What is a pressure ulcer?

According to the National Institute for Health and Care Excellence (NICE), a pressure ulcer is damage to the skin and the deeper layer of tissue under the skin. They are also referred to as pressure sores or bedsores. (April 2004)

Pressure ulcers occur when an area of skin is subjected to pressure for a period of time. The ulcer forms because the blood supply to the skin is reduced and the skin becomes starved of oxygen and nutrients. People who have to stay in bed or sit in a chair for long periods of time are the most susceptible.

If left untreated, pressure ulcers can become very serious, causing pain, and can result in a hospital admission. Muscle or bone can also be badly damaged by severe pressure ulcers, with healing taking a very long time.

Most vulnerable parts of the body

  • 30% of all pressure sores occur around the sacrum, the triangular, curved bone above the buttocks
  • 25-30% of pressure sores occur on the heals
  • 10% of pressures injuries occur on the buttocks

Influences on pressure sores

  • Individual’s knowledge of importance of repositioning
  • Duration of pressure caused by remaining in same position
  • Poor posture or positioning in a chair – Sliding down a chair increases the risk of shear and friction
  • Being moved across a bed – Increased risk of shear and friction
  • Degree of care available
  • Mattress or cushion type. The surface an individual lies or sits on can profoundly influence pressure over bony prominences
  • External factors including urine, faeces, starch from sheets, perfume

Contributory Factors


Those aged over 65 are at the highest risk of pressure ulcers. This is due to difficulty with changing positions and other health problems limiting movement. Older people are also more at risk of their skin becoming thinner and becoming more vulnerable due to the loss of protective fat and muscle mass.


If an individual is unwell, they are at increased risk. Acute illness can cause changes in the body’s normal functioning, e.g. raised temperature, low blood pressure, constriction of blood vessels. Certain medications can also increase the risk.


Patients who have reduced mobility or are immobile are most at risk because they are less able to relieve pressure by moving their position.

Previous history

Individuals who have suffered from pressure damage in the past are more likely to develop pressure ulcers.


Obese individuals are at risk because there is more weight on the pressure points. Underweight individuals are also more at risk. Being underweight can mean there is less natural padding on bony areas such as the bottom and hips.


Those who are malnourished or dehydrated are at most at risk. The skin needs a good supply of fluid and nutrients to maintain its circulation and keep it supple.

Sensory Function

If you cannot feel pain or pressure, you are at higher risk of developing a pressure ulcer. Patients who fit into this category include patients with spinal cord damage, stroke, MS, neuropathy and other conditions that compromise one’s ability to perceive pain and/or pressure.

Urinary and bowel incontinence

When the skin comes into contact with fluid, for example sweat, urine or faeces or a combination of factors, for any sustained length of time, it becomes soft and wrinkled, and eventually saturated. This makes it more susceptible to friction damage, increasing the risk of pressure ulceration.

Medical Conditions

Individuals with medical conditions that affect blood supply or reduces movement are at increased risk of developing pressure ulcers. These include individual’s living with diabetes, peripheral arterial disease, kidney failure, heart failure, stroke, multiple sclerosis, motor neurone disease and Parkinson’s disease.


Pain may prevent individuals from moving, even when they are feeling the unpleasant effects of pressure. Too much pain medication may sedate patients to the point where they don’t change position as often as they should.

Mental status

Individuals living with dementia or other cognitive disorders may be unable to comprehend instruction given that could help prevent pressure injuries, or may fail to recognize discomfort as a signal to change position.