Pressure ulcers are mainly found on bony prominences and are caused due to consent applied pressure to that specific area.
Blood flow is thus restricted causing ischemia.
There are different levels of development for a pressure ulcer.
At first it affects the epidermis then the dermis , tissue and fat and then the muscle and bone.
If pressure is relieved from that area and it turns bright red, this is due to vasodilation. The blood is then rushing to the tissues and should return back to normal colour. If it does not this means that the tissue and small blood arteries are damaged.