A few days ago, an anesthetic allergic reaction occurred during anesthesia in a surgical patient, with a transient decrease in blood pressure, decreased respiration, and a minimum oxygen saturation of 40% for about 5 minutes. The patient was stabilized after intubation and pressure boosting, but did not regain consciousness, and on examination: agitation, no response to call, eyes can be opened automatically, pupils are equally large and rounded bilaterally, light reflex exists, stimulation of both lower extremities can be flexed, and the Bartholin’s sign is negative. GCS: 8 points. Consider: qualitative: ischemic-hypoxic encephalopathy, localized in the cortex. The patient’s consciousness gradually turned clear during the night, and the next morning the patient was fully conscious with a GCS score of 15. For acute ischemic-hypoxic encephalopathy caused by various reasons, oxygen therapy is one of the primary treatments. Hyperbaric oxygen can significantly increase the partial pressure of cerebral tissue blood oxygen and can rapidly improve the state of cerebral tissue hypoxia, and theoretically, hyperbaric oxygen should be the preferred treatment modality. However, hyperbaric oxygen needs to be carried out in a specific closed oxygen chamber, and the patient needs to be transported from the ward to the oxygen chamber, and the patient’s life may be in danger at any time on the way, and the patient’s condition is unstable in the early postoperative period, and hyperbaric oxygen may cause changes in the condition due to the elevated pressure. Therefore, hyperbaric oxygen therapy is rarely given to these patients. Normobaric oxygen (NBO) is pure oxygen administered under atmospheric pressure at different flow rates for different periods of time, and is characterized by its simplicity, lack of known safety issues, readily available on site, and multiple mechanisms of action. We have tested the arterial blood gas of a patient who underwent normobaric oxygen and the results showed that the partial pressure of oxygen is close to 500 mmHg, which is 4-5 times of normal, so normobaric oxygen can be fully used as an alternative treatment to hyperbaric oxygen in the treatment of hypoxic encephalopathy at an early stage.