or more weeks and the ‘normal’ wound healing process has been disrupted. However, if it is a recurring wound or has an underlying comorbidity it can be considered chronic from as early as 2 weeks, i.e. leg ulceration.⁴

WOUND CLOSURE

Wounds can be ‘closed’ in various ways:

• Primary intention – where the edges are brought together intentionally with glue, sutures, paper-strips or clips
• Secondary intention – where the wound is left to heal naturally, from the wound bed upwards, utilising appropriate wound dressings
• Tertiary intention – also known as delayed primary intention, where the wound is left open or reopened and then formally closed later.

MOISTURE BALANCE

Finding the most favourable balance of moisture enhances natural autolysis, which aids desloughing and debridement. This will promote faster healing and has the potential to reduce pain during the healing process.⁵

George Winter first introduced the concept of moist wound healing in 1962.⁵ His research demonstrated that epithelialisation was twice as fast in wounds covered with a film dressing than in those left to allow scab formation. The creation of an optimum, moist, wound healing environment allows epithelial cells to slide across the wound surface easily, allowing faster wound healing. In contrast, epithelial cells in exposed wounds had to ‘burrow’ beneath a dried scab in order to find enough moisture to enable them to slide across the wound surface to complete healing. This concept of favourable moisture balance in wound healing became prominent in the late 1980s and many wound care dressings are developed to ensure they provide the optimum, moist, wound healing environment.

PHASES OF HEALING

The four main phases of wound healing encompass:

1. Haemostasis

2. Inflammation

3. Proliferation

4. Maturation.

During the haemostatic phase, which may only last a few hours, platelets play a crucial role by aiding clot formation. The inflammatory phase, lasting up to 3 days, is the body’s natural response to trauma. White blood cells initiate the ‘cleaning’ process, removing wound debris by autolysis. Angiogenesis, epithelialisation and granulation take place during the proliferative phase, lasting up to 21 days. Maturation is the final phase, lasting up to 2 years. During maturation the wound is visibly healed but the cells are reorganising themselves and the presence of collagen is increasing the tensile strength of the scar.⁶

It is possible for more than one phase to be present in the same wound simultaneously and, during healing, for the phases to overlap. This is the normal progression of the wound healing process. Some wounds, however, become uncontrolled and the wound healing phases do not always advance. Any non-healing wound is likely to have regressed or become stuck in the inflammatory phase. Any clinician involved in wound care needs to be able to correctly identify the current phase of wound healing to enable the correct choice of treatments and dressings. Any incorrect selection can delay the wound healing process.³

To facilitate correct dressing selection a full, holistic assessment is required. Any underlying pathophysiological factors need to be addressed prior to progressing onto wound-specific information gathering. Patient concordance also needs to be considered. Different wound assessment frameworks allow a structured, effective and thorough wound appraisal. (See Activity 1) The main areas focus on determining the wound aetiology and any systemic factors that impact wound recovery, wound assessment and the status of the skin around the wound.⁷

WOUND TISSUE TYPES

Wound tissue types are often classified by clinicians according to colour, based on the wound healing continuum.⁸ The 5 main colours used are:

1. Black, for necrotic tissue

2. Green, for infected tissue

3. Yellow, for sloughy tissue

4. Red, for granulating tissue

5. Pink, for epithelial tissue.

To aid dressing selection many wound dressing companies have utilised these colours on their dressing packaging. Once the tissue type has been determined a course of action can be planned to allow effective wound bed preparation, which in turn will lead to wound healing.

If the wound bed is obscured by devitalised tissue, such as necrosis or slough, this needs to be removed. Desloughing or debridement can be achieved in various ways:

• Sharp or surgical debridement – needs to be done by a specialist
• Enzymatic – often non-selective and will therefore damage healthy tissue
• Mechanical – pressured irrigation or slough trapping dressings
• Biological – such as maggots
• Autolytic – a natural process occurring in an optimum, moist, wound healing environment created by the advanced technology within modern dressings.

