To assess the derangement of oxygen metabolism in 28 patients with severe brain damage, near-infrared spectroscopy (NIRO-300^®) was used in the intensive care unit. The consciousness in all patients scored 300 on the Japan Coma Scale (score 3 on the Glasgow Coma Scale) and bilateral pupils were dilated without light reflex. In addition to changes in oxygenated, deoxygenated, and total hemoglobin concentration, a tissue oxygenation index (TOI)--the ratio of oxygenated to total tissue hemoglobin--was measured at the forehead (TOI-B) and arm (TOI-A) simultaneously. Data was compared to that from 5 healthy subjects. Representative cases showed a correlation between TOI-B and the change in hemoglobin concentration or parameters monitored concurrently. In healthy subjects, TOI-B tended to be higher than TOI-A. In contrast, TOI-B of 28 patients was lower than TOI-A except for 1 with brain stem infarction. The time course of changes in TOI-A and B in transient cardiac arrest whole brain ischemia indicated that TOI-B fluctuated widely, whereas variations in TOI-A were not significant after the return of spontaneous circulation. This sharp variation was not observed in a good recovery without neurological deficit despite transient cardiac arrest. Multiple parameter recording showed a good correlation between the fluctuation in TOI-B and concentration in hemoglobin or cerebral perfusion pressure. We concluded that the breakdown of the relationship between oxygen delivery and consumption in the damaged brain reducted TOI-B. NIRO-300^® may therefore have potential for simple, noninvasive diagnostic monitoring in patients with severe brain damage.

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The word “flat EEG” should not be used in diagnosing brain death. In its place, the American EEG Society and the International Federation of Societies for EEG and Clinical Neurophysiology recommended elecrocerebral inactivity (ECI) or elecrocerebral silence (ECS). ECI is defined as no EEG activity over 2μV in recording from scalp electrode pairs 10 or more cm apart with inter-electrode impedance below 10, 000 ohms but over 100 ohms. Intensive care units present an extremely hostile environment for recording ECI. We developed a shielding system for EEG recording and the Artifact Banish Control Manual for ECI Recording (ABC Manual). We present the key points of Artifact Banish Control in diagnosing brain death.

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An epidemiological study was conducted on sudden death in students in Tokyo's 23 wards over the 20-year period from 1976 to 1995. The 255 cases were classified by year, month, status at death, school year, gender, health, causes of death, mode of treatment, and examination. Results are summarized below. Sudden death occurred at 12.8 cases a year, and changes over time were almost constant. Death occurred more often in August and to about 30% of students while at school. Of these, death occurred in about 60% during sports. The male-to-female ratio was 2:1. The ratio of those who viewed themselves as healthy (healthy) and those with an indicative medsical history (diseased), possibly leading to death was about 1:1. The causes of death were acute heart failure in 63, bronchial asthma in 34, and myocarditis in 22 cases, in decreasing order. In the healthy group, the most frequent causes of death were acute heart failure, myocarditis, intracranial hemorrhage, subarachnoid hemorrhage, and digestive tract disease. In myocarditis, digestive tract diseases, and bronchial asthma, death occurred more often during medical treatment. In ischemic cardiac disease, death occurred more often during sports, while in hypertrophic cardiomyopathy, death was occurred more often during walking. In about 60% of cases, cardiopulmonary arrest was found on arrival at the hospital, and about 20% occurred while not hospitalized or after emergency admission or during medical examination. Death occurred abruptly in 117 cases (45.9%), and in 60% (23.5%) of those who had symptoms but did not receive medical examination until sudden aggravation of symptoms. Those who had symptoms and received medical examination but whose symptoms suddenly became aggravated at home numbered 37 (14.5%). Such a course was found in 60% in digestive tract diseases and 45.5% of those with myocarditis. To reduce sudden death among students, it is necessary to clarify mechanisms of sudden death from acute heart failure of unknown cause, which was found most frequently. For myocarditis, exhibiting a certain course from disease onset, it appears essential to establish reliable methodology for early diagnosis and adequate observation of the disease course.

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