1.What is hyperbaric oxygen therapy: Hyperbaric oxygen therapy is a treatment method of inhaling high concentration of oxygen in a high pressure environment, which can correct local tissue hypoxia due to the greatly improved diffusion and permeation ability of oxygen, and solve the problem that cannot be solved by atmospheric pressure oxygenation. The whole process of hyperbaric oxygen therapy usually takes 110 minutes, including 20 min for pressurization, 70 min for pressure stabilization, and 20 min for decompression. the treatment time may change due to the change of pressurization and decompression time, but the total time of oxygen inhalation will not change. The treatment pressure also varies from patient to patient, but is generally between 2.2 ATA and 2.5 ATA. Since the chamber is pressurized by air and there is a separate oxygen supply line, oxygen cannot leak into the chamber, so the appropriate oxygen intake device must be selected for each patient. 2. The therapeutic effect of hyperbaric oxygen on traumatic brain injury: (1) Correction of local brain tissue hypoxia: Correction of local tissue hypoxia is the special therapeutic effect of hyperbaric oxygen, only hyperbaric oxygen can solve the problem of local tissue hypoxia. Hyperbaric oxygen improves the transport of oxygen and significantly increases the amount of dissolved oxygen; hyperbaric oxygen increases the partial pressure of oxygen by nearly 20 times, which enhances the ability of oxygen penetration into local brain tissues. (2) Wakefulness: In the environment of hyperbaric oxygen, the blood vessels of the posterior circulation are dilated, thus improving the oxygen and blood supply to the reticular system of the brainstem and increasing the excitability of brain cells, which has a good wakefulness effect. The literature reports that comprehensive hyperbaric oxygen therapy can reduce the development of vegetative state (VS) into persistent vegetative state (PVS), and the rate of promoting wakefulness for persistent vegetative state is about 40%. (3) Eliminate cerebral edema and protect brain cells: hyperbaric oxygen can enhance the ability of oxygen penetration into local brain tissue, improve the oxygen supply to local brain cells, restore the normal metabolism of dying brain cells, and protect brain cells; (4) Promote neurological recovery and reduce sequelae: It is proved that hyperbaric oxygen can promote the recovery of neurological functions such as hemiplegia, aphasia and memory comprehension after traumatic brain injury, and greatly reduce sequelae. 3. Several aspects related to treatment: (1) Timing of treatment: Traumatic brain injury should strive to start treatment in the edema stage. Since there is local hypoxia in the edematous brain cells, and hyperbaric oxygen is the only way to correct local hypoxia, which helps to save and protect the dying brain cells, the treatment is more effective in the edematous stage. Early intervention can reduce the incidence of vegetative state (VS) developing into persistent vegetative state (PVS). If the vital signs of severe traumatic brain injury are stable and contraindications are excluded, hyperbaric oxygen therapy can be considered to be started within 7 to 15 days. (2) Treatment course: The treatment course is an important factor affecting the efficacy of hyperbaric oxygen. Light treatment is 10-20 times, medium treatment is 20-30 times, and heavy treatment should be more than 30-50 times. Patients in vegetative state should be treated for 6 weeks and then evaluated for efficacy to decide whether to treat further, and the literature suggests that the appropriate course of treatment is 70 to 90 times. (3) Comprehensive treatment: Hyperbaric oxygen therapy should be combined with drugs and rehabilitation at the same time. Long-term application of vasodilator drugs and anti-free radical drugs should be applied simultaneously. There is basically no abnormality in strength, orientation, limb activity and speech function.