The following information was taken from a brochure:
Critical Care Nursing
The Ohio State University Medical Center

What Is Coma? Coma means that a person does not respond in an appropriate way to what is around them. There are different levels of coma. In a very deep coma, a person may not respond at all or may react only to pain. A person can not speak and their eyes are closed. In a mild coma, a person may open their eyes, but not recognize things they see. They may move parts of their body, but with little purpose.

What Causes Coma? Special parts of the brain control a person's ability to wake up and respond. Head injury, trauma, stroke, brain tumors, cardiac arrest, or other medical conditions may cause a person to be in a coma.

How Long Does Coma Last?It is difficult to predict how long someone will be in a coma. Coma may last from days to years. Some people may never wake up from a coma, while others only partially recover.