Heidi Guy outlines the key points that need to be considered in the risk assessment and grading of pressure ulcers
Author Heidi Guy, BSc, RN is tissue viability clinical nurse specialist, East and North Hertfordshire NHS Trust, Hertford.
Abstract Guy, H. (2007) Pressure ulcer risk assessment and grading. Nursing Times; 103: 15, 38–40.
Pressure ulcers have been estimated to cost the NHS £1.4–2.1bn per annum (Bennet et al, 2004) and this cost may be added to by litigation. In terms of human cost, pressure ulcers affect quality of life and can contribute to cause of death.
The Department of Health (1993) has recognised the financial impact of pressure ulcers including them within the Essence of Care document (DH, 2001). In addition NICE (2005, 2003, 2001) has produced three sets of guidelines. A European Pressure Ulcer Advisory Panel (EPUAP) study found that 18.1% of a hospital patient population may have a pressure ulcer at any one time (Clark et al, 2002) and it is estimated that between 4% and 25% of a hospital population may develop a pressure ulcer (Bennet et al, 2004). An accurate statistic for how many people are at home with pressure ulcers is not available.
It is still believed that most, but not all, pressure ulcers can be prevented (Bliss, 2000). In order to ‘prove’ that a pressure ulcer was not preventable it is necessary to demonstrate that every possible care intervention has been carried out to prevent it; this process begins with a risk assessment.
Formal pressure ulcer risk assessment involves the use of a tool that assists in identifying those patients likely to develop a pressure ulcer. Although this is now an established nursing practice, there is little evidence to support the accuracy of these tools (Franks et al, 2003). One of the earliest pioneers in the 1970s and 1980s of a tool to assist this process was Norton. Since that time others have expanded on this early work, adding in factors that they found contributed to risk (Waterlow, 2005; Bergstrom et al, 1987; Waterlow, 1985), creating two of the most widely used risk-assessment tools: Waterlow and Braden.
There are multiple factors that may increase a person’s risk of developing a pressure ulcer. These can be broadly separated into two categories:
- Extrinsic – that which is external to the body and can be influenced;
- Intrinsic – that which is within the body and often cannot be influenced.
Pressure, shear and friction are the dominant forces leading to pressure damage (Collier and Moore, 2006). The addition of moisture can increase the likelihood of skin damage (Andrychuk, 1998). Informal risk assessment forms the basis of clinical judgement, which includes assessment for the affects of these forces and/or moisture. This assessment would need to consider the following.
When they initially present to a healthcare practitioner, a patient’s skin should be inspected to assess its general condition and determine any existing damage. Aged, moist or very dry skin may be more at risk of breakdown than well-nourished, adequately hydrated skin. The first sign of pressure damage is often blanching erythema presenting over a bony prominence. Any areas of redness must be tested with light finger pressure for blanching and preventative measures introduced.
Identifying erythema in darkly pigmented skin is often difficult and NICE (2001) recommends observing for purplish/bluish discolouration, localised oedema, heat and induration. Blistering may well be an indication of shear or friction forces, especially if it occurs over a body part that moves against a surface, such as the heel. Special consideration needs to be given to high-risk areas, such as the heels, when visual inspection is obscured by anti-embolism stockings.
The length of time a person is subjected to pressure forces depends on their ability to independently change position and detect that they need to do so. High points of pressure over short periods of time can be sustained – for example, this occurs every time our elbows are resting on a table. Pressure damage does not occur in this instance because the elbows are moved when they become uncomfortable. If an individual cannot independently do this, then the length of time the skin is subjected to pressure has to be shortened by changing their position or providing a surface that redistributes the pressure.
The type of surface a person is sitting or lying on can affect the risk of pressure damage occurring and will require assessment. The larger the surface area the wider the spread of pressure distribution, unless the surface is hard, such as a floor. A viscoelastic foam mattress will redistribute pressure across the whole body length, providing a large surface area. In contrast, the floor creates several smaller surface areas over the bony prominences (heels, bottom, scapula, head) that come into contact with it. When assessing seating, it is important to also consider the height and seat depth of the chair and how this correlates with a person’s size and stature.
Consideration needs to be given to the position in which a person is sitting or laying. How much pressure and shear will be exerted in the position they are in? If it is suspected that this will be high then a plan of care to include repositioning will need to be instigated. It is important to check whether bony prominences are resting against each other, particularly on the legs when the patient is lying on their side. NICE (2005) recommends a high-specification foam theatre mattress or other pressure-redistributing surface for all patients undergoing surgery.
Moist skin can be weak and susceptible to breakdown. Faecal and urinary incontinence are defined as intrinsic risk factors because the cause of the problem is internal to the patient. However, the effects of this are external. Excessive sweating, high temperature and exudate leakage from wounds or oedematous limbs may also be a cause of moisture (Andrychuk, 1998).
Treatment plans need to include strategies to address the cause of the moisture. If this cannot be resolved then absorbent pads can take the moisture away from the skin if the patient is incontinent of urine. However, where pads are used, consideration needs to be given to the effect they may have on the skin and the interface with the support surface (Fader et al, 2004). Barrier creams or films can also reduce the detrimental effects of moisture, as can using alternatives to soap with water.