BACTERIAL BALANCE AND INFECTION

All wounds contain bacteria and the bacterial balance must be maintained to allow healing to progress. The wound infection continuum aids the clinician to determine what type of intervention is required. Contamination and colonisation do not require antimicrobial dressings. However, if any classic signs of infection become visible, such as friable tissue, increased exudate, new or increasing pain, warmth, odour or purulent discharge, these are a clear indication of local infection. Antimicrobial dressings should be initiated for the presence of local infection with the addition of antibiotics if the infection spreads or becomes systemic.⁹ Any infection must be removed and bacterial balance restored to allow healing to progress.

EVIDENCE-BASED PRACTICE

It is essential that we use evidence-based practice, but finding the evidence to support dressing choice can sometimes be a challenge. How do we know when we have the right dressing for the patient?

Randomised controlled trials (RCTs) are a robust form of evidence. However, there are few of these within the wound care dressing arena. Case studies provide an alternative form of evidence, often with photographic verification of the wound healing progress, but consideration must be given to all variables that affect wound healing. Evidence via anecdotal peer support and individual clinician experience is also very valuable when determining the most appropriate dressing.

POINTS TO CONSIDER IN DRESSING SELECTION

The range of modern, advanced, wound care dressings is able to alleviate devitalised tissue by creating the optimum environment to allow autolytic debridement and desloughing. Their advanced technology allows rebalancing of bacteria, moisture and the uncontrolled inflammatory responses. They have the ability to absorb and donate moisture and protect new growth and fragile skin by being a truly non-adherent dressing.

If an unsuitable dressing is chosen it can delay the wound healing process. A suitable dressing can only be chosen once the aim of the dressing has been determined. What phase of wound healing is the wound in and what does the wound require currently? Does it need:

• Protection
• Restoration of bacterial balance
• Regulation of the matrix metalloproteinases (MMPs) when the inflammatory phase is uncontrolled
• Provision of the optimum moist wound healing environment to promote autolysis and odour control?

Not all wounds, however, can be healed. For example a fungating wound would require protection and potential odour control, or a haemostat.

It is essential to be aware of the dressing’s mode of action and any potential contraindications before use, such as avoiding honey dressings for uncontrolled diabetic patients. Additionally, knowledge of how long the dressing can remain in situ and any visible indications of the need to change the dressing is essential. Knowledge of the correct dressing application and removal, plus choosing the appropriate size, together with not mixing different primary dressings should be standard, but if you are in any doubt specialist advice may be required.

WOUND CARE DRESSING TYPES

There are two main dressing categories:

• Primary dressings that are applied directly in contact with the wound bed
• Secondary dressings that often have the ability to be used as either type.

A more traditional secondary dressing is used solely for retention. There are, however, a range of advanced secondary dressings that are used to either enhance longevity of the primary dressing or have the ability to be placed directly in contact with the wound bed (i.e. silicone foams).

Primary dressings or wound contact layers

These vary from simple, low adherent layers that may consist of gauze, polyester or viscose, to the more advanced technology dressings consisting of a soft silicone or combinations of hydrocolloids and petroleum jelly and Technology Lipido-Colloid (TLC). Generally, these dressings would be chosen for wounds that were lightly exuding or in the proliferative phase. However, as with many advanced wound care dressings, they can be used in all of the wound healing phases dependent on an accurate assessment.

Film dressings

These are non-absorbent, semi-permeable films. They have varying levels of permeability but, generally, these dressings are required to be impermeable to fluids and bacteria while simultaneously being permeable to air and water vapour allowing the wound to breathe. Usually they are given a moisture vapour transmission rate (MVTR) indicating the rate of moisture evaporation.

Foams

These consist of polyurethane or silicone foams that come with or without a border. They will differ in composition, absorbency and performance depending on the brand.

Absorbent dressings

These can be referred to as super absorbents. They can come with an adhesive border and are sometimes referred to as island dressings. These dressing types are non-occlusive, permeable dressings that allow any moisture absorbed to disperse into the atmosphere and they will vary in absorbency capacity.¹⁰

Alginates

These are dressings made from ’seaweed’. They are a polymer of alginic acids (guluronic + mannuronic acid) and the tensile strength of this dressing type is dependent on the percentage mix of the various alginic acids. They can absorb 15-20 times their weight in fluid,10 but fluid is required for the fibres to gel. They are not to be used on necrotic wounds.

