The clinical manifestation of deep coma is that the patient does not respond to any stimulus, the peripheral muscles are flaccid, the eyes are fixed, the pupils are dilated, and the pupil direct light reflex, indirect light reflex, and corneal reflex are all absent. Cough reflex, swallowing reflex, abdominal wall reflex, tendon reflex, and brainstem reflex are also symptoms of disappearance. The heart rate will gradually slow down, the blood pressure will gradually decrease, the pulse rate will gradually decrease, and the respiration will gradually slow down from a faster rate at the beginning, and the body temperature will gradually decrease. All these conditions belong to the patient’s deep coma involving the brainstem, resulting in changes in clinical signs.