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RESEARCH PRODUCT

Cerebral Blood Flow Regulation Under the Conditions of Arterial Hypoxia

subject

description

Pronounced arterial hypoxia induces a decrease of cerebrovascular resistance and an increase of total and regional cerebral blood flow. Under the conditions of normal arterial blood pressure and normal acid base status, the changes of both parameters commence when the oxygen tension in the arterial blood decreases below approximately 50 mm Hg. At the same time, the oxygen tension in the cerebral venous blood reaches values below approximately 28 mm Hg. Different authors [23, 28, 30, 31, 33] reported that cerebral blood flow responses to PaO2 decrease are threshold at these oxygen tensions. The threshold oxygen tension of cerebral venous blood was accorded a special significance because Noell and Schneider [30, 31] observed that, under the conditions of insufficient oxygen supply in the brain tissue induced by different causes, an increase of the total cerebral blood flow always occurred when cerebral venous oxygen tension values were nearly constant between 25–28 mm Hg.