Effects of different speeds of induction with sevoflurane on the EEG in Man

Abstract

The effects of two kinds of induction speed of sevoflurane anesthesia on the EEG pattern were compared in the same individual using medical student volunteers: a first exposure of 4% was given, followed after full recovery, by incremental doses of 1, 2 and 4% successively, each being administered for 10 min. The arterial blood level of the anesthetic was measured using gaschromatograph. The changes of EEG pattern during fast induction with 4% were not represented by the abbreviation of those observed during the slow induction with the incremental doses. The administration of 4% induced a sudden appearance of high voltage, rhythmic slow waves of 2-3 Hz at 1-3 min when the arterial blood anesthetic level increased maximally, which was then followed by a pattern of faster activities of 10-14 Hz mixed with 5-8 Hz slow waves. In contrast, the administration of incremental doses induced an increase in frequency and amplitude of EEG activities in the light plane, followed by their decreases in deeper planes. The final EEG patterns were identical for both these methods of induction. These findings confirmed our previous hypothesis that not only the arterial blood level of anesthetics but the rate of its increase are important factors determining the EEG pattern of anesthesia

Pro-and Anticonvulsant Effects of Anesthetics (Part I)

“…Sevoflurane and desflurane (1-653) are newly synthesized volatile anesthetics that are structurally similar to enflurane and isoflurane. The low solubility of both agents makes them potentially usetul when rapid awakening is desired (e.g., outpatient anesthesia) (86,87). In unpremeditated volunteers, successive incremental inspired sevoflurane doses of 1%, 2%, and 4% produced EEG patterns that contrasted with those commonly observed during the administration of most anesthetics (86).…”

Relationship Between Regional Cerebral Blood Flow and Electrocorticographic Activities Under Sevoflurane and Isoflurane Anesthesia

“…Their neuroexcitatory effects are still controversial. Among healthy volunteers, EEG studies during sevoflurane anesthesia have reported no evidence of neuroexcitation (Avramoc et al, 1987). Yet, some studies on dogs and cats showed epileptiform EEG discharges and clinical seizures under sevoflurane anesthesia (Osawa et al, 1994;Scheller et al, 1988).…”

Seizure-Like Movements During Induction of Anaesthesia With Sevoflurane

“…In the present case, we induced anaesthesia with incremental doses of sevoflurane and nitrous oxide in oxygen. The rate of increase in concentration, however, was high, probably resulting in a condition similar to that produced by Avramov and colleagues [11].…”

“…In sevoflurane-anaesthetized adult male volunteers, Holaday and Smith did not find any significant changes in several variables, including EEG [10]. Avramov and colleagues induced anaesthesia in five young male volunteers (23-25 yr) with 4 % sevoflurane in oxygen and observed high amplitude, rhythmic slow waves on EEG at 1-3 min [11]. They did not describe any seizure movements in the volunteers.…”