What is the pathogenesis of pressure (decubitus) ulcers requiring wound care?

Updated: Apr 24, 2020
  • Author: Brian J Daley, MD, MBA, FACS, FCCP, CNSC; Chief Editor: Zubin J Panthaki, MD, CM, FACS, FRCSC  more...
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Answer

Pressure (decubitus) ulcers occur because of prolonged ischemia-producing external pressure, usually to a soft tissue region overlying a bony prominence. Tissue ischemia results when external pressure exceeds capillary closing pressure (ie, 25-32 mm Hg in healthy individuals), the minimum pressure that causes collapse of the capillary when applied to a capillary bed.

Shearing forces, exposure to constant moisture, and heat buildup also are major contributing factors. For example, the stratum corneum, the outer layer of skin, becomes 25 times more fragile at a relative humidity of 100% when compared with a relative humidity of 25%, and it becomes 4 times more fragile at 95°F (35°C) than at 86°F (30°C).


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