A pressure ulcer (also called pressure sore, decubitus ulcer, bed sore) is damage to the skin and, in more serious cases, the underlying tissue. It is caused by impaired circulation due to pressure on a specific area. The skin begins to die when the supply of blood is stopped. Pressure ulcers most commonly occur in individuals who spend a majority of their time in a bed or chair without repositioning, such as people in hospitals or nursing homes.

Pressure ulcers also may occur from straps, splints, casts or ill-fitting clothes. Ulcers break the protective barrier of the skin and thus are prone to infection. When pressure ulcers become infected (bacteria or viruses come into contact with the ulcer and begin to grow there), they form pus.

Bony areas beneath the skin and areas in contact with a bed or chair are more vulnerable to developing pressure ulcers. These body parts include the elbows, shoulders, back, buttocks, hips, ankles, heels and the back of the head. Sustained pressure can kill skin and tissue in less than 12 hours. If normal circulation is not restored, the damage may be irreversible.

Pressure ulcers frequently become infected. Untreated, the infection can spread throughout the body with serious or even fatal consequences. An infected ulcer may exude thick green or yellow pus, as well as a foul odor. The skin around the ulcer may redden, swell and feel tender.

Not all ulcers are pressure ulcers. The term ulcer refers to any open sore or break in the skin that extends into the middle layer of the skin (dermis) or below and is accompanied by the sloughing off of dead tissue. There are many different types of ulcers depending on the cause (e.g., injury, pressure, sheering forces), duration and progression.

Pressure ulcers often heal on their own when they are detected early and the source of pressure is removed. However, serious cases, such as pressure ulcers that move through the entire thickness of a body part (perforating ulcer), can lead to infection of the underlying muscle and even of the bone. These conditions are dangerous and often require serious medical intervention, such as an amputation of a limb.

Pressure ulcers may surround a body part and destroy tissue to the bone (amputating ulcer). In some cases, ulcers may not heal (atonic ulcers) or they may extend to another area as the previous area heals (serpiginous or creeping ulcer). Ulcers that rapidly spread as tissue deteriorates and dead tissue is discharged are called phagedenic ulcers.

There are six stages of pressure ulcers:

• Stage 1: Skin is red or may appear dusky but remains intact. The area may also feel warmer than the surrounding skin.
  
  
• Stage 2: Skin is swollen and often has blisters (raised areas on the skin surface that contain fluid).
  
  
• Stage 3: The sore has ulcerated, revealing deeper layers of skin.
  
  
• Stage 4: The sore extends into muscle.
  
  
• Stage 5: Muscle is destroyed.
  
  
• Stage 6: Bone is exposed, damaged and possibly infected.