When skin lesions occur in unusual places where a piece of equipment is in use, consider how the equipment – for example, CPAP masks, plaster casts, pulse oximeters, splints and urinary catheters – may be contributing to the damage. Where possible, ensure these pieces of equipment are not left in place for longer than necessary. If this is not possible, consider methods to alleviate the pressure such as protecting the bridge of the nose under CPAP masks or ensuring catheters are not pulling tight against the glans penis.
Assessment of the intrinsic factors that may increase a person’s risk of pressure ulcer development usually involves the use of a formal assessment tool such as Waterlow (2005, 1985) or Braden (Bergstrom et al, 1987). Despite the plethora of risk-assessment tools there is little robust evidence clearly identifying the risk factors that have a direct correlation with pressure damage (Clark, 2004). If this were the case the tools would identify correctly all those who will develop a pressure ulcer (sensitivity) and all those who will not (specificity) (Nixon and McGough, 2001).
The predictive validity of these tools has also been challenged (Franks et al, 2003; Nixon and McGough, 2001) demonstrating that they may:
- Overpredict risk, incurring cost implications as expensive, preventative equipment is employed when it may not be necessary; or
- Underpredict risk so that someone assessed as not being at risk develops a pressure ulcer.
Over the years practitioners have adapted tools or created new ones designed for specialist areas (such as intensive care, obstetrics or paediatrics) following research demonstrating that different factors increase the risk of particular groups of patients developing pressure ulcers. However, some are based on assumptions regarding causative factors rather than evidence.
No two tools include the exact same subgroups of risk factors (Schoonhoven et al, 2006). There are several articles discussing the individual factors that may be high predictors of pressure ulcer development (Schoonhoven et al, 2006; Reed et al, 2003; Perneger et al, 1998; Allman et al, 1995; Brandeis et al, 1994). Studies that have sought to clearly define these risk factors are often on specific groups of patients for example paediatrics, hospital patients or orthopaedic patients. Unfortunately, the discussion of these is too complex for the purposes of this article.
It is not possible to provide a definitive list of risk factors that could conclusively represent the sole factors that identify an individual’s likelihood of developing a pressure ulcer. The risk factors that may identify, for instance, the likelihood that an 80-year-old lady with a fractured neck of femur will develop a pressure ulcer during her hospital stay may be different to those that will predict the same for an 80-year-old male nursing home resident with several underlying medical illnesses.
An additional complication of these tools is user input. Many of the subcategories can be reviewed subjectively. Clearly a measurement centred around BMI is an objective measurement but mental awareness or mobility may be less so.
Inter-rater reliability of some of the risk-assessment tools has been found to be poor (Kelly, 2005; Bergstrom et al, 1987).
The Waterlow (2005) scoring system has recently been updated to include more objective measurements such as BMI and weight loss. There is no published information on whether the inter-rater reliability of the tool has been improved by these changes. It is acknowledged that this is a fundamental flaw of these tools and hence clinical judgement must always support the decisions made by the results of the assessment. NICE clearly recognise this by advising their use as an aide-mémoire (2001).
As well as the intrinsic and extrinsic factors, there may be certain circumstances that increase a person’s likelihood of pressure ulcer development:
- History of recent pressure ulcer;
- Length of hospital stay (de Laat et al, 2006);
- Length of time of surgery.
Classification of pressure ulcers
Pressure ulcers develop in varying degrees of severity. It is because of this that over the years many systems have been designed to classify the degree of damage. Commonly these classification systems describe the tissue involved and the depth of the damage. As with risk-assessment tools, they have often been developed to improve on earlier work and frequently use a numerical score or grade for definition.
The classification of pressure ulcers is important for incidence/prevalence rates as well as improving communication between health professionals regarding pressure damage and the degree of treatment required.
The use of various classification systems has made the comparison of incidence/prevalence rates difficult as different systems define damage differently. For instance a Stage 4 Torrance (Russell, 2002a) is different to a Grade 4 EPUAP (1998). NICE (2005) has recommended the use of the EPUAP (1998) classification system in the UK. Certainly, if all care settings within the UK adopt the same classification system it will improve meaning of definitions between settings, professionals and the literature. However, as with the risk-assessment tools, the reliability and validity of the classification systems is low (Defloor et al, 2006). Consequently, the quality of data regarding grades of pressure ulcers is limited.
The two levels of pressure damage that have generated the most confusion are the lowest and the highest. This is because of debate surrounding blanching and non-blanching erythema (Russell, 2002b) and the diagnosis of true ulcer depth in those areas of damage that appear intact. There are instances where the area of damage presents as a black or purple hue under the intact epidermis. The depth of tissue involvement in these lesions is not clear and debridement is not always appropriate. Where a necrotic eschar is present debridement may be required to facilitate diagnosis of depth. The EPUAP classification system has attempted to address this by using descriptive definitions for grade four damage such as ‘extensive destruction’, ‘tissue necrosis’ and ‘with or without full thickness skin loss’.
Another area that creates confusion centres around defining what constitutes a pressure ulcer and what constitutes a lesion secondary to some other cause, often moisture (Defloor et al, 2006). Subsequently incontinence or moisture lesions may be incorrectly defined as pressure ulcers by health professionals.
The assessment of risk of pressure ulcer development requires multifactorial consideration. Risk-assessment tools are a useful signpost to risk factors but must not be used in isolation to identify risk. Once a patient is identified as being at risk of developing a pressure ulcer it is important to instigate a plan of care to prevent the occurrence of pressure damage.
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