What damage can an eight year coma do to a person?

Duration of coma: Coma itself is not a progressive disorder. It is induced by an underlying condition. Unless there a progression of the cause of coma, the coma will not cause additional changes. Caring for someone in coma, care must be taken for appropriate nutrition, oxygenation, skin to avoid ulceration and monitor for infection, since persons in coma may have compromised immune systems.