On July 5, 2014, we attended the 4th National Neurocritical Care Conference and were impressed by the comprehensive and advanced monitoring techniques for neurocritical patients. In addition to the common body circulation monitoring: heart rate, blood oxygen, blood pressure, myocardial contractility, preload and afterload, etc., intracerebral monitoring has become very popular including: intracranial pressure, cerebral perfusion pressure, BIS of EEG, cerebral blood flow (CBF), and then more refined intracerebral microdialysis techniques (monitoring oxygen partial pressure, oxygen, sugar and other metabolism in the brain). So what is the purpose of these techniques? The goal is to restore as stable an internal environment as possible to the damaged brain tissue through interventions to reduce secondary brain damage and achieve optimal brain protection. So what is the core of brain protection? The core is to restore the normal delivery of nutrients such as oxygen and glucose through stable cerebral perfusion as much as possible (see the figure below), because we know that brain tissue can only rely on two substances, oxygen and glucose, for energy supply, and the brain usually has almost no reserves, so when the circulation stops in 10 seconds there can be impaired consciousness, and in 5-6 minutes there can be irreversible damage to the brain nerves. Since oxygen and glucose are so important, wouldn’t it be more beneficial to give large amounts of these two substances in the acute phase of neurological critical illness for the patient to recover? According to current research, large amounts of glucose infusion in the early stages of neurological injury are unfavorable because the ability of brain tissue to utilize glucose is reduced at this time, so instead of supplying brain tissue with energy, it will also raise the body’s blood sugar, which will affect the prognosis. Is the same true for oxygen? Obviously not for oxygen, because maintaining a stable oxygen saturation is a very important thing for any critically ill patient, so oxygenation is definitely necessary in critical care. So is the normal form of oxygen administration (nasal cannula, mask or ventilator assisted) enough for neurocritical patients? Obviously, it is not enough. Numerous studies have confirmed that the local partial pressure of oxygen in damaged brain tissue is reduced due to factors such as cerebral ischemia and edema, so the partial pressure of blood oxygen to maintain normal body circulation is unable to meet the oxygen supply to brain tissue. We know that oxygen is free to pass through the blood-brain barrier, so increasing oxygen levels can improve brain function. But how is oxygen transported through the blood to the brain tissue? It’s hemoglobin! But hemoglobin is fixed, and in the early stages of severe disease hemoglobin is often reduced, so it is obviously not possible to go through this route. This is when we think of the usually negligible oxygen-carrying method – physical dissolved oxygen, because it is possible to transport oxygen directly to the tissues without relying on hemoglobin, as long as there is a blood supply. So who can increase physical dissolved oxygen? Only hyperbaric oxygen! Hyperbaric oxygen can exponentially increase the partial pressure of blood oxygen, thus increasing physical dissolved oxygen. There have been numerous basic and clinical studies showing that hyperbaric oxygen can reduce cerebral edema and improve oxygen supply to damaged brain tissue. However, there are still many issues to be resolved in the treatment of neurocritical conditions, such as: when is the best time to intervene? How much pressure should be given? How long should oxygen be administered? But I believe that as the research progresses, the role of hyperbaric oxygen in the field of neurocritical care will become more and more important!