Measurement of cerebral blood flow (CBF) with the Kety and Schmidt technique during craniotomy

In this study cerebral blood flow (CBF) and cerebral metabolic rate of oxygen (CMRO2) were measured twice during craniotomy for supratentorial cerebral tumors by the Kety and Schmidt technique. The anaesthetic procedures included halothane, enflurane isoflurane and continuous infusion with midazolam, etomidate, althesin and neurolept anaesthesia (dehydrobenzpyridol). Moderate hypocapnia was used and the anaesthesia was supplemented with nitrous oxide and fentanyl. In general, both CBF and CMRO2 were decreased. However, with inhalation anaesthetics an increase in concentration resulted in an increase in CBF (halothane) or unchanged CBF (isoflurane and enflurane) and a decrease in CMRO2. With the hypnotic agents a dose related decrease in CMRO2 was observed, while CBF either was unchanged (midazolam) or decreased (Althesin and etomidate).