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 flui d (CSF) formation (Vf) and resistance to reabsorption of CSF (Ra) is incomp lete, and no such information is available for remifentanil. The present st udy examined the dose-related effects of sevoflurane and remifentanil on Vf and Ra in rabbits. Eight rabbits were studied during isoflurane 1.4% (base line) and sevoflurane 1.4%, 2.5%, and 3.7%, and eight were studied during i soflurane 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 an d 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 conce ntrations. 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 remifenta nil doses. Vf and Ra during either sevoflurane or remifentanil were not sig nificantly different from Vf and Ra during the two isoflurane baseline cond itions (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 no t significantly alter Vf or Ra.