KEY POINTS
hypercapnia
EVENTS, VASODILATION
Cerebral autoregulation (CA) maintains cerebral blood flow more or less constantly across a wide range of mean arterial pressures.Cerebrovascular tone may be proportionally related to CA efficacy, as shown by the effects of vasoactive events (e.g. hypo- or hypercapnia) on CA. Specifically, vasodilation seems to impair dynamic CA whereas vasoconstriction appears to improve it.We manipulated cerebrovascular tone by step-wise increases in mean blood pressure using phenylephrine during either propofol- or sevoflurane anaesthesia, and studied its effect on CA.We found that increasing blood pressure improved CA in both propofol- and sevoflurane-anaesthesia, but this was more pronounced with propofol (a cerebral vasoconstrictor) compared with sevoflurane (a vasodilator).