Cerebral Vascular Reactivity to Hyperventilation

　Cerebral hemodynamic and oxygen consump-tion were studied before and during hyperventi-lation in 36 patients in average age of 53．　The　patients were divided into three groups to the　initial value for CBF　(normal, moderately re-duced and markedly reduced).

　1)　In the patient who has no cerebral circu-latory disturbance the decrease of CB　during hyperventilation were 40％.

　2)　The reduced cerebrovascular reactivity to　brief hyperventilation were observed in　patient with more reduced CBF.