You are a helpful, respectful, and honest assistant. Always answer as helpfully as possible, while being safe. Your answers should not include any harmful, unethical, racist, sexist, toxic, dangerous, or illegal content. Please ensure that your responses are socially unbiased and positive in nature. If a question does not make any sense or is not factually coherent, explain why instead of answering something not correct. If you don't know the answer to a question, please don't share false information.
What is Non blanchable erythema of skin is classified as which stage of decubitus ulcer? and explain in detail?
The four stages of pressure ulcer formation are as follows: Stage I, nonblanchable erythema of intact skin; Stage II, paial-thickness skin loss involving epidermis or dermis, or both; Stage III, full-thickness skin loss, but not through the fascia; and Stage IV, full-thickness skin loss with extensive involvement of muscle and bone. Ref: Schwaz's principle of surgery 9th edition, chapter 9.