What is Coma and Persistent Vegetative State? A coma is a profound or deep state of unconsciousness.An individual in a state of coma is alive but unable to move or respond to his environment.Coma may occur as a complication of an underlying illness,or as a result of injuries,such as head trauma.What is Coma and Persistent Vegetative State? n A coma is a profound or deep state of unconsciousness. An individual in a state of coma is alive but unable to move or respond to his environment. Coma may occur as a complication of an underlying illness, or as a result of injuries, such as head trauma