The development of hyperbaric oxygen medicine has a history of 100 years, involving multiple disciplines and fields. Currently, there are more than 100 indications recommended by the Chinese Hyperbaric Oxygen Society. (Common clinical indications and contraindications can be found in my article “Hyperbaric Oxygen Therapy Indications and Contraindications”) What is Hyperbaric Oxygen? Breathing pure oxygen at more than one atmosphere of pressure is called hyperbaric oxygen therapy. Zhang Yi, Department of Hyperbaric Oxygen, Chaoyang Hospital, Beijing What is the difference between normobaric oxygen and hyperbaric oxygen? Ordinary oxygen is breathed in an environment of one atmosphere pressure and the oxygen inhaled is not pure oxygen. In hyperbaric oxygen therapy, the oxygen content is significantly higher than ordinary oxygen inhalation. Many of the therapeutic effects of hyperbaric oxygen are unique and cannot be replaced by normobaric oxygen. Moreover, for some special diseases, such as gas embolism, gas gangrene, decompression sickness, etc., the therapeutic effects of hyperbaric oxygen cannot be replaced by normobaric oxygen or medication. How many stages are there in hyperbaric oxygen therapy? There are three stages of treatment: pressurization, stabilization and decompression. (1) Pressurization – i.e., compressed gas is fed into the hyperbaric chamber to raise the chamber pressure to a predetermined therapeutic pressure. (2) Pressure stabilization – when the pressure is raised to the desired therapeutic pressure, it is stabilized. The patient is administered oxygen at this stage. (3) Decompression – the process of gradually reducing the chamber pressure to atmospheric pressure using appropriate protocols once the stabilized oxygen has been administered.