Regional cerebrovascular responses to acute ischaemia in normocapnia and hypercapnia. An experimental study in baboons.

Arterial and venous pressures have been measured in the cortical circulation of baboons. Arterial perfusion pressure was found to be relatively lower in hypercapnia than in normocapnia, while venous pressure was higher in hypercapnia than normocapnia. In hypercapnia, during middle cerebral occlusion, the arteriovenous pressure differences virtually disappeared and evidence of collateral inflow to the ischaemic zone was absent. Reactive hyperaemia after middle cerebral occlusion was reduced or abolished in hypercapnia. The significance of these findings in relation to treatment of ischaemic vascular disease with CO(2) is discussed.