Pressure ulcers in bed are prevented by addressing four things in combination: redistributing pressure through the right support surface, repositioning the person frequently enough to relieve sustained loading, managing skin moisture and integrity, and ensuring nutrition and hydration are sufficient for tissue health. No single intervention works in isolation. The widely used SSKIN framework - Surface, Skin inspection, Keep moving, Incontinence, Nutrition - captures the five clinical priorities and is endorsed by NHS England and NICE.
What is a pressure ulcer?
A pressure ulcer (also called a pressure injury or, historically, a bedsore) is localised damage to the skin and underlying tissue caused by sustained pressure, shear, or friction. They typically develop over bony prominences - sacrum, heels, hips, elbows, occiput - where soft tissue is compressed between bone and an external surface.
Pressure ulcers are categorised in four stages by the European Pressure Ulcer Advisory Panel (EPUAP):
- Category 1 - non-blanchable erythema of intact skin
- Category 2 - partial-thickness skin loss involving epidermis and/or dermis
- Category 3 - full-thickness skin loss extending into subcutaneous tissue
- Category 4 - full-thickness tissue loss with exposed bone, tendon, or muscle
Two additional categories - unstageable and deep tissue injury - describe ulcers where the depth cannot be determined or where damage is suspected beneath intact skin.
Category 3 and 4 ulcers are reportable patient safety incidents in NHS settings and carry significant cost to the system - recent estimates place the annual cost to the NHS at over £3.8 billion. The human cost - pain, sepsis risk, prolonged hospitalisation, loss of independence - is greater still.
Who is at risk of pressure ulcers?
Risk increases with reduced mobility, reduced sensation, poor perfusion, malnutrition, incontinence, and advanced age. Specific populations at high risk include:
- People with spinal cord injury
- People with advanced dementia
- People receiving end-of-life care
- People with diabetes and peripheral vascular disease
- People immediately post-surgery, particularly orthopaedic
- People in critical care
- People with severe obesity (where skin folds create their own pressure points)
- People who are underweight (where bony prominences have less soft tissue covering)
Risk assessment tools such as the Waterlow score, Braden scale, or PURPOSE-T provide a structured way to quantify risk, but they are screening tools - they do not replace clinical judgement. A person scoring "low risk" on a tool but spending 20 hours a day in the same position is still at risk.
What is the SSKIN framework?
SSKIN is the most widely used clinical framework for pressure ulcer prevention in UK practice:
S - Surface
Provide an appropriate support surface. This means a pressure-redistributing mattress matched to the person's risk level, plus pressure-relieving cushions for any time spent sitting. The mattress is not optional - for a high-risk bed-bound patient, the wrong mattress will cause damage that no amount of repositioning can prevent.
S - Skin inspection
Inspect the skin at every position change, at minimum twice a day. Look for non-blanchable erythema, warmth, induration, or pain over bony prominences. Document findings. Photograph if appropriate. Escalate Category 1 changes - they are the warning sign that intervention is needed now, not when the skin breaks.
K - Keep moving
Reposition at intervals appropriate to the person's risk. The traditional two-hourly turn is a starting point, not a rule - some people need more frequent repositioning, some less. Use the 30-degree tilt where possible to avoid loading the trochanter directly. Encourage and assist any self-initiated movement.
I - Incontinence and moisture
Manage incontinence promptly. Use barrier creams. Avoid prolonged contact between skin and wet pads. Moisture-associated skin damage is not technically a pressure ulcer but dramatically increases the risk of one.
N - Nutrition and hydration
Protein, calorie, and fluid intake must be adequate for tissue maintenance and repair. Refer to dietetics where intake is poor or where wounds are present. Vitamin C, zinc, and arginine play specific roles in wound healing.
How do you choose the right pressure-redistributing mattress?
Mattresses are broadly grouped into three categories:
Static (foam) mattresses redistribute pressure through the properties of the foam itself - usually a layered construction with high-density support foam and a pressure-reducing visco or castellated top layer. Suitable for low to medium risk. Cost-effective, silent, and require no maintenance.
Hybrid mattresses combine foam with alternating-pressure air cells. They function as a static mattress when the pump is off and as a dynamic surface when activated. Suitable for medium to high risk and useful where risk fluctuates.
Dynamic (air) mattresses use alternating-pressure cells to periodically offload tissue. The cell depth and alternation cycle determine the level of pressure relief. Suitable for high and very high risk, including active Category 3 and 4 ulcers.
Selection should be driven by risk assessment, the presence or absence of existing damage, the person's weight and posture, the care environment, and - importantly - what the person finds comfortable. A clinically excellent mattress that the person refuses to lie on is not the right mattress.
Other features to consider:
- Firm-edge construction for people who transfer in and out of bed independently
- Heel slope or zoned heel offloading for people at risk of heel ulceration
- Bariatric width and weight rating where appropriate
- Infection control - wipeable, vapour-permeable covers that meet healthcare hygiene standards
- Quiet operation for dynamic mattresses, particularly in homecare
How often should a person be repositioned?
There is no single correct interval. The widely cited "every two hours" guidance is a default position, not a rule. The right interval is:
- More frequent for people at higher risk, with existing damage, or on inadequate surfaces
- Less frequent for people on high-specification dynamic mattresses who are tolerating the regime
- Driven by skin response - if redness persists after a position change, the interval was too long
- Adjusted overnight only if a documented clinical decision supports it
The 30-degree lateral tilt is generally preferred to a full 90-degree side-lying position because it avoids loading the greater trochanter directly. Pillows, wedges, or repositioning slides should be used to maintain the tilt.
For people who can reposition themselves, encourage micro-movements and weight shifts. For people who cannot, the responsibility for movement lies with the care team.
What is the role of the bed itself in pressure care?
The profiling bed and the mattress work together. The bed's role in pressure care includes:
- Enabling repositioning - the profiling sections allow tilt, side-lying, and varied positions without manual handling effort
- Supporting the mattress - the platform must be compatible with and supportive of the prescribed mattress
- Enabling skin inspection - the bed must rise to a working height where skin can be properly examined
- Reducing shear - knee-break before head-up adjustment reduces sliding down the bed, which causes shear damage
A bed that does not raise to working height forces carers to stoop, which leads to skipped inspections and rushed repositioning. The cost of the right bed is often recouped within months in reduced pressure ulcer incidence.
For guidance on bed prescription, see how to choose the right profiling bed.
How Accora supports pressure care
Accora's Allevia mattress range spans static foam, hybrid, and dynamic air systems to match the full spectrum of clinical risk. The Allevia Comfort and Comfort FirmEdge cover low to medium risk; the Allevia Prima adds firm-edge transfer support; the Allevia Duo and Duo Plus provide hybrid foam-and-air systems for medium to high risk; and the Allevia Sense delivers dynamic alternating-pressure therapy for high and very high risk.
Our beds - including the FloorBed range, CommunityBed, and care home beds - are designed to integrate with the Allevia range and support the full SSKIN framework in practice. We publish a mattress selection guide and offer free joint visits with prescribing clinicians.
Related clinical questions
References and further reading
- NICE NG143: Pressure ulcers - prevention and management
- EPUAP/NPIAP/PPPIA International Clinical Practice Guideline
- NHS Improvement Pressure Ulcers: revised definition and measurement framework
- Stop the Pressure campaign - NHS England