What is a Pressure Sore?

Pressure Sores (also known as bedsores or decubitus ulcers) are ulcers of the skin (due to pressure) causing a lack of blood supply to the area.

How do they develop?

Pressure ulcers occur when pressure is applied to the same area of the body for an extended length of time. The skin has a rich blood supply that delivers oxygen to all its layers. This pressure prevents blood travelling to the area and restricts the flow of oxygen, causing body tissue to die.

If that blood supply is cut off for more than 2 or 3 hours, the skin dies, beginning at its outer layer (the epidermis). The dead skin breaks down and forms an open sore or ulcer. Once the skin is broken, bacteria may cause an infection.

Pressure sores can cause pain, illness, reduced self esteem and delay rehabilitation efforts making it harder to return to independence.

Where do they develop?

Pressure ulcers tend to develop on areas of the body that have bony projections where pressure is concentrated, such as the hips, heels, shoulder blades and the small of the back. They may occur where pressure from a bed, wheelchair, cast, splint, or other hard object contacts and presses on the skin. Pressure sores may be painful and can be life threatening.

What happens if untreated?

Unrelieved pressure on an area of the body will affect the blood supply to the skin and underlying tissues causing that area to become damaged. Mild tissue damage results in skin discolouration, giving a brown or purple appearance. This may look darker if the skin is very fair. More severe damage can expose muscle and even bone. The area around the dead tissue will look red and inflamed and may become infected. For most people, pressure sores cause some pain and itching. However, in people whose senses are dulled, even severe, deep sores may be painless.

Infection delays healing of minor sores and can be life threatening in deeper sores. Infection can even enter the bone, requiring weeks of treatment with antibiotics. In the most severe cases, infection can spread into the bloodstream. Signs of infection include an unpleasant smell coming from the sore and warm or swollen skin around the area.

Pressure sore categories

Pressure sores are categorised into 4 stages of severity:

• Grade 1 – reddened skin which persists for more than 30 minutes after pressure has been relieved.
• Grade 2 – superficial skin damage. May present as a blister or as an abrasion.
• Grade 3 – full thickness skin loss not extending to bone or muscle. This grade is not usually painful.
• Grade 4 – full thickness skin loss with extensive tissue damage through muscle and bone.

With higher stages of ulcer, healing time is prolonged. While about 75% of stage 2 ulcers heal within 8 weeks, only 62% of stage 4 pressure ulcers ever heal, and only 52% heal within one year (Thomas et al., 2005).

Glossary of terms

Alternating Air Pressure Mattresses, also known as replacement or dynamic mattress systems – mattresses which have cells of air which alternately inflate and deflate in a cycle to relieve pressure on the body.

Bottoming-Out - if a mattress or cushion is too soft or thin, it may become compacted which will remove any pressure relieving qualities.

Breathable – a fabric which permits air to pass through.

Conformity – water, gel, air and memory foam moves to conform to the shape and movement of the body. However conformity does affect the ability to relieve pressure by leaning to one side as the surface will conform to the user’s new position.

Contamination - the presence of extraneous, especially infectious, material that renders a substance or preparation impure or harmful.

Decubitus – a lying down or horizontal position.

Durable – a product or fabric which is capable of withstanding wear, tear and decay.

Fire Retardancy – pressure relief cushions and mattresses are tested to Medical Devices Agency (MDA) criteria. There are similar standards set by the British Standards Institute (BSI) which are particularly important for users who smoke or have difficultly moving in an emergency.

Friction – occurs when the skin is rubbed against a surface such as bed sheets.

Incontinence – the inability to control the bladder and/ or bowel which can increase the risk of pressure sores due to the dampness of the skin causing the skin to breakdown.

Ischaemia – deficiency in the blood supply to a part of the body.

Ischial tuberosity - a bony swelling on the posterior part of the superior ramus of the ischium that gives attachment to various muscles and bears the weight of the body in sitting, the bones under the buttocks.

Norton Scale - a risk assessment scale designed to help identify a person at risk of developing pressure sores.

Pressure – when skin and tissue is compressed between bone and a hard place, such as a bed or wheelchair.

Pressure Sore – is an ulcer of the skin due to pressure causing a lack of blood supply to the area.

Sacrum - triangular bone forming the back of the pelvis and a common location of pressure sores.

Shear – occurs when the tissue of the body and the skin are pulled in different directions for example when a person is dragged or slips down on bed sheets.

Trochanter – part of the femur bone, one of two rough knobs on the upper thigh bone where the thigh muscles between the thigh and the pelvis are attached.

Waterlow Scale – a risk assessment scale designed to help identify a person at risk of developing pressure sores.