Pressure ulcer prevention, patient positioning and protective equipment

Pressure ulcer (PU) prevention is a high priority for all health professionals. While this is pertinent given the ageing population and demographic changes in the UK and Europe (Office for National Statistics, 2018; Eurostat, 2020), PUs can develop in individuals of any age with one or more aetiological variables (Table 1). An assessment tool that considers such variables can be used to ascertain whether a person is at risk (Waterlow, 2005).

Further to the costs and resource implications and the impact that PUs have on patients' quality of life, morbidity and mortality, national and international PU prevention initiatives have been launched. These include the Department of Health's Pressure Ulcer Productivity Calculator (NHS England, 2010); Stop the Pressure campaign (launched in 2012 by NHS England Midlands and East, now part of the National Wound Care Strategy Programme (2022)), and educational efforts by the Society of Tissue Viability, the European Wound Management Association and the National Pressure Ulcer Advisory Panel (NPUAP), European Pressure Ulcer Advisory Panel (EPUAP) and Pan Pacific Pressure Injury Alliance (PPPIA) through their publications and websites.

Despite investments in PU prevention strategies during the last decade by healthcare trusts, reported PU prevalence in the UK and Europe remains higher than anticipated. It could be argued that the main reasons for the original targets not being met are the above-mentioned demographic changes as well as the increased number of associated comorbidities in patients attending healthcare settings. For example, in 2002 a pilot study covering five countries in Europe (Belgium, Italy, Portugal, Sweden and the UK) reported that the average prevalence rate of PUs was 17.2% (Clark et al, 2002). More recently, a systematic review of 79 articles reporting prevalence figures across Europe indicated that the median prevalence was 10.8% (Moore et al, 2019).

In the UK, the Stop the Pressure campaign initially stated that all PUs were avoidable harms and, as a result, a zero tolerance policy to the development of PUs was adopted within the NHS. PU prevalence data was collected monthly from all NHS healthcare settings (primary, secondary and tertiary settings, and NHS nursing homes) via the Safety Thermometer tool (NHS Digital, 2017). The final PU prevalence figure reported from this tool in February 2017 (before it was discontinued) was 4.5%, compared with 4.6% in the corresponding month in 2014.

In the author's experience, there has been an acceptance that not all PUs are preventable, although all healthcare settings in the UK should still aim to prevent all PUs that, further to patient assessment and preventive interventions, are deemed avoidable (Edsberg et al, 2014).

In 2017, Guest et al (2017) reported the number of patients developing a PU and the associated costs incurred by the NHS. Up to 200 000 people developed a new PU in 2017–2018 and treating those patients cost the NHS more than £1.4 million every day – an annual cost of more than £511 million.

The rising costs of managing patients with PUs result from extended lengths of stay in hospital, more community clinic or home visits being required, and a greater use of associated staff and material resources, such as specialist equipment, wound dressing materials and medications (Guest et al, 2017). Furthermore, patients are at an increased risk of acquiring an associated wound infection and or requiring readmission to a inpatient setting because of pre-existing associated comorbidities or comorbidities that have arisen since the development of a PU (Guest et al, 2017).

PUs can have negative effects on a patient's quality of life and their ability to carry out daily activities and work because of pain and reduced mobility. The patient may also require more visits to a health centre or by a district nurse, and have an increased risk of being discharged with a PU wound and its associated symptomatology. This can lead to a greater risk of infection and anxiety and stress (Graves et al, 2005).

PUs are part of the NHS CQUIN and QIPP programmes, although it should be acknowledged that the current PU CQUIN applies to all providers of community inpatient services (including nursing care homes) and was developed to promote consistency in the assessment and documentation of PU risk in NHS care settings. The key aims of CQUIN payments are to reward high-quality improvements and innovation, with the intention of improving care by reducing healthcare-acquired PUs (Newton, 2010). QIPP (payment by results), however, encourages the NHS to be more innovative, improve quality, deliver on prevention activities and become more productive (NHS Networks, 2022). Thus, the QIPP programme aims to encourage the NHS to meet growing healthcare needs from the same resources, minimising the need to increase healthcare budgets (Royal College of Nursing, 2012).

Pressure ulcer aetiology, assessment and classification

A PU has been defined as ‘localised injury to the skin and/or underlying tissue usually over a bony prominence, as a result of pressure, or pressure in combination with shear. A number of contributing or confounding factors are also associated with PUs; the significance of these factors is yet to be elucidated’ (NPUAP/EPUAP/PPPIA, 2014). This definition has been adopted by the National Institute of Health and Care Excellence in its latest PU guideline update (2019). PU should be used instead of previous terminology such as pressure sore or bed sore.

