The duration of deep coma can vary depending on the cause, and generally patients in deep coma last for several days or even weeks. Deep coma is usually caused by loss of consciousness due to brain lesions. This condition is often caused by traumatic brain injury, cerebral hemorrhage, cerebral infarction, etc. and is accompanied by changes in respiration, heart rhythm and other vital signs. If not treated effectively, the patient will eventually die. Deep coma leads to prolonged cerebral ischemia and hypoxia, which can have serious effects on brain cells and may result in irreversible lesions, including brain cell death and multi-organ failure. It is very important to treat and care for patients in deep coma. Patients must be closely observed for changes in their condition, including the course of coma, degree of coma, body temperature, pulse, and neurological signs and symptoms. Patients should be kept in a lying position with the head turned to the side to prevent vomit from accidentally entering the trachea, and pay attention to nutrition and water and electrolyte balance. For patients in deep coma, timely treatment and care is often the key to survival. Once deep coma occurs, it means the condition is critical, and if there is no active treatment, the patient often ends up dying.