Enflurane causes a prolonged and reversible increase in the rate of CSF production in the dog

Using the open ventriculocisternal perfusion method, rates of cerebrospinal fluid (CSF) production and reabsorption by bulk flow were examined in dogs anesthetized with either enflurane (2.2%) in nitrogen (60-70%) and oxygen, or nitrous oxide (60-70%) and enflurane (less than 0.2%) in oxygen (controls). The mean rate of CSF production increased significantly with enflurane (2.2%), from 0.055 +/- 0.020 ml/min (mean +/- SD) in controls to 0.082 +/- 0.033 ml/min (n = 12). After this initial increase of approximately 50%, the production rate decreased significantly by about 7.4%/h. When the expired concentration of enflurane was decreased from 2.2% to less than 0.2%, the mean rate of CSF production decreased to control values at 45-50 min. An intracerebral accumulation of CSF resulting from this enflurane-induced increase in CSF production may contribute in part to increased intracranial pressure when the dura is intact.