In 1984, McClemont identified that pressure exerted on the deeper tissues was far greater than that at the skin surface, resulting in a greater degree of tissue damage nearer the bone than at the surface of the skin. This phenomenon is known as McClemont's cone of pressure theory (McClemont, 1984). Initial tissue damage is often limited to a simple hyperaemia, which, if the pressure is relieved, will disappear or blanche on light finger pressure (Cooper, 2006).

Bennett et al (1979) state that pressure is ‘a perpendicular load or force applied to a specific surface unit area’; this gravitational force is also often referred to as compression. The average pressure exerted on the skin can be calculated with pressure-sensitive measurement sensors or other equipment, or by using the following formula:

Pressure = Body weight ( force ) Skin contact area ( surface area )

Shear: a stretching force. Shear is a mechanical stress that occurs in tissues as a result of a force being applied tangentially to the plane of interest (Reichel, 1958), which is the surface of the patient's skin. When the level of shear rises, the amount of deformation in the affected tissues increases.

When a patient is subjected to both shear and pressure forces, the amount of pressure needed to produce vascular occlusion is only approximately half than would be the case if shear were not present (Bennett and Lee, 1985).

It is thought that sacral skin damage resulting from shear typically develops when the patient sits or lies in the semi-recumbent position and the sacral skin adheres to the bed linen and the deep fascia move downwards with the skeletal structure because of gravity while the sacral fascia remain attached to the sacral dermis (Reger et al, 2010).

If shear is prolonged or exacerbated by the presence of moisture, regional stretching and narrowing of the microcirculation of the skin may also occur (Linder-Ganz and Gefen, 2007). Left unchecked, this can lead to the avulsion of local capillaries and arterioles, increasing the possibility of localised tissue necrosis (Shea, 1975).

Although shear can be differentiated from pressure, it is difficult to create pressure without shear and shear without pressure (Bridel, 1993; Coleman et al, 2014).

Friction: friction occurs when two surfaces move across one another (Krouskop et al, 1978), for example when a patient undertakes a sliding transfer from a bed to a wheelchair.

Friction is not thought to be a prime aetiological factor in pressure ulceration, as it does not directly compromise the circulation. However, it can exacerbate the stripping of broken epidermis or cause an initial break in the skin, which may then be compounded by the effects of pressure and shear, increasing the patient's risk of PU development (Clark and Black, 2011). Furthermore, if the support surface is moist, the friction coefficient—the force that resists the relative motion of two objects that are touching (Reger et al, 2010)—will rise and, if great enough, will cause the patient's skin to adhere to a damp surface (Lowthian et al, 1976), exacerbating any associated shearing effects.

Table 1 shows some of the intrinsic and extrinsic physiological factors associated with the development of PUs, exacerbating factors and considerations for the selection of patient support surfaces.

Prevention strategies

One of the most common prevention strategies used in all healthcare settings is the frequent repositioning of patients who have been assessed as at risk of PU development.

‘Repositioning is an integral component of pressure ulcer prevention and treatment; it has a sound theoretical rationale and is widely recommended and used in practice. The lack of robust evaluations of repositioning frequency and position for pressure ulcer prevention mean that great uncertainty remains about its effectiveness, but it does not mean these interventions are ineffective.’

(Gillespie et al, 2014)

Notwithstanding this conclusion, a patient may be maintained in the position in which they have been placed by the use of repositioning products with pressure-redistributing properties.

A number of pressure-redistributing products are available, some of which are made from high-density, single-patient-use foam and gel. Gel and high-density, single-patient-use foam products can help prevent shearing, support repositioning of the patient and prevent ‘bottoming out’ (Bateman, 2012).

If pressure is not relieved, the hyperaemic response may persist or increase, leading to a local release of histamine. Here, the affected tissue is already damaged, and hyperaemia or erythema will not disappear under light finger pressure (Cooper, 2006). This is known as non-blanching erythema. If pressure continues to be unrelieved, there is a further risk of ischaemia to the area. The continued release of histamine increases vessel permeability, which, in turn, causes the tissue to appear oedematous. Under ischaemic conditions, cell death will occur, with harmful cellular contents spilling out into the surrounding tissues, creating further necrosis (Newton, 2010) (Table 2). In summary, PUs occur initially from within the tissues, which explains why, when a patient's skin breaks, there is often greater depth (previously unseen) to the PU than when initially assessed.

