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Pressure ulcer risk assessment in patients with darkly pigmented skin

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Elizabeth Scanlon, MSc, RGN, RM, Cert DN.

Nurse Consultant - Tissue Viability, Leeds Teaching Hospitals Trust, Leeds

The vulnerable areas at risk of pressure ulceration often depend upon visual assessment by a nurse, carer or patients themselves in order to determine any signs of skin breakdown or injury (NICE, 2003). 

Although some patients report feelings of discomfort or pain when pressure damage is occurring, many of the patients at greatest risk have either impaired sensation or impaired ability to communicate that discomfort.

The effectiveness of visual assessment depends upon the skills of the carer, nurse or patient and upon their ability to detect skin changes.

When caring for patients who are at risk or potentially at risk of developing pressure damage, skin assessment is key to the planning of care. Traditionally, when assessing patients with white skin, most nurses look for areas of erythema (redness) which are quick and easy to identify. This can be done while carrying out other care and requires minimal expertise.

The identification of pressure damage on white skin has traditionally been by identifying non-blanching erythema but this is difficult to detect in darkly pigmented skin.

This issue has now been recognised by national and international committees. A task force was asked to review the National Pressure Ulcer Advisory Panel’s (NPUAP) definition of Grade I ulcers in 1998; this was then amended to provide a more detailed and specific definition (NPUAP, 1998).

This paper intends to highlight some of the issues related to the assessment of patients at risk of pressure ulcer development who have darkly pigmented skin.

Pressure ulcer development and assessment

When an area of skin and soft tissue is compressed between bone and a support surface the blood vessels are occluded and tissue is starved of oxygen and nutrients. If this occurs over a short period of time and the pressure is released there is a rush of incoming arterial blood that is known as ‘reactive hyperaemia’. This can be easily visually identified in individuals with lightly pigmented skin as an area of erythema.

If the erythematous area blanches (turns white) with light finger pressure this indicates that the patient’s microcirculation is intact. If the erythema does not blanche, this is indicative of microcirculatory damage due to the intensity or duration of the pressure. This is known as non-blanching hyperaemia and is classified as a Stage 1 pressure ulcer according to the majority of classification systems (Bethnell, 2003).

At this stage the introduction of further preventive measures is needed to prevent more damage and tissue breakdown.

An inflammatory reaction will take place if microcirculatory and tissue damage has occurred and this will be associated with localised oedema, heat and pain. If the damage is so severe that localised necrosis is present then the area will feel cool to touch, may have a bluish tinge (due to the ischaemia) and if situated over an area of soft tissue (for example the buttock) may feel harder or more resistant (known as induration) than the surrounding tissue.

If the damage is not detected immediately then the body will have initiated the repair process and will attempt to remove the internal necrotic tissue by autolytic digestion. The area of damage may feel ‘boggy’ or sponge-like as the tissue is liquefied.

If the pressure is associated with friction there may be evidence of ‘scuffing’ of the skin, particularly if moisture is present or blisters. Scuffing usually involves the loss of the stratum corneum layer of the skin’s outermost surface.

Pressure ulcer assessment

The NICE guidelines (NICE, 2003) recommend that when assessing patients at risk of pressure ulceration a skin inspection should be conducted in order to determine that individual’s response time to pressure. The findings of this inspection should be used in conjunction with the nurse’s clinical judgement of the patient’s risk and with a risk assessment tool as an memory aid to ensure that the main risk factors relating to pressure area damage have been considered (Box 1).

The skin inspection should be carried out on the body sites known to be vulnerable to tissue breakdown, such as the heels, sacrum, ischial tuberosities, femoral trochanters, temporal region of skull, shoulders, back of head and toes and any areas where pressure, sheer or friction are caused by motion, clothing or equipment.

An accurate and reliable assessment requires details of medical history and recent treatments as well as physical examination of the skin.

The nurse should be looking for persistent erythema; non-blanching hyperaemia; blisters; discolouration; localised heat; localised oedema and localised induration (Table 1).

With the increase in the use of gloves the identification of temperature changes may be limited and it is preferable for nurses to use ungloved hands to fully assess the skin (this may require the cleaning of body fluids before skin assessment).

Assessment of darkly pigmented skin

Tissue damage in individuals with darkly pigmented skin requires close examination and is often not as clearly visible as in lightly pigmented skin. The principle signs to look for are (NICE 2003):

- Purplish/bluish discoloration to localised areas of skin

- Localised heat which, if the tissue becomes damaged, is replaced by coolness

- Localised oedema

- Localised induration.

