A pressure ulcer is localised injury to the skin and/or underlying tissue as a result of inappropriate pressure – intense or prolonged pressure or pressure in combination with shear. It usually occurs over bony prominences. Oxygen and nutrients are carried around to all cells in the body by the blood. If any cells are deprived of this supply for too long, they die – this is called ischaemia. It is thought that a too inappropriate pressure collapses or even crushes the vessels and impede the blood supply to the cells for long enough to also kill a certain amount of soft-tissue cells in the area. This combination leads to tissue death / necrosis that cannot be rapidly contained and repaired due to the impairment of the paths that are necessary in order to carry the supplies required for restructure (the blood vessels) as well as the paths of the repair personnel (the lymph vessels). The presence of dead tissue for a too long period of time in the deeper layers of the skin and/or the underlying soft-tissue, gives rise to an inflammatory process that can spread rapidly to the surrounding tissue causing further tissue death. This inflammation is seen on the skin surface as “inexplicable” redness. At this stage it is of paramount importance to react quickly and make sure that any pressure is taken off that body area immediately and until there are no more traces of redness (usually days) as this will indicate that restructuring and healing has taken place. If the developing injury is not detected and off-loaded of any pressure at this early stage, it will break through the skin and an ulcer will have formed. Once this happens, the area will immediately be colonised by the microbes that are present on the surrounding skin and in the immediate environment. To prevent an infection and to support healing, it is important to support and maintain a balanced microbiome in the wound and surrounding area.

Pressure ulcers tend to develop quickly and are prone to infection. As the vessels in the area are involved, pressure ulcers have a high prevalence of septicaemia / blood infection or blood poisoning, i.e. bacteria and other microbes passing into the blood stream and being carried around in the entire body, including to the vital organs. As pressure ulcers often develop over bony structures, they are also often associated with osteomyelitis, i.e. infection of the bone. Also, skin infection / cellulitis is closely associated with pressure ulcers. Septicemia, osteomyelitis and cellulitis are common complications of pressure ulcers and high risk factors of developing sepsis.