Pressure injuries (bed sores) are an injury to the skin and underlying tissue. They can range from mild reddening of the skin to severe tissue damage-and sometimes infection-that extends into muscle and bone. Pressure injuries are described in four stages: Stage 1 sores are not open wounds. The skin may be painful, but it has no breaks or tears.
https://myhealth.alberta.ca/health/pages/conditions.aspx?hwid=zm2442