An evidence-based strategy for PU prevention is shown in Table 3.

Assessment

A patient's skin should be assessed as part of a holistic assessment process incorporating a validated PU risk assessment tool (Brown and Flannagan, 2013) as soon as possible after admission to any healthcare setting. Any early signs of pressure damage should be identified, classified and acted upon.

Classification

A number of PU classification systems have been introduced and developed. However, the most commonly used in clinical practice, both in the UK and internationally, is that of the NPUAP, EPUAP and PPPIA (2014) (Table 4).

Devon positioning products

The Devon positioning products (Cardinal Healthcare, formerly Covidien) are a range of single-patient-use devices intended to provide comfortable, safe positioning and support in healthcare, particularly in surgical settings.

These devices can be used to protect a patient's skin, in particular over bony prominences, and help redistribute pressure and position patients in bed and on the operating table (Bateman, 2012). These pressure-redistributing products work by spreading the weight of the patient over a larger surface area. Therefore, instead of pressure being concentrated on one small area, the force is dissipated across the foam (overlay) and away from the patient, reducing the interface pressure (Bateman, 2012).

The products available in the Devon range include operating table pads, body alignment wedges, lower extremity positioners including heel protectors, head positioners and chest rolls.

Evidence to support these products

As with all new products or product ranges being introduced or considered for patient use, it is important that practitioners are aware of both the products' properties and the evidence supporting their use (Table 5).

The Devon products' pressure-redistributing properties have been assessed and reported independently by Shelanski and Holley (2009). This study involved male and female healthy volunteers who were chosen to represent a cross-section of a patient population, with subsets organised by weight range; subjects were placed on Devon foam equipment and gel devices. The foam positioning devices performed more favourably than the commonly-used gel positioning aids with respect to total pressure distribution and patient surface area exposed to pressure levels that may interfere with tissue perfusion—the closing capillary pressure. A 48% reduction in pressure distribution at levels above 32 mmHg was achieved using the Devon foam positioning device (Shelanski and Holley, 2009); 32 mmHg was identified as the pressure to close blood vessels supplying the capillary loops, as per the results of an experimental study (Gaskell and Krisman, 1958). Furthermore, a 38% reduction in surface area with levels above 32 mmHg was realised using the Devon foam product.

In summary, superior results were noted with respect to both total pressure redistribution and pressure levels that could interfere with tissue perfusion (Shelanski and Holley, 2009). In light of these findings, it could be postulated that if these products were used as part of an assessed PU prevention and management strategy (in combination with other care interventions such as patient repositioning), they could help minimise the progression of any developed PU to a higher classification (Table 4).

After carrying out an internal audit of 25 patients within the frail elderly care assessment unit at University Hospitals of North Midlands NHS Trust, Fumarola (2014) identified this cohort was often the most vulnerable to heel pressure injuries and ulcer development. She concluded that this was because following admission to the emergency department, they remained on trolleys for prolonged periods before transfer to the frail elderly care unit. She suggested that the use of a single-patient-use foam heel boot would benefit a high proportion of this patient group.

Evidence for the clinical use of Devon foam products in operating theatres and during the postoperative phase in other clinical areas (such as hospital wards) is highlighted above. Additionally, clinical properties of the foam operating table and utility pads (overlays) are that they:

• Are made of non-toxic, firm-density foam
• Reduce interface pressure (compression), shear and friction forces
• Reduce the risk of PUs and nerve damage while maintaining a patient's circulation
• Provide the ‘ideal’ combination of patient stability and cushioning (Bateman, 2012).

Furthermore, it could be argued that the use of pressure redistribution devices (such as the foam overlay, head positioners and the chest roll in particular) to offload pressure from the bony prominences should be considered as part of a PU prevention strategy in intensive therapy units (ITUs) when patients are placed in the prone position to minimise the effects of acute respiratory distress syndrome (ARDS); the incidence of ARDS has increased significantly since the onset of the COVID-19 pandemic (Team et al, 2021).

Hospital-acquired pressure injury has been reported to be the most common complication related to prone positioning, both before the pandemic (Bloomfield et al, 2015) and since the COVID-19 outbreak (Binda et al, 2021). Pressure points identified as at highest risk during prone positioning include the forehead, cheeks, nose, chin, clavicle or shoulder, elbow, chest or breasts, genitalia, anterior pelvic bones (iliac crests, ischium and symphysis pubis), knees or patella, dorsal feet and toes (NPIAP, 2022).

