Generally speaking, if a patient remains in a coma for more than 4 weeks, it can be determined whether he or she is a vegetative state by combining clinical symptoms and relevant examinations. A vegetative state is a state in which the cerebral hemispheres are severely damaged while the brainstem functions remain relatively preserved. Its onset is related to acute brain injury, hypoxia, etc. Patients will show no perception of themselves and the outside world, and completely lose cognitive ability and the ability to take care of themselves. However, some basic functions of the body can be preserved, there is voluntary breathing and blood pressure, there is a sleep-wake cycle, some autonomic and motor reflexes are preserved, etc. Patients need to be judged carefully in combination with imaging and EEG, etc. A diagnosis by a professional doctor is recommended. Once the vegetative state persists for more than a few months, there is little chance of getting better. Although it is possible for a vegetative patient to revive under the careful care of the family, the probability is not very high.