Q. How do pressure ulcers occur?

Human beings spend one third of their lives in bed (Aminoff et al. 2011) and bed rest is frequently prescribed as a means of facilitating the processes of healing. It has been noticed that some people can develop chronic wounds known as pressure ulcers due to bed rest (Takashini et al. 2010; Phillips et al. 2011). Pressure ulcers occur when the delicate vasculature within skin tissues are compressed between the bone that is above it and the mattress that is below it (Bryant & Nix 2012; Takashini et al. 2010). This impedes the flow of blood and lymphatic fluid; both of which are essential to homeostasis and human health (Bryant & Nix 2012). 

Pressure ulcersare caused by the interruption of the supply of blood to the skin and tissues that are in contact with a support surface such as a mattress. According to (Bryant and Nix, 2012), the pathologic effect of excessive pressure on soft tissue can be attributed to three variables;


  •        Intensity of pressure.
  •        Duration of pressure.
  •        Tolerance of tissue to pressure.


Keane, (1978) stated that most humans will offset the risks of interface pressure by moving in bed once every 11.6 minutes or so to relieve the tissues that are under load. Failure to reposition frequently leads to tissues being denied oxygen and nutrients, and allows the build-up of harmful toxins in the cells.

There are various additional intrinsic and extrinsic factors that can lead to a pressure ulcer. These include (but are not limited to) diet, nutrition, mobility, medication and any underlying illness (European Pressure Ulcer Advisory Panel and National Pressure Ulcer Advisory Panel, 2014).