For additional evidence, see the case study reports below.

Advantages and disadvantages

The advantages of the Devon range of products can be summarised as:

• Low cost
• Effective
• Have been used in a variety of clinical settings, as reported in published evidence (Table 5)
• Provide patient stability and elevation during surgery, imaging and rehabilitation, and maintain the correct patient position during scans, surgical procedures and during the postoperative recovery phase of treatment
• Reduce the risk of PUs and nerve damage without adversely affecting the patient's circulation
• Non-toxic and latex free
• Fire retardant
• Lightweight, non-slip and simple to position
• Long lasting and disposable for single patient use.

Disadvantages can be summarised as:

• No cover
• Could be perceived as an unnecessary cost if patient stays are short
• Single-use foams add to landfill and do not biodegrade easily
• A lack of high-quality, peer-reviewed published evidence to support the clinical use of the product range or its integration into an existing or a developing PU prevention strategy or programme.

Case studies

Case study 1: cerebral palsy and dystonia

The Devon heel convoluted foam positioners were used to offload and protect the skin of a patient in a paediatric critical care unit setting.

Poppy-Grace (not her real name), a 13-year-old girl with tetraplegic cerebral palsy and ongoing issues with dystonia had a Glamorgan PU risk assessment tool (Willock et al, 2009) score of 33, which indicated she was at a very high risk of PU development. During dystonic episodes, her feet were at most risk with friction forces from movement and the bed sheet; while she was settled at rest, her heels were at risk from pressure. Staff nursed the patient on an alternating air mattress and previously had used gel heel pads. Because of the dystonia, the gel heel pads were ineffective.

With the use of heel convoluted foam positioners, the patient's heels were offloaded, and no deterioration was noted in the skin there. Because the foam positioners covered more of the patient's feet and were held in place with a Velcro strap, they remained in place, protecting the feet from friction force.

During the patient's 4-month stay in paediatric critical care while using the heel foam positioners, she did not develop any PUs on her heels and feet. During the 2022 heat wave, the foam did not become wet with sweat causing moisture damage, and no marking was noted to the patient's skin. The foam positioners are latex free and there were no signs that it caused any skin irritation.

The child's mother was pleased with the heel positioners; she said they were comfortable, soft, easy to use and protected her child's feet. The mother liked that the foam positioners stayed in place with the Velcro strap when her child was having dystonic episodes.

Case study 2: after spinal surgery

Devon convoluted foam positioners that conformed to the heels were used to offload and protect the skin of a patient on the general paediatric medical ward. Molly (not her real name), aged 13 years, had spinal injury to T12 following scoliosis repair, resulting in lower limb weakness and altered sensation.

The Braden Q PU risk assessment tool (Quigley and Curley, 1996) indicated she had a very high risk of PU development. Staff noted category 1 PUs to the heels during her admission on the ward for spinal rehabilitation. They nursed the patient on an alternating air mattress and had previously used boots providing intermittent pneumatic compression and gel heel pads; however, PUs continued.

With the foam positioners in place, the patient's heels were offloaded, and no deterioration was noted in the skin of the heels. The PUs resolved with no adverse outcomes. As the foam positioners covered the patient's feet and were held in placer with the Velcro strap, the foam positioner remained in place, protecting the feet from pressure and shear forces when in different positions.

During her 4-month stay in ward for spinal rehabilitation, Molly did not develop any PUs on her heels and feet while using the heel foam positioners and the category 1 pressure ulceration resolved. During the 2022 heat wave, the foam did not become wet with sweat causing moisture damage; no marking was noted to the patient's skin. The foam positioners are latex free and there were no signs of any skin irritation from the foam on the patient, who had sensitive skin.

Molly was pleased with the heel positioners, saying they were very comfortable and soft, and liked the colour. The mother liked that the foam positioners as they stayed in place with the Velcro strap, and reversed pressure damage and prevented any further skin damage occurring.

Case study 3: multiple sclerosis in an older person with frailty

The Devon heel convoluted foam positioners were used to offload and protect the skin of a patient in his own home.

