Cerebrovascular response to dynamic changes in pCO2.

Fifty-six subjects with carotid artery disease were assessed by measuring the cerebral blood flow velocity (CBFV) change in response to inhalation of 5% CO2 in air whilst continuously monitoring the blood pressure (BP). Coherent averaging of the data characterised differences in CBFV, BP, resistance area product and critical closing pressure during changes in end-tidal CO2 (ETCO2). The results primarily demonstrate that the augmentation of ETCO2 increases the CBFV and BP, causing a pressure autoregulatory response, and allows the processes of pressure autoregulation and cerebral vascular reserve to be differentiated.