When hyperbaric oxygen is needed depends on the patient’s condition.1. For patients with carbon monoxide poisoning, hyperbaric oxygen therapy in a hyperbaric chamber is required as soon as possible after the onset of the disease. It is also recommended to continue to maintain the treatment for a period of time after the patient’s condition has improved to avoid delayed encephalopathy after carbon monoxide poisoning.2. For patients with facial neuritis and polyneuritis, hyperbaric oxygen therapy can also be arranged as soon as possible after a clear diagnosis.3. Patients with cerebral infarction and traumatic brain injury, which are very common in clinical practice, can start hyperbaric oxygen therapy within a week after the onset of the disease, and the effectiveness of this treatment after one month can reach 90%.4. 4. If patients with sudden deafness can receive hyperbaric oxygen therapy within two weeks, the prognosis can also be significantly improved.