The National Pressure Ulcer Advisory Panel (NPUAP) defines a pressure ulcer as a localized injury to the skin and/or underlying tissue usually over a bony prominence (Fig. 36-1). It is the result of pressure or pressure in combination with shear. Prominence means to stick out. A bony prominence is an area where the bone sticks out or projects from the flat surface of the body. The back of the head, shoulder blades, elbows, hips, spine, sacrum, knees, ankles, heels, and toes are bony prominences (Fig. 36-2). Decubitus ulcer, bed sore, or pressure sore are other terms for pressure ulcer.

Fig. 36-1 A pressure ulcer. (From Proceedings from the November National V.A.C.^®, *Ostomy Wound Management,* Feb 2005, 51[2A, Suppl]:7S, HMP Communications.)

The Centers for Medicare & Medicaid Services (CMS) defines a pressure ulcer as any lesion caused by unrelieved pressure that results in damage to underlying tissues. According to the CMS, friction and shear are not the main causes of pressure ulcers. However, friction and shear are important contributing factors. Shear is when layers of the skin rub against each other. Or shear is when the skin remains in place and underlying tissues move and stretch and tear underlying capillaries and blood vessels. Tissue damage occurs. Friction is the rubbing of one surface against another. The skin is dragged across a surface. Friction is always present with shearing.

The CMS has standards focusing on pressure ulcers. Some persons are admitted to the center with pressure ulcers. They come from hospitals or from home. According to the CMS, nursing centers must ensure that:

• A person does not develop a pressure ulcer after entering the center. However, for some persons, developing a pressure ulcer cannot be avoided. A pressure ulcer occurs despite efforts to prevent one through proper use of the nursing process. This is called an unavoidable pressure ulcer. An avoidable pressure ulcer is one that develops from the improper use of the nursing process. The center must:

• Evaluate the person’s condition and pressure ulcer risk factors.

• Identify and implement measures that meet the resident’s needs and goals.

• Monitor and evaluate the effect of such measures.

• Revise the measures as needed.

• A person with a pressure ulcer must receive the necessary treatment and services to promote healing, prevent infection, and prevent new sores.

Centers must identify persons at risk for developing pressure ulcers. Some persons are at greater risk than others. And the person’s risk may increase during an illness (cold, flu) or when his or her condition changes. Many pressure ulcers occur within the first 4 weeks of admission to a nursing center. A person at risk can develop a pressure ulcer within 2 to 6 hours after the onset of pressure. The center must develop a comprehensive care plan to meet the person’s needs. The care plan must include measures to reduce or remove the person’s risk factors.

Risk factors

Pressure is the major cause of pressure ulcers. Shearing and friction are important factors. They also cause skin breakdown (Box 36-1) that can lead to a pressure ulcer. Risk factors include breaks in the skin, poor circulation to an area, moisture, dry skin, and irritation by urine and feces. Older and disabled persons are at great risk for pressure ulcers. Their skin is easily injured. Causes include age-related skin changes, chronic disease, and general debility.

Box 36-1

Skin Breakdown—Common Causes

• Age-related changes in the skin

• Dryness

• Fragile and weak capillaries

• General thinning of the skin

• Loss of the fatty layer under the skin

• Decreased sensation to touch, heat, and cold

• Decreased mobility

• Sitting in a chair or lying in bed most or all of the day

• Chronic diseases (diabetes, high blood pressure)

• Diseases that decrease circulation

• Poor nutrition

• Poor hydration

• Incontinence (urinary, fecal)

• Moisture in dark body areas (skin folds, under breasts, perineal area)

• Pressure on bony parts

• Poor fingernail and toenail care

• Friction and shearing

• Edema

Unrelieved pressure squeezes tiny blood vessels. The skin does not receive oxygen and nutrients. Tissues die and a pressure ulcer forms when the skin is starved of oxygen and nutrients for too long. For example, pressure occurs when the skin over a bony area is squeezed between hard surfaces (Fig. 36-3). The bone is one hard surface. The other is usually the mattress or chair seat. Squeezing or pressure prevents blood flow to the skin and underlying tissues. Oxygen and nutrients cannot get to the cells. Involved skin and tissues die.

Fig. 36-3 Tissue under pressure. The skin is squeezed between two hard surfaces: the bone and the mattress. (Redrawn from *Understanding your body: what are pressure ulcers?* U.S. Department of Health & Human Services, Agency for Healthcare Research and Quality, Sept 2009.)

Friction scrapes the skin, causing an open area. The open area needs to heal. A good blood supply is needed. A poor blood supply or an infection can lead to a pressure ulcer.