The medical career of hyperbaric oxygen in China started from the 1960s and 1970s, and developed rapidly in the mid to late 1980s (after the reform and opening up). The diseases treated by hyperbaric oxygen have been involved in emergency medicine, internal medicine, surgery, obstetrics and gynecology, pediatrics, neurology, osteopathy, orthopedics, plastic surgery, dermatology, oncology, infectious diseases, occupational diseases and geriatrics, etc., and developed to rehabilitation, health care, diving, aviation, highland medicine and sports medicine. According to the literature, the number of diseases treated with hyperbaric oxygen has reached 122. For some of these diseases, hyperbaric oxygen therapy has achieved efficacy and become the main means of clinical rescue treatment; however, for some other diseases, hyperbaric oxygen therapy is still only an auxiliary treatment method in comprehensive treatment; and for some diseases, it is only a trial treatment. In order to accurately and effectively perform hyperbaric oxygen therapy, it is necessary to develop a classification of indications for reference by clinicians, especially hyperbaric physicians. However, there is no consensus on what principles and criteria should be used to classify the more than 100 diseases. Some advocate the classification of diseases by specialty, while others advocate the classification according to clinical efficacy. In fact, both have their advantages and disadvantages, but the simpler and more practical is the international common classification and arrangement according to the efficacy, and this classification method is more used at present. In 1982, the National Committee of Hyperbaric Oxygen Therapy formulated indications for 44 diseases, which are divided into three major categories. The first category: hyperbaric oxygen as the main treatment method with significant clinical effect, such as acute carbon monoxide poisoning, gas gangrene, etc.; the second category: hyperbaric oxygen as one of the comprehensive treatment methods, which can significantly improve the efficacy, such as skin transplantation, coronary heart disease, ischemic cerebrovascular disease, etc.; the third category: belongs to a certain efficacy, which needs further exploration, such as encephalitis, hepatitis, collagen disease, etc. In 2004, the Chinese Medical Association of Hyperbaric Medicine revised the recommended indications again, including 12 acute indications and 48 non-acute indications. (1) acute carbon monoxide poisoning and other harmful gas poisoning; (2) gas gangrene, tetanus and other anaerobic bacterial infections; (3) decompression sickness; (4) gas embolism; (5) acute brain dysfunction after cardiopulmonary resuscitation from various causes; (6) adjuvant treatment of shock; (7) cerebral edema; (8) pulmonary edema (except cardiogenic pulmonary edema); (9) extrusion syndrome; ( (10) blood transport disorders after amputation (finger, toe) and skin transplantation; (11) drug and chemical poisoning; (12) acute ischemic-hypoxic encephalopathy. (2) Non-emergency indications (1) carbon monoxide poisoning and other toxic encephalopathies; (2) sudden deafness; (3) ischemic cerebrovascular disease (cerebral arteriosclerosis, TIA, cerebral thrombosis, cerebral infarction); (4) craniocerebral injury (concussion, cerebral contusion, intracranial hematoma removal, brainstem injury); (5) recovery from cerebral hemorrhage; (6) fracture and poor bone healing after fracture; (7) central (8) vegetative state; (9) plateau maladaptation; (10) peripheral nerve injury; (11) postoperative benign intracranial tumors; (12) periodontal disease; (13) viral encephalitis; (14) facial neuritis; (15) osteomyelitis; (16) aseptic osteonecrosis; (17) cerebral palsy; (18) intrauterine fetal growth retardation; (19) diabetes mellitus and diabetic foot; (20) coronary atherosclerotic heart disease (angina pectoris, myocardial infarction); (21) tachyarrhythmias (atrial fibrillation, premature beats, tachycardia); (22) myocarditis; (23) peripheral vascular disease (vasculitis, Raynaud’s disease, deep vein thrombosis, etc.); (24) vertigo; (25) chronic skin ulcers (arterial blood supply disorders, venous stasis, bedsores); ( (26) spinal cord injury; (27) peptic ulcer; (28) ulcerative colitis; (29) infectious hepatitis (use of special cabin for infectious diseases); (30) burns; (31) frostbite; (32) post-plastic surgery; (33) post-implantation; (34) sports injuries; (35) radioactive injuries (bone, soft tissue, cystitis, etc.); (36) malignant tumors (with radiotherapy or chemotherapy) ); (37) optic nerve injury; (38) fatigue syndrome; (39) vasoneurotic headache; (40) impetigo; (41) psoriasis; (42) pityriasis rosea; (43) multiple sclerosis; (44) acute infectious polyneuritis; (45) recurrent oral ulcers; (46) paralytic intestinal obstruction; (47) bronchial asthma; (48) acute respiratory distress syndrome. Contraindications are certain diseases or conditions that are not suitable for hyperbaric oxygen therapy, and if receiving hyperbaric oxygen therapy will lead to adverse consequences, causing damage to the body or even death. The contraindications of hyperbaric oxygen therapy are the lessons learned from long-term repeated clinical practice. I. Contraindications published by the Chinese Medical Association of Hyperbaric Medicine 1. Absolute contraindications (1) untreated pneumothorax, mediastinal emphysema; (2) pulmonary herpes; (3) active internal bleeding and hemorrhagic diseases; (4) tuberculous cavity formation and hemoptysis. 2. Relative contraindications (1) severe upper respiratory tract infection; (2) severe emphysema; (3) bronchiectasis; (4) severe sinusitis; (5) cardiac atrioventricular block of degree II or higher; (6) excessive blood pressure (>160/100mmHg); (7) bradycardia (<50 beats/min); (8) untreated malignancy; (9) patients with retinal detachment; ( (10) early pregnancy (within 3 months).