Summary
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1.
The relationship between cortical blood flow and the frequency content of the EEG was studied in a circumscribed area of the exposed cerebral cortex in cats under nitrous oxide-oxygen anaesthesia. Autoregulation of the cortical blood flow was also tested during step-changes of the arterial blood pressure. Observations were made before and after an episode of severe hypoxia.
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2.
An episode of systemic hypoxia disrupted the normal high correlation between cortical blood flow and EEG frequency content. In the post-hypoxic period cortical flows of up to about three times normal values were recorded together with brain swelling and a slow wave EEG. The hyperemia and swelling subsided during 1–2 h after the hypoxic episode, and were accompanied by partial or complete recovery of the EEG. In the post-hypoxic period a defective autoregulation of the cortical blood flow to changes in the systemic blood pressure was demonstrated.
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3.
The cerebral post-hypoxic state with hyperaemia, brain swelling, EEG depression, and loss of autoregulation of blood flow, is probably caused by an accumulation of anaerobic metabolites which lead to cerebral tissue acidosis.
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Nuffield Foundation Travelling Fellow.
This investigation was aided by grants from the Swedish Medical Research Council (projects No. 21X-84-01 and 21X-84-02), and from the Wallenberg Foundation, Stockholm.
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Freeman, J., Ingvar, D.H. Elimination by hypoxia of cerebral blood flow autoregulation and EEG relationship. Exp Brain Res 5, 61–71 (1968). https://doi.org/10.1007/BF00239906
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DOI: https://doi.org/10.1007/BF00239906