Measurement of regional cerebral blood flow (rCBF) was performed in 6 healthy baboons during ventilation with 35% stable xenon in artificial air. rCBF was measured with the intraarterial xenon-133 method. EEG was recorded continuously. All CBF areas of interest over one hemisphere reacted in the same way. Mean flow increased during short-term exposure to stable xenon and decreased if stable xenon inhalation was continued for at least 24 minutes. EEG showed a decrease of a-and /3-wave patterns a short tune after the start of stable xenon inhalation without further changes over the period when rCBF finally decreased. CO 2 reactivity increased in most animals, and autoregulation to mild arterial hypotension was significantly unpaired with increased flow. It is concluded that 35% stable xenon in artificial air increases rCBF after short-term exposure and decreases rCBF after longer exposure. EEG changes were noted after short-term exposure. rCBF and EEG recovered rapidly after the end of stable xenon inhalation. (Stroke 1987; 18:643-648)
Sixty patients with borderline or frank insufficiency of their cerebrovascular reserve undergoing carotid endarterectomy were given enough short acting barbiturates, during cross clamping of the internal carotid artery, to cause EEG burst suppression. Arterial and venous concentrations of lactate were measured in blood samples taken before, 30 min after occlusion of the artery and 10 min after reperfusion. The amount of lactate produced depended on the length of time of burst suppression; the shorter it lasted, the larger the amount of lactate produced. Only in patients with the shortest burst suppression times did the blood lactate levels rise above normal levels. The lactate levels can be used as indicators of how effective barbiturates are being in preventing ischaemia during the time of carotid artery occlusion.
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