“Carbon monoxide poisoning late onset encephalopathy” is a serious comorbidity unique to CO poisoning, which is a series of neurological, psychiatric or behavioral abnormalities that appear after a period of “pseudo-healing” after basic or complete recovery from acute CO poisoning symptoms. Its incidence is about 10%, and most of them occur within one month after CO poisoning, especially in elderly people, patients who have been in coma for a long time and whose early treatment is untimely and incomplete. Individual patients can also enter the late onset encephalopathy state directly from coma without obvious pseudo-healing period. The pathogenesis of delayed-onset encephalopathy in carbon monoxide poisoning is not well understood, but the more recognized mechanism is the result of demyelination of the nervous system, which makes the nerve impulses cannot be effectively transmitted to the target organs. I. Pathogenesis Late onset encephalopathy is roughly divided into the following four stages: 1. Pseudo-healing period: refers to a period of time when the condition gradually returns to normal after acute carbon monoxide poisoning after rescue and enters a so-called normal life or work state, followed by the gradual appearance of progressive dementia, memory loss, unsteady walking, feeding difficulties, incontinence, and even bed-ridden coma and other symptoms. Late onset encephalopathy almost always occurs within one month after acute carbon monoxide poisoning, and the earlier the onset of the disease, the more serious the disease, absolutely no 2~3 months after the onset; individual critical patients can be no pseudo-healing period, from acute poisoning directly into the late onset encephalopathy state. 2. Exacerbation period: It refers to the beginning of half a month after the appearance of late-onset encephalopathy symptoms. Once the symptoms of late-onset encephalopathy appear, it is difficult to control the development of the disease and worsen day by day, and this period usually lasts for about two weeks, during which it is easy to cause panic among family members or doctors and mistakenly believe that the treatment is inappropriate. 3.Stabilization period: 1~2 months after the exacerbation period. This period is a test of the family’s will and the doctor’s treatment experience, many due to see no signs of improvement and wrongly give up treatment, shedding myelin repair is a certain amount of time, on the basis of the relative stability of the disease, due to colds and fevers, diarrhea and other conditions may have small fluctuations, but this period will not appear significantly better. 4.Recovery period: refers to a period of time after 2~3 months of late-onset encephalopathy. Generally 2~3 weeks patients will recover from the inability to take care of themselves to basic self-care, the recovery process is fast, after that the advanced intelligence recovery will enter a relatively long phase, the disease will be in the process of gradual recovery within a year after the onset. Second, treatment measures There is no special treatment for late-onset encephalopathy, the general use of hyperbaric oxygen-based comprehensive treatment measures, against excessive reliance on drugs, of which care is very important, the care mentioned here include: (1) diet: to ensure that the daily intake, feeding difficulties in a timely manner to give nasal feeding, pay attention to multivitamin supplementation; (2) clothing: because most patients have incontinence, so to timely (3) Activity: especially for bedridden patients, insist on daily movement of limbs and joints to prevent contracture deformity or disuse muscle atrophy, otherwise it will directly affect the later activities on the ground. How to prevent (1) Once acute carbon monoxide poisoning occurs, systematic hyperbaric oxygen therapy should be carried out in the acute stage, and it is recommended to do at least 5 times for mild poisoning, 10~20 times for moderate, and 30 times for severe, and only after the EEG is normal on recheck. (2) Within one month after poisoning is a high risk period for late onset encephalopathy. The most common triggers are excessive sadness, anger, mental depression and other stimulating factors, so the above factors should be avoided and a good state of mind should be maintained. (3) Pay attention to rest and avoid overexertion after poisoning. The increase of oxygen consumption during activities will cause relative hypoxia of the body, which is not conducive to the recovery of the disease. (4) Eat more vegetables, fruits and other foods with high vitamin content, which are beneficial to the recovery of nerve function. (5) Smoking or excessive alcohol consumption may aggravate nerve damage, so avoid it as much as possible. (6) The earliest symptom of delayed onset encephalopathy is “confusion”, inability to accurately name people they frequently come in contact with in their lives, and inability to do simple things in a timely manner. Four, prognosis In observing the condition and judging the prognosis, EEG is more meaningful than the head “CT”, normal people can have mild abnormalities, but mild abnormalities are not always normal people, need to be combined with clinical judgment, moderate or severe abnormalities must adhere to treatment. After 3~5 months of active systemic treatment, almost all patients can return to self-care and general work, and individual patients may have small changes in personality compared with before the onset of the disease, such as the former cheerful personality will become less talkative.