Hydrocolloids

An occlusive dressing type that offers an effective barrier to micro-organisms. They are absorbent and most of the hydrocolloid sheets have a semi permeable outer surface making them waterproof.

Hydrogel dressings

These can be amorphous or sheet hydrogels and, while some absorb moisture, others donate it.

Odour absorbing dressings

These often utilise charcoal which, by absorbing bacteria, is a very effective deodoriser.

Antimicrobials

A range of topical antiseptics are available in a wide range of applications. These consist of preparations containing well known antiseptics such as silver, iodine, chlorhexidine, polyhexamethylbiguanide (PHMB) and honey, but also lesser known antiseptics such as octenidine dihydrochloride. This dressing category is often not fully understood and considered costly.

Protease modulator dressings

The protease modulator dressing group has the ability to influence the wound protease environment. These are often used when the proteases have already become imbalanced within a chronic wound, but there is evidence to suggest that earlier intervention will prevent disruption of the proteases.¹¹

All dressing categories come in a range of presentations and many dressings fall into more than one category, such as an antimicrobial foam or an amorphous alginate. Compression bandages and skin protectants also support both wound healing and prevention, although they are not a ‘dressing’ as such.

All dressings vary in composition and mode of action. Creating a ‘sandwich’ of a variety of dressings can therefore impact on their individual mode of action, inhibit performance and could potentially be detrimental. Often, dressings are not licenced to be used together and the potential for litigation should therefore be considered. Even when the appropriate treatment has been selected, if the wound ceases to progress as expected, some element of the treatment will require amendment.

CONCLUSION

Although dressing selection can be daunting, when they are selected appropriately for the current wound state, and used as instructed, they are very effective. Taking the time to consider what is required for the wound at that moment in time, as well as having knowledge of the type and mode of action of the dressing and the confidence to make any changes, has the potential to greatly improve patient outcomes.

REFERENCES

1. Thomas S. A structured approach to the selection of dressings. World Wide Wounds 1997 worldwidewounds.com/1997/july/Thomas-Guide/Dress-Select.html

2. Guest JF, Ayoub N, McIlwraith T, et al. Health economic burden that wounds impose on the National Health Service in the UK. BMJ Open 2015; 5(12) bmjopen.bmj.com/content/5/12/e009283

3. Brown A. Phases of the wound healing process. Nursing Times 2015; 111(46): 12-13 nursingtimes.net/download?ac=3000502

4. NICE Clinical Knowledge Summaries. Leg ulcer – venous. February 2016

5. Winter G. Formation of the scab and the rate of epithelialisation of superficial wounds in the skin of the young domestic pig. Nature 1962; 193: 293-294

6. Simon P. Skin Wound Healing. Medscape. Jan 16

7. Romanelli M, Dowsett C, Doughty D, et al. Position document: Advances in wound care: the triangle of wound assessment. Wounds International. World Union Resources, 2016. woundsinternational.com/wuwhs/view/position-document-advances-in-wound-care-the-triangle-of-wound-assessment

8. Gray D, White R, Cooper P, Kingsley A, Young T. Applied wound management and its use in the assessment of wounds. In: Wounds UK. Applied wound management supplement. Part 3: Use in Practice 2009; 5(4):4-9

9. Swanson T, Haesler E, Angel D, Sussman G. Wound infection in clinical practice consensus document 2016 update. International Wound Infection Institute. Wound Practice and Research 2016; 24(4): 194-198 woundsaustralia.com.au/journal/2404_02.pdf

10. Cowan, T. (ed). Wound Care Handbook 2017-2018 (10th edn). Mark Allen Healthcare, 2017

11. Munter K, Meaume S, Augustin M, et al. The reality of routine practice: a pooled data analysis on chronic wounds treated with TLC-NOSF wound dressings. JWC, WUWHS Supplement Vol 26; Feb2017