What is a pressure ulcer?

 
 

ARTICLE WRITTEN BY SYLVIE HAMPTON

 
 

Pressure ulcers are an injury that occurs when the skin over a bony prominence dies because of prolonged pressure.

Over a period of time (different  for each individual), the tiny microcirculation vessels collapse under the pressure and the vessels begin to clot (micro thrombi) so that when pressure is removed the blood cannot return to the area in order to recover the health of the tissue. The cells then die and turn black. 

This pressure can either be a large amount of pressure applied to an area of skin over a short period or when less pressure is applied over a longer period, possibly with occasional relief of pressure. 

Only when we are suspended in water or are weightless in space, can it be said that pressure is evenly distributed. 
The ulcers are almost always over a bony prominence. If the redness and soreness is over a large area of the buttocks, it is not a pressure ulcer but will be a moisture lesion. We will learn more about this later in the book. 

Pressure ulcers can range in severity from patches of reddened skin over a bony prominence to a deep and open wound that exposes the underlying bone or muscle. 

The pressure ulcer will take on the shape of the bone (Fig 1) if it is direct pressure but will be an irregular shape if due to shearing (Fig 2). 

 
 

 
 
 Fig. 1  A pressure ulcer over the ischial tuberosity. Due to direct and unrelieved pressure over a 6 hour period.

Fig. 1

A pressure ulcer over the ischial tuberosity. Due to direct and unrelieved pressure over a 6 hour period.

 Fig. 2  A pressure ulcer due to shearing forces. This is like a pocket and a probe can be placed inside undermined wound to 5cms under the skin.

Fig. 2

A pressure ulcer due to shearing forces. This is like a pocket and a probe can be placed inside undermined wound to 5cms under the skin.