What is a bed sore?
Bed sores, also called pressure ulcers or decubitus ulcers, are areas of broken skin that can develop in people who:
Have been confined to bed for extended periods of time
Are unable to move for short periods of time, especially if they are thin or have blood vessel disease or neurological diseases
Use a wheelchair or bedside chair (a hospital chair that allows a patient to sit upright next to the bed)
Bed sores are common in people in hospitals and nursing homes and in people being cared for at home. In the United States, approximately 9% of all hospitalized patients develop bedsores. Three percent to 14% of people in home care get them and so do 3% to 12% of all nursing home residents. People transferred from hospitals to nursing homes are particularly vulnerable, with 10% to 35% having sores when they are admitted to the nursing home.
Bed sores can lead to severe medical complications, include bone and blood infections, infectious arthritis, holes below the wound that burrow into bone or deeper tissues, and scar carcinoma, a form of cancer that develops in scar tissue.
Bed sores form where the weight of the person's body presses the skin against the firm surface of the bed. In people confined to bed, bedsores are most common over the hip, spine, lower back, shoulder blades, elbows and heels. In people who use a wheelchair, bedsores are most common on the lower back, buttocks and legs. This pressure temporarily cuts off the skin's blood supply. This injures skin cells and can cause them to die. Unless the pressure is relieved and blood flows to the skin again, the skin soon begins to show signs of injury. At first, there may be only a patch of redness. If this red patch is not protected from additional pressure, the redness can form blisters or open sores (ulcers). In severe cases, damage may extend through the skin and create a deep crater that exposes muscle or bone.
Muscle is even more prone to severe injury from pressure than skin. A mild injury to the skin may cover a deeper, more pronounced injury to muscle.
The pressure that causes bedsores does not have to be very intense. Pressure of less than 25% the pressure of a normal mattress can lead to bedsores. Normally, our skin is protected from being injured by this pressure because we move frequently, even when asleep.
Although pressure on the skin is the main cause of bedsores, other factors often contribute to the problem.
These factors include:
Shearing and friction — Shearing and friction causes skin to stretch and blood vessels to kink, which can impair blood circulation in the skin. In a person confined to bed, shearing and friction can occur when the person is dragged or slid across the bed sheets. This can also occur when the head of the bed is raised more than 30 degrees. This increases shearing forces over the lower back and tailbone.
Moisture — Wetness from perspiration, urine or feces can make the skin too soft and more likely to be injured by pressure. For this reason, people who can't control their bladders or bowels (incontinent) are at high risk of developing bedsores.
Decreased movement — Bed sores are common in people who can't move because they are paralyzed, recuperating from surgery for a prolonged time, being treated in intensive care for a long time, or are incapacitated by severe arthritis, stroke or a neurological problem such as multiple sclerosis. (People who can move without assistance have a lower risk of bedsores because they can shift their weight periodically.)
Decreased sensation — Bed sores are common in people who have spinal cord injuries or other neurological problems that decrease their ability to feel pain or discomfort. Without these feelings, the person cannot feel the effects of prolonged pressure on the skin.
Circulatory problems — People with atherosclerosis, circulatory problems from long-term diabetes or localized swelling (edema) may be more likely to develop bed sores. This is because the blood flow in their skin is weak even before pressure is applied to the skin. People with anemia are also at risk because their blood cannot carry enough oxygen to skin cells, even though circulation may be normal.
Poor nutrition — Studies show that bedsores are more likely to develop in people who don't get enough protein, vitamin C, vitamin E, calcium or zinc.
Age — Elderly people, especially those over 85, are more likely to develop bed sores because skin usually becomes thinner with age. Also, as we age, fat tends to shift away from the body surface, where it acts as a cushion, to deeper areas of the body.
Sometimes bed sores are classified into stages, depending on the severity of skin damage:
Stage I (earliest signs of skin damage) — White people or people with pale skin develop a lasting patch of red skin that does not turn white when you press it with your finger. In people with darker skin, the patch may be red, purple or blue and may be more difficult to detect. The skin may be tender or itchy, and may feel warm or cold and firm.
Stage II — The injured skin blisters or develops an open sore or abrasion that does not extend through the full thickness of the skin. There may be a surrounding area of red or purple discoloration, mild swelling and some oozing.
Stage III — The ulcer becomes a crater and that goes below the skin surface.
Stage IV — The crater deepens and reaches into a muscle, bone, tendon or joint.
Because broken skin is a prime spot for bacteria, bed sores are extremely vulnerable to infection.