## INTRODUCTION

Pressure ulcers are a significant cause of morbidity, mortality, and cost in the United States. The incidence and prevalence of pressure ulcers vary widely from study to study likely due to the differences in reporting and classification. The incidence of pressure ulcers ranges from 0.4 to 38% in acute care, 2.2 to 23.9% in long-term care, and 0 to 29% in home care.1 The Centers for Disease Control and Prevention (CDC) estimated in 2004 that 11% of nursing home patients had a pressure ulcer.2 The estimated cost during a hospital stay related to a pressure ulcer is $43,180, with a total cost of$70,000 to manage a single full-thickness pressure ulcer.3 The total US expenditures for treating pressure ulcers have been estimated at \$11 billion per year.4 A 2006 report found that there were 503,300 pressure-related hospitalizations in the United States, with 45,500 admissions in which pressure ulcers were the primary diagnosis.5 Of those admissions, 1 in 25 ended in death.6

## PATHOPHYSIOLOGY

Skin wounds may occur from multiple mechanisms. Pressure injuries are caused by unrelieved compression of the skin usually over a bony prominence and result in damage to the underlying tissue. Although there is variability in the pressure needed to cause damage, animal models have suggested that pressures greater than 60 mm Hg lead to profound tissue ischemia.7 Measurable histologic changes usually occur at between 2 and 6 hours.8 Animal models have also shown that cell death is proportional to the amount of pressure applied, with very high pressure forces eliciting faster cell death. Interestingly, muscle has been shown to be affected before skin. Damage from pressure ulcers often forms internally prior to being evident on the skin and superficial underlying tissue. The overlying skin may appear intact despite significant underlying damage.9 Although more than 200 risk factors are described in the literature, the most common factors are immobility, sensory loss, breakdown of skin integrity (influenced by factors such as age, nutrition, and circulation), moisture, and the presence of friction or shearing forces.10

In 2014, the National Pressure Ulcer Advisory Panel, the European Pressure Ulcer Advisory Panel, and the Pan Pacific Pressure Injury Alliance (NPUAP/EPUAP/PPPIA) defined a pressure ulcer as “localized injury to the skin and/or underlying tissue, usually over a bony prominence, resulting from sustained pressure.” This definition included pressure ulcers associated with shear forces. A number of contributing factors are also associated with pressure ulcers—the primary of which is impaired mobility.11 Although pressure ulcers may occur anywhere, they occur most often over a bony prominence, such as the sacrum, calcaneous, coccyx, heel, and greater trochanter (Fig. 52–1). For the rehabilitation patient, such ulcers may often result from pressure and shear secondary to a cast, brace, orthotic device, or medical equipment.

###### Figure 52–1

Pressure ulcer locations. The most common sites of pressure ulceration are the ...

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