In patients with darkly pigmented skin the observation of erythema is prevented (Bennett, 1995) due to the high melanin concentrations present.

It can be seen from Table 1 that, although traditionally erythema has been viewed as the key sign of early pressure damage (Grade I pressure ulcer) there are many other signs and symptoms which are also present. Although skin discoloration in the form of redness (erythema) can be an indication of pressure damage, erythema can occur for a number of other reasons. Infection, excoriation from body fluids and allergic reactions, for example, all present with reddening of the skin. Conversely, the absence of erythema does not mean absence of pressure damage. For example, the thickened epidermal layer on the heels may not look red when damage has occurred. The key to making an accurate differential diagnosis is assessment, both of the risk factors and of any other associated conditions that present in that individual.

Training and education of nurses in pressure ulcer assessment

It can be seen from the complex nature of this assessment that it is a skill based on knowledge of aetiology and clinical expertise but very few nurses receive enough formal training and clinical supervision in this area.

If this assessment is not carried out and early stages of reversible damage are not detected then the necessary changes in care will not be implemented. This will result in the causative factors not being eliminated or compensated for (with more frequent turning or using equipment designed for patients at higher risk of developing pressure ulcers). The patient’s pressure ulcers will continue to deteriorate, resulting in deterioration in quality of life, morbidity and even mortality and all the accompanying costs to the health service.

NICE (2003) recommends that personnel who have undergone appropriate training should carry out risk assessment. It is the responsibility of trusts and individual nurses to ensure appropriate training is available and accessed by all nurses caring for patients potentially at risk.

As with all nursing assessments, the collection of the information is of little use unless it communicated to all other care-givers. This is achieved most reliably and efficiently through documentation. Many trusts now have specific documentation for pressure ulcer risk assessment but few have the scope to record all the signs and symptoms listed above.

The cost of managing patients with pressure ulcers is estimated at around £321 million per annum (Department of Health, 1992). Despite our advancing knowledge of pressure ulcer development and high-technology equipment there is no evidence that we are significantly reducing our incidence of pressure ulcers.

It may be that, by highlighting the problems of detecting erythema in darkly pigmented skin, we are alerting nurses to elements of assessment that should be included with all our patients. Better detection of Grade I ulcers will lead to improved preventive care and reduce the overall incidence figures.

Conclusion

As the recently published NICE (2003) guidelines suggest, there is much that we as a profession need to learn about the prevention of pressure ulcers. However, what is equally important is that we use what we do know to identify and care for patients screened as being at risk of pressure ulcer damage.

As this paper highlights, skin assessment is fundamental to the identification of the early warning signs of pressure damage and the implementation of a plan of individualised care for that patient.

The individualised assessment of the skin is the key to all the other aspects of pressure ulcer prevention in that it can help to determine a turning schedule and can direct the level of equipment required to reduce risk.

It can be difficult when the traditionally accepted warning signs of erythema, induration and oedema are less easily identifiable as a result of darker skin pigmentation and nurses may then need to observe for persistent red, blue, or purple changes in skin tone (NPUAP, 1998).

Nurses must realise that they cannot always rely upon visual signs of pressure damage and must employ other senses to identify Grade 1 pressure ulcers in their patients. For example, nurses may need to touch the skin to assess for any signs of oedema or induration.

In the future technology may be able to help us with this complex process of appropriate diagnosis and subsequent prevention of further damage. Researchers are working to provide us with those methods. Testing is currently under way on a variety of devices that could be used to detect and diagnose - regardless of skin colour - alterations in blood flow and other changes that are specific to ischaemia and reperfusion injury. These include visible and near infrared spectroscopy, pulse oximetry, laser Doppler, and ultrasound (Salcido, 2002).

We know that pressure ulcers have a negative effect upon the social, financial and physical aspects of people’s lives (NICE, 2003). In order to reduce this negative impact we need to employ all measures at our disposal to assess skin damage and reduce risk. Our patients should not go undiagnosed because of the colour of their skin.

Further reading

European Pressure Ulcer Advisory Panel. (1998)Pressure Ulcer Prevention Guidelines. Oxford: EPUAP.

Fletcher, J. (2001)How can we improve prevalence and incidence monitoring? Journal of Wound Care 10: 8, 311-314.

Moore, Z. (2001)Improving pressure ulcer prevention through education. Nursing Standard 16: 6, 64-70.

Royal College of Nursing. (2003)Clinical Practice Guidelines: Pressure ulcer risk assessment and prevention. Implementation guide and audit protocol. London: RCN.

 

 

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