tokens: Flow and metabolism were measured 5 - 13 days after the subarachnoid haemorrhage by a modification of the classical Kety - Schmidt technique using xenon - 133 i . v . Anaesthesia was maintained with an inspired isoflurane concentration of 0 . 75 % ( plus 67 % nitrous oxide in oxygen ) , during which CBF and CMRO2 were 34 . 3 + / - 2 . 1 ml / 100 g min - 1 and 2 . 32 + / - 0 . 16 ml / 100 g min - 1 at PaCO2 4 . 1 + / - 0 . 1 kPa ( mean + / - SEM ) .