No abstract

to changes in PaCO 2 between 27-50mmHg remains intact during propofol anaesthesia in healthy individuals. Our absolute CBF values are similar to those previously reported during fixed dose propofol anaesthesia but are lower than those we haye recorded during propofol-N20 anaesthesia ~,z. Similarly, the slope of CBF-PaCO 2 relationship is less than during propofol-N20 anaesthesia. These differences may be explained by either the c e r e b r o v a s o d i l a t i n g e f f e c t of N20 or the quantity of propofol used. During hypocapnia, CBF was low, but there were no changes clinically or in the evoked potentials to suggest ischaemia. Propofol may therefore reduce the CBF threshold for cerebral isohaemia as assessed by evoked potentials.