Transient responses of cerebral blood flow and ventilation to changes in PaCO2 in normal subjects and patients with cerebrovascular disease.

In the present study, the dynamics of the cerebral blood flow (CBF) and ventilatory response to hypercapnia was investigated in a group of patients with a cerebrovascular disease and compared to responses measured in a group of normal volunteers. There was a significant correlation between the rapidity of the transient CBF and ventilatory responses and the severity of the cerebrovascular disease. While the steady state CBF response showed no such correlation, the steady state ventilatory response was reduced in patients with severe cerebrovascular disease. Various explanations for the differences in the dynamic responses of CBF and ventilation in patients with mild or severe cerebrovascular disease compared to normal subjects are considered. Measurement of these circulatory and ventilatory responses may be sensitive means for assessing the changing statls of patients with cerebrovascular disease.