Relationship between cerebral blood volume and CSF pressure during anesthesia with halothane or enflurane in dogs

Cerebral blood volume (CBV) and intracranial pressure (ICP) were examined in dogs during 3.5 h anesthesia with halothane (0.8%) or enflurane (2.2%), and after decreasing the concentration of halothane to less than 0.1% or enflurane to less than 0.2%. As compared with animals breathing N2O and O2, halothane (0.8%) increased CBV 11-12%, while ICP remained increased (4-5 cmH2O) for 3.5 h. Both at 0.8% and less than 0.1% ICP correlated positively with changes in CBV. Enflurane (2.2%) increased CBV by 8-10%, and while ICP correlated with changes in CBV during the initial 30 min, ICP increased independently of CBV thereafter.