Rate of CSF formation and resistance to reabsorption of CSF during sevoflurane or remifentanil in rabbits

Information on the effects of sevoflurane on the rate of cerebrospinal fluid (CSF) formation (Vf) and resistance to reabsorption of CSF (Ra) is incomplete, and no such information is available for remifentanil. The present study examined the dose-related effects of sevoflurane and remifentanil on Vf and Ra in rabbits. Eight rabbits were studied during isoflurane 1.4% (baseline) and sevoflurane 1.4%, 2.5%, and 3.7%, and eight were studied during isoflurane 1.4% (baseline) and remifentanil 0.30, 0.67, and 1.00 mu g . kg(-1) . min(-1) in randomized order. Ventriculocisternal perfusion at two CSF pressure states for each experimental condition was used to determine Vf and Ra. There was no dose-response relation for Vf (10.4 +/- 2.5, 9.0 +/- 2.0, and 10.0 +/- 3.0 mu l . min(-1)) or Ra (0.81 +/- 0.33, 1.35 +/- 0.54, and 0.84 +/- 0.27 cm H2O . mu l(-1) . min) between the three sevoflurane concentrations. There also was no dose-response relation for Vf (7.8 +/- 1.2, 8.8 +/- 3.0, and 6.5 +/- 2.3 mu l . min(-1)) or Ra (1.07 +/- 0.54, 1.23 +/- 0.50, and 1.13 +/- 0.51 cm H2O . mu l(-1) . min) between the three remifentanil doses. Vf and Ra during either sevoflurane or remifentanil were not significantly different from Vf and Ra during the two isoflurane baseline conditions (Vf = 8.5 +/- 2.5 and 9.8 +/- 1.3 mu l . min(-1), and Ra = 0.97 +/- 0.36 and 1.38 +/- 0.55 cm H2O . mu l(-1) . min, mean +/- SD). Vf and Ra are of interest because they influence CSF volume, intracranial pressure, and/or intracranial elastance. In our model, sevoflurane or remifentanil did not significantly alter Vf or Ra.