John (not his real name), a 72-year-old man with multiple sclerosis and wheelchair dependent had a Waterlow PU risk assessment tool score of 23 (Waterlow, 2005), which indicated that he was at a very high risk of PU development. His feet, ankles and sacrum were at most risk of friction forces from uncontrolled movements/spasms when in bed. While John was in his wheelchair, his heels and ankles were at risk from downward pressure through his heels and ankles that, at times, rested on the metal frame of the wheelchair leg support/foot plates. John had been reluctant to try heel protection as he felt they were too bulky and went up his whole leg making his trousers too tight. In August 2022, it was noted that he had a 1.5cm break on his left outer malleolus. At this time he agreed to use a heel convoluted foam heel protector. This allowed both heels to be offloaded, and no deterioration was noted in the skin on this right foot/ankle. The foam positioners covered more of the patient's feet and had a Velcro straps; however John did not like the Velcro so a cotton stockinette was applied to secure the positioners. They remained correctly in place, protecting the feet from friction force and pressure from the wheelchair.

During John's ongoing care, he continued to wear the heel foam positioners, the initial PU healed and he did not develop any damage to his other foot. He found them to be comfortable, light weight and unobtrusive. While the foam positioners are latex free and there were no signs that it caused any skin irritation, John did not like the feel against his skin so a cotton stockinette sleeve was applied for comfort.

Case study 4: end-of-life care

Devon convoluted foam positioners that conformed to the heels were used to offload and protect the skin of a patient who was reaching end of life and at high risk of developing PUs as they were less mobile and relied on carers to support with positioning.

David (not his real name), aged 83 years had Alzheimer's disease, which impaired his understanding of offloading and protecting his heels from injury.

The Waterlow risk assessment tool score indicated a high risk of developing PUs (Waterlow, 2005). His carer and wife noted an intact blister to the left heel during routine care. They contacted the community nursing team for advice and support. The nursing team recommended sheepskin heel protectors and asked David's wife to purchase them. At consecutive visits, these had not been purchased and the blister de-roofed, leaving a category 2 PU. At this point the decision was made to supply the Devon heel protectors as his risk of deterioration was increasing, the need to increase the care package to support David and his wife was being looked at, but due to carer shortages this would take some time to organise. The wife stated that she was finding it hard to cope but wished for David to stay at home with her and see if her family could help a little too.

With the foam positioners in place, the patient's heels were offloaded, and no deterioration was noted in the skin of the right heel and the PU on the left heel began to improve and show signs of healing. The foam positioners remained in place, protecting the feet from pressure and shear forces when in different positions in bed and seated. They did remove them to enable David to go out in the car as he needed to wear proper shoes, but this did not exacerbate the wounds and David's quality of life was maintained and enabled his wife to have some interaction outside of their home.

Over a 3 month period, the PU showed signs of healing and it reduced in size. Both David and his wife found the heel protectors to be of benefit, David tolerated them well and did not try to remove them. The reduction in exudate as a result of healing, was supported by offloading the heels and this was a benefit to the wife as she did not have to worry about additional laundry from the heel wound leaking.

Conclusion

PU prevention is everybody's responsibility regardless of healthcare setting. It can therefore be argued that it is imperative that all health professionals should be aware of the aetiology and consequences of PU development, as well as local and national guidance, prevention strategies and the indications for and properties of preventive equipment available in their healthcare setting.

Some evidence for the Devon positioning products has been reviewed and referred to within this product focus and they appear to have been best used in emergency care (including ITU), operating theatres and postsurgical settings. However, the author would suggest that further audit and comparative clinical evaluations are carried out to provide evidence to support their wider incorporation in existing and future PU prevention strategies, for the benefit of patients, colleagues and others.

KEY POINTS

• The focus on pressure ulcer (PU) prevention has increased in the past decade since the development of national and international initiatives
• Despite investment in PU prevention during the last decade, prevalence in the UK and Europe remains higher than anticipated
• Treating patients with PUs costs the NHS more than £511 million per year.
• PUs have significant effects on patients' quality of life and increase their risk of developing an infection, within the wound or systemic
• Pressure and shear forces exerted on a patient's anatomy may directly result in pressure ulcer development and need to be identified and addressed
• A range of preventive equipment and techniques can assist health professionals to minimise PU development and deterioration

CPD reflective questions

• What are and how would you define (for a colleague) the main forces that, when exerted on a patient's skin, could lead to the development of a pressure ulcer if not recognised and addressed as soon as possible?
• Make a list of the main factors that the literature indicates would increase your patients' risk of pressure ulcer development. Consider the patient group you care for on a regular basis
• What preventive interventions do you use on a regular basis to prevent your patients developing pressure ulcers and are there any other preventive interventions you could consider?
• What could you do to improve the evidence base for a range of products relevant to your patients that have been developed to minimise a person's risk of pressure